17.07.2013 Views

FOUNDATIONS OF COGNITIVE SCIENCE - of Kai-Uwe Carstensen

FOUNDATIONS OF COGNITIVE SCIENCE - of Kai-Uwe Carstensen

FOUNDATIONS OF COGNITIVE SCIENCE - of Kai-Uwe Carstensen

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

<strong>FOUNDATIONS</strong> <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong><br />

<strong>Kai</strong>-<strong>Uwe</strong> <strong>Carstensen</strong><br />

<strong>Kai</strong>.<strong>Carstensen</strong>@CogSci.Uni-Osnabrueck.de<br />

University <strong>of</strong> Osnabrück Winter semester 1998/99<br />

Information about the lecture can be found at:<br />

http://www.cogsci.uni-osnabrueck.de/lectures/foundations/Foundationsscript.zip<br />

THE IMPORTANCE <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong><br />

This lecture introduces Cognitive Science, a new (inter-)discipline whose centerpiece is the investigation <strong>of</strong><br />

cognition. Cognitive Science brings together evidence from various disciplines about how our mind and<br />

brain work, integrating the knowledge gained from different approaches to cognition. Cognitive Science<br />

views the mind as an information processing system. The results <strong>of</strong> empirical observation, theoretical<br />

analysis and computational modelling <strong>of</strong> mental activity are supposed to have a tremendous impact on future<br />

information technology:<br />

"I believe that the discovery by cognitive science and artificial intelligence <strong>of</strong> the technical challenges<br />

overcome by our mundane mental activity is one <strong>of</strong> the great revelations <strong>of</strong> science, an awakening <strong>of</strong> the<br />

imagination comparable to learning that the universe is made up <strong>of</strong> billions <strong>of</strong> galaxies or that a drop <strong>of</strong> pond<br />

water teems with microscopic life"<br />

(Steven Pinker, How the mind works, p. 4).<br />

MOTIVATION<br />

You may ask why a new discipline is needed for the study <strong>of</strong> cognition and why establishing this discipline<br />

should be regarded as a good idea. Here are a few reasons:<br />

Eternal questions are still unanswered<br />

Some questions about our mind have been asked for thousands <strong>of</strong> years but still haven´t been given satisfying<br />

answers: How do we think, understand, speak, learn …; what is the relation <strong>of</strong> body and mind; what is<br />

consciousness? These questions have been investigated in different, loosely related disciplines, but theoretical<br />

progress has been hindered by reformulations and reinterpretations <strong>of</strong> questions and (partial) answers. The<br />

new joint effort made in Cognitive Science can be expected to give answers to them by simply bringing<br />

together evidence from different viewpoints.<br />

Clear old problems recognized<br />

Perhaps the most famous theoretical problem is the "Frame problem" (McCarthy/Hayes 1969) well known<br />

in the field <strong>of</strong> Artificial Intelligence: The problem <strong>of</strong> specifying what exactly belongs to a certain piece <strong>of</strong><br />

knowledge or, e.g., what is relevant for planning and performing a certain action. This is most clearly<br />

exemplified in Dennett´s story <strong>of</strong> the little robot.<br />

Once upon a time there was a robot, named R1 by its creators. Its only task was to fend for<br />

intself. One day its designers arranged for it to learn that its spare battery, its precious enerfy<br />

supply, was locked in a room with a time bomb set to go <strong>of</strong>f soon. R1 located the room, and the<br />

key to the door, and formulated a plan to rescue its battery. There was a wagon in the room, and<br />

the battery was on the wagon, and R1 hypothesized that a certain action which it called<br />

PULLOUT(WAGON,ROOM) would result in the battery being removed from the room.<br />

Straighaway it acted, and did succeed in getting the battery out <strong>of</strong> the room before the bomb went<br />

<strong>of</strong>f. Unfortunately, however, the bomb was also on the wagon. R1 knew that the bomb was on the<br />

wagon in the room, but didn't realize that pulling the wagon would bring the bomb out along with<br />

the battery. Poor R1 had missed that obvious implication <strong>of</strong> its planned act.<br />

Back to the drawing board. "The solution is obvious," said the designers. "Our next robot must be<br />

made to recognize not just the intended implications <strong>of</strong> its acts, but also the implications about<br />

their side-effects, by deducing these implications from the descriptions it uses in formulating its<br />

[ 1 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

plans." They called their next model the robot-deducer R1D1. They placed R1D1 in much the<br />

same predicament the R1 had succombed to, and as it too hit upon the idea <strong>of</strong><br />

PULLOUT(WAGON,ROOM), it bafan, as designed to consider the implications <strong>of</strong> such a course<br />

<strong>of</strong> action. It had just finished deducing that pulling the wagon out <strong>of</strong> the room would not change<br />

the color <strong>of</strong> the room's walls, and was embarking on a pro<strong>of</strong> <strong>of</strong> the further implication that pulling<br />

the wagon out would cause its wheels to turn more revolutions than there were wheels on the<br />

wagon - when the bomb went <strong>of</strong>f.<br />

Back to the drawing board. "We must teach it the difference between relevant implications and<br />

irrelevant implications," said the designers. "And teach it to ignore the irrelevant ones." So they<br />

developed a method <strong>of</strong> tagging implications as either relevant or irrelevant to the project at hand,<br />

and installed the method in their net model, the robot-relevant-deducer, R2D1. When they<br />

subjected R2D1 to the test that had so unequivocally selected its predecessors for extinction, they<br />

were surprised to find it sitting, Hamlet-like, outside the room containing the bomb, the native<br />

hue <strong>of</strong> its resolution sicklied o'er with the pale case <strong>of</strong> thought, as Shakespeare has aptly put it.<br />

"DO something!" its creators yelled.<br />

"I am," it replied. "I'm busily ignoring some thousands <strong>of</strong> implications I have determined to be<br />

irrelevant. Just as soon as I find an irrelevant implication, I put it on the list <strong>of</strong> those I must<br />

ignore, and..." the bomb went <strong>of</strong>f.<br />

from: Dennett, D., Cognitive Wheels: The Frame Problem in AI. In Minds, Machines, and<br />

Evolution. C. Hookway, ed. Pp. 128-151. Cambridge University Press, 1984.<br />

The robot´s failure can be blamed to two problematic aspects: First, the assumption that all problems can/have<br />

to be solved by conscious, rational thinking, that is, by the serial, step-by-step application <strong>of</strong> rules to arrive at<br />

a solution [an extreme version <strong>of</strong> this is also known as Ryle´s regress: the fallacious assumption that every<br />

conscious mental act needs deliberate planning (as well as its parts, its parts´ parts …)]. Second, seriality<br />

itself: although for small domains it is still a good idea to serially check the possibilities <strong>of</strong> what should/could<br />

be done in a certain situation (just look at the success <strong>of</strong> current chess computers), such serial thinking leads<br />

to a bottleneck in performance and is, in general, grossly inadequate both for biological (massive parallelity in<br />

the brain) and practical reasons.<br />

New insights gained<br />

The pop-out phenomenon and parallel computation: Why is it sometimes difficult to identify certain elements<br />

in our visual field (e.g., the "T" in a.) while sometimes certain elements can not be missed (they "pop up" in<br />

front <strong>of</strong> our "mental eye" as in b.)? We now know that there is a stage <strong>of</strong> parallel processing <strong>of</strong> different<br />

aspects <strong>of</strong> the visual field that must be distinguished from a stage <strong>of</strong> serial processing. An important aspect <strong>of</strong><br />

our visual cognition is therefore a clever division <strong>of</strong> labour between "dumb" parallel processing (highlighting<br />

"interesting" locations in the visual field) and attentive, serial processing <strong>of</strong> such locations (identifying what is<br />

there, a kind <strong>of</strong> "looking at" these locations). [Mind the metaphors used here simply for abbreviation and<br />

illustration: Of course there is not a little person in our head (a homunculus) looking at our visual field (this is<br />

just what Ryle criticised)! In a sense, Cognitive Science is about replacing such inadequate metaphors by<br />

mechanisms.]<br />

Do you see the outstanding objects in both pictures? In the first one, it is not so easy to see the "T", because<br />

there are many vertical and horizontal lines in the display, making their combination less salient.<br />

[ 2 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

New technologies invented<br />

For a long time, the investigation <strong>of</strong> how the mind works has been in the hands <strong>of</strong> philosophers and<br />

psychologists. Now we do not only use computers for modelling the mind´s operations (or for building<br />

artificially intelligent systems), but with new neuroimaging techniques and devices (e.g., PET scans), we are<br />

even beginning to be able to "see the mind at work".<br />

Innovative methods found<br />

Artificial Neural Networks and Connectionism: In the past years, new methods <strong>of</strong> computing have been<br />

developped which are more or less inspired by the information processing in our brain. Some old and difficult<br />

problems (like face or voice recognition) can be handled much better with these methods.<br />

SYLLABUS<br />

· What is Cognitive Science? Basics. History.<br />

· The architecture <strong>of</strong> mind/cognition: CRUM (computational-representational understanding <strong>of</strong> the<br />

mind)<br />

· Non-classical approaches to cognition<br />

· The brain and its structure<br />

· The relation <strong>of</strong> mind and brain<br />

· Language<br />

· Artificial intelligence<br />

· Philosophy <strong>of</strong> mind<br />

· Visual cognition/ Imagery<br />

· Attention<br />

· Consciousness<br />

„COGNITION“<br />

Derived from lat. cognoscere, gr. gignoskein (perceive, (get to) know)<br />

Introduced in modern psychology in demarcation to behaviorism<br />

· cognitive psychology (as a new branch <strong>of</strong> psychology established in the sixties)<br />

Cognition comprises, e.g., the functions <strong>of</strong> perception, imagination, planning, problem solving,<br />

remembering, recognizing, learning, language generation and understanding<br />

[ 3 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

WHAT IS THE AIM <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong>?<br />

-> "reverse engineering" (How did nature do it?)<br />

rather than or before "engineering"<br />

Basic research questions (from Eckhardt 1995, What is Cognitive Science ?):<br />

• For the normal, typical adult, what is the capacity to ...?<br />

• In virtue <strong>of</strong> what does a normal, typical adult have the capacity to ...?<br />

• How does a normal, typical adult typically ...?<br />

• How does the capacity to … <strong>of</strong> the normal, typical adult interact with the rest <strong>of</strong> his or her cognitive<br />

capacities?<br />

CONTROVERSIAL AIMS<br />

· Does Cognitive Science include the study <strong>of</strong> the cognition (or intelligence) <strong>of</strong> man-made-computers?<br />

· Does Cognitive Science include the study <strong>of</strong> the cognition (or intelligence) <strong>of</strong> non-human animals?<br />

· Does Cognitive Science include the study <strong>of</strong> human mental phenomena other than cognition (such as<br />

emotions)?<br />

In my opinion, <strong>of</strong> course!<br />

THE RESEARCH FRAMEWORK <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong><br />

· The domain <strong>of</strong> Cognitive Science consists <strong>of</strong> the (human) cognitive capacities, which have a number <strong>of</strong><br />

properties, among them<br />

· Intentionality (aboutness)<br />

Ð Productivity (i.e., to be used in novel ways)<br />

· The capacities make up a system according to which answers to the basic questions can be found<br />

· The (human,) cognitive mind/brain is a computational and representational device; hence, cognitive<br />

capacities consist <strong>of</strong> a system <strong>of</strong> computational and representational capacities<br />

REVISED RESEARCH QUESTIONS<br />

• For the normal, typical adult, what precisely is the information-processing function that underlies the<br />

capacity to ...?<br />

• When a normal, typical adult has the capacity to …, in virtue <strong>of</strong> what computational and<br />

representational resources is he or she able to compute the function ... ?<br />

[ 4 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

• When a normal, typical adult typically exercises his or her capacity to …, how is the function<br />

computed?<br />

• How does the information-processing function to … <strong>of</strong> the normal, typical adult interact with the rest<br />

<strong>of</strong> his or her information-processing functions?<br />

ASPECTS <strong>OF</strong> THE INVOLVED DISCIPLINES<br />

Philosophy:<br />

· Strong influences on theories <strong>of</strong> mind, language, and knowledge<br />

· Syllogisms (Aristotle)<br />

· „thinking as mental calculation“-view (Hobbes, Leibniz)<br />

· Mind-body-problem (Descartes)<br />

· Ideas, categories (Plato, Kant, Wittgenstein)<br />

· Logic (Frege, Carnap)<br />

Neuroscience:<br />

Ð Lashley (ablation technique, lesions)<br />

Ð Hebb (connectivity <strong>of</strong> cell assemblies)<br />

Ð McCulloch (+ Pitts) (logical abstractions <strong>of</strong> biological neurons)<br />

Ð Hubel/Wiesel (single-cell recordings)<br />

Psychology:<br />

Ð Information processing replaces behaviourism as the dominant paradigm (-> “cognitive" psych., -><br />

George Miller)<br />

Ð Thinking as symbol manipulation, computer simulation as a method for the development <strong>of</strong> theories<br />

<strong>of</strong> the functioning <strong>of</strong> the mind<br />

Linguistics:<br />

· Generative grammar replaces structural linguistics (Noam Chomsky). (+ psycho-, computational-L.)<br />

Computer Science/Artificial Intelligence:<br />

· Symbolic computation replaces mere numerical calculation as main focus <strong>of</strong> the discipline (symbolic<br />

programming language LISP, ->McCarthy)<br />

· Programming in Logic (PROLOG)<br />

· Parallel Distributed Processing (PDP, ->Rumelhart/McClelland)<br />

(Cognitive) Anthropology:<br />

· Social/cultural variation <strong>of</strong> cognitive functions<br />

Mathematics (as a background discipline):<br />

· Establishment <strong>of</strong> basic formal concepts and formalisms<br />

· Mathematical logic (Frege, Russel/Whitehead)<br />

· Theory <strong>of</strong> computation (Turing, Church)<br />

· Formal semantics <strong>of</strong> natural language (Montague)<br />

THE RISE <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong><br />

• Hixon-Symposium (1948, California Institute <strong>of</strong> Technology) („Wie steuert das Nervensystem<br />

Verhalten?“): First counter-reaction against behaviorism (-> Skinner)<br />

participants: Lashley (Psych.), von Neumann (Math.), McCulloch (Neurophys.)<br />

• Symposium on Information Theory (1956)<br />

participants : George Miller (Psych.), Allan Newell/Herbert Simon (Inf.), Noam Chomsky (Ling.)<br />

• Meeting at the Dartmouth College (1956)<br />

participants : McCarthy, Minsky, Newell, Simon<br />

• Chomsky: review <strong>of</strong> Skinners „Verbal Behaviour“ (1959)<br />

• Establishment <strong>of</strong> the Center for Cognitive Studies in Harvard (Miller, Jerome Bruner)<br />

• Initiative <strong>of</strong> the Sloan Foundation (since 1975)<br />

• Establishment <strong>of</strong> the journal „Cognitive science“ (1977)<br />

• Establishment <strong>of</strong> the Cognitive Science Society (1979)<br />

[ 5 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

• Establishment <strong>of</strong> the journal „Kognitionswissenschaft“ (1990)<br />

• Establishment <strong>of</strong> the „Gesellschaft für Kognitionswissenschaft“ (GK) (1994)<br />

THE CLASSICAL VIEW <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong> I<br />

„What has brought the field into existence is a common research objective: to discover the representational<br />

and computational capacities <strong>of</strong> the mind and their structural and functional representation in the brain“<br />

(from a report <strong>of</strong> the Sloan foundation 1978)<br />

• Cognition is computation, the Turing-machine is the adequate most general construct for the<br />

description <strong>of</strong> computability<br />

• Cognitive processing is information processing<br />

• Information processing presupposes internal states, according to which outputs are computed with<br />

respect to given inputs<br />

• The basis <strong>of</strong> cognitive performance is the ability <strong>of</strong> cognitive systems to represent aspects <strong>of</strong> the<br />

environment relevant for action<br />

TURING MACHINE<br />

THE CLASSICAL VIEW <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong> II<br />

• Aspects <strong>of</strong> representation can be formally (i.e., mathematic-logically) described and processing<br />

aspects can be modelled by general or specific inference mechanisms<br />

• Cognition is described at several levels<br />

- knowledge level, symbol level (representation), implementational level (physical, biological<br />

realization)<br />

- computational level, algorithmic level, implementational level (point <strong>of</strong> view: top-down)<br />

• Cognitive systems are composed <strong>of</strong> various components (modules) which constitute an information<br />

processing system (IPS)<br />

[ 6 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Computational level: What information-processing problem is the system solving?<br />

Algorithmic level: What method is the system using to solve that informationprocessing<br />

problem?<br />

Implementational level: What physical properties are used to implement the (functional)<br />

method that the system uses to solve this information-processing<br />

problem?<br />

THE CLASSICAL VIEW <strong>OF</strong> <strong>COGNITIVE</strong> <strong>SCIENCE</strong> III<br />

• With the relations <strong>of</strong> their components, IPSs show a certain architecture, by which the behavior <strong>of</strong> the<br />

system is determined<br />

• IPSs are symbol processing systems which are somehow physically implemented<br />

(physical symbol systems hypothesis, Newell&Simon)<br />

"A physical symbol system consists <strong>of</strong> a set <strong>of</strong> entities, called symbols, which are physical<br />

patterns that can occur as components <strong>of</strong> another type <strong>of</strong> entity called an expression (or symbol<br />

structure). Thus, a symbol structure is composed <strong>of</strong> a number <strong>of</strong> instances (or tokens) <strong>of</strong> symbols<br />

related in some physical way (such as one token being next to another). At any instant <strong>of</strong> time<br />

the system will contain a collection <strong>of</strong> these symbol structures. Besides these structures, the<br />

system also contains a collection <strong>of</strong> processes that operate on expressions to produce other<br />

expressions: processes <strong>of</strong> creation, modification, reproduction and destruction.<br />

The Physical Symbol System Hypothesis.<br />

A physical symbol system has the necessary and sufficient means for general intelligent action.<br />

By necessary we mean that any system that exhibits intelligence will prove upon analysis to be a<br />

physical symbol system. By sufficient we mean that any physical symbol system <strong>of</strong> sufficient<br />

size can be organized further to exhibit general intelligence. By general intelligent action we<br />

wish to indicate the same scope <strong>of</strong> intelligence as we see in human action. "<br />

[from: Allen Newell and Herbert Simon, "Computer Science as Empirical Inquiry: Symbols and<br />

Search," Communications <strong>of</strong> the ACM, March 1976, pp 113-126.]<br />

• Cognition/mind can be described functionally (-> Functionalism), i.e. independently <strong>of</strong> its material<br />

realization<br />

Structure and behavior <strong>of</strong> IPSs can be reasonably put into analogy with the structure and behavior <strong>of</strong><br />

existing computers (Von-Neumann-computer)<br />

Computer-Metaphor<br />

clear distinction <strong>of</strong> machine and program<br />

WHEN IS A MACHINE INTELLIGENT? TURING´S IDEA<br />

Turing believed that by the end <strong>of</strong> the century, machines would be able to converse and think to<br />

the point where no one would bother debating the issue anymore. The only problem was trying<br />

to figure out how we could tell if a machine was intelligent.<br />

After all, mankind has tried to define intelligence for ages and had made little progress except to<br />

decide that whatever it is, we've got it.<br />

Turing came up with a elegant solution. He constructed the simple proposition that if human<br />

beings are intelligent, and if a machine can imitate a human, then the machine, too, would have<br />

to be considered intelligent.<br />

The test may seem stupendously simplistic, but given the abysmally circular discussions about<br />

the nature <strong>of</strong> consciousness, meaning and thought, Turing's idea was at least a solid point <strong>of</strong><br />

[ 7 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

reference that researchers could hold onto and discuss without getting lost in debates over how<br />

many bytes could dance on the head <strong>of</strong> pin.<br />

In Turing's proposal, a human interrogator sits in a room opposite a teletype or computer<br />

terminal. Hidden from the interrogator is a computer and another human being. The interrogator<br />

interviews both and tries to determine which is human and which is a computer. If the computer<br />

can fool the interrogator, it is deemed intelligent.<br />

Turing called this the "imitation game," although it is now universally known as the Turing Test.<br />

Given the simplicity <strong>of</strong> the Turing Test, it is surprising that for decades no one ever tried to<br />

actually conduct a Turing Test. Turing himself saw it as more a theoretical proposition to discuss<br />

the nature <strong>of</strong> machine intelligence. Over the years, perhaps researchers thought it obvious that no<br />

modern machine could yet pass the test.<br />

taken from:<br />

http://www-rci.rutgers.edu/~cfs/472_html/Intro/NYT_Intro/History/MachineIntelligence1.html<br />

see also<br />

http://www.cs.bilkent.edu.tr/~psaygin/ttest.html (great page on Turing test)<br />

VON-NEUMANN MACHINE<br />

IN SHORT: CRUM (COMPUTATIONAL-REPRESENTATIONAL<br />

UNDERSTANDING <strong>OF</strong> THE MIND) -> THAGARD<br />

· Thinking can best be understood in terms <strong>of</strong><br />

· representational structures in the mind and<br />

· procedures operating on those structures<br />

· Analogy: Program Mind<br />

· data structures + algorithms = running programs<br />

· Mental representations + computational procedures = thinking<br />

[ 8 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

PROBLEMS <strong>OF</strong> THE CLASSICAL VIEW<br />

• The notion „representation“ is controversial<br />

• Symbol grounding is not ensured („symbol grounding problem“, -> Stevan Harnad)<br />

• The relation <strong>of</strong> mind and brain remains unclear<br />

• Inadequacy <strong>of</strong> the computer metaphor (massive parallel processing in the brain vs. sequential<br />

processing in the von Neumann-computer)<br />

• Top-down-conception<br />

• Missing content addressability<br />

There is a meanwhile classical while at the same time highly controversial critique <strong>of</strong> the functionalist<br />

(CRUM) view <strong>of</strong> cognition by the philosopher John R. Searle.<br />

Searle considers the following thought-experiment. Suppose that a person were given a set <strong>of</strong><br />

purely formal rules for manipulating Chinese symbols. The person does not speak or understand<br />

written Chinese, and so he does not know what the symbols mean, though he can distinguish<br />

them by their differing shapes. The rules do not tell him what the symbols mean: they simply<br />

state that if a symbol <strong>of</strong> a certain shape comes into the room, then he should write down a<br />

symbol with a certain other shape on a piece <strong>of</strong> paper. The rules also state which groups <strong>of</strong><br />

symbols can accompany one another, and in which order. The person sits in a room, and<br />

someone hands in a set <strong>of</strong> Chinese symbols. The person applies the rules, writes down a different<br />

set <strong>of</strong> Chinese symbols as specified by the rules on a sheet <strong>of</strong> paper, and hands the result to a<br />

person waiting outside the room. Unknown to the person in the room, the rules that he applies<br />

result in a grammatically correct conversation in Chinese. For example, if someone hands in a set<br />

<strong>of</strong> Chinese symbols that mean, "How do you feel today?" the symbols he writes down (as<br />

specified by the rules) mean, "Fine, thank you." In sum, the rules are a complete set <strong>of</strong><br />

instructions that might be implemented on a computer designed to engage in grammatically<br />

correct conversations in Chinese. The person in the room, however, does not know this. He does<br />

not understand Chinese.<br />

taken from: http://oit.iusb.edu/~lzynda/cogsci_lecture16.html<br />

[see also http://www.cas.ilstu.edu/PT/chinroom.htm]<br />

Thus, according to Searle, although artificial systems may (seem to) be intelligent (that is, show intelligent<br />

behaviour), they differ fundamentally from us as their intelligence is not based on embodied cognition [there<br />

are many, who do not subscribe to this view, however].<br />

[ 9 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

ALTERNATIVES/ ALTERNATIVE VIEWS<br />

• The architecture <strong>of</strong> the brain is relevant (neuroimaging, lesions)<br />

• connectionism/neuronal nets, ->subsymbolic representation and processing<br />

• ecological and social context are considered relevant (situated action)<br />

• „Natural Computation“ (i.e., „brain-like“ computation), Dana Ballard<br />

-> Important elements/concepts:<br />

• Minimal description length (programs as compact code)<br />

• Learning (developmental, behavioral, evolutionary)<br />

• Specialized architectures<br />

Minimum Description Length. The only answers that are practical to compute are those that<br />

retreat from the best answer in some sense. Answers can be just good, approximately correct, or<br />

correct to a certain probability. A universal metric for all these approximations is the minimum<br />

description length principle, which measures the cost <strong>of</strong> encoding regularity in data.<br />

Learning. Biological systems can amortize the cost <strong>of</strong> algorithms over their lifetime by learning<br />

from examples. Such learning can be seen as the ``on-line'' detection <strong>of</strong> regularity.<br />

Specialized Architectures. The massively parallel organization <strong>of</strong> the brain's neurons can<br />

compensate dramatically for their millisecond speeds. Particularly if the input is bounded at<br />

some fixed size, as it is with a retina or cochlea, then it can be very cost effective to design<br />

special-purpose architectures. In addition, to manage complexity the brain has evolved many<br />

hierachical structures.<br />

taken from: http://www.cs.rochester.edu/users/faculty/dana/comp.html<br />

GENERAL DISPUTES<br />

Ð Nativism vs. Empirism<br />

Ð Functionalism vs. eliminative Materialism<br />

Ð Associationism vs. Representationalism<br />

Ð Localizability <strong>of</strong> cognitive functions vs. distributedness <strong>of</strong> their representation<br />

Ð (Descartes, Gall, Broca/Wernicke, Hubel/Wiesel)<br />

Ð Modularity vs. Non-modularity <strong>of</strong> cognitive (sub)systems<br />

Ð Competence (ability to do sth.) vs. performance (behavior itself)<br />

Ð Weak psychological AI vs. strong psychological AI<br />

Strong AI aims at producing thinking machines, and assumes that implementing computer<br />

programs can be sufficient for producing a thinking thing.<br />

Weak AI aims at (a) producing machines that can perform complex tasks normally performed by<br />

intelligent beings, and/or (b) studying human cognitive processes by simulating them on a<br />

computer.<br />

Ð „G<strong>OF</strong>AI“ (Good Old Fashioned AI) vs. „New AI“<br />

<strong>COGNITIVE</strong> <strong>SCIENCE</strong> AS AN “INTER”-DISCIPLINE<br />

Disciplinary structure at universities: Necessary, but not sufficient<br />

-> Cognitive Science as an interdisciplinary venture<br />

Problem <strong>of</strong> pure interdisciplinary proceeding:<br />

"Dabei hat sich jedoch gezeigt, daß die Schwierigkeiten interdisziplinärer Zusam-menarbeit im<br />

kognitionswissenschaftlichen Bereich viel größer sind als angenommen. Eine fruchtbare<br />

Zusammenarbeit kommt in vielen Fällen erst nach Jahren zustande. Das größte Hindernis bei der<br />

gemeinsamen Arbeit sind Statusprobleme der beteiligten Wissenschaften, gefolgt von der<br />

weitgehenden Unkenntnis des Problembewußtseins, der Begriffssysteme, des Wissensstandes und des<br />

methodisch-praktischen Vorgehens in den jeweils anderen Disziplinen" (Roth 1996:10).<br />

[ 10 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Gardner:<br />

this is a „weak“ version <strong>of</strong> Cognitive Science "[das] kaum das Etikett einer bedeutenden neuen<br />

Wissenschaft [verdient]" (Gardner 1992:407)<br />

IS <strong>COGNITIVE</strong> <strong>SCIENCE</strong> A DISCIPLINE (IN A „STRONG“ SENSE)?<br />

If so, what is its content, what are its independent contributions?<br />

"Ich vertrete eine völlig andere, bislang noch umstrittene Meinung. Aus meiner [...] Sicht sind die<br />

wirklich wichtigen Grenzlinien in der Kognitionswissenschaft nicht die gleichen wie die der<br />

traditionellen Disziplinen, sondern vielmehr die zwischen speziellen kognitiven Inhalten. Darum<br />

sollten Wissenschaftler nach dem Kognitionsbereich definiert werden, der im Mittelpunkt ihrer Arbeit<br />

steht [...]"<br />

(Gardner 1992:407)<br />

Properties <strong>of</strong> the discipline :<br />

Ð Variety <strong>of</strong> methods (empirical, analytic, constructive)<br />

Ð accumulative as regards content<br />

Ð Information processing als paradigm<br />

Ð topic centered + multi-leveled<br />

TO WHAT EXTENT DOES <strong>COGNITIVE</strong> <strong>SCIENCE</strong> <strong>OF</strong>FER A GENERAL<br />

EDUCATION, TO WHAT EXTENT A JOB-RELATED ONE?<br />

-> both<br />

• generality <strong>of</strong> education achieved through multidisciplinary methodical abilities<br />

• specialization through thematic/topical deepening<br />

• education is basis for new cognitive information technology<br />

[ 11 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

ASPECTS <strong>OF</strong> COGNITION (CLASSICAL VIEW)<br />

<strong>COGNITIVE</strong> ARCHITECTURE<br />

¥ Basic assumption: IPSs are not (completely) homogeneously structured<br />

¥ IPSs consist <strong>of</strong> a set <strong>of</strong> interacting subsystems, which are functionally defined<br />

¥ Kinds <strong>of</strong> subsystems and their relations determine the „cognitive architecture“ <strong>of</strong> an IPS<br />

¥ Further assumption: cognitive architectures <strong>of</strong> normal, typical adults are roughly the same<br />

GLOBAL VIEW ON THE <strong>COGNITIVE</strong> ARCHITECTURE<br />

MEMORY<br />

¥ Long-term memory<br />

Ð declarative memory (-> Tulving)<br />

¥ semantic m. (concepts, “What is X”)<br />

¥ episodic (autobiographic) m. (events, “When did X happen”)<br />

Ð procedural memory (“How to do X”)<br />

¥ Short-term memory<br />

Ð Working memory (-> Baddeley)<br />

¥ central executive<br />

¥ specific subsystems (Visuo-spatial sketchpad, phonological loop)<br />

Ð Working memory (alternative view)<br />

¥ Set <strong>of</strong> active representations<br />

¥ Further distinction: explicit vs. implicit memory<br />

MEMORY REPRESENTATION<br />

¥ Memory<br />

Ð stores aspects <strong>of</strong> the perceived world<br />

Ð contains knowledge representation structures<br />

¥ For what?<br />

Ð Storing information makes it possible to learn, to recognize, categorize, plan, and reason<br />

Ð Storing information makes it possible to „represent the world“<br />

¥ How much is stored?<br />

Ð Long term memory: everything? (problem <strong>of</strong> forgetting)<br />

Ð Short term memory: little (7±2 “chunks”, Miller)<br />

¥ How long? -> unlimited?<br />

[ 12 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

REPRESENTATION<br />

¥ Representation =<br />

(Symbolic data)structures + access processes<br />

¥ Different kinds (formats) <strong>of</strong> representation<br />

Ð Logic<br />

Ð Semantic networks, concept hierarchies<br />

Ð Schemata<br />

Ð Rules<br />

Ð mental images/models<br />

¥ Processes operate on representations<br />

Ð mental functions are realized<br />

Ð behavior is produced<br />

THEREFORE (REPRESENTATIONAL STANCE)<br />

Why do people have a particular kind <strong>of</strong> intelligent behavior?<br />

Explanatory pattern:<br />

¥ People have mental representations<br />

¥ People have algorithmic processes that operate on those representations<br />

¥ The processes, applied to representations, produce the behavior<br />

LOGIC<br />

¥ Motivation:<br />

Ð Many ideas about representation and computation come from the logic tradition<br />

Ð Languages <strong>of</strong> logic are suitable as universal knowledge representation languages (?)<br />

Ð Logic is a suitable/ the single suitable means for the formal representation <strong>of</strong> deduction (?)<br />

Ð Logical deduction corresponds (somehow) to natural reasoning (??)<br />

VARIOUS LOGICS<br />

¥ Propositional logic (Aussagenlogik)<br />

Ð Elements: Propositions p, q...<br />

Ð Connectors & (and), v (or), -> (if-then)<br />

Ð Negation (~p)<br />

¥ The relation <strong>of</strong> language, logic, and deduction:<br />

Ð “If it rains (p), then it is wet (q)”: p -> q<br />

Ð Patterns <strong>of</strong> inference/inference rules:<br />

¥ Modus ponens (MP) (If p -> q and p, then deduce q)<br />

¥ Modus tollens(MT) (If p -> q and ~q, then deduce ~p)<br />

Ð Thus:<br />

¥ “It rains” allows to infer “It is wet” (via MP)<br />

¥ “It is not wet” allows to infer “It does not rain” (via MT)<br />

¥ First order predicate logic (FOPL)<br />

Ð (Prädikatenlogik erster Stufe, PL/1)<br />

Ð allows statemenst about (relations holding between) objects<br />

Ð Quantification:<br />

¥ “All men are mortal”: "x man(x) -> mortal(x)<br />

¥ “There exists a mortal man”: $x man(x) & mortal(x)<br />

¥ Further logics (extensions <strong>of</strong> FOPL) for individual aspects <strong>of</strong> cognition/knowledge, z.B.<br />

Ð Modal logics (“it is necessary/possible that”)<br />

Ð Deontic logics (“may/must”)<br />

Ð Default-logics (“typically”) /Non-monotonic logics<br />

Ð Spatial, temporal, sortal … logics<br />

[ 13 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Ð Many-valued logics, Fuzzy-Logic<br />

THEOREM PROVING: TYPES <strong>OF</strong> INFERENCE<br />

¥ Deduction (application <strong>of</strong> MP)<br />

Ð Is a monotonic procedure<br />

Ð Does not correspond to „learning“<br />

¥ Induction (inferring a universal statement from single observations)<br />

Ð Could be expected to correspond to „learning“<br />

Ð However: Induction is not correct, is “impossible”<br />

¥ Abduction (from p->q and q: infer p)<br />

Ð “It is wet” ---> “It has rained”<br />

Ð yields explanations<br />

Ð is defeasible<br />

<strong>COGNITIVE</strong> PLAUSIBILITY<br />

3 positions:<br />

Ð Formal logic is an important part <strong>of</strong> human reasoning (“mental logic”, Rips)<br />

Ð Formal logic is only distantly related to human reasoning, but that does not matter<br />

Ð Formal logic is only distantly related to human reasoning, so Cognitive Science should pursue other<br />

approaches (“mental models”, Johnson-Laird)<br />

THEREFORE (LOGICAL STANCE)<br />

Why do people make the inferences they do?<br />

Explanation:<br />

¥ People have representations similar to sentences in logic<br />

¥ People have deductive and inductive procedures that operate on those sentences<br />

¥ The deductive and inductive procedures, applied to the sentences, produce the inferences<br />

WASON’S SELECTION TASK<br />

¥ given: cards with letters on the one side and numbers on the other<br />

A B 4 7<br />

¥ Rule: If there is an A on the one side <strong>of</strong> a card, then there is a 4 on the other side<br />

¥ Question to subjects: Which card(s) must be turned over in order to verify the rule?<br />

¥ Result contradicts the assumption <strong>of</strong> a mental theorem prover<br />

RULES (PRODUCTIONS)<br />

¥ IF CONDITION THEN ACTION<br />

¥ ACTIONs are implication/deductions (A) or actions (B)<br />

¥ Logic Theorist (Newell, Shaw, Simon, 1958)<br />

Ð Modelling <strong>of</strong> human theorem proving in logic<br />

¥ GPS (General Problem solver, Newell/Simon 1972)<br />

Ð Generalization to human thinking and reasoning<br />

¥ ACT (“adaptive character <strong>of</strong> thought”, J. Anderson, 1983, 1993)<br />

¥ SOAR (“State, Operator, Apply and Result”, Newell,Laird, Rosenbloom 1993)<br />

DIFFERENCE TO LOGIC<br />

[ 14 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

¥ Simpler structure (condition-action)<br />

¥ Less strict: “p(x) -> q(x)” not necessarily interpreted as universal statement<br />

¥ Properties <strong>of</strong> the architecture<br />

Ð Working memory<br />

Ð Rule memory (procedural memory)<br />

Ð Control mechanism<br />

¥ Processing properties<br />

Ð E.g. “chunking” <strong>of</strong> rules<br />

PROBLEM SOLVING<br />

¥ Problem solving as search<br />

Ð Initial state<br />

Ð Goal state<br />

Ð Search space<br />

¥ Constraining the search space<br />

Ð by heuristic rules<br />

Ð by the constrained working memory<br />

¥ Different kinds <strong>of</strong> rule processing<br />

Ð forward<br />

Ð backward<br />

Ð bidirectional<br />

EXAMPLE: TIC-TAC-TOE<br />

¥ WIN: IF there is a row, colum, or diagonal with two <strong>of</strong> my pieces and a blank space THEN play the blank space to<br />

win<br />

¥ BLOCK: IF there is a row, colum, or diagonal with two <strong>of</strong> my opponent´s pieces and a blank space, THEN play the<br />

blank space to block the opponent<br />

¥ PLAY CENTER: IF the center is blank, THEN play the center<br />

¥ PLAY EMPTY CORNER: IF there is an empty corner, THEN move to an empty corner<br />

THEREFORE (RULE STANCE)<br />

Why do people have a particular kind <strong>of</strong> intelligent behavior?<br />

Explanation:<br />

¥ People have mental rules<br />

¥ People have procedures for using these rules to search a space <strong>of</strong> possible solutions, and procedures for<br />

generating new rules<br />

¥ Procedures for using and forming rules produce the behavior<br />

CONCEPTS<br />

¥ What is X?<br />

[ 15 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Ð Plato: Knowledge about X is innate (Nativism)<br />

Ð Locke/Hume: Knowledge about X is gained through experience (Empirism)<br />

Ð Kant: both is correct<br />

¥ Concepts are used for categorization and inference<br />

Ð Input I is INSTANCE <strong>OF</strong> concept C<br />

Ð If I is INSTANCE <strong>OF</strong> C then it has properties P1, P2, …<br />

The purpose <strong>of</strong> categorisation is to avoid the consequences <strong>of</strong> miscategorisation. Categorisation<br />

means responding differentially to certain KINDs (or classes, or categories) <strong>of</strong> input. The<br />

purpose <strong>of</strong> the data-reduction is to get out <strong>of</strong> the […] problem <strong>of</strong> unique instances with which<br />

you can do nothing. To reduce is to select what is invariant in the inputs and will reliably allow<br />

them to be categorised correctly, and to ignore the rest.<br />

This is not just "processing economy": It is part to what it means to learn and to generalise.<br />

Stevan Harnad in an email<br />

( http://cogsci.soton.ac.uk/~harnad/Hypermail/Foundations.Cognition/0061.html )<br />

[Just imagine that situation in which you have correctly categorized that animate thing with four legs coming<br />

running towards you as a bulldog. You should therefore be able to deduce the ‘may bite me‘ property and to<br />

draw the inference that it would be a good idea to run away or to hide. Luckily, there´s more to thinking and<br />

acting than only conscious deliberation…]<br />

¥ Approaches in AI /psychology<br />

Ð Networks <strong>of</strong> concepts (Semantic Nets (Quillian 1968))<br />

➥ spreading activation Aktivationsausbreitung<br />

Ð Schemata (Frames (Minsky (1974), scripts (Schank/Abelson 1977))<br />

SEMANTIC NETS<br />

¥ Relations between concepts<br />

¥ In general: links (<strong>of</strong> a certain type) between nodes (<strong>of</strong> a certain type)<br />

¥ Used for the representation <strong>of</strong> linguistic (semantic) knowledge<br />

¥ E.g., “Peter gives Mary a book” will be mapped on<br />

Sentences like the following can be ruled out as semantically ill-formed:<br />

*”The tower gives an ice to the idea”<br />

FRAMES<br />

Representation <strong>of</strong> (non-linguistic) knowledge (¹ semantic nets)<br />

Starting point:<br />

Emphasis on the structure <strong>of</strong> knowledge (as against unstructured sets <strong>of</strong> logical propositions)<br />

-> Schemata<br />

Frames as data structures for knowledge „chunks“<br />

Ð stereotypical situations (“What happens on a birthday party?")<br />

Ð prototypical objects (representatives <strong>of</strong> a category, cp. “How does a typical chair look like?")<br />

Idea: Frames serve to<br />

Ð categorize sensoric input (by “Matching”)<br />

[ 16 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Ð memorize and organize new information relative to old information<br />

Ð infer further information<br />

FRAMES II<br />

¥ Nets <strong>of</strong> nodes and links (similar to semantic nets)<br />

¥ Object centered, independent data structure<br />

¥ Hierarchy <strong>of</strong> frames: Inheritance<br />

Ð Taxonomies (kind hierarchies, IS-A-hierarchies, ontologies),<br />

Ð Partonomies (part hierarchies)<br />

FRAMES III<br />

¥ Entries in a frame ("Slots") may have certain values ("Fillers")<br />

also: pointers to sub-frames<br />

¥ Restrictions on fillers<br />

Ð Value is <strong>of</strong> a certain type<br />

Ð complex complex conditions on relations between fillers<br />

Ð “attached procedures” for computing filler values<br />

¥ If-needed<br />

¥ If-added<br />

¥ "Default"-entries as fillers<br />

¥ typical values to be assumed in the lack <strong>of</strong> better evidence<br />

¥ may be overwritten<br />

EXAMPLE: A COURSE FRAME<br />

Course<br />

A_kind_<strong>of</strong>: process (systematic series <strong>of</strong> actions)<br />

Instructor: _<br />

Room: _<br />

Meeting_time: _<br />

Requirements: exams, essays etc.<br />

Instances: Foundations_<strong>of</strong>_Cognitive_Science, Mathematics_I ...<br />

ASPECTS <strong>OF</strong> CONCEPT STRUCTURES<br />

Eleanor Rosch´s findings regarding structuring <strong>of</strong> concept knowledge:<br />

¥ Vertical dimension (inheritance)<br />

Ð Different levels <strong>of</strong> representation<br />

¥ Superordinate Level (furniture, tree)<br />

¥ Basic Level (chair, table, birch tree, oak tree)<br />

¥ Subordinate Level (stool, silver birch)<br />

Ð Basic Level is a distinguished level<br />

[The distinguished basic level may vary according to context and/or expertise; it is therefore sometimes called<br />

"entry" level.]<br />

¥ Horizontal dimension<br />

Ð Members <strong>of</strong> a category are not equal<br />

Ð There are no clear (necessary and sufficient) criteria for membership in a category<br />

Ð Prototypicality<br />

The traditional recipe <strong>of</strong> the Classic Theory is as follows: take a category and a set <strong>of</strong> defining features. The<br />

ingredients are:<br />

· categories are arbitrary;<br />

Ð categories have defining or critical attributes;<br />

Ð the intension (or set <strong>of</strong> attributes) determines the extension <strong>of</strong> a category (which items are members).<br />

[ 17 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

The idea is that categories are held together by defining features, which are together necessary and jointly<br />

sufficient, and that allinstances <strong>of</strong> a category possess the requisite defining features. Someone who is an<br />

unmarried adult male belongs to the category *bachelor* having the defining properties *unmarried*, *adult*,<br />

and *male* (Some people may wonder why these properties have asterisks surrounding them, i.e. why they<br />

are treated as categories. Well, properties can themselves be categories, e.g. we can include the Dutch soccer<br />

team in the category <strong>of</strong> #orangeness#. Nothing prevents properties from being categories.<br />

This way <strong>of</strong> conceptualising categorization has its problems. The deathblow for this theory was given by the<br />

research on color terms. Before this research it was assumed that categorization and naming <strong>of</strong> colors were<br />

arbitrary; the lines between colors were arbitrary, drawn as seen fit by a culture. Individuals <strong>of</strong> a culture<br />

would simply mirror these boundaries in their own classificatory and mnemonic behavior. However, Berlin<br />

and Kay [69] showed with a series <strong>of</strong> anthropological experiments that every culture shares the same focal<br />

areas for colors, irrespective <strong>of</strong> whether or not they have names for them. That is, they all agree about what is<br />

a "good blue" or a "poor yellow", even if a culture lacks labels for them. Moreover, this universalist view on<br />

basic color categorization has been supported by developmental [Bornstein, Kessen, & Weiskopf 76] and<br />

animal studies [Sandell, Gross, & Bornstein 79]. Berlin and Kay also found a presence <strong>of</strong> fixed order in the<br />

construction <strong>of</strong> color lexicons. If a culture has only two color terms, terms will code for black and white. If a<br />

third term is added, it will be red; fourth and fifth will be yellow and green; blue and brown will be the next<br />

pair; and purple, pink, orange, and gray will be the last four names. These findings seem to be a consequence<br />

<strong>of</strong> the structure <strong>of</strong> the nervous system <strong>of</strong> the primate [ibid.; Gardner 87]. Rosch [73] continued on these<br />

experiments and found that while the naming practices turned out to be incidental, the categorization <strong>of</strong> colors<br />

seemed to reflect the organization <strong>of</strong> the nervous system, not the structure <strong>of</strong> particular lexicon. She found this<br />

in other domains as well.<br />

Rosch discovered more properties when she investigated categorization in other domains, namely, categories<br />

seemed to be organized in a taxonomy. Categorization is performed at the basic level (table, dog, NBAplayer).<br />

Above the level <strong>of</strong> basic objects is the layer <strong>of</strong> superordinate objects, being generalizations <strong>of</strong> the<br />

basic ones like furniture, animal, basketball-player. Below the basic layer is the subordinate layer containing<br />

the specializations like diner-table, Mastiff, Shawn Kemp. The possible reasons that we and especially<br />

children categorize at the basic level is that members <strong>of</strong> basic level categories tend to look alike, that the basic<br />

categories have many describable features (cows give milk, say "moooh", and have yellow labels in their ears<br />

(in the Netherlands)), that our physical interactions with members <strong>of</strong> such a category are the same (we use<br />

different chairs the same way), and that it allows easy communication in general situations (compare "A man<br />

was bitten by a dog" with "John was bitten by Fifi" and "A person was bitten by an animal" (Wolters,<br />

personal communication)). […]<br />

Other findings questioned the claim that categories have defining features. There are few categories, from<br />

natural ones like birds to artificial ones like tables, that seem to obey the classical rule <strong>of</strong> finite lists <strong>of</strong> critical<br />

features [see also Gardner 85]. Even when categories do have definitions, rules seem less important than<br />

prototypes (see below). In the case <strong>of</strong> the bachelor: Henry is unmarried, adult, and male. Then he is a bachelor<br />

according to the classicists. If we know that he lives together with his girlfriend, then he is certainly not a<br />

bachelor to us, but he still fits the necessary and sufficient conditions to be a bachelor. There are many other<br />

exemplars fitting the conditions: a homo-sexual, a monkey. Because these examples are not similar to the<br />

prototypical bachelor, they do not seem to belong in the category, even though technically they do [Barsalou<br />

92].<br />

Wittgenstein [53] has given another and probably the most persuasive argument against Classical Theory. He<br />

showed that the concept *game* does not have unambiguous defining properties. In case <strong>of</strong> doubt try to<br />

characterize poker, tic-tac-toe, Russian roulette, chess, and trivial pursuit with defining features shared by all<br />

these instances. The concept *game* is kept together by a set <strong>of</strong> relationships and similarities. The principle is<br />

that each instance shares some subset <strong>of</strong> properties an instance <strong>of</strong> a category can have. Some, all, or none <strong>of</strong><br />

the properties <strong>of</strong> this subset may be shared by another instance. This is called a family resemblance<br />

[Wittgenstein 53].<br />

taken from:<br />

SCRIPTS<br />

http://www.soton.ac.uk/~coglab/coglab/Thesis/chptr3.html<br />

¥ Representation <strong>of</strong> situation specific knowledge (Schank, Abelson (1977): Scipts, Plans, Goals, and<br />

[ 18 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Understanding)<br />

¥ Example: What happens in a restaurant?<br />

Ð Entry conditions?<br />

Ð Entering etc.<br />

Ð Order meal<br />

Ð Eating<br />

Ð Paying<br />

Ð Exiting<br />

Ð Post conditions (results)?<br />

THEREFORE (CONCEPT STANCE)<br />

Why do people have a particular kind <strong>of</strong> intelligent behavior?<br />

Explanation:<br />

¥ People have a set <strong>of</strong> concepts, organized via slots that establish kind and part hierarchies and other<br />

associations.<br />

¥ People have a set <strong>of</strong> procedures for concept application, including spreading activation, matching, and<br />

inheritance.<br />

[ 19 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

¥ The procedures applied to the concepts produce the behavior.<br />

REPRESENTATION MEMORY<br />

¥ Necessary distinction:<br />

Ð Information stored in long term memory<br />

Ð Representation instantiated in working memory<br />

¥ Which information is filed in long term memory?<br />

Ð (only) Definitions (for concepts)?<br />

Ð (only) Abstractions/Schemata/Prototypes?<br />

Ð (only) Instances/Exemplars?<br />

¥ Propositional elements as basic cognitive building blocks ?<br />

¥ Pylyshyn [propositions are units <strong>of</strong> information]<br />

¥ “Language <strong>of</strong> thought” (Fodor) [propositions are units <strong>of</strong> representations]<br />

ANALOGIES AND CASES<br />

-> “Case based reasoning”<br />

Analogical Reasoning:<br />

¥ Starting point: Problem to be solved (target)<br />

¥ Remembering a similar problem (source) for which a solution is known<br />

¥ Structural comparison <strong>of</strong> source and target (putting their relevant components in correspondence with<br />

each other)<br />

¥ Adaptation <strong>of</strong> the source problem to produce a solution to the target problem<br />

¥ -> The tumor problem and the fortress story<br />

THEREFORE (ANALOGY STANCE)<br />

Why do people have a particular kind <strong>of</strong> intelligent behavior?<br />

Explanation:<br />

¥ People have verbal and visual representations <strong>of</strong> situations that can be used as cases or analogs<br />

¥ People have processes <strong>of</strong> retrieval, mapping, and adaptation that operate on those analogs<br />

¥ The analogical processes, applied to the representations <strong>of</strong> analogs, produce the behavior<br />

MENTAL IMAGES<br />

For answering questions like the following, we obviously do not deduce an answer from a set <strong>of</strong> premises in a<br />

logic-like reasoning scheme, but we build a mental picture <strong>of</strong> the scene ("pictorial representation") in which<br />

the answer can be "read <strong>of</strong>f":<br />

How many windows are there on the front <strong>of</strong> your house or apartment building?<br />

¥ Spatial aspects <strong>of</strong> pictorial representations and temporal aspects <strong>of</strong> their processing correspond to the<br />

represented aspects in the world (mental rotation, distance estimation)<br />

¥ Visual perception and mental imagery involve (in part) the same brain structures<br />

THEREFORE (IMAGERY STANCE)<br />

Why do people have a particular kind <strong>of</strong> intelligent behavior?<br />

Explanation:<br />

¥ People have visual images <strong>of</strong> situations<br />

¥ People have processes such as scanning and rotation that operate on those images<br />

¥ The processes for constructing and manipulating images produce the intelligent behavior<br />

[ 20 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

ASPECTS <strong>OF</strong> COGNITION (NON-CLASSICAL VIEW)<br />

CONNECTIONISM<br />

¥ Is also based on nets (networks) <strong>of</strong> nodes and links<br />

Ð Nodes: Cells, neurons, elements, units<br />

¥ However: (at least) the links do not have any meaning<br />

¥ Differentiation <strong>of</strong><br />

Ð localistic networks (nodes still have a clear meaning)<br />

Ð distributed networks (even nodes have no meaning)<br />

¥ Related terms:<br />

Ð parallel distributed processing<br />

Ð artificial neural networks<br />

Ð subsymbolic paradigm<br />

¥ Historical starting point: Networks <strong>of</strong> McCulloch-Pitts cells<br />

THE ARCHITECTURE <strong>OF</strong> CONNECTIONIST NETWORKS<br />

ELEMENTS <strong>OF</strong> NEUR(ON)AL NETWORKS<br />

¥ Cells with<br />

Ð State <strong>of</strong> activation (a i(t))<br />

Ð Activation function (f act)<br />

Given the threshold <strong>of</strong> activation q j<br />

¥ a j(t+1) = f act( a j(t), net j(t), q j )<br />

Ð Output function f out<br />

¥ o j = f out(a j)<br />

¥ Network <strong>of</strong> arcs (directed graph)<br />

Ð with weights w ij between the cells i and j<br />

¥ Propagation function<br />

Ð net j (t) = S o i (t) w ij<br />

¥ Learning rule<br />

[ 21 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

AN EXAMPLE: XOR-NETWORK<br />

TOPOLOGY (ARCHITECTURE) <strong>OF</strong> A NETWORK<br />

¥ Is crucial for what can be represented<br />

¥ In the second place: for what can be learned<br />

¥ Networks without hidden units<br />

Ð cannot represent XOR<br />

¥ Perceptrons (Rosenblatt 1958)<br />

¥ Critique: Minsky/Papert 1969<br />

Ð Are only suitable for linearly separable sets <strong>of</strong> inputs (¹XOR)<br />

THEORETICALLY POSSIBLE KINDS <strong>OF</strong> LEARNING<br />

IN NEURAL NETWORKS<br />

¥ Development <strong>of</strong> new connections<br />

¥ Extinction <strong>of</strong> existing connections<br />

¥ Modification <strong>of</strong> strength w ij <strong>of</strong> links<br />

¥ Modification <strong>of</strong> the threshold <strong>of</strong> neurons<br />

¥ Modification <strong>of</strong> activation, propagation or output function<br />

¥ Development <strong>of</strong> new cells<br />

¥ Deletion <strong>of</strong> cells<br />

[ 22 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

LEARNING RULES<br />

TYPES <strong>OF</strong> LEARNING<br />

¥ Supervised learning (Überwachtes Lernen)<br />

Ð Desired output (teaching input) is given<br />

¥ Reinforcement learning (Bestärkendes Lernen)<br />

Ð Feedback whether classification was corrrect<br />

¥ Unsupervised learning (Unüberwachtes Lernen)<br />

Ð Selforganisation<br />

Ð Kohonen-maps<br />

ATTRACTIVITY <strong>OF</strong> CONNECTIONISM:<br />

NEURONAL PLAUSIBILITY<br />

¥ Similarity to biologiccal neural networks<br />

Ð Cells as processing units<br />

Ð Parallelity <strong>of</strong> processing<br />

Ð Learning as change <strong>of</strong> weights (synaptic strengths)<br />

Ð relatively few serial steps <strong>of</strong> processing (~100/sec in the brain)<br />

¥ Distributed representation<br />

Ð in case <strong>of</strong> lesions: “graceful degradation”<br />

¥ But in addition: Abstraction from given biological realisation<br />

ATTRACTIVITY <strong>OF</strong> CONNECTIONISM:<br />

<strong>COGNITIVE</strong> PLAUSIBILITY<br />

¥ Approach for representing the Microstructure <strong>of</strong> cognition<br />

¥ General principles are <strong>of</strong>fered for the solution <strong>of</strong> basic problems in theories <strong>of</strong> cognition, e.g.<br />

Ð Categorization (e.g., taste, color, smell)<br />

Ð Prototypicality effects, context phenomena<br />

Ð Face recognition<br />

[ 23 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Ð Content addressable memory<br />

¥ Defeating the “brittleness” <strong>of</strong> systems in AI<br />

EXAMPLE: NETTALK<br />

(SEJNOWSKI/ROSENBERG 1987)<br />

¥ System mapping written onto spoken language<br />

¥ Feedforward-net<br />

Ð input layer with 203 units<br />

¥ divided into 7 groups (seven text symbols are coded)<br />

¥ each with 29 units (letters + blank + punctuation)<br />

Ð hidden layer with 80 units<br />

Ð output layer with 26 units<br />

¥ each unit codes a phonetic feature, syllable or intonation boundary<br />

Ð levelwise connectivity (18320 connections)<br />

¥ Supervised learning (via backpropagation)<br />

PERFORMANCE <strong>OF</strong> NETTALK<br />

¥ Text with 1024 words<br />

¥ 50 passes (ca. 250000 training pairs)<br />

¥ After that:<br />

Ð 95% correctness for elements <strong>of</strong> the same text<br />

Ð 78% correctness for elements <strong>of</strong> a new 439-word-text<br />

¥ distributed representation and graceful degradation<br />

THEREFORE (CONNECTIONIST STANCE)<br />

Why do people have a particular kind <strong>of</strong> intelligent behavior?<br />

Explanation:<br />

¥ People have representations that involve simple processing units linked to each other by excitatory and<br />

inhibitory connections.<br />

¥ People have processes that spread activation between the units via their connections, as well as processes<br />

for modifying the connections<br />

¥ Applying spreading activation and learning to the units produces the behavior<br />

ADVANTAGES <strong>OF</strong> PDP<br />

¥ Speed and power (the parallelity aspect)<br />

¥ Functional persistence/fault tolerance (graceful degradation in case <strong>of</strong> damage)<br />

¥ Content addressability<br />

¥ Recovering information <strong>of</strong> a whole given only partial information<br />

¥ Categorization: Classifying new things as instances <strong>of</strong> known types<br />

¥ Recognition: Classifying input as being a certain known object (despite noise)<br />

¥ The „pop-out“ <strong>of</strong> relevant information (as opposed to exhaustive search)<br />

DIFFERENCES <strong>OF</strong> CONNECTIONIST MODELS TO THE BIOLOGICAL<br />

REALITY<br />

¥ Much lower number <strong>of</strong> neurons (10 2 -10 4 vs. 10 11 )<br />

¥ Much lower number <strong>of</strong> connections (~10 5 connections in a net vs. 10 3 -10 4 synapses <strong>of</strong> a neuron)<br />

¥ Only one parameter <strong>of</strong> synaptic coupling (“weight” vs. different neuro transmitters)<br />

¥ Amplitude modulation vs. frequency modulation<br />

¥ Violation <strong>of</strong> the locality principle for synapses<br />

[ 24 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

¥ No modelling <strong>of</strong> the synaptic structure <strong>of</strong> dendrites<br />

¥ No exact modelling <strong>of</strong> the temporal processes in neural circuits<br />

¥ Only homogeneous networks have been theoretically investigated<br />

¥ No consideration <strong>of</strong> chemical influences on neighbouring neurons<br />

¥ Biologically implausible learning rules (e.g. supervised learning)<br />

[ 25 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

ASPECTS <strong>OF</strong> (<strong>COGNITIVE</strong>) NEURO<strong>SCIENCE</strong><br />

recommended reading: W.H. Calvin, G.A. Ojeman (1994), Conversations with Neil´s Brain.<br />

http://weber.u.washington.edu/~wcalvin/bk7/bk7.htm<br />

QUESTIONS<br />

“Cognition is what the brain does”<br />

(S. Pinker, How the mind works)<br />

Ð How is information processed in the brain?<br />

¥ Neurophysiology<br />

Ð What kind <strong>of</strong> different structures are there in the brain and how are they related?<br />

¥ Neuroanatomy<br />

Ð How/where are specific cognitive structures/processes realized in the brain?<br />

¥ Cognitive Neuroscience<br />

Ð In which way can behavior (or higher cognitive functions) be explained by reference to brain<br />

structures/processes?<br />

¥ Neuropsychology<br />

MOTIVATION: THE VIEW FROM OUTSIDE THE BRAIN<br />

(STORIES, PHENOMENA, AND DISEASES)<br />

· Phrenology (Gall, Spurzheim): The view that ~35 brain functions can be localized in specific brain<br />

regions and that there is a direct relation <strong>of</strong> the intensity <strong>of</strong> a function and anatomical properties <strong>of</strong> the<br />

corresponding region (such that personal characteristics <strong>of</strong> a person can be judged by outward appearance<br />

<strong>of</strong> the skull).<br />

· Hemispheric differences:<br />

· Language and Aphasia<br />

· Broca and Wernicke (regions): The observation that specific brain regions relevant for language are left-hemispheric<br />

· Words and their context: Why aphasics laugh at the president´s speech (Sacks): People whose left hemisphere is damaged (i.e.,<br />

aphasics) may not understand what is said but may still be able to evaluate a person´s speech with respect to the overall visua l<br />

and/or acoustic properties; on the other hand, people whose right hemisphere is damaged may not understand jokes any more<br />

· What people recognize/say/do when their corpus callosum is (partially) damaged<br />

· Confabulation<br />

· The woman whose right hand had to prevent herself from strangling herself with the left hand (Ramachandran)<br />

· Damage to the right hemisphere may lead to<br />

· not attending to the left side (unilateral neglect)<br />

· not recognizing their own deficits (anosognosia)<br />

· Processing <strong>of</strong> global/local information: Global information is processed preferably in the right hemisphere<br />

· Delis/Bihrle: the observation that down syndrome (known for disproportionately impaired language ability relative to other<br />

cognitive functions) correlates with preserved global processing<br />

· Frontal damage:<br />

· The story <strong>of</strong> Phineas Gage ( http://www.toto.com/butler/fam_tree/p_gage.htm )<br />

· Occipital damage:<br />

· Blindsight (reacting correct to visual stimuli despite cortical blindness due to corresponding damage)<br />

· Parietal damage:<br />

· Spatial Disorientation,<br />

· Attentional failures (neglect, simultanagnosia): not being able to attend to the left side or to more than one object<br />

· ideomotor apraxia (left parietal): not being able to imagine an action<br />

· Temporal damage:<br />

· Seeing but not recognizing:<br />

· Visual Agnosia (The man who mistook his wife for a hat, Sacks),<br />

· Seeing but not believing: Capgras (Ramachandran): visually recognized close relatives are thought to be impostors<br />

· Loss <strong>of</strong> declarative memory:<br />

· Korsakow syndrome<br />

· The patient H.M.<br />

· Degenerative diseases:<br />

· Huntington<br />

· Parkinson<br />

[ 26 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

· Alzheimer<br />

· Thunderstorms in the brain: Epilepsy<br />

· Specific phenomena (Ramachandran): Processing with respect to specific cognitive functions may be quite<br />

localized<br />

· The woman who died laughing<br />

· The man who can´t subtract three from seventeen<br />

· „Mirror“ neurons (which fire if an ape either performs or sees a certain gesture/manual action)<br />

· Mind blindedness (Baron-Cohen)<br />

LEVELS <strong>OF</strong> DESCRIPTION<br />

BASIC NEUROANATOMY<br />

Nervous system is divided in<br />

¥ central and peripheral NS<br />

¥ Central NS (Brain and spinal cord)<br />

Ð Endhirn (Telencephalon)<br />

¥ Subpallium (Septum, Basal ganglia/Striatum) and Pallium (Cortex)<br />

Ð Zwischenhirn (Diencephalon)<br />

¥ Epithalamus, Thalamus, Hypothalamus<br />

+ pituitary gland (Hirnanhangdrüse)<br />

Ð Mittelhirn (Mesencephalon)<br />

¥ Mittelhirndach/Tectum (superior and inferior colliculi), Tegmentum<br />

Ð Hinterhirn (Metencephalon)<br />

¥ Cerebellum (Kleinhirn)<br />

Ð Nachhirn (Myelencephalon)<br />

Ð Spinal cord (Rückenmark)<br />

SOME FUNCTIONAL ASPECTS<br />

¥ Spinal cord<br />

Ð Control <strong>of</strong> simple reflexes<br />

¥ Medulla<br />

Ð Regulation <strong>of</strong> heartbeat and breathing<br />

¥ Cerebellum<br />

Ð Coordinaton <strong>of</strong> fine muscle movement, balance<br />

¥ Pons (Brücke)<br />

Ð Relaying <strong>of</strong> information between cerebral cortex and cerebellum<br />

¥ Reticular formation(Formatio reticularis)<br />

Ð involved in the control <strong>of</strong> arousal and in the sleeping and waking cycles<br />

¥ Locus coeruleus: Destruction leads to coma<br />

¥ Raphe nuclei: Destruction leads to insomnia<br />

[ 27 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

SOME FUNCTIONAL ASPECTS II<br />

¥ Hypothalamus<br />

Ð Important for the autonomic nervous system and the endocrine system<br />

Ð Besides projecting to other structures, influences activity <strong>of</strong> other neurons via neuromodulatory processes<br />

(hormone secretion)<br />

¥ Thalamus<br />

Ð Relay station between sensory areas and primary cortical sensory receiving areas<br />

Ð Connections from and to basal ganglia, cerebellum, cortex, and medial temporal lobe<br />

Ð Important substructure: pulvinar (-> attentional processing)<br />

¥ Basal ganglia( Caudate nucleus, Putamen, Globus pallidus )<br />

Ð Planning <strong>of</strong> movements, control <strong>of</strong> action<br />

THE LIMBIC SYSTEM<br />

¥ Hippocampus<br />

¥ Amygdala (Mandelkern)<br />

¥ Cingulate gyrus<br />

¥ Septum<br />

¥ Mammillary bodies<br />

¥ Nucleus anterior thalami<br />

Important for emotional expression, valuation <strong>of</strong> events and (declarative) memory<br />

LOCATING STRUCTURES IN THE BRAIN: SPATIAL NOTIONS<br />

Orientations<br />

Ð Rostral / anterior = towards the nose or front end<br />

Ð Caudal /posterior = towards the tail in animals or towards the feet in humans<br />

Ð Dorsal = the back side<br />

Ð Ventral = the belly side<br />

Ð Lateral = toward the outside and away from the midline<br />

Ð Medial = toward the midline and away from the periphery<br />

Views<br />

Ð Sagittal view (from the side)<br />

Ð Transverse view (from above/below along the rostral/caudal dimension)<br />

Ð Horizontal (from above/below with respect to the ground, when the subject is standing)<br />

Ð Coronal view (from front/back with respect to the forebrain)<br />

IMPORTANT SPATIAL DIVISIONS<br />

Brain: Two halves, connected by the Corpus Callosum<br />

¥ Division <strong>of</strong> the cerebral cortex (Großhirnrinde ):<br />

Ð lateral Pallium (Paleocortex)<br />

Ð medial Pallium (Archicortex)<br />

Ð dorsal Pallium (Neocortex or Isocortex)<br />

¥ Division <strong>of</strong> the Isocortex:<br />

Ð Frontal lobe (Stirnlappen)<br />

Ð Parietal lobe (Scheitellappen)<br />

Ð Temporal lobe (Schläfenlappen)<br />

Ð Occipital lobe (Hinterhauptslappen)<br />

¥ Cytoarchitectonic divisions <strong>of</strong> the brain: 50 Brodman areas (Hirnrindenfelder)<br />

[ 28 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

ROUGH FUNCTIONAL DIVISIONS <strong>OF</strong> ISOCORTEX<br />

¥ Frontal lobe: Motor areas (planning and execution <strong>of</strong> movements)<br />

Ð prefrontal cortex: processing <strong>of</strong> higher cognitive functions<br />

¥ Parietal lobe: Somatosensory areas<br />

Ð attentional and spatial processing<br />

¥ Temporal lobe:<br />

Ð Auditory processing, object recognition<br />

¥ Occipital lobe: Visual processing<br />

Ð Ventral pathway to the temporal lobe („what“, object processing)<br />

Ð Dorsal pathway to the parietal lobe („where“, spatial processing)<br />

¥ Association cortex<br />

ISOCORTEX<br />

¥ Thickness:<br />

Ð 2-5mm (Æ 3mm)(grey matter)<br />

¥ Surface area:<br />

Ð 2200-2400 cm 2<br />

¥ Highly folded surface<br />

Ð Gyri (crowns <strong>of</strong> the folded tissue)<br />

Ð Sulci (infoldings)<br />

¥ Consists <strong>of</strong> six layers<br />

CELLS <strong>OF</strong> THE NERVOUS SYSTEM<br />

¥ Glia cells<br />

¥ Neurons<br />

Ð Consist <strong>of</strong><br />

¥ Dendritic tree (postsynaptic), in part with spines (Dornfortsätzen )<br />

¥ Soma (cell body )<br />

¥ Axon (presynaptic)<br />

Ð Up to 1m long<br />

Ð Contacts to up to 10000 other neurons via synapses (ø1000)<br />

Ð Transmission <strong>of</strong> action potentials (spikes) with ~100 m /sec<br />

Ð Different types<br />

Ð Different arrangement<br />

¥ in layers/lamina (e.g. in the cortex)<br />

Ð in mini columns (consisting <strong>of</strong> ca. 100 Neuronen), orthogonal to cortex surface, and macro columns (consisting <strong>of</strong> ca.<br />

300 mini columns)<br />

¥ in groups (-> nuclei)<br />

SYNAPSES<br />

¥ electrical synapses<br />

Ð electrical activity is transmitted directly (cells being very close to one another)<br />

Ð via plasma bridges (gap junctions)<br />

¥ chemical synapses<br />

Ð Presynapse, Postsynapse, synaptic cleft<br />

Ð transmission by transmitters<br />

¥ excitatory:<br />

Ð Acetylcholin, Noradrenalin, Serotonin, Dopamin, Glutamat<br />

¥ inhibitory:<br />

Ð Gamma-Aminobuttersäure (GABA), Glycin<br />

[ 29 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

EXPERIMENTAL TECHNIQUES FOR THE INVESTIGATION <strong>OF</strong> NEURAL<br />

STRUCTURES<br />

¥ Lesion studies<br />

Ð Destruction <strong>of</strong> selected cells and observation <strong>of</strong> degeneration in other areas as a result <strong>of</strong> the lesion<br />

¥ Labeling procedures<br />

Ð Observation <strong>of</strong> the transportation <strong>of</strong> labeled chemicals, i.e.,<br />

Ð <strong>of</strong> anterograde transportation (by autoradiographic tracing)<br />

Ð <strong>of</strong> retrograde transportation (from synaptic terminals back to the cell body)<br />

¥ Single cell recording<br />

Ð Observation whether or when a cell fires (by recording the electrical activity with microelectrodes)<br />

RESULTS <strong>OF</strong> MICROINVESTIGATIONS<br />

¥ Discovery <strong>of</strong> functional pathways<br />

Ð Transport <strong>of</strong> specific information through different brain areas<br />

¥ Discovery <strong>of</strong> columnar organization<br />

Ð Vertical organisation <strong>of</strong> cells in the cortex<br />

Ð Microcolums: Local processing <strong>of</strong>, e.g., orientation-specific or eye-specific information in the visual<br />

system<br />

¥ Discovery <strong>of</strong> topographic maps<br />

Ð Areas dedicated to the processing <strong>of</strong> specific information<br />

FUNCTIONAL NEUROIMAGING (FUNKTIONELLE BILDGEBENDE VERFAHREN):<br />

METABOLIC TECHNIQUES<br />

Emission Tomography<br />

Measuring brain activity by assessing regional cerebral blood flow (rCBF)<br />

¥ Single Photon Emission Tomography (SPECT)<br />

Ð Injection <strong>of</strong> HMPAO or inhaling air-xenon mixture<br />

¥ Positron Emission Tomography (PET)<br />

Ð Injection <strong>of</strong> labeled substances (e.g. water)<br />

¥ Functional Magnetic Resonance Imaging (fMRI)<br />

Ð Imaging <strong>of</strong> changes in the level <strong>of</strong> blood oxygenation<br />

FUNCTIONAL NEUROIMAGING:<br />

ELECTROPHYSIOLOGICAL TECHNIQUES<br />

¥ Electroencephalogram (EEG)<br />

Ð Detection <strong>of</strong> different rhythms <strong>of</strong> electrical activity (alpha, beta, theta etc.)<br />

¥ Event-Related Potentials (ERPs, Ereignis-korrelierte Potentiale)<br />

Ð Consist <strong>of</strong> a series <strong>of</strong> positive and negative changes from a baseline<br />

Ð Properties <strong>of</strong> the ERP (given the performance <strong>of</strong> a cognitive event) are analyzed<br />

¥ Probe-Evoked Potentials<br />

Ð How does performing a (cognitive) task influence a probe-dependent potential?<br />

¥ Magnetoencephalogram (MEG)<br />

Ð Detection <strong>of</strong> magnetic fields induced by active neurons , by a superconducting quantum interference device (SQUID)<br />

Ð Evoked fields (EF) or magnetic event-related fields (MEF)<br />

[ 30 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

BRAINPART FUNCTIONS<br />

¥ Hippocampus: Anchoring <strong>of</strong> new information in declarative memory<br />

¥ Amygdala: emotional tagging <strong>of</strong> events (somatic markers)<br />

¥ Occipital cortex: primary visual system<br />

¥ Temporal cortex: object recognition<br />

¥ Parietal cortex: spatial orientation, visuo-spatial attention<br />

¥ Prefrontal cortex:<br />

Ð voluntary planning and acting (~ lateral)<br />

Ð personality / social behavior (~ ventromedial)<br />

MALFUNCTIONS <strong>OF</strong> THE BRAIN<br />

¥ Agnosia: not being able to recognize<br />

Ð objects/forms, colors, faces (prosopagnosia)<br />

Ð the own deficits (anosognosia)<br />

Ð more than one object at a time (simultanagnosia )<br />

¥ Apraxia: not being able to act<br />

Ð Ideomotor apraxia: no voluntary movements (left parietal damage)<br />

¥ Anomia: not being able to name things<br />

¥ Alexia: not being able to read<br />

¥ Amusia: not being able to recognize melodies<br />

¥ Aphasia: language-related dysfunctions<br />

Ð Broca- (motoric)<br />

Ð Wernecke- (semantic)<br />

¥ Amnesia: not being able to memorize<br />

¥ Neglect: not being able to attend to<br />

EMOTIONS AND FEELINGS<br />

-> DAMASIO 1994, LEDOUX 1996<br />

¥ Emotions<br />

Ð Involve necessarily the amygdala and other parts <strong>of</strong> the limbic system<br />

Ð Can be induced by external stimuli or internal representations (e.g., fear vs. anxiety)<br />

Ð Correspond to activities in different emotional systems<br />

Ð Distinction <strong>of</strong> primary and secondary emotions<br />

¥ Primary e.: depend on limbic system circuitry (especially amygdala and anterior cingulate (e.g. stimulus-driven fear)<br />

¥ Secondary e.: based on systematic connections between categories <strong>of</strong> objects and situations, on the one hand, and primary<br />

emotions, on the other hand (involves also prefrontal and somatosensory cortices)<br />

¥ Emotional feelings<br />

Ð Correspond to being consciously aware <strong>of</strong> having an emotion<br />

¥ Somatic markers:<br />

Ð „gut feelings“ that result from emotion memory recall („how it feels“ if something happens)<br />

[ 31 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

VISUAL PERCEPTION AND ATTENTION<br />

VISION: THE PROBLEM<br />

¥ How do we attain constant visual experiences/knowledge about a structured three-dimensional world<br />

consisting <strong>of</strong> objects, given that<br />

Ð the input is solely the intensity <strong>of</strong> incoming light (luminance) in a certain range <strong>of</strong> wavelengths, projected onto a<br />

discontinuous two-dimensional surface (the retinae <strong>of</strong> both eyes)<br />

Ð the perceiving subject can be in motion<br />

Ð the perceived world may change continuously (e.g., moving objects)<br />

Ð a large number <strong>of</strong> goals relevant for behaviour must be fulfilled simultaneously<br />

Ð the ressources (memory, processing time) are limited<br />

ROOTS <strong>OF</strong> RESEARCH IN VISUAL PERCEPTION<br />

Helmholtz:<br />

depth clues<br />

Gestalt psychology (Wertheimer, Köhler, K<strong>of</strong>fka):<br />

Gestalt principles<br />

Gibson:<br />

ecological theory <strong>of</strong> vision, „direct perception“, extraction <strong>of</strong> invariants<br />

Cybernetics:<br />

Coupling <strong>of</strong> perception and action (control)<br />

Neisser:<br />

Preattentive/perceptual vs. attentive/cognitive<br />

Hubel/Wiesel:<br />

„detectors“, hypercolumns<br />

Marr:<br />

Computational vision<br />

Aloimonos:<br />

“Active vision“<br />

NEUROPHYSIOLOGICAL ASPECTS:<br />

FROM THE RETINA TO THE VISUAL CORTEX<br />

¥ Photoreceptors, two types, distributed differently on the retina:<br />

Ð Cones (Zäpfchen)<br />

¥ Predominate in and around fovea<br />

¥ Require more intensive light<br />

¥ Essential for color vision<br />

¥ Three types <strong>of</strong> cones („blue“ (short wavelengths), „green“ (middle), „red“ (long)) with overlapping areas <strong>of</strong> response<br />

distribution<br />

Ð Rods (Stäbchen)<br />

¥ Percentage <strong>of</strong> rods increases towards periphery <strong>of</strong> retina<br />

¥ Sensitive to low levels <strong>of</strong> stimulation<br />

¥ Slow regeneration <strong>of</strong> photopigments<br />

¥ Interneurons<br />

Ð Receive activations from receptors, excitatory or inhibitory influence on retinal ganglion cells<br />

NEUROPHYSIOLOGICAL ASPECTS:<br />

FROM THE RETINA TO THE VISUAL CORTEX II<br />

¥ Retinal ganglion cells with concentric receptive fields<br />

Ð [receptive field: area on the retina from which a cell receives activation]<br />

Ð Two types <strong>of</strong> cells<br />

¥ Parvocellular („color“ sensitive, high spatial resolution, less contrast sensitive, slow transmission <strong>of</strong> activation) [P system]<br />

¥ Magnocellular (large receptive fields) [M system]<br />

[ 32 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Ð Antagonistic behavior<br />

¥ On-center/<strong>of</strong>f-surround-cells (react to bright spots in the center)<br />

¥ Off-center/on-surround-cells (react to dark spots)<br />

¥ Red-green and yellow-blue color antagonism<br />

Ð Project via the optic nerve<br />

¥ To the lateral geniculate nucleus (LGN) [~90% <strong>of</strong> the fibers]<br />

¥ To the superior colliculus<br />

NEUROPHYSIOLOGICAL ASPECTS:<br />

FROM THE RETINA TO THE VISUAL CORTEX III<br />

¥ The nasal branch <strong>of</strong> each eyes´optic nerve projects to the contralateral brain half, crossing at the optic<br />

chiasm<br />

Ð Each half <strong>of</strong> the visual field is projected to the contralateral hemisphere!<br />

¥ Seitlicher Kniehöcker (corpus geniculatum laterale, LGN)<br />

Ð Six layers which alternately receive input from different eyes so that<br />

Ð corresponding receptive fields <strong>of</strong> both eyes are adjacent in LGN [here comes together what belongs together]<br />

Ð Fixed order <strong>of</strong> projection:<br />

¥ Ipsilateral retina -> layers 2, 3, 5<br />

¥ Contralateral retina -> layers 1, 4, 6<br />

¥ Layers 1 and 2 contain the magnocellular neurons<br />

Ð All layers project to layer 4 [<strong>of</strong> six cortical layers] <strong>of</strong> region V1 in primary visual cortex<br />

NEUROPHYSIOLOGICAL ASPECTS:<br />

FROM THE RETINA TO THE VISUAL CORTEX IV<br />

¥ Streifencortex (striate cortex, V1, area 17)<br />

Ð Blobs: regions <strong>of</strong> high activityin layer 2 and 3 <strong>of</strong> V1<br />

¥ P cells project to blobs<br />

¥ M cells project to complementary interblob regions<br />

Ð Hypercolumnar organisation:<br />

¥ Alternating adjacent left eye/right eye information in layer 4 [ocular dominance colums]<br />

¥ Within them, smaller colums <strong>of</strong> cells react to stimuli with a certain orientation (steps <strong>of</strong> 15°) [orientation colums]<br />

FURTHER ASPECTS <strong>OF</strong> VISUAL PERCEPTION<br />

¥ Main functions <strong>of</strong> other visual areas<br />

Ð V2: binokular reaction, V3: Form and depth, but not color<br />

Ð V4: Color perception, V5: Motion perception, V6: Form perception<br />

¥ Types <strong>of</strong> cells:<br />

¥ Simple cells: mostly reaction to edges (position specific, in LGN)<br />

¥ Complex cells: react to contours <strong>of</strong> edges (not position specific)<br />

¥ Hypercomplex cells: react to corners and angles<br />

¥ Object recognition is assumed to derive from collective activation in different areas („feature maps“)<br />

Ð Ensemble hypothesis vs. „grandmother cell hypothesis“<br />

¥ (the view that there are even more complex, „gnostic“ cells reacting to objects <strong>of</strong> specific types)<br />

ATTENTION<br />

"Everyone knows what attention is. It is the taking possession by the mind, in clear and vivid form, <strong>of</strong> one out <strong>of</strong><br />

what seems several simultaneously possible objects or trains <strong>of</strong> thought".<br />

William James<br />

But:<br />

"In reviewing the literature on attention we were struck by several observations. One was a widespread reluctance<br />

to define attention. Another was the ease with which competing theories can accommodate the same empirical<br />

phenomena. A third observation was the consistent appeal to some intelligent force or agent in explanations <strong>of</strong><br />

attentional phenomena. [...] As a consequence , the more we read, the more bewildered we became"<br />

(Johnston/Dark 1986:43)<br />

[ 33 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

3 WAYS TO VIEW „ATTENTION“<br />

¥ As a process<br />

Ð managing the (limited) ressources needed for cognitive processes (-> control)<br />

Ð regulating the attentiveness to stimuli (-> alertness)<br />

Ð selecting relevant information (-> filter)<br />

¥ from different modalities (visuell vs. auditiv)<br />

¥ from different spatial locations<br />

¥ from different features (e.g., color vs. form)<br />

METAPHORS <strong>OF</strong> SELECTIVE ATTENTION<br />

¥ Attention as a<br />

Ð Spotlight (highlighting regions)<br />

Ð Zoom lens (focused vs. distributed attention)<br />

Ð Gradient (no sharp boundaries <strong>of</strong> the attended region)<br />

Ð Glue (attention is necessary for conjoining features)<br />

FEATURE INTEGRATION THEORY (TREISMAN)<br />

NETWORKS <strong>OF</strong> ATTENTION<br />

¥ Visuo-spatial orientating<br />

Ð DISENGAGE-mechanism (parietal Cortex)<br />

Ð MOVE-mechanism (Superior Colliculus)<br />

Ð ENGAGE (Pulvinar (Thalamus))<br />

¥ Executive Network<br />

(anterior cyngulate gyrus)<br />

¥ Vigilance network (right parietal and right frontal lobes)<br />

[ 34 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

APPENDIX:DER SCHRIFTSTELLER UND DIE VIELEN PROGRAMMIERER<br />

EIN MODERNES MÄRCHEN (?)<br />

erzŠhlt von <strong>Kai</strong>-<strong>Uwe</strong> <strong>Carstensen</strong>-Grimm<br />

Irgendwann einmal, in nicht allzu ferner Zukunft oder Vergangenheit, gibt es einen ganz<br />

au§ergewšhnlichen Romanschriftsteller. Au§ergewšhnlich deshalb, weil er nicht nur Romane verfa§t,<br />

sondern sich auch Gedanken darŸber macht, wie dies geschieht. Kein Mittel lŠ§t er unversucht, um<br />

herauszufinden, durch welche Prinzipien sein Tun geleitet wird. Schlie§lich versucht er sogar,<br />

Computerprogramme zu entwickeln, in denen sich seine natŸrliche schriftstellerische Kompetenz<br />

widerspiegeln soll, sprich, die selbst Romane schreiben kšnnen.<br />

Allerdings Ð er bleibt nicht der einzige, der das versucht. FŸr einige scheint es, aus verschiedenen<br />

GrŸnden, ebenfalls erstrebenswert, ein Schriftstellerei-Programm zu besitzen. Eines Tages gibt es solch ein<br />

Programm. Es ist ein Ideales Programm zum Schreiben (IPS), das seinen FŠhigkeiten nahe, in mancher<br />

Hinsicht sogar gleich kommt. Und so macht sich auch unser Schriftsteller auf, um es sich anzuschauen. Kaum<br />

hat er jedoch einen Blick auf Dokumentation und Programmcode des IPS geworfen, macht sich in ihm eine<br />

gro§e EnttŠuschung breit: Keine Kommentarzeile in dem ganzen Programm handelt von Schriftstellerei;<br />

stattdessen findet er nur Verweise auf BŸcher Ÿber Statistik und Differentialgleichungen. Und wie er genauer<br />

nachfragt, so bringt ihn die Unkenntnis der Programmierer Ÿber die vielfŠltigen Aspekte der Schriftstellerei<br />

ebenso zum Schaudern wie seine allmorgendliche kalte Dusche. "Wozu der analytische Aufwand", sagen sie<br />

nur, "unser Programm lernt alles von selbst."<br />

Insbesondere darŸber Šrgert sich unser Schriftsteller aber. Schlie§lich ist er der Fachmann fŸr<br />

Schriftstellerei. Wo genau stehen denn dort so wesentliche Wissensbausteine wie da§ man erst eine Idee<br />

haben mu§, bevor man Ÿberhaupt zu schreiben anfŠngt? Er selbst hingegen hat schon Programme entworfen,<br />

in denen Regeln wie "Wenn Du eine Idee hast, dann verfolge sie und arbeite einen Plot aus" eingebaut<br />

gewesen sind. Gro§e und komplexe Programme, die von vielen als "wundersam" angesehen worden sind (ob<br />

ihrer seltsamen Symbole wie z.B. '"' und '$'). All diese Programme haben aber nicht so richtig funktioniert.<br />

Weil er alles ganz genau hat hinschreiben mŸssen, gab es immer irgendetwas, das er nicht berŸcksichtigt hat.<br />

Vor allem ist ihm bis zuletzt nicht klar gewesen, was eigentlich eine 'Idee' ist, die man verfolgen mu§, und<br />

was ihr in seinen wundersamen Programmen entsprechen sollte.<br />

"Idee", denkt er eines Abends, den Kopf in die Ÿber seinem Laptop (auf dem das IPS lŠuft)<br />

verschrŠnkten Arme gelegt, "Idee, Idee, Idee". Und schon schlŠft er, mŸde vom langen Suchen und enttŠuscht<br />

Ÿber das, was er gefunden hat, ein. Die Gedanken verschwimmen, und plštzlich erscheint ihm eine Fee. "Du<br />

hast einen Wunsch frei", denkt er, ohne die Wšrter zu hšren. SelbstverstŠndlich wŸnscht er sich nichts<br />

sehnlicher als zu wissen, wer denn nun recht hat mit seiner Herangehensweise an die Schriftstellerei, er oder<br />

die Programmierer (so eine Frage kann wirklich nur in einem MŠrchen beantwortet werden).<br />

[ 35 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

Als er erwacht, flimmern die folgenden Zeilen Ÿber das LCD-Display seines Notebooks:<br />

"Du mu§t die Forschung anderer tolerieren"<br />

"Du mu§t die Forschung anderer respektieren"<br />

"Du mu§t bei der Bewertung Deiner oder anderer Forschung alle relevanten Aspekte in Betracht ziehen"<br />

"Du mu§t Latein lernen"<br />

"Nec vitae, nec universitatis, sed posteritatis scientiae pervestigamus"<br />

Erstaunt stellt er fest, da§ ihm všllig klar ist, was diese SŠtze bedeuten (und da§ sich aus ihnen die Antwort<br />

auf seine Frage ableiten lŠ§t). "Das wird nicht jedem so gehen", denkt er.<br />

"Ich war eindeutig intolerant, gegenŸber dem Erfolg eines nicht nur kŸnstlichen, sondern auch<br />

undurchsichtigen schriftstellernden Systems" (tatsŠchlich war es diese besondere Mischung, die in ihm ein<br />

urtŸmliches Unbehagen hervorgerufen hat).<br />

"Und ich habe die IPS-Schriftstellerei nicht als solche anerkannt und respektiert. Wie borniert",<br />

tadelt er sich selbst. Schlie§lich lŠuft das Programm doch. Und da§ es bei der KomplexitŠt des Gegenstands<br />

nicht trivial sein kann, ist fŸr ihn nun <strong>of</strong>fensichtlich. Wo war also das Problem? Es war ihm tatsŠchlich<br />

entfallen. Ach ja, die Bewertung.<br />

Da§ jeder seinen eigenen Ansatz zu ungunsten anderer bevorzugt und hervorhebt, glaubt er schon<br />

immer gewu§t zu haben. Deshalb auch sein Disput mit den Programmierern. Er erinnert sich der kontroversen<br />

Diskussionen, der beiderseitigen Arroganz und gegenseitigen Ignoranz. Schmunzelnd denkt er daran zurŸck,<br />

da§ er in den letzten Jahren zuerst insgeheim und dann immer <strong>of</strong>fener ausgelacht wurde, ebenso wie man ihm<br />

zuletzt mit einem hŠmischen Grinsen (was er zu Recht als "na, willst Du jetzt endlich in Rente gehen?"<br />

interpretierte) das IPS Ÿberreicht hat. "Da haben wir wohl alle etwas Ÿbersehen", fŠllt ihm angesichts der<br />

Tatsache ein, da§ es sicherlich nicht darum gegangen sein konnte, das erste oder beste Schriftsteller-System<br />

zu bauen. Dies wollte er nicht einmal den Programmierern unterstellen. Schlie§lich orientieren die sich schon<br />

lange an biologischen Vorbildern. Unser Schriftsteller kennt sich da zugegebenerma§en nicht aus; ihm fallen<br />

nur Schlagworte ein: neuronal, genetisch, Virus, KŠfer (die er allerdings nicht zuordnen kann).<br />

"Wie konnte ich Ÿbersehen, da§ bei den unterschiedlichen Perspektiven auf und Herangehensweisen<br />

an die Schriftstellerei gar keine Vergleichbarkeit gegeben, also auch keine einheitliche Bewertung mšglich<br />

ist? ", fragt er sich verwundert. "Hey, ich will beschreiben und sie wollen konstruieren; ich will explizieren,<br />

und sie wollen generieren; ich will Kontrolle, sie wollen Selbstorganisation. Kein Wunder, da§ kaum eine<br />

gemeinsame Basis vorhanden ist." Kein Wunder auch, so wird ihm bewu§t, da§ er so viele Schwierigkeiten<br />

hatte bei dem Versuch, ein System zu bauen.<br />

"Das mit dem Latein lernen ist wohl ein Scherz", denkt er dann, "aber da§ wir fŸr die Nachwelt<br />

forschen, hatte ich tatsŠchlich vergessen." Hierzu gehšrt aber unbedingt eine auf prŠziser Analyse basierende<br />

explizite Wissensvermittlung. Denn was wŠre wohl, wenn er seinen Studenten im Theorieteil seines Kurses<br />

'Creative Writing:Theory and Praxis' einige Romane mit den Worten 'Lest dies und ihr wi§t, was<br />

Schriftstellerei ist' Ÿbergeben oder mit Šhnlich suggestiven Worten das IPS starten wŸrde?<br />

So sitzt er da, unser Schriftsteller, den Kopf sinnierend auf die rechte Hand gestŸtzt, und denkt an all<br />

die, die schon immer behauptet haben, da§ man Programmiererei und Schriftstellerei zwar nicht miteinander<br />

vereinbaren, aber doch immerhin unter- oder nebeneinander akzeptieren kann. "Wie gut hŠtten wir<br />

zusammenarbeiten kšnnen", grŸbelt er, einen wichtigen Aspekt hinzudenkend, "jeder hŠtte vom anderen<br />

lernen, von den Erkenntnissen des anderen pr<strong>of</strong>itieren kšnnen." Schlie§lich ist er Ñbei aller AnerkennungÑ<br />

keineswegs uneingeschrŠnkt zufrieden mit dem IPS. S<strong>of</strong>ort kommen ihm daher einige bedeutungsschwere<br />

WortungetŸme wie 'Interpr<strong>of</strong>essionelle Kollaboration' oder 'Synergistische Progression' in den Sinn.<br />

"Praktisch, unter solchen cover terms subsummierbar zu sein", so sein vorlŠufiges Fazit, "aber es<br />

wird schwierig sein, allen Beteiligten ihre Bedeutung so zu vermitteln, da§ der Sinn und Zweck des ganzen<br />

Ÿber kurz oder lang nicht doch wieder in Frage gestellt wird und es zu denselben HahnenkŠmpfen kommt wie<br />

gerade gehabt. Na, und vom ErklŠrungsbedarf der Unbeteiligten mal ganz zu schweigen".<br />

Ganz plštzlich, als hŠtten diese †berlegungen eine Sperre beseitigt, kommt ihm die Idee zu einem<br />

neuen Roman. Ohne lange zu Ÿberlegen beginnt er mit der Arbeit. Wenn er seine Ideen ausgearbeitet hat und<br />

der Roman geschrieben ist (wie lange hŠtte es wohl gedauert, die entsprechenden Parameterwerte des IPS zu<br />

setzen?), dann will er wieder daran gehen herauszufinden, was eigentlich eine 'Idee' ist. Dazu wird er<br />

vielleicht ein weiteres wundersames Programm schreiben (ohne da§ er den Anspruch hat, da§ es jemals<br />

perfekt funktionieren wird). Jetzt wei§ er schlie§lich, in welcher Hinsicht eine solche Vorgehensweise als<br />

[ 36 ]


Foundations <strong>of</strong> Cognitive Science <strong>Carstensen</strong> 01.03.1999<br />

lobenswert, und in welcher sie als lŠcherlich zu bewerten ist. Reden will er z.B., mit Leuten (Kollegen,<br />

Interessierten, Nachkommen), die an Schriftstellerei interessiert sind, und nicht an Programmiererei, so<br />

schwierig und wichtig die auch immer ist. Mit diesen Leuten wird er sich dann vor seinen Laptop setzen, das<br />

Icon des IPS anklicken (es zeigt eine Vielzahl kleiner schwarzer Kisten, die in einer Art Netz miteinander<br />

verbunden sind) und ihnen beschreiben und gleichzeitig erklŠren, was gerade passiert. Wenn sie Fragen zu<br />

dem Programm selbst haben (was unweigerlich passieren wird), wird er sie an die Programmierer verweisen.<br />

Mit einigen von diesen hat er nŠmlich mittlerweile ein ÔInterdisziplinŠres Institut fŸr SchriftstellereiÕ<br />

gegrŸndet. Und selbstverstŠndlich gibt es einen Studiengang ÔComputational Creative WritingÕ, in dem seine<br />

Studenten auch lernen, IPSe zu entwickeln. Klar, da§ sie damit eine optimale Ausbildung erhalten und da§<br />

sich Ihnen dadurch ganz neue Berufsperspektiven eršffnen (auch wenn es immer wieder schwierig ist, diese<br />

neuen QualitŠten nach au§en hin angemessen darzustellen).<br />

Und wenn er schon gestorben ist, werden ihm die Leute noch dankbar dafŸr sein, da§ sie Konzepte<br />

wie 'Idee' und ÔPlotÕ nicht immer wieder neu entdecken mŸssen.<br />

[ 37 ]

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!