A HYBRID MODEL OF REASONING BY ANALOGY

of connectivity of the element in question with all other elements of that context. This criterion is
based on the reasoner's implicit assumption that things that happen simultaneously are probably
causally related (which forces a tendency to link co-occuring events or features). This is not always
true, but it provides a criterion for relevance that is both dynamic and easy to test. I call this
associative relevance.
Why do we need both types of relevance? In an artificial situation where only the problem
description forms the context, e.g. where the list of all possible actions and/or instruments is
provided for in the problem description, it is possible, at least theoretically, to test the causal
relevance of each action or instrument. In a realistic context, however, the reasoner has to elicit the
possible actions from memory and the possible instruments from the real-world environment. Thus
it is impossible simply to test all the possibilities since explicit knowledge about most (or all) of
them will be unavailable a priori.
People, however, have an intuitive idea of the important aspects of a situation even before there is
any possibility of formal analysis of the situation and sometimes even before the goals are defined
or made explicit. In other words, the reasoner will know that a particular element is somehow
connected to other pieces of knowledge, presently considered as relevant, without being able to
report the exact nature of these connections or a particular path followed. In this way associative
relevance can be considered as a preliminary and approximate estimation of the relevance of all
memory elements to the whole context. Only the ones estimated as most relevant are eventually
tested for their causal relevance, i.e. for their particular relevance to the goal of the reasoner.
Let us recall some famous examples where the particular external context has reportedly played a
crucial role in human reasoning:
- Archimedes discovered his law in the bathroom seeing the water overflowing the bath when
he entered it;
- seeing an apple falling from a tree gave Newton inspiration for his theory of gravity;
- John Atanassov (one of the inventors of digital computers) decided to use electronic tubes
for his computer when he saw a row of bottles in a bar.
In all those cases it was the particular external context which made the corresponding memory
elements associatively relevant and only then a more formal analysis elucidated the causal relations
(if any) between the perceived event and the goal of the reasoners. Formal analysis of all events
perceived from the environment was definitely not performed; only those "felt" to be relevant were
formally analyzed.
On the other hand, the priming effects demonstrated in our experiments manifest the influence of
the particular internal context on the associative relevance of memory elements and thus on the line
of reasoning.
Differences between causal and associative rele vance. The two types of relevance considered above
seem to have very different properties (Table 3). For example, causal relevance appears to be more
static since it depends on the problem goal and is thus highly connected to the problem itself, i.e.
whenever we present one and the same problem, the same elements are expected to be considered
important as they will always be connected to the goal of the problem. 1 On the contrary, associative
relevance is highly dynamic and variable because of the continuously developing external and
internal contexts (note that it is impossible to replicate any particular context). This throws light on
the causes for the variability of human problem solving behavior and in particular - for the priming
effects demonstrated in section 2.2.
1
However, since the finding of a causal path can depend on its associative relevance, causal
relevance can also be considered as dynamic and context-dependent.