Bachelor's Thesis - Christian Hoffmann - Cognitive Science ...

Universität Osnabrück 

Cognitive Science Bachelor Program 

Bachelor’s Thesis 

The influence of prepositions on 

attention during the processing of 

referentially ambiguous sentences 

Christian Hoffmann 

September 29, 2009 

Supervisors: 

Prof. Dr. Peter Bosch 

Computational Linguistics Working Group, 

Institute of Cognitive Science 

University of Osnabrück 

Germany 

Prof. Peter König 

Neurobiopsychology Working Group, 

Institute of Cognitive Science 

University of Osnabrück 

Germany

Abstract 

The present study uses eye-tracking to investigate the role of prepo- 

sitions in resolving referential ambiguities. Playmobil sceneries and 

prerecorded sentences were presented and fixation behaviour on possi- 

ble referents of the discourse was recorded. 

The sentences investigated contained a subject NP whose head NP 

refers to two objects in the scenery modified by a PP that uniquely 

identified the referential object of the subject NP. The hypothesis was 

that when a preposition can uniquely identify an object in a scenery 

then the fixation probability of said object should rise already prior 

to the processing of the following prepositional NP. If the preposition 

does not uniquely identify an object, then the fixation probability of 

the referential object should only rise after processing the prepositional 

NP. The results seem to imply that there are no major differences in 

fixation probabilities connected to the prepositions. Bootstrapping 

analyses revealed that there are some significant differences, namely 

more fixations on the target in the ambiguous block. 

2

Contents 

1 Introduction 4 

2 Methods 8 

2.1 Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

2.2 Experimental stimuli . . . . . . . . . . . . . . . . . . . . . . . 8 

2.2.1 Visual stimuli . . . . . . . . . . . . . . . . . . . . . . . 10 

2.2.2 Auditory stimuli . . . . . . . . . . . . . . . . . . . . . 11 

2.2.3 Filler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

2.3 Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

2.4 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

2.5 Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

2.5.1 Regions of Interest . . . . . . . . . . . . . . . . . . . . 16 

2.5.2 Statistics . . . . . . . . . . . . . . . . . . . . . . . . . 16 

3 Results 19 

3.1 Subject Validity . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

3.2 Stimulus Validity . . . . . . . . . . . . . . . . . . . . . . . . . 19 

3.3 Time Course of Fixations . . . . . . . . . . . . . . . . . . . . 22 

3.4 Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

4 Discussion 28 

References 30 

A Visual Stimuli 31 

B Auditory Stimuli 33 

C Fillers - Visual 36 

D Fillers - Auditory 39 

E Statistics 41 

F Complementary Figures 43 

G Consent Sheet 48 

3

1 Introduction 

“Linguistic theory [...] may inform a theory of language processing. And 

observations about language processing may inform linguistic theory, i.e. 

support or disconfirm its predictions.”(Bosch (2009)) 

In the last few decades, interest in neuroscientific methods for analyzing 

linguistic processing has been on the rise. More and more research areas 

develop which incorporate paradigms and methods from both theoretical 

linguistics and neuroscience. 

Specifically the method of analyzing the gaze of people, known as eye- 

tracking, generated major interest in the linguistic community, due to the 

seminal paper of Cooper (1974), who showed that people fixate elements of 

a visual scene that had a connection to spoken language stimuli to which 

they listened at the same time. Many researchers focused on eye-tracking 

as a method to investigate ongoing linguistic processing. 

As Michael K. Tanenhaus puts it, “eye movements provide a continu- 

ous measure of spoken-language processing in which the response is closely 

time locked to the input without interrupting the speech stream. [...] The 

presence of a visual world makes it possible to ask questions about real- 

time interpretation.” Tanenhaus et al. (2000) Eye-tracking has been used 

before to investigate topics like overt attention and its modulation, reading 

behaviour (in particular the implications on online lexical access and syn- 

tactic processing, e.g. garden-path sentences) and others. For an overview, 

see Rayner (1998). 

Of most importance for the understanding of the findings from Tanen- 

haus, Rayner, Cooper, Chalmers and others are the visual world paradigm 

and the linking hypothesis. The visual world paradigm serves as a blueprint 

for psycholinguistic experiments. Basically, subjects fixations are measured 

as they interact in some fashion with a visual scenery according to tasks pro- 

posed by the experimenter, thereby integrating linguistic and non-linguistic 

knowledge and action. The linking hypothesis proposes an intrinsic connec- 

tion between eye movements and lexical access, making it possible to derive 

knowledge about linguistic processing from analyzing non-linguistic actions. 

In his overview (Tanenhaus et al. (2000)) Tanenhaus shows that visual 

context and even real-world knowledge (see also Chambers et al. (1998)) can 

help to resolve apparent (or temporal) syntactic ambiguity and is rapidly 

4

1 INTRODUCTION 5 

integrated throughout the processing of linguistic utterances and also that 

linguistic experience (such as relative frequencies of lexical competitors) can 

influence fixation behaviour. 

A major topic in this field is the question of how referential expressions 

(e.g. “The cat on the tree”) are processed. As Chambers et al. (1998) shows, 

even prepositions suffice in certain tasks to identify the referential object of 

an expression by restricting the domain of interpretation. Studies conducted 

at the University of Osnabrück show that determiner gender 1 and adjectival 

constructions ensuring referential uniqueness already give rise to a higher fix- 

ation probability on the referential object due to an anticipation effect, even 

before the onset of the noun itself (Hartmann (2006)). Kleemeyer (2007) and 

Bärnreuther (2007) showed that top-down influences had a much higher im- 

pact on attention modulation than bottom-up processes when presented in 

parallel. Karabanov (2006) showed what differences in fixation probabilities 

arise when processing full noun phrases compared to pronouns. 

The last three studies mentioned used a more natural visual world than 

Tanenhaus and the others, by providing Playmobil R○ sceneries as visual 

stimuli. Furthermore, subjects did not have to perform complex tasks while 

viewing the sceneries, as it was the case in Chambers et al. (1998) and 

Hartmann (2006). 

The object of this study is to investigate a problem posed by Peter Bosch 

in Bosch (2009). The basic question is in which way does the uniqueness con- 

straint of the definite determiner contribute to the processing of potentially 

ambiguous referential expressions. For a sentence like: 

(1) Put the red block on the block on the disk. 

which is syntactically ambiguous, one finds two constituent structures: 

(2) put [the [red block]] [on [the [block [on [the [disk]]] 

(3) put [the [red [block [on [the block]]] [on [the disk]]] 

If this sentence is presented while figure 1 is shown, which contains more 

than one red block (one of which is even on another block), and a third 

block on a disk, the uniqueness constraints of the first two definite deter- 

miners are not met when analyzing their corresponding constituents. But 

1 determiners in German have gender markers


somehow, most people intuitively chose sentence 3 as the correct meaning of 

the sentence. Bosch proposes two alternatives: either constraints of single 

constituents are collecting during incremental construction of the semantic 

representation of the determiner phrase so that the meaning becomes clear 

after processing the second “block”-phrase, where it becomes clear that the 

DP describes a red block which is on another block. Or the violated unique- 

ness constraint leads to a modulation of processing ressources: the deref- 

erence of said DP becomes the most important point on the agenda of the 

parser, which immediately uses the information obtained from the following 

preposition to decide which block is the referential object of the DP. 

Figure 1: Example block world, taken from Bosch (2009) 

The hypothesis behind this experiment is that when in such a sentence 

(or any other expression containing a definite determiner and a referentially 

ambiguous DP) a preposition can give the information needed to resolve 

such an ambiguity, then this fact should be easily be seen in an earlier 

rise of the fixation probability on the referential object of that DP. If the 

preposition cannot provide such information 2 , then the fixation probability 

on the referential object should rise only after the onset of the prepositional 

NP-head. 

2 In said case, picture the second block on a hat, then the ambiguity cannot be resolved 

solely by the preposition, as both blocks are “on” something


In order to test this hypothesis, several visual stimuli were constructed 

bearing exactly those characteristics mentioned before and were shown to 

subjects while they were listening to matching spoken stories.

2 Methods 

This part contains all important information about the participants of this 

study, the materials used for preparation and experimental design and pro- 

cedures used during the experiment and for subsequent analysis. 

2.1 Participants 

Participants were contacted through personal contacts and the internal mail- 

ing lists of the student bodies of the cognitive science and psychology pro- 

grammes at the University of Osnabrück, Germany. The actual subjects of 

this study were almost equally distributed among those programmes. They 

had to be native German speakers, have normal or corrected-to-normal vi- 

sion and had to have no hearing deficits. For their participation, subjects 

were rewarded with either course credit or 5 Euros. All subjects partici- 

pated voluntarily and were naïve with regard to the purpose of this study. 

Fixations were recorded from 25 subjects. Of those data sets, four had to 

be rejected. For two subjects, the data files were corrupt and therefore not 

readable. The experiment for one subject ended prematurely, rendering the 

data set unusable. One subject had a red-green color blindness, but as the 

subjects fixation behaviour was the same as of the other remaining subjects 

(see subject validity of subject 21 in table 6), the data set of said subject 

was used nevertheless. One subjects performance was significantly different 

from the rest (see subject validity of subject 5) and its data set was dis- 

regarded. All in all, 21 data sets were used for subsequent analysis. The 

characteristics taken from the subject questionnaires are shown in table 1. 

2.2 Experimental stimuli 

Subjects received multi modal stimuli, composed of photographs of Playmobil R○ 

sceneries and auditory stimuli which were semantically related to them. See 

Karabanov (2006), Kleemeyer (2007), Bärnreuther (2007) and Karabanov 

(2006) for similar designs. 

Ten stimuli were assembled from stimuli and filler material from prior 

experiments collectively used in Alexejenko et al. (2009). The pictures were 

edited with GIMP 2.6 in such a way as to conform to the constraints of 

the experimental design. Information about the construction of the original 

8

2 METHODS 9 

Category Range Median Mean ± SD 

Age (yrs) 18-28 22 22.5 ± 2.26 

Height (cm) 154-193 174 172.8 ± 8.63 

Daily screen time (hours) 2-10 5 5 ± 2.53 

Language knowledge (no.) 1-5 2 2.56 ± 0.96 

Previous eye-tracking studies (no.) 0-6 1 1.24 ± 1.67 

Gender Number Percent 

Female 14 56% 

Male 11 44% 

Education Number Percent 

High school diploma 22 88% 

University degree 3 12% 

Occupation Number Percent 

Student 24 96% 

Unemployed 1 4% 

Vision aids Number Percent 

None 14 56% 

Glasses 6 24% 

Contact lenses 5 20% 

Occular dominance Number Percent 

Left 10 40% 

Right 11 44% 

Unclear 4 16% 

Handedness Number Percent 

Left 1 4% 

Right 23 92% 

Unclear 1 4% 

Color Vision Number Percent 

Red-green colour blind 1 4% 

Perfect 24 96% 

Table 1: Statistics of study participants, collected from subject questionnaires

2 METHODS 10 

stimuli and filler can be found in Kleemeyer (2007). As some of the original 

images reused here had a resolution of 1024x768 pixels, all final images were 

downscaled to this resolution. 

Auditory stimuli were constructed corresponding to the experimental 

question raised in Bosch (2009). In order to find out what role prepositions 

may play during the processing of referential ambiguities, sentences were 

constructed whose subject phrase (sentence head) consisted of a noun phrase 

modified with a prepositional phrase. The whole phrase uniquely identified 

an object of the visual stimulus matching the auditory stimulus. The head 

of the subject phrase matched two objects of the visual stimulus, as did 

the NP of the prepositional phrase. In one condition, the preposition was 

supposed to uniquely identify the referential object of the subject phrase 3 , 

whereas in the other condition, the ambiguity could only be resolved when 

processing the prepositional NP. 

2.2.1 Visual stimuli 

Every stimuli/filler depicted a natural scenery constructed from Playmobil R○ 

objects. Those sceneries consisted of multiple objects referred to during the 

course of the corresponding auditory stimulus and also contained a vast 

amount of other objects serving as distraction, ensuring a higher possibility 

that a fixation on an object of interest is related to the auditory stimulus, 

and not to general browsing of the scenery. 

In particular, every scenery had two identical objects (identical in the 

sense of being part of the same category, e.g.“owl”,“man”,“cat”) serving as 

target and competitor. In addition, two objects served as their “location- 

ary” identifiers, i.e. identifying the location of the target/competitor in the 

scenery. 4 It is important to mention that there were matching distractors 

for the locationary identifiers as well. This was required in order to keep all 

references to the locationary identifiers in the auditory stimuli ambiguous. 

3 

E.g.“The cat in front of...” uniquely identifies a cat if the other cat in the picture is 

not in front of something. 

4 

To give an example, in one picture two owls were amidst a woodland scenery, one in 

a tree, the other on on a hill. The target here was the owl in the tree (the tree therefore 

being the locationary identifier of the target), the distractor the owl on the hill (the hill 

therefore being the locationary identifier of the competitor).

2 METHODS 11 

There was also a reference object in every picture to study the attention 

shift of participants to an easily identifiable, salient target and to compare 

those shifts to those elicited by the relevant part of the auditory stimulus. 

Figure 2: Exemplary visual stimulus. The target is circled in red, the competitor 

in green. The locationary object of the target and its distractor are 

circled in purple, the locationary object of the competitor and its distractor 

in blue. The reference object is circled in yellow. 

2.2.2 Auditory stimuli 

As already stated, there were two conditions for every stimulus, i.e. two sto- 

ries were designed that solely differed in one preposition in the last sentence. 

The stimuli consisted of four to six sentences in four slots. The first sentence 

was an informal overview of the scenery, without any direct reference to any 

object in it. 

1. In der Savanne. (In the savannah.) 

The reason for the introduction of that sentence was to measure participants’ 

fixations on the stimuli while not guided by linguistic input. The next one 

to two sentences introduced (referred to) the locationary objects.

2 METHODS 12 

2. In der felsigen Landschaft traben zwei Elefanten. (Two elephants 

are trotting through the rocky countryside.) 

The one to two sentences in the third slot contained references to the tar- 

get/competitor, as well as distractors and the reference object. 

3. Die beiden Männer beobachten die vielen durstigen Tiere am einzigen 

Wasserloch 5 . The two men are watching the many thirsty animal near 

the watering hole. 

The only difference between the two conditions could be found in the fourth 

slot. As explained above, the sentence consisted of a subject NP composed 

of an NP and a prepositional phrase. In one case, the preposition was a 

more regular one, not capable of identifying the referential object by itself, 

i.e. prepositions able to convey more possible relations than others. The 

german prepositions auf, neben and bei were used in this condition (meaning 

“on”, “next to” and “near”, respectively. In the other, due to the relation 

between subject head and prepositional NP conveyed by the preposition, 

the ambiguity posed by the subject head could have already been resolved 

by the preposition. Here, the german prepositions in, vor, hinter, unter and 

an were used, meaning “in”, “in front of”, “behind”, “below/under” and 

“at.” 

4. Der Mann vor dem grauen Felsen ist ein erfahrener Jäger. (The man 

in front of the grey rock is an experienced hunter.) 

See Figure 2 for an exemplary stimulus. 

All sentences were recorded 6 by using a Trust HS-2100 Headset and Au- 

dacity 1.2.6 7 and Cool Edit Pro 2.0 8 . Noise and pitch reduction procedures 

were carried out on all audio files. Furthermore, silent intervals were cut to 

ensure equal length of all files (18.770s - 19.962s). The number of syllables 

differed slightly among all sentences (58-62 syllables). Manual alignment 

was performed to ensure that onsets of the subject head NP, the preposi- 

tion and the prepositional NP only differed on a small scale. See Table 2 

for details. By adding a non-disambiguating adjective to the PP, a time 

window of approximately 800 ms between preposition onset and the onset 

of the prepositional NP could be ensured for further analysis. 

5 This is the reference object. 

6 Sentences were all spoken by the experimenter himself. 

7 (http://audacity.sourceforge.net/) 

8 (http://www.adobe.com/products/audition/)

2 METHODS 13 

Stimulus Nr. Onset subj-head NP Onset prep. Onset prep. NP 

1 15,348 15,946 16,786 

2 15,362 15,911 16,766 

3 15,330 15,940 16,704 

4 15,319 15,909 16,842 

5 15,357 15,919 16,757 

6 15,338 15,980 16,736 

7 15,358 15,960 16,777 

8 15,336 15,930 16,778 

9 15,353 15,970 16,792 

10 15,328 15,964 16,721 

11 15,343 15,877 16,757 

12 15,333 15,946 16,780 

13 15,325 15,928 16,719 

14 15,330 15,944 16,765 

15 15,334 15,925 16,732 

16 15,348 15,887 16,771 

17 15,345 15,948 16,744 

18 15,328 15,970 16,739 

19 15,329 15,901 16,623 

20 15,319 15,968 16,698 

mean 15,338 15,936 16,749 

Table 2: Onsets of subject head NP, prepositions and prepositional NPs. 

Even Stimulus numbers correspond to the ambiguous case, odd to the unambiguous 

case. The first two stimuli correspond to visual stimulus 1, the 

next two to visual stimulus 2, and so on.

2 METHODS 14 

2.2.3 Filler 

Filler images were all those images from the material of Alexejenko et al. 

(2009), which had not been used to construct stimuli. For each of those 

filler images an auditory filler was recorded, which was of equal length as 

the auditory stimuli and consisted of 3-5 sentences. 

2.3 Apparatus 

A head-mounted binocular Eye-Tracker(“Eye Link II”, SR Research, Mis- 

sissauga, Ontario, Canada) was used to record subjects’ eye movements. 

Two infrared cameras tracked the movements of the participants’ pupils, 

one tracked the head position relative to the monitor. A Pentium 4 PC 

(Dell Inc., Round Rock, TX, USA) was used to control the eye-tracker. See 

figure 3 for an overview of the system 9 . A second PC (Powermac G4 8000 

MHz) controlled the stimulus presentation. Stimuli were presented on a 21” 

cathode ray tube monitor (SyncMaster 1100DF 2004, Samsung Electronics 

Co, Ltd, Korea), resolution set to 1024x768 and a refresh rate of 100Hz. 

Pupil positions were tracked using a 500 Hz sample rate. 

Figure 3: Eye Link II Head-Mounted Eye-Tracking System 

9 Image taken from Karabanov (2006)

2 METHODS 15 

2.4 Procedure 

The experiment was conducted in a dimly lit room. Prior to the experiment 

itself, subjects were welcomed and the experiments procedure was explained 

to them. Subjects were informed that they could interrupt the experiment 

at any time. Subjects then had to fill out a consent sheet (see section G) 

and a standardized questionnaire (see table 1). Tests for ocular dominance 

and color deficiency were performed. If subjects were able to follow the in- 

structions up until now, it was assumed that their hearing was also sufficient 

for the experiment. 

Subjects were then seated 80 cm from the monitor and the eye-tracker 

was fitted on their head. Afterwards, a 13 point calibration and valida- 

tion procedure was started. Participants were asked to fixate a small dot 

showing up in a random order at thirteen different locations on the screen. 

During calibration, the raw eye-data was mapped to gaze-position. During 

validation, the difference between computed fixation and target point was 

computed, in order to obtain gaze accuracy. The procedure was repeated 

until the mean error for one eye was below 0.3 ◦ , with a maximum error below 

1 ◦ , this eye was subsequently tracked during the whole experiment. Subjects 

then were provided with headphones (WTS Philips AY3816), through which 

the auditory stimuli were presented. The headphones also served the pur- 

pose of blocking out background noise in order to ensure full concentration 

on the task. 

Subjects were told to carefully listen to the auditory stimuli and look at 

the visual stimuli. Before each stimulus, a small fixation spot in the middle 

of the screen was presented, so that drift correction could be performed 

and subjects had the chance to have a small break in between trials. If 

the difference between gaze and computed fixation position was too high, 

calibration and validation were repeated. The stimuli were presented in a 

random order, with the constraints that no more than two actual stimuli 

were presented in a row and that every subject was presented with exactly 

five stimuli conforming to the ambigue condition and five stimuli of the 

unambigue condition. Furthermore, for every subject there was another 

subject that was presented with the same order of stimuli, but with exactly 

the opposite conditions, as to assure that all stimuli and all conditions were 

presented equally often without fully giving up randomization. The ten 

stimuli and 15 fillers were presented as one block. After the experiment,

2 METHODS 16 

participants were informed about the goal of this study. 

2.5 Data Analysis 

It has already been shown extensively that measuring eye movements seems 

to be an adequate tool for the investigation of attention and is especially 

useful when trying to understand the mechanisms behind language process- 

ing Tanenhaus et al. (2000). With the help of Playmobil R○ scenarios it has 

also been shown that top-down influences seem to at least partially override 

bottom-up influences on attention (Kleemeyer (2007), Bärnreuther (2007)). 

It therefore seems to be an adequate instrument to study the processing 

of prepositions and its influence on attention. A fixation is defined as the 

inverse of a saccade, i.e. whenever the eye-tracker does not measure a sac- 

cade, there is a steady fixation. The acceleration threshold for a saccade was 

8000 ◦ /sec 2 , the velocity threshold 30 ◦ /s and the deflection threshold 0.1 ◦ . 

Fixation locations and durations were calculated online by the eye-tracking 

software and later converted into ASCII text. All further analysis was done 

with MATLAB 10 

2.5.1 Regions of Interest 

In order to find out whether a subject fixated a referent of the discourse, re- 

gions of interest (ROIs) were manually chosen around each referent in every 

scene using MATLABs build-in function roipoly. The borders of the referent 

were chosen as close as possible around the actual figurine in the scene. As 

part of the fixations in question lay outside the manually chosen regions of 

interest, they were scaled up 12 pixel in the horizontal axis (being equiva- 

lent to 0,552 ◦ of visual angle) and 20 pixel in the vertical axis (equivalent to 

0.76 ◦ of visual angle). For an example, see figure 4. An example of all the 

fixation outside of the regions of interest can be seen in figure 5. 

2.5.2 Statistics 

The time course of the probabilities to fixate a certain referent throughout 

viewing the scenery is the important part of analysis. In order to inter- 

pret rise and fall of fixation probabilities, 150 ms time windows were chosen 

in which all relevant statistical analysis was implemented. This particular 

10 (www.mathworks.com)

2 METHODS 17 

Figure 4: Example image for regions of interest. Left: target (woman) and 

target locationary object (car), right: competitor (woman sitting), competitor 

locationary object (tree), front: reference object (man) 

Figure 5: Example of fixations not belonging to any region of interest 

length was chosen as the data was somewhat scarce. In order to test stimu- 

lus validity, the first 2.5 seconds (in which no reference to any object in the

2 METHODS 18 

scenery was yet made in the auditory stimulus) were analyzed by adding 

up all fixations on referents and comparing them among images. As this 

revealed some minor issues (see Results [3]), the time window between 2500 

ms and 15000 ms was also analyzed (being the time window in which all 

referents were introduced) in the same way. Subject validity was analyzed 

by summing up all fixations over the different images. For both validity 

analyses, MATLABs lillietest function was used to ensure normal distribu- 

tions. The influence of prepositions on fixation probabilities (and therefore 

on attention) was then tested using bootstrapping algorithms. Both intra- 

conditional and inter-conditional testing was performed 11 . For all statistic 

tests, a significance level of α = .05 was used. 

11 Intra-conditional meaning the comparison of fixation probabilities between different 

ROIs of the same condition, inter-conditional being the comparison of fixation probabilities 

for a specific ROI in the two different conditions.

3 Results 

3.1 Subject Validity 

The first statistical test conducted was to find out whether the fixations on 

the different ROIs over all subjects constituted normal distributions. For 

that, all fixations over the whole time course of the stimulus presentation 

were summed up and MATLABs lillietest function was used as a test for 

normality. The findings are visualized in figure 6, an overview over the 

statistics can be found in table 3. As it could be easily discerned that 

subject number 5 was a statistical outlier, all further statistical tests were 

conducted without the data of that subject. 

The lillietest revealed that all fixation distributions were normalized, 

except for the fixations on the locationary object of the competitor. This 

could be due to the fact that this object was mostly inanimate and most 

stimuli contained considerable amounts of animate distractors, so that fixa- 

tions on those objects could be unstable due to the fact that, as Karabanov 

(2006) already pointed out, subjects prefer fixations on animate/human ob- 

jects over inanimate. This did not pose a problem however, as the data 

clearly shows that all subjects fixated the object during the presentation 

(mean = 4.3536%, std. − dev. = 0.8902%), i.e. identified it either before or 

during the presentation of the relevant part of the stimulus. 

3.2 Stimulus Validity 

Following that, a series of normality tests was conducted to ensure stimulus 

validity. Contrary to previous studies, it could not be shown that fixation 

behaviour in the first part of the stimulus, where no objects were yet in- 

troduced, could be a reliable baseline for test statistics concerning fixation 

behaviour mediated by auditory stimuli. 

As can be seen in figure 7 and in table 4, there was quite a large variance 

in fixation probabilities, especially on target, competitor and the distractor 

of the targets locationary object. This is due to the fact that those objects 

varied in size and that each stimulus contained a great amount of distrac- 

tor objects. But this also ensured that fixations done on objects during 

their introduction via the auditory stimulus could be considered to be di- 

rectly linked to the linguistic input, and not to attentional browsing of the 

19

3 RESULTS 20 

picture 12 . 

Figure 6: Subject validity, fixations over all images 

That browsing occurred nevertheless can be seen in light of the large 

number of fixations on beyond-ROI regions. This was partly also due to the 

limited accuracy of the eye-tracker, leading to the fact that a percentage of 

fixations that should have counted towards one of the ROIs was off by a few 

degrees. Also see figure 5. As can be seen in table 4, fixation probabilities 

on target and competitor were nevertheless a normal distribution. To en- 

sure that the stimuli were really valid and appropriate for further statistical 

testing, the time interval between 2500 and 15000 ms was tested, under the 

hypothesis that the auditory stimuli presented similar objects for all stimuli, 

so that fixation probabilities should be similar as well. The results are visu- 

alized in figure 8 and table 5. One can see quite clear that in every picture 

all the relevant objects were fixated prior to the investigated stimulus part. 

Thus it was secured that all objects have been seen before and subjects do 

not have to search for objects first, overt attention that is due to linguistic 

input should be immediately visible. 

12 If one has many objects in a stimulus, fixation on one of them precisely at the point 

when it is presented in a concomitant auditory stimulus get more and more unlikely to 

have been a coincidence with increasing number of objects.

3 RESULTS 21 

Figure 7: Stimulus validity, fixations over all subjects, between 0 and 2500 

ms 

Figure 8: Stimulus validity, fixations over all subjects, between 2500 and 

15000 ms

3 RESULTS 22 

3.3 Time Course of Fixations 

The time course of fixation probability over all images are shown in figures 9 

and 10. As expected, the fixation probabilities on both target and competi- 

tor object rise twice during the whole presentation of the stimulus. A small 

peak beginning around 9000 ms can be distinguished, representing the time 

frame in which the target/competitor compatible NP is introduced. This 

clearly shows that subjects shift their attention on visual sceneries in line 

with the linguistic processing of additional linguistic stimuli. 

The second rise of the fixation probabilities (i.e. the relative number of 

fixations) occurs concurrently with the second naming of said NP. Around 

the time of the onset of the prepositional head-NP, the fixation probabilities 

diverge and a considerable number of fixations is directed towards the tar- 

get, implying that the subjects we’re focusing their attention on it, having 

understood that the subject-NP refers to it. Throughout the rest of the 

stimulus, most fixations stay on either the target or the target locationary 

object, shifting back and forth between them. To better understand the 

Figure 9: Time course of fixation probabilities, ambiguous condition. Yellow 

stripe: first introduction of target/competitor-NP. First line: mean onset 

subject-head-NP, second line: mean onset prepositional NP-head.

3 RESULTS 23 

Figure 10: Time course of fixation probabilities, unambiguous condition. 

Yellow stripe: first introduction of target/competitor-NP. First line: mean 

onset subject-head-NP, second line: mean onset prepositional NP-head. 

stages of linguistic processing of ambiguous sentences and to compare it to 

the processing of unambiguous sentences, a closer visual inspection of the 

time frame in question was necessary. A visualization of the fixation prob- 

abilities of said time frame for both the unambiguous and the ambiguous 

condition can be found in figures 11 and 12. 

A few observations can be made: first and foremost, the differences in 

the time course of fixation probability are minimal at best. Second, there 

seems to be an early peak of fixations on the target in the ambiguous case 

around 16400 ms, which would have been suspected in the unambiguous case 

when the integration of the proposition alone would be enough to resolve the 

ambiguity of the subject-NP. Third, increased fixations on both target and 

target locationary object seem to last longer in the ambiguous case than in 

the unambiguous one (the last peak in the ambiguous case is at 19350 ms). 

All of those observations have to be treated carefully, as the dataset is 

small and therefore statistical significance cannot be guaranteed.

3 RESULTS 24 

Figure 11: Time course of fixation probabilities, unambiguous condition, 

time span between subject head onset and end of stimulus 

Figure 12: Time course of fixation probabilities, ambiguous condition, time 

span between subject head onset and end of stimulus

3 RESULTS 25 

3.4 Bootstrapping 

Bootstrapping analyses were conducted to find out if there are any signif- 

icant differences between fixation probabilities on target and competitor. 

Both differences between conditions and in the conditions were analyzed. 

Bootstrapping algorithms were applied both over all images and all sub- 

jects, to find out for how many images and subjects significant differences 

can be found, respectively. Bootstrapping was applied to time windows of 

150 ms width, between 15200 ms (shortly before the onset of the subject- 

head-NP) and 22000 ms (the last recorded fixations). 1000 bootstrap sam- 

ples were taken from the vector of fixations on either ROI1 (target) or ROI2 

(competitor), for both the ambiguous and the unambiguous condition. 

As a test statistic, the difference of means was calculated and compared 

to the actual difference of means, both in and between conditions 13 . A 

difference was considered significant if it fell either into the 2,5 percentile 

or was larger than the 97,5 percentile. The figures 13, 14, 15 and 16 depict 

the results of bootstrapping analyses over images. No graphs are given for 

the results of bootstrapping over the subjects, as it did not yield a single 

significant difference. 

From figure 13 it can be concluded that fixation behaviour on the tar- 

get does indeed differ between conditions. Further analysis confirmed the 

observation made earlier, namely that the target object gets significantly 

more fixations in the ambiguous case. For all four images for which the time 

window between 15950 ms and 16100 ms became significant, the difference 

between unambiguous and ambiguous case was negative. Interestingly, this 

is the time window right after the onset of the preposition. The other peaks 

seem to support the claim that in the ambiguous case, fixations stayed more 

often on the target for a longer time. The differences here are also all neg- 

ative. As there is mostly only one or two pictures that lead a significant 

difference, this hypothesis cannot be proven. 

There are also significant differences in the fixation probabilities on the 

competitor object between conditions. They are even less pronounced than 

in the case of the target object. The relevant time frames can be observed 

in figure 14. 

13 I.e. mean(ROI1 unamb) - mean(ROI1 amb), mean(ROI1 unamb) - mean(ROI2 un- 

amb), ...

3 RESULTS 26 

Figure 13: Significant Differences after Bootstrapping - Fixations on Target 

unamb. vs amb. Condition 

Figure 14: Significant Differences after Bootstrapping - Fixations on Competitor 

Unamb. vs Amb. Condition, peaks at 16100, 17750 and 19700 ms

3 RESULTS 27 


vs Competitor Ambiguous Condition 

Interestingly, the differences seen in the time course of fixations in both 

conditions do not seem to be that significant. For the ambiguous case, there 

are 15 time windows in which the differences become significant for one 

image. For the unambiguous one, there are 17 time windows, two of which 

show two images with significant differences.


vs Competitor Unambiguous Condition 

4 Discussion 

This study about the linguistic processing of prepositions has some interest- 

ing implications. Due to the scarcity of the data 14 most of the implications 

are in need of future research. It seems that contrary to e.g. Chambers 

et al. (1998), prepositions do not seem to provide as much information into 

the processing stages of natural language understanding as for experiments 

in which choices are limited and subjects rely heavily on them. 

It seems that people process the prepositional NP-head fully when faced 

with a referentially ambiguous phrase and only then shift their attention to 

the referent. It could also be the case that the time window in which an 

influence of the preposition was suspected did not suffice. Therefore one 

proposal for future research would be to widen the gap between preposi- 

tion and PP-head-NP even further. As far as this study is concerned, there 

are a few significant differences in fixation probabilities, oddly enough there 

14 As could be seen by the fact that no bootstrapping analysis over the subjects yielded 

significant results - in most time windows, the single subject did not look at either target 

or competitor, only the average over subjects shows results 

28

4 DISCUSSION 29 

seem to be more fixations on the target in the ambiguous case. This could 

be an artifact of this study, i.e. there could be a bias towards fixating the 

competitor (even though none of the earlier time windows shows such a dis- 

crepancy). Nevertheless, it should be subject of future research. The results 

of this study seem to be in favor of the theory that constraints from single 

constituents are collected during an incremental construction of semantic 

representations.

References 

Alexejenko, S., Brukamp, K., Cieschinger, M., and Deng, X. (2009). Mean- 

ing, vision and situation - study project. 

Bärnreuther, B. (2007). Investigating the influence of visual and semantic 

saliency on overt attention - bsc. thesis univ. osnabrueck, cognitive science. 

Bosch, P. (2009). Processing Definite Determiners. Formal Semantics Meets 

Experimental Results. Lecture Notes on Computer Science. 

Chambers, C. G., Tanenhaus, M. K., Eberhard, K. M., Carlson, G. N., 

and Filip, H. (1998). Words and worlds: The construction of context for 

definite references. 

Cooper, R. M. (1974). The control of eye fixation by the meaning of spoken 

language. Cognitive Psychology, 6. 

Hartmann, N. (2006). Processing grammatical gender in german - an eye- 

tracking study on spoken-word recognition - bsc. thesis univ. osnabrueck, 

cognitive science. 

Karabanov, A. N. (2006). Eye tracking as a tool for investigating the compre- 

hension of referential expressions - bsc. thesis univ. osnabrueck, cognitive 

science. 

Kleemeyer, M. (2007). Contribution of visual and semantic information and 

their interaction on attention guidance - an eye-tracking study - bsc. thesis 

univ. osnabrueck, cognitive science. 

Rayner, K. (1998). Eye movements in reading and information processing: 

20 years of research. Psychological Bulletin, 124(3). 

Tanenhaus, M. K., Magnuson, J. S., Dahan, D., and Chambers, C. (2000). 

Eye movements and lexical access in spoken-language comprehension: 

Evaluating a linked hypothesis between fixations and linguistic processing. 

30

A Visual Stimuli 

Figure 17: Visual Stimuli 1-6 

31

A VISUAL STIMULI 32 

Figure 18: Visual Stimuli 7-10

B Auditory Stimuli 

(a) is the unambiguous condition, (b) is the ambiguous one. 

1. (a) Im Wald ist viel los. Ein paar Hügel säumen die kleine Lichtung. 

Bäume spenden Schatten. Zwei Eulen schauen sich um, Rehe 

spielen am Wasser und auch ein Fuchs traut sich dazu. Die Eule 

in dem kleinen Baum hält nach Beute Ausschau. 

(b) Im Wald ist viel los. Ein paar Hügel säumen die kleine Lichtung. 

Bäume spenden Schatten. Zwei Eulen schauen sich um, Rehe 

spielen am Wasser und auch ein Fuchs traut sich dazu. Die Eule 

auf dem kleinen Baum hält nach Beute Ausschau. 

2. (a) In der Savanne. In der felsigen Landschaft traben zwei Elefan- 

ten. Die beiden Männer beobachten die vielen durstigen Tiere 

am einzigen Wasserloch. Der Mann vor dem grauen Felsen ist 

ein erfahrener Jäger. 

(b) In der Savanne. In der felsigen Landschaft traben zwei Elefan- 

ten. Die beiden Männer beobachten die vielen durstigen Tiere 

am einzigen Wasserloch. Der Mann neben dem grauen Felsen ist 

ein erfahrener Jäger. 

3. (a) Im Wartezimmer. Die Kisten sind voller Spielzeug. Die Frauen 

warten schon lange. Die beiden Kinder langweilen sich trotz der 

vielen Spielsachen. Auf dem Tisch liegen Zeitschriften. Das Kind 

vor der einen Kiste wird gerade aufgerufen. 

(b) Im Wartezimmer. Die Kisten sind voller Spielzeug. Die Frauen 

warten schon lange. Die beiden Kinder langweilen sich trotz der 

vielen Spielsachen. Auf dem Tisch liegen Zeitschriften. Das Kind 

bei der einen Kiste wird gerade aufgerufen. 

4. (a) Der erste Frühlingstag. Die Kinder spielen vergnügt, nur mit den 

Eimern spielt gerade keins. Zwei Kätzchen schleichen herum, und 

Blumen blühen überall. Die Frau geniesst die Sonne. Die Katze 

vor dem kleinen Kind geht jetzt auf Erkundungstour. 

(b) Der erste Frühlingstag. Die Kinder spielen vergnügt, nur mit den 

Eimern spielt gerade keins. Zwei Kätzchen schleichen herum, und 

33

B AUDITORY STIMULI 34 

Blumen blühen überall. Die Frau geniesst die Sonne. Die Katze 

bei dem kleinen Kind geht jetzt auf Erkundungstour. 

5. (a) Nachmittags im Park. Bänke laden zum Ausruh’n ein. Zwei 

Frauen sind mit ihren Enkeln da. Zwei Picknickkörbe steh’n 

bereit, die Kinder spielen Fussball und ein Hund tollt freudig 

umher. Der Korb hinter der einen Frau ist voller Leckereien. 

(b) Nachmittags im Park. Bänke laden zum Ausruh’n ein. Zwei 

Frauen sind mit ihren Enkeln da. Zwei Picknickkörbe steh’n 

bereit, die Kinder spielen Fussball und ein Hund tollt freudig 

umher. Der Korb bei der einen Frau ist voller Leckereien. 

6. (a) Im vollen Wirtshaus. An den Tischen sitzen ein paar Männer 

und trinken etwas. Zwei Hunde schnüffeln neugierig, die Männer 

warten auf’s Essen und die Kellnerin serviert ein Bier. Der Hund 

unter dem einen Tisch bettelt um einen Knochen. 

(b) Im vollen Wirtshaus. An den Tischen sitzen ein paar Männer 

und trinken etwas. Zwei Hunde schnüffeln neugierig, die Männer 

warten auf’s Essen und die Kellnerin serviert ein Bier. Der Hund 

bei dem einen Tisch bettelt um einen Knochen. 

7. (a) Im Klassenzimmer. Es gibt ein paar Tische und Hocker für die 

Schüler. Die beiden Kinder setzen sich gerade, die Spielsachen 

sind weggeräumt und die Lehrerin beginnt die Stunde. Das Kind 

vor dem einen Tisch hört ihr noch nicht richtig zu. 

(b) Im Klassenzimmer. Es gibt ein paar Tische und Hocker für die 

Schüler. Die beiden Kinder setzen sich gerade, die Spielsachen 

sind weggeräumt und die Lehrerin beginnt die Stunde. Das Kind 

bei dem einen Tisch hört ihr noch nicht richtig zu. 

8. (a) Ein Grillfest im Sommer. Die Familie ist mit zwei Autos da. Bei 

den Bäumen spielt ein Hund. Die zwei Frauen sind schon hungrig, 

die Kinder sitzen am Feuer und der Vater passt aufs Essen auf. 

Die Frau hinter dem grossen Auto holt noch mehr Kohle. 

(b) Ein Grillfest im Sommer. Die Familie ist mit zwei Autos da. Bei 

den Bäumen spielt ein Hund. Die zwei Frauen sind schon hungrig, 

die Kinder sitzen am Feuer und der Vater passt aufs Essen auf. 

Die Frau neben dem grossen Auto holt noch mehr Kohle.

B AUDITORY STIMULI 35 

9. (a) Auf dem Bauernhof. Die Kinder beobachten die Enten und Gänse 

an den Teichen. Zwei Katzen streifen umher, und Hühner gackern 

um die Wette. Die Bäuerin hat viel zu tun. Die Katze an dem 

kleinen Teich hat grad einen Fisch entdeckt. 

(b) Auf dem Bauernhof. Die Kinder beobachten die Enten und Gänse 

an den Teichen. Zwei Katzen streifen umher, und Hühner gackern 

um die Wette. Die Bäuerin hat viel zu tun. Die Katze bei dem 

kleinen Teich hat grad einen Fisch entdeckt. 

10. (a) Mitten in der Prärie. Kakteen wachsen auf den Felsen. Zwei Cow- 

boys schlagen ein Lager auf. Zwei Geier suchen nach Nahrung 

und Pferde laufen herum. Ein schwarzer Hund schaut sich um. 

Der Geier vor dem einen Cowboy ist schon ganz abgemagert. 

(b) Mitten in der Prärie. Kakteen wachsen auf den Felsen. Zwei Cow- 

boys schlagen ein Lager auf. Zwei Geier suchen nach Nahrung 

und Pferde laufen herum. Ein schwarzer Hund schaut sich um. 

Der Geier bei dem einen Cowboy ist schon ganz abgemagert.

C Fillers - Visual 

Figure 19: Filler Images 1-6 

36

C FILLERS - VISUAL 37 

Figure 20: Filler Images 7-12

C FILLERS - VISUAL 38 

Figure 21: Filler Images 13-15

D Fillers - Auditory 

1. Beim Zahnarzt. Die Arzthelferin holt die nötigen Instrumente aus 

den Schränken. Der Zahnarzt steht noch hinter dem Trennschirm 

am Tisch und trinkt noch seinen Kaffee aus. Der Patient auf dem 

Behandlungsstuhl fühlt sich schon ein wenig unwohl. 

2. Im grossen Burghof. Der grosse goldene Ritter bringt dem kleinen 

gerade den Schwertkampf bei. Der Mann bei den Fässern betrinkt 

sich und die Marktfrau bietet ihre Waren feil. Der Ritter mit der 

Hellebarde bewacht das Stadttor. 

3. Nachmittags im Zoo. Zwei Löwen stehen an der Tränke und ein Elefant 

ist eine Portion Heu. Die Oma und ihr Enkel beobachten begeistert die 

vielen Tiere. Der Tierpfleger will gleich das Elefantengehege sauber 

machen. 

4. Tief im Dschungel. Auf den Bäumen hocken Vögel und auf dem Boden 

streiten sich zwei Affen um Bananen. Die Schildkröte versucht die 

reifen Früchte zu erreichen. Der einzelne Affe versucht die anderen 

vor der Schlange zu warnen. 

5. In der Zirkusmanege. Die Affen und der Elefant rollen Fässer umher 

während ein Clown jongliert. Der Dompteur passt auf dass die Tiere 

alles richtig machen. Die Zuschauer auf den Rängen amüsieren sich 

prächtig. 

6. Auf einer Lichtung Bei den Bäumen und an den Blumen tummeln 

sich viele Tiere. Zwei Frischlinge halten sich nah bei ihrer Mutter auf, 

die kleinen Füchse trauen sich weiter weg. Das Eichhörnchen klettert 

lieber auf dem Baum umher. 

7. Auf dem Wochenmarkt. In den Körben und auf dem Tisch liegt 

frisches Gemüse. Der Mann ist mit dem Fahrrad gekommen um bei 

der Bäuerin seine Einkäufe zu erledigen. Die Bäuerin begrüsst ihn und 

seinen Hund gerade freundlich. 

8. Beim Familienausflug. Die Mutter und ihr Kind wollen gleich mit 

dem Kanu los paddeln Der Vogel beim Korb versucht etwas zu essen 

39

D FILLERS - AUDITORY 40 

zu ergattern und die Enten gehen schwimmen. Der Junge hat seinen 

Fussball zum spielen mitgenommen. 

9. Auf einer Ranch. Der Bulle frisst Stroh dass die Rancher gerade 

zusammengeharkt haben. Das Gras hat der Rancher gebündelt um 

es später den Pferden zu geben. Die Frau vor dem Wagen wird gleich 

noch die Pferde striegeln. 

10. Beim Kinderarzt. Beim Bett stehen allerlei medizinische Gerätschaften 

und im Schrank liegt Spielzeug. Der Junge auf dem Stuhl hat sich beim 

Sportunterricht verletzt. Die ärztin sagt ihm dass er wahrscheinlich 

auf Krücken nach Hause gehen muss. 

11. Ein Tag im Stadtpark. Ein paar Hasen und Rehe ruhen sich unter den 

Bäumen aus. Die Frau macht einen Spaziergang mit ihrem Hund. Sie 

unterhält sich gerade mit dem Mann. Die Ente am Teich schaut ihren 

Jungen beim Schwimmen zu. 

12. In einem kleinen Park. Die Blumen blühen und die vielen Bäume sind 

voller Blätter. Die Oma und ihr Enkel sind mit dem Hund zum Spielen 

in den Park gekommen. Das Fahrrad an dem einen Baum gehört den 

kleinen Jungen. 

13. Morgens in der Schule. Die Kleiderschränke sind noch leer und die 

Stühle noch nicht besetzt. Nur die Lehrerin und ein Schüler sind 

schon da. Sie fragt ihn wo die anderen bleiben. Die Aktentaschen im 

blauen Schrank gehören der Lehrerin. 

14. Auf dem Reiterhof. Beim Zaun liegt in einer Schubkarre Stroh für die 

Pferde. Auf dem Zaun hängen auch ein paar Sattel. Das kleine Kind 

will gleich einen Ausritt machen. Das Pferd neben der Tränke hat 

schon einen Sattel auf dem Rücken. 

15. Im Indianerdorf. Ein grosses Tipi ist aufgebaut und die Pferde haben 

Jagdbemalung. Der Häuptling redet mit dem Cowboy über die bevorste- 

hende Jagd. Das braune Pferd, dass gerade am Fluss trinkt, gehört 

dem Häuptling.

E Statistics 

ROI H mean std-dev. 

1 0 10.5542 2.1560 

2 0 5.8977 1.1071 

3 0 8.7508 1.5973 

4 0 5.3703 0.8303 

5 1 4.3536 0.8902 

6 0 6.0272 0.9649 

7 0 9.2993 2.2232 

8 0 49.7469 5.0927 

Table 3: Statistics of the Subject Validity - H: Outcome of the Lilliefors-test 

with α = 0.05, mean value of ROI, standard deviation (both in percent). 

Fixations on (from top to bottom): target object, competitor object, target 

locationary object, distractor for target locationary object, competitor 

locationary object, distractor for competitor locationary object, reference 

object, beyond ROI 


1 0 7.1418 5.5750 

2 0 3.6015 2.5735 

3 1 8.2362 7.5051 

4 1 5.7861 7.8266 

5 0 3.3063 4.3488 

6 1 8.0087 13.1942 

7 0 12.7139 8.3210 

8 0 51.2055 10.8276 

Table 4: Statistics of the Stimulus Validity, for the first 2500 ms - H: Outcome 

of the Lilliefors-test with α = 0.05, mean value of ROI, standard 

deviation. ROIs like above. 

41

E STATISTICS 42 


1 0 6.9826 2.5666 

2 0 6.1760 2.8477 

3 0 6.1081 1.7871 

4 0 6.0384 3.5721 

5 1 5.2184 1.6377 

6 1 6.6296 7.2425 

7 0 9.7145 3.5632 

8 1 53.1324 10.8374 

Table 5: Statistics of the Stimulus Validity, for the timespan between 2500 

and 15000 ms - H: Outcome of the Lilliefors-test with α = 0.05, mean value 

of ROI, standard deviation. ROIs like above. 


1 0 10.4496 3.4217 

2 0 5.9346 2.2071 

3 0 8.7613 2.6996 

4 0 5.3531 3.5624 

5 1 4.3345 1.8885 

6 1 6.0183 7.2006 

7 0 9.1997 3.6903 

8 0 49.9490 9.5045 

Table 6: Statistics of the Stimulus Validity, for the whole presentation of 

the stimulus - H: Outcome of the Lilliefors-test with α = 0.05, mean value 

of ROI, standard deviation. ROIs like above.

F Complementary Figures 

Figure 22: Timecourse of total fixations, ambiguous condition 

43

F COMPLEMENTARY FIGURES 44 

Figure 23: Timecourse of total fixations, unambiguous condition 

Figure 24: Timecourse of total fixations, unambiguous condition, timespan 

between subject head onset and end of stimulus

LIST OF FIGURES 45 

Figure 25: Timecourse of total fixations, ambiguous condition, timespan 

between subject head onset and end of stimulus 

List of Figures 

1 Example block world, taken from Bosch (2009) . . . . . . . . 6 

2 Exemplary visual stimulus . . . . . . . . . . . . . . . . . . . . 11 

3 Eye Link II Head-Mounted Eye-Tracking System . . . . . . . 14 

4 Example image for regions of interest . . . . . . . . . . . . . . 17 

5 Fixations not belonging to any region of interest . . . . . . . 17 

6 Subject validity, fixations over all images . . . . . . . . . . . . 20 

7 Stimulus validity, fixations over all subjects, between 0 and 

2500 ms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

8 Stimulus validity, fixations over all subjects, between 2500 

and 15000 ms . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

9 Time course of fixation probabilities, ambiguous condition. 

Yellow stripe: first introduction of target/competitor-NP. First 

line: mean onset subject-head-NP, second line: mean onset 

prepositional NP-head. . . . . . . . . . . . . . . . . . . . . . 22

10 Time course of fixation probabilities, unambiguous condi- 

tion. Yellow stripe: first introduction of target/competitor- 

NP. First line: mean onset subject-head-NP, second line: 

mean onset prepositional NP-head. . . . . . . . . . . . . . . . 23 

11 Time course of fixation probabilities, unambiguous condition, 

time span between subject head onset and end of stimulus . . 24 

12 Time course of fixation probabilities, ambiguous condition, 

time span between subject head onset and end of stimulus . . 24 

13 Significant Differences after Bootstrapping - Fixations on Tar- 

get unamb. vs amb. Condition . . . . . . . . . . . . . . . . . 26 

14 Significant Differences after Bootstrapping - Fixations on Com- 

petitor Unamb. vs Amb. Condition . . . . . . . . . . . . . . . 26 


get vs Competitor Ambiguous Condition . . . . . . . . . . . . 27 


get vs Competitor Unambiguous Condition . . . . . . . . . . 28 

17 Visual Stimuli 1-6 . . . . . . . . . . . . . . . . . . . . . . . . 31 

18 Visual Stimuli 7-10 . . . . . . . . . . . . . . . . . . . . . . . . 32 

19 Filler Images 1-6 . . . . . . . . . . . . . . . . . . . . . . . . . 36 

20 Filler Images 7-12 . . . . . . . . . . . . . . . . . . . . . . . . . 37 

21 Filler Images 13-15 . . . . . . . . . . . . . . . . . . . . . . . . 38 

22 Timecourse of total fixations, ambiguous condition . . . . . . 43 

23 Timecourse of total fixations, unambiguous condition . . . . . 44 

24 Timecourse of total fixations, unambiguous condition, times- 

pan between subject head onset and end of stimulus . . . . . 44 

25 Timecourse of total fixations, ambiguous condition, timespan 

between subject head onset and end of stimulus . . . . . . . . 45 

46

List of Tables 

1 Statistics of study participants, collected from subject ques- 

tionnaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

2 Onsets of subject head NP, prepositions and Prepositional NP 13 

3 Statistics Subject Validity . . . . . . . . . . . . . . . . . . . . 41 

4 Statistics Stimulus Validity 0-2500 ms . . . . . . . . . . . . . 41 

5 Statistics Stimulus Validity 2500-15000 ms . . . . . . . . . . . 42 

6 Statistics Stimulus Validity whole timecourse . . . . . . . . . 42 

47

G Consent Sheet 

Christian Hoffmann 

Arbeitsgruppe Computerlinguistik 

Universität Osnabrück 

Albrechtstrasse 28 

49069 Osnabrück 

email: chrihoff@uos.de 

Aufklärung/Einwilligung 

Sehr geehrte Teilnehmerin, sehr geehrter Teilnehmer, 

Sie haben sich freiwillig zur Teilnahme dieser Studie gemeldet. Hier erhalten 

Sie nun einige Informationen zu Ihren Rechten und zum Ablauf des folgen- 

den Experiments. Bitte lesen Sie sich die folgenden Abschnitte sorgfältig 

durch. 

1) Zweck der Studie 

Ziel dieser Studie ist es, neue Erkenntnisse über das Satzverständnis anhand 

von Eye-Tracking-Daten zu erhalten. 

2) Ablauf der Studie 

In dieser Studie werden Ihnen 25 Bilder auf einem Computermonitor gezeigt. 

Bitte sehen sie sich die Bilder sorgfältig an. Zugleich werden Sie einen kurzen 

Text zu hören bekommen. Hören Sie aufmerksam zu. 

Um Ihre Blickposition zu errechnen, wird Ihnen ein ”Eye-Tracker” auf den 

Kopf geschnallt. Dieses Gerät erfasst die Position Ihres Auges mit Hilfe von 

kleinen Kameras und Infrarotsensoren. Dieses Verfahren ist ein psychome- 

trisches Standardverfahren, das in dieser Art bereits vielfach angewandt und 

getestet wurde. Bei unseren bisherigen Erfahrungen und Experimenten mit 

dem Gerät ist keine Versuchsperson zu Schaden gekommen. 

Zu Beginn der Untersuchung muss der ”Eye-Tracker” eingestellt werden, 

dieser Vorgang dauert etwa 10-15 Minuten. Das eigentliche Experiment 

48

G CONSENT SHEET 49 

dauert dann etwa 15 Minuten. Der Versuchsleiter wird während des ganzen 

Experiments mit Ihnen im Versuchsraum sein und steht Ihnen für Fragen 

jederzeit zur Verfügung. Nach der Studie erhalten Sie weitere Informationen 

zum Sinn und Zweck dieser Untersuchung. Bitte geben Sie diese Informatio- 

nen an niemanden weiter um die Objektivität eventueller Versuchspersonen 

zu wahren. 

3) Risiken und Nebenwirkungen 

Diese Studie ist nach derzeitigem Wissenstand des Versuchsleiters ungefährlich 

und für die Teilnehmer schmerzfrei. Durch Ihre Teilnahme an dieser Studie 

setzen Sie sich keinen besonderen Risiken aus und es sind keine Neben- 

wirkungen bekannt. Da diese Studie in ihrer Gesamtheit neu ist, kann 

das Auftreten von noch unbekannten Nebenwirkungen allerdings nicht aus- 

geschlossen werden. 

Wichtig: Bitte informieren Sie den Versuchsleiter umgehend, wenn Sie unter 

Krankheiten leiden oder sich derzeit in medizinischer Behandlung befinden. 

Teilen Sie dem Versuchsleiter bitte umgehend mit, falls Sie schon einmal 

einen epileptischen Anfall hatten. Bei Fragen hierzu wenden Sie sich bitte 

an den Versuchsleiter. 

4) Abbruch des Experiments 

Sie haben das Recht, diese Studie zu jedem Zeitpunkt und ohne Angabe 

einer Begründung abzubrechen. Ihre Teilnahme ist vollkommen freiwillig 

und ohne Verpflichtungen. Es entstehen Ihnen keine Nachteile durch einen 

Abbruch der Untersuchung. 

Falls Sie eine Pause wünschen oder auf die Toilette müssen, ist dies jederzeit 

möglich. Sollten Sie zu irgendeinem Zeitpunkt während des Experiments 

Kopfschmerzen oder Unwohlsein anderer Art verspüren, dann informieren 

Sie bitte umgehend den Versuchsleiter. 

5) Vertraulichkeit 

Die Bestimmungen des Datenschutzes werden eingehalten. Personenbezo- 

gene Daten werden von uns nicht an Dritte weitergegeben. Die von Ihnen 

erfassten Daten werden von uns anonymisiert und nur in dieser Form weit- 

erverarbeitet oder veröffentlicht.

G CONSENT SHEET 50 

6) Einverständniserklärung 

Bitte bestätigen Sie durch Ihre Unterschrift die folgende Aussage: 

”Hiermit bestätige ich, dass ich durch den Versuchsleiter dieser Studie über 

die oben genannten Punkte aufgeklärt und informiert worden bin. Ich habe 

diese Erklärung gelesen und verstanden. Ich stimme jedem der Punkte zu. 

Ich ermächtige hiermit die von mir in dieser Untersuchung erworbenen Daten 

zu wissenschaftlichen Zwecken zu analysieren und in wissenschaftlichen Ar- 

beiten anonymisiert zu veröffentlichen. 

Ich wurde über meine Rechte als Versuchsperson informiert und erkläre mich 

zu der freiwilligen Teilnahme an dieser Studie bereit.” 

Ort, Datum Unterschrift 

Bei Minderjährigen, Unterschrift des Erziehungsberechtigten

Acknowledgments 

I want to thank Prof. Peter Bosch and Prof. Peter König for their con- 

stant support during the development of this thesis and the opportunity to 

conduct research of my own in such an exciting field. Furthermore, I want 

to thank Torsten Betz and Frank Schumann from the NBP-group for their 

open ear and advice when it was dearly needed. Lastly, I want to thank 

Vera Mönter for her moral support and permanent motivation. 

51

Confirmation 

Hereby I confirm that I wrote this thesis independently and that I have not 

made use of any other resources or means than those indicated. 

Hiermit bestätige ich, dass ich die vorliegende Arbeit selbständig verfasst 

und keine anderen als die angegebenen Quellen und Hilfsmittel verwendet 

habe. 

Christian Hoffmann, Nijmegen, September 29, 2009 

52

Bachelor's Thesis - Christian Hoffmann - Cognitive Science ...

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