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THE RELATIONSHIPS BETWEEN EYE MOVEMENTS AND COGNITIVE

FUNCTIONS

Nevil Abraham, Rachana Balasubramanian, Grace Chen, Saavan Chintalacheruvu, Rajeshwari

Enjeti, Cynthia Guo, Bum Shik Kim, Kang Woo Kim, Emma Leeds, Jessica Mui, Ellen Wu,

Rong Xiang

Advisor: Minjoon Kouh

Assistant: Frank Minio

ABSTRACT

This study focused on the effects of different internal states and external stimuli on the

eye movement patterns employed by the eyes in a variety of daily visual interactions. The study

analyzed the effects of differential line spacing on the level of comprehension and speed of

reading a passage of text. In another experiment, the placement of text above or below images in

public service announcements was studied in regard to length of gaze fixations. The study also

focused on whether telling a lie altered a subject’s oculomotor patterns as compared to telling the

truth. Finally, it compared subjects’ ability to voluntarily look away from peripheral stimuli,

called antisaccade, under static and moving fixation points. In most of these experiments, there

were no significant results. However, the ability to perform antisaccades was significantly

reduced when the eye was moving before the stimulus event as expected. Moreover, the direction

of eye movement in relation to the stimulus also affected antisaccade ability.

INTRODUCTION

Human eye movements can provide interesting and dynamic insights into complex

cognitive processes. Human vision has adapted to serve distinct functions, as foveal vision

provides narrowly-focused, high resolution visual information and a peripheral vision provides a

wider range of view with less resolution. This difference in resolution and dependence on the

foveal vision to deliver more information about the surroundings causes the eyes to make quick

movements in the direction of movement or a sudden disturbance detected by peripheral visions.

These quick movements, called saccades, occur roughly 3 times per second. Visual information

from fixations and saccades can be analyzed to establish a correlation between oculomotor

movement and cognition.

In 1967, Alfred Yarbus confirmed the relation between cognitive functions and eye

movements by monitoring subjects’ eye movements as they performed different mental tasks (1).

This test was one of the first studies in which the exact movement of a subject’s eyes was traced

over an image. When the subject was given various tasks, fixation patterns were different from

when he/she looked at the painting without any objective. Yarbus observed that fixation was

drawn to areas that the brain determined would provide the most information to satisfy the

respected task. Thus, cognitive tasks affected the eye movement patterns; after seeing one

portion of an image, the frontal cortex analyzes the input to decide the next area of interest. This

study attempts to follow in Yarbus’ footsteps by studying eye movements in response to a

variety of visual stimuli to further our understanding of brain function in response to visual

information.

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The current study focused on four main topics: the effects of line spacing on fixation

duration and comprehension during reading, effect of text placement on eye movements in

Public Service Announcements, variability of eye movements during lying, and the effect of a

moving fixation point on the success rate of antisaccades.

Line Spacing

The reading patterns of individuals have recently been the subject of extensive research,

and many studies have been conducted to investigate methods that can improve reading

efficiency (2,3). One factor that has been tested is line spacing, which has been a notable subject

of study because of its inverse relationship to word crowding. Word crowding is an adverse

spatial interaction that results from close proximities between words in a visual frame (4). After

observing the effects of line spacing on the reading patterns of individuals, Chung reasoned that

increased line spacing facilitates reading by decreasing spatial interference in the periphery; the

effect is an increase in clarity and visibility of adjacent words (4). These results are important

because they suggest that increased line spacing decreases spatial distractions, and thus, allows

readers to focus on individual words for longer amounts of time. It would therefore be relevant to

pursue a deeper investigation into how line spacing affects the average fixation duration of

readers. Eye movements provide valuable insight into reading patterns and reading efficiencies.

For example, by analyzing eye movement data, information on the location and duration of an

individual's focus (fixations) can be extracted. Moreover, past studies suggest that there is a

relationship between eye movements and comprehension levels of readers. Specifically, Kleigel

observed evidence that the majority of information processing occurs during eye fixations (5).

Therefore, the results imply that increased fixation duration results in better understanding of

texts.

Using these previous studies as a foundation, the relationship between line spacing,

fixation duration (and therefore comprehension levels of readers) was explored. This experiment

was designed with three objectives: 1) to investigate the effects of line spacing on fixation

duration of readers, 2) to explore the effects of line spacing on comprehension levels of readers,

and 3) to study the relationship between comprehension levels and fixation durations of readers.

The hypothesis was that increased line spacing would result in increased fixation duration of

readers, which would result in increased comprehension levels of readers. The hypothesis was

that there would be a direct relationship between comprehension level and fixation duration.

Public Service Announcement Fixations and Saccades

The average person interacts with advertisements, Public Service Announcements,

illustrations, and other text and picture combination messages on a daily basis. The common

element between these seemingly unrelated items is the importance of attracting and holding

viewer attention while conveying a message. Public Service Announcements (PSAs) warn

citizens of dangers they could be facing, problems they may not be aware of, or issues that relate

to them. They cover a wide range of topics, from abuse to political issues. PSAs can include

hotlines to call in cases of emergency, encouragement and methods to get help for a variety of

problems, or simply provide information to keep the average citizen informed and aware of his

or her surroundings.

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In order for a PSA to be effective, a person scrolling through a web page or passing a

billboard on the side of the road should be first attracted to the PSA, then pay attention to it and

be able to understand it in order to extract its message properly. Advertisers base their ads on the

same information that makes PSAs effective. In the case of ads, the message is to buy the

advertised product. Illustrations, another use for this information, are also inherently text based

(6). Text placement may be one of the factors determining the success of ads, PSAs, illustrations,

and other similar mediums for information communication. This experiment tests the hypothesis

that text placement at the top would create longer fixations and thus higher comprehension than

if text was at the bottom. People read from top to bottom - so if the text was at the top,

participants would read the text first and would then understand the picture (7). To test this

hypothesis, this experiment looks at text placement as one of the properties involved in the

efficacy of a PSA specifically by measuring how well people understand it and whether it

attracts their attention at all.

Eye Movements When Lying

It is a commonly stated notion that people are unable to maintain eye contact when telling

a lie. The source of this is a group of ideas referred to as Neuro-linguistic Programming (NLP).

This group of ideas states that the way a subject is thinking is correlated with a specific area of

focus in vision. For example, a person recalling a visual stimulus will look to the top right of

their vision, while someone constructing and auditory idea will look to their center-left (8).

According to NLP, constructing a either a sound or picture causes the person to look to the left or

top-left respectively, both of which are involved in the construction of a lie. As a result,

according to NLP, telling a lie will cause the liar’s eyes to shift, and indicate their verity. This

idea draws from the assumption that when people are nervous, in this case due to lying, they

become more jittery, making their eye movements more often, and over a longer period of time.

This experiment was designed to determine how either lying or telling the truth affects a person’s

eye movement, specifically the duration of both saccades and fixations, as well as the percentage

of time the gaze is concentrated on the face. It is hypothesized that if people lie, their fixation

duration drops, saccade duration increases, and percentage of gaze duration on the face

decreases. This hypothesis makes sense, since when people lie, they tend to be anxious, which

would cause them to scan more often than fixate, in order to search for possibilities of their lies

being detected. As a result, the gaze would be concentrated a less amount of time on the face,

and more on the surrounding area.

Antisaccade Variation

Humans reflexively perform saccades, or eye movements, toward new visual cues that

appear in their periphery (9). The ability of a subject to perform antisaccades is frequently used

to test normal cortical function. An antisaccade is a voluntary eye movement in the opposite

direction from novel stimuli. Antisaccades require top-down inhibition of the saccadic reflex; the

subject is instructed to make a saccade towards the opposite direction of the stimulus when the

cue pops up (e.g. if a cue is presented on the right side of the screen, the subject will attempt to

look towards the left side of the screen) (10). Antisaccade tasks have previously been

administered as a means of testing the frontal cortex ability, by asking subjects to concurrently

perform tasks requiring frontal-executive control. These tests are thus a useful diagnostic tool for

various cognitive disorders. This study, a variation of the antisaccade experiment, compared the

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ability of subjects to perform antisaccades with a moving fixation point, in contrast to a static

fixation point in the antisaccade experiment. This study further analyzes whether pre-movement

of the eye toward or away from the location of the stimuli would cause immediate prepotency in

subjects’ ability to perform antisaccades. It is hypothesized that 1) subjects whose eyes are

moving in the direction of the cue will be less likely to perform a successful antisaccade and 2) a

constantly moving fixation point will decrease success rates of inhibitory eye movement.

MATERIALS AND METHODS

All experiments used a Tobii T60 Eye Tracker, an infrared eye tracker with a 60 Hz

sample rate, 0.5 degree precision, 17 inch TFT, and a 1280 x 1024 pixel resolution. This was

integrated into a computer monitor. The Tobii Studio program was used to interface with the eye

tracker for stimulus presentation and data exports. All subjects for the experiments were in the

16-17 year old age group in the 2014 New Jersey Governor’s School in the Sciences.

Line Spacing

Ten subjects (four males and six females) participated in the experiment. Each subject

read a series of six reading passages labeled A through F, which were taken from past SAT and

PSAT standardized tests produced by the College Board. Each passage was approximately 100

words long and was presented in two different forms: a single-spaced version (1) and a double-

spaced version (2). Each subject read one of the two different versions of each passage.

Specifically, the ten subjects were divided into two groups, with each consisting of two males

and three females. Group I subjects first read a single-spaced version of passage A and alternated

versions for each subsequent passage (A1, B2, C1, D2, E1, F2). Conversely, Group II subjects

began with the double-spaced version of passage A and alternated versions for each subsequent

passage (A2, B1, C2, D1, E2, F1). In this way, each version of each passage was read five times.

Furthermore, testing alternated between subjects in Group I and subjects in Group II to assure

that time of day was controlled. After reading each passage, the subjects were given four

multiple choice comprehension questions to test their understanding. The comprehension

questions consisted of both SAT exam questions as well as original questions. Subjects could not

return to the passages when answering the questions. As shown in Figure 1, subjects were

presented with a passage in either a double or single space format and subsequently shown a

series of four questions. Each subject had 40 seconds to read each passage and a subsequent 40

seconds to answer the corresponding comprehension questions. A 15-second break was then

given before the next passage. All subjects alternated between single-spaced reading and double-

spaced reading. The reading material was presented in a constant font and font size. After

collecting data, the influence of line spacing has on eye movement and comprehension was

evaluated by analyzing the subjects’ fixation duration and comprehension scores. Data from the

first twenty seconds of each reading period was evaluated to discount any inaccuracy that may be

caused by the subject rereading the passage.

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Public Service Announcement Fixations and Saccades

Two sets of PSAs, Test A and Test B, were created, each with identical text and image.

The only difference between the PSAs was whether the text was on the top of the image or on

the bottom, as seen in Figure 2. Although the text placement varied, the pictures were always in

the same location. The PSAs covered topics including verbal abuse, voting rights, drunk driving,

adoption, anorexia, female domestic abuse, male domestic abuse, poaching animals, internet

safety, abuse of Muslim women, and smoking. Each test had 12 different PSAs, 6 with the words

on the top and 6 with the words on the bottom, in a random order to prevent participants from

anticipating text location. The eight participants were split into two groups of four, and each

group only saw one set of pictures.

Figure 2. PSA variations example. Four subjects saw the version of the PSA to the left in Test

A and the other four subjects saw the version of the PSA to the right in Test B.

Participants were given five seconds to observe and comprehend each PSA. After each

picture, the participant was asked to write a brief summary of the PSA’s message as a test of

their comprehension. The participant indicated to the test administrator when they were finished

writing and were ready for the next PSA, after which they would view the next image for five

seconds until the entire test was administered.

Eye Movements When Lying

Six participants (one male and five females) participated in this experiment. Videos of a

person asking each question were created. After the question was asked, a cue (Lie or Truth)

would flash on the screen instructing the participant to either lie or tell the truth. Two tests

containing ten questions were created, so three subjects answered each question truthfully while

Figure 1. Passage A screens. A1 passage, A2 passage, and Passage A questions.

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the other three lied. Participants were instructed to act as if they were conducting an actual

conversation with the person asking the questions in the video. Each participant watched the

video and answered the question for approximately 15 seconds. The questions they were asked

include: “What did you do last night?”, “Who is your best friend?”, “What is one of your

hobbies?”, “What is your favorite childhood memory?”, “What is your favorite school subject?”,

“What do you think is your best quality?”, “What is your favorite part of Governor’s School so

far?”, “What is the exterior of your house like?”, “What do you want to be when you grow up?”,

and “What was your first impression of Professor Kouh?”. The data was analyzed through a

macro created in Excel using Microsoft Visual Basic (Appendix E).

Antisaccade Variation

This experiment consisted of two parts: the first tested the success rate of the antisaccade

task (used as the control) with a static fixation point, and the second tested the success rate of the

antisaccade task changed with a moving fixation point. The video used for testing was created

using Adobe Professional Flash CC. There were a total of 7 subjects, consisting of 2 males and 5

females. One subject’s data was discarded due to both the subject’s misunderstanding of the task

instructions and error of the Tobii eye tracking system.

In the control, subjects were presented with a white background and instructed to stare at

the gray cross (fixation point) in the center of the room and look in the opposite direction of the

cue once the cue popped up. Blue circular cues would pop up for 550 ms on the same horizontal

axis of the gray cross in either the left or right direction for a total of 30 trials. Cues appeared at

random intervals to prevent subjects from predicting when the cues would appear. Subjects were

not told in advance of how long the testing would last. A successful antisaccade was defined as

looking away from the cue, while making a reflexive saccade eye movement towards the cue was

considered a failure. After the cue disappeared, the fixation point would reappear at the center of

the screen, at which point the subject would return their gaze to the center of the screen.

The test contained a fixation point moving in constant periodic motion between the left

and right sides, as opposed to the static fixation point in the control. The subject was instructed

to follow the moving fixation point (moving left and right on the center of the screen at a

constant rate of 3 seconds/cycle). After 1.5-3.5 seconds, the circular blue cue appeared at either

the left or right side of the screen for 550 ms. 64 trials were conducted on each trial, 32 of the

cues appearing in the same direction of eye movement and 32 appearing in the opposite direction

(Fig 3). Furthermore, the cue location (left or right) was also counterbalanced for each direction

that the fixation point moved.

Figure 3. Sample antisaccade test stimuli. The gray cross (left) moves back and forth across

the screen. At random intervals when the cross reaches the center, it momentarily disappears and

a blue cue (right) appears on either the far left or right of the screen for 550 ms. Then, the cross

reappears and the motion continues.

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In order to account for the possibility of improvements in antisaccade ability through

practice, the order of the control or variation tests was randomly assigned different orders. To

control for this problem, half of the subjects received the control then moving fixation trials, and

the other half of subjects received the reverse order. The timing of the cues was also randomized

as to avoid rhythmic behavior that would make the stimuli more predictable.

In analyzing the data, gaze events with X-coordinates of greater than 800 were

considered right saccades, while gaze events with X-coordinates of less than 400 were

considered left saccades. Then, the saccade directions were compared with cue directions to

determine success of the antisaccade and the percentage of successful antisaccades out of the

total (30 in control and 64 in test) was defined as the antisaccade success rate. The data obtained

from the experiment was analyzed using a one- tailed paired t test with an alpha-value of 0.05 to

determine whether or not the results were significantly different under the different experimental

treatments.

RESULTS

Line Spacing

The average fixation duration for the first 20 seconds for single-spaced passages was 180

± 33 ms, while the average fixation duration for double-spaced passages was 183 ± 30 ms. After

performing a paired two-sample t-test, the p-value was found to be 0.696. Because this p-value is

greater than 0.05, the evidence suggests that there is no statistically significant difference

between the fixation durations for single-spaced and double-spaced passages. This lack of

significance is illustrated in Figure 4. The average comprehension score for single-spaced

passages was 64% while the average comprehension score for double-spaced passages was 70%.

A paired two-sample t-test resulted in a p-value of 0.354, which was greater than 0.05. Therefore

there is no statistically significant difference between average single-spaced comprehension

scores and average double-spaced comprehension scores.

Figure 4. Average fixation duration and comprehension scores. There is no significant

difference in both average fixation durations and comprehension scores between single-spaced

passages and double-spaced passages.

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Public Service Announcement Fixations and Saccades

As shown in Figure 5, the average fixation time over the entire image and text for the

PSAs when the text was placed above the picture was 209 ms while the average fixation time

when the text was at the bottom was 201 ms. The t-test of these two values gave a p-value of

0.351 which is not statistically significant. The matched paired t-test for scores on

comprehension tests after viewing PSA’s with text on top and bottom yielded a p-value of 0.732,

which means the differences were not statistically significant.

Figure 5. Fixation averages for PSA’s and Comprehensions Percentages. The average

fixation for PSA’s with the text at the top was 209 ms and the average fixation for PSA’s with

text at the bottom was 201 ms. The line graph shows that 69% of both PSA’s with text at the top

and text at the bottom were comprehended correctly.

Eye Movements When Lying

Once the subjects began to respond, their eye movements were recorded. The data

collected focused on fixation duration, saccade duration, and the amount of time the subjects

gaze was concentrated on the face of the interviewer. As seen in Figure 6 when telling the truth,

the subject had an average fixation duration of 0.35 ± 0.37 ms. When instructed to lie, this

changed to 0.37 ± 0.40 ms. While the averages are very distinct, the large amount of error

resulted in p = 0.468, meaning there is no statistically significant difference in fixation duration

when telling the truth and when lying. When telling the truth, the subject had an average saccade

duration of 36 ± 19 ms. When instructed to lie, this changed to 59 ± 135 ms. The average upon

lying seemed to be very different that when the truth was told, however due to an outlier at 775

ms, a t-test resulted in p = 0.178. When this data point was omitted, the averages became nearly

identical (36 ± 7 ms, p = 0.488), meaning there is no statistically significant difference. The test

for amount of gaze time on face was notable for its low amount of error, obtaining averages of

92 ± 7 ms when telling the truth, and 92 ± 5 ms when lying. A t-test yielded a result of p = 0.321,

making this statistically insignificant as well.

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Figure 6. Average Fixation Duration for Truths and Lies. The subjects’ average fixation

duration compared with the truthfulness.

Antisaccade Variation

Across the six subjects, the average rate of successful antisaccades for the control

treatment with the static fixation point was 78.1%, with a standard deviation of 9.9%, as shown

in Figure 7. The average rate of successful antisaccades for the test with a moving fixation point

was 58.7%, with a standard deviation of 11.6%. A 2-tailed t-test was performed for the mean

success rate on the two treatments; the p-value of 0.0060 indicates that the mean success rate for

the experimental treatment was significantly lower than the success rate on the control

Figure 7. Average antisaccade success rates. Rates are shown in the control (static fixation

point), when the cue was in the same direction as the fixation point movement, and when the cue

was in the opposite direction of the fixation point movement.

All of the subjects were less successful with a moving fixation point than with a static

one. A matched pair test for the mean differences in accuracy for each subject between the two

antisaccade tests showed the sample mean decreased in success rate is 19.4%, with a standard

deviation of 0.0937. The p-value of 0.00077 indicates that the decrease in success rates for a

moving fixation point as compared to a static one is statistically significant.

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Finally, the subjects’ success rates on the experimental antisaccade test could be

categorized by whether the fixation point was moving towards or away from the location of the

cue immediately before the cue appeared (Figure 8). A matched pair t-test for average successful

antisaccade rates for fixation points moving away from as compared to toward the cue had a

statistically significant p-value of0.0059. This indicates that the antisaccade success rate when

the fixation point moves away from the cue is significantly higher than the success rate when the

fixation point moved toward the cue location.

DISCUSSION

Several sources of error were common to all the studies. The sample size was small,

reducing the reliability of statistical inference. In addition, the Tobii Eyetracker system only

collects data every 16-17 ms, so that changes in eye position or movement lasting less than that

time span may not have been accurately accounted for. Finally, the lack of a chin rest for

subjects during use of the Tobii system means that subjects may have moved their heads during

trials, affecting the calibration and accuracy of data collection.

Line Spacing

The original hypothesis was that increasing line spacing would decrease spatial

interference and thus increase average fixation duration comprehension performance. As shown

in the results, the average fixation duration differed by only 3.4 ms. Likewise, the comprehension

scores also varied by a small, statistically insignificant margin of 6%. There is therefore

insufficient evidence to suggest that differences in line spacing affect the fixation duration and

comprehension scores of readers. The hypothesis was not supported by the results of this

experiment.

Despite the statistical insignificance, it is still notable that both the average fixation

duration and the comprehension scores depicted similar trends, and thus, potential for

correlation. Subjects possessed greater average fixation durations and higher average

comprehension scores for double-spaced readings than for single-spaced readings. There was a

small, positive correlation between line spacing, fixation duration, and comprehension scores.

Furthermore, a larger number of subjects scored higher on double-spaced reading comprehension

questions than on single-spaced comprehension questions, as can be seen in Figure 4. There were

only two subjects who scored higher on single-spaced questions. Similarly, a larger number of

subjects had higher average fixation durations for double-spaced passages, as can be seen in

Figure 4. Therefore, in spite of the statistical insignificance, there may still be reason to believe

that increased line spacing increases fixation times and enhanced comprehension levels. These

results suggest that upon further investigation, there may still be a relationship that exists

between comprehension and fixation duration.

Furthermore, several sources of error may have reduced the potential effect of the

difference in line spacing. For one, participants may not have received enough time to answer

comprehension questions. If this was the case, then an individual could have fully comprehended

a passage, but done poorly on the comprehension questions. Consequently, the comprehension

scores would not be an accurate indicator of the effect of line spacing on comprehension

performance. Additionally, the conditions of the experiment may not have been significant

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enough to generate prominent results. Perhaps the spacing of single-spaced and double-spaced

passages is not different enough to create an effect on eye movements. To improve the design of

the experiment, more time could be given to each reader to answer comprehension questions to

improve accuracy of comprehension scores. Also, a more pronounced difference in spacing

could be implemented so that a greater effect can be observed on the average fixation duration

and comprehension score.

Public Service Announcement Fixations and Saccades

The difference between the average fixation lengths when the text was above the picture

was 8 ms more than when the text was below the picture. Although this follows the hypothesis, 8

ms is not statistically significant, as shown by the t test result of 0.3151.

After finding that text placement had no significant effect on fixation length or

comprehension, other factors were investigated to see whether they actually did have an effect.

The average fixation lengths of each picture were graphed to see if pictures that had a lower

comprehension level (specifically pictures 2 and 7 as in Appendix E) also had lower fixation

lengths compared to the other photos. The average fixation length for each PSA was about the

same and there was no correlation between fixation length and comprehension.

Under the parameters of this study, there was no significant correlation between text

placement and fixation duration on the PSA or on comprehension. However, the conditions

could be changed to further study this relationship. One possible change to continue this study

could be to measure the effect of text placement on average fixations on the text itself, rather

than on the entire PSA. The fixations over the words instead of the entire picture would be

calculated. Additionally, most of the images were relatively symmetric between the top and

bottom. A future study could focus on the effect of placing text near a crowded part of an image

verses placing the same text in a less crowded part.

Eye Movements When Lying

It was hypothesized that when telling a lie, an individual would have displayed the

following eye movements: lower fixation durations, higher saccade durations and less eye

contact with the face in the stimulus. The data obtained from this experiment does not support

the three hypotheses made. In Figure 7, the average fixation durations for Truth and Lying were

found to not be statistically significant from each other. A similar result was found for the

average saccade duration for participants. For both conditions, the participants spent an

overwhelming majority, over ninety percent, of their time looking at the face on the screen;

moreover, the t-test done shows that there is no statistical difference for this condition.

While it seems that this data shows that there is no statistical difference between lying

and telling the truth for the three variables tested, the limitations of the data collected preclude

the formation of any true conclusions. For both average fixation duration and average saccade

duration, the standard deviations were extremely high. So while there was no significant

difference, there was still a very high amount of variability in the data. The most obvious reason

for the high standard deviations obtained is the low sample size used. However, this variability

may also come from the flaws in the methodology of the experiment. For example, the lack of a

chin rest to keep the head of the participant from moving added another variable to the

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experiment. Some subjects moved their heads, while others did not. On the other hand, the data

for the experiment testing for eye contact with the face in the stimulus had relatively low

standard deviations. While the data stated that there was no correlation between eye movements

and truthfulness, this result needs further testing.

As stated above, further testing is needed to amend some of the errors in the experiment.

The media that showed the person asking the question was only the size of about a quarter of the

screen. This amplified any inaccuracies of the Tobii eye tracker. Additionally, since the media

was so small, the participant’s eyes were constantly leaving the media. This may have especially

played a part in the high percentage of time that the participants spent looking at the face in the

media. Lastly, the small size of the media took away from the realism of the project. If this

experiment were to be repeated, it is recommended that a larger stimulus is used to create a better

resolution on the gaze location.

The foremost problem comes from the nature of the stimulus used. When people lie, they

have a reason for doing so. They may do it to protect themselves or simply to gain attention.

Moreover, when they lie they are usually talking to a real person, who can consciously judge

their statements. This usually creates a sense of nervousness or even excitement in the individual

that is lying. On the other hand, in this experiment, the participants had no reason to lie.

Moreover, they were lying to essentially a computer screen. Without any motivation to lie or

anyone to judge their lies, this experiment is a poor representation of the act of lying and any eye

movements that may accompany the act.

If this experiment were to be repeated, changes to the methodology must be

implemented. First off, the participants should lie to an actual person. This could be done if the

individual wears a headset that has eye-tracking capabilities. Additionally, the participants must

have a motivation to lie. For example, they could be asked an embarrassing question, which

make them more likely to give a realistic response. Finally, the participants should be asked to

talk for longer periods of time to allow for the collection of more data.

Antisaccade Variation

In this experiment, it was hypothesized that (1) subjects whose eyes are moving in the

direction of the cue will be less likely to perform a successful antisaccade and (2) a constantly

moving fixation point will decrease success rates of inhibitory eye movement. The results of this

experiment supported both hypotheses. There was a statistically significant decrease in the

ability of the subjects to perform antisaccades when their eyes are initially moving as compared

to when they are static. Moreover, the results indicate that it is significantly more difficult to

inhibit the saccadic reflex when the eye is already moving towards the cue. For instance, if your

gaze is already moving toward the door, it is much more difficult to look away if a tiger were to

suddenly enter through that door.

The rates of successful antisaccades on the control test with static fixation points very

closely mirrored the success rates for Roberts’ study “Prefrontal Cognitive Process: Working

Memory and Inhibition in the Antisaccade Task” conducted in 1994, whose methodology was

used (10). Roberts found that subjects were successful in performing antisaccades 78.9% of the

time, very similar to the 78.1% success rate of our sample. Such consistency supports the

credibility of our results. Moreover, the success rate that Roberts found for subjects

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simultaneously performing mental arithmetic (58.5%) almost matched the average success rate

for a moving fixation point identified in this study (58.7%). This may indicate that mental math

and tracking a moving point may be equally taxing on cognitive ability, as reflected by the

amount by which they distract from antisaccade ability.

In the future, various improvements and modifications of this experiment could be made

to yield further insight into how moving fixation points can affect the ability of a subject to

perform the antisaccade and how this reflects cognitive function. For example, the moving

fixation testing could be analyzed for reaction times and its correlation with the movement. In

addition, right and left-brain functions could be related to the movement of the fixation point and

direction of the cue by engaging subjects in activities that stimulate either left or right brain

function during the antisaccade test. Incorporating a target fixation point after the cue appeared

could also improve the accuracy of the analysis of eye movement by testing the subjects on their

accuracy when instructed to identify the quickly flashed target.

CONCLUSION

Overall, these four studies analyzed changes in oculomotor patterns by analyzing the

characteristic fixations and saccades. Each study shows the dynamic nature of the relationship

between cognitive processes and visual input; the sensory data collected from each gaze event is

used by the brain to determine where to look next. This cycle is constantly altered by

environmental and internal factors, including reading text, viewing images, telling lies, and

responding to peripheral cues. Most of the studies found that the stimuli tested did not produce

significant results; this may indicate that the normal patterns of eye movement are very robust

and not easily altered. Future studies may utilize more extreme contrasts in stimuli to try to elicit

significant changes in oculomotor patterns. The antisaccade study did reveal that movement of

the fixation point significantly impaired antisaccadic ability, showing that this particular

modification altered the top-down control of eye movement. Understanding how visual patterns

change in response to stimuli have useful functions in developing effective advertising or

communication channels to optimize comprehension; more importantly, the movement of the

eyes provides a valuable medium for understanding the underlying cognitive processes of the

brain.

[7-14]

REFERENCES

1. DeAngelus M, Pelz J. Top-down control of eye movements: Yarbus revisited. Visual

Cognition. 2009. 17(6/7): 790-811.

2. Falkenberg HK, Rubin GS, Bex PJ. Acuity, crowding, reading and fixation stability.

Vision Research. 2007; 47(1):126-135.

3. Zorzia M, Barbiero C, Facoetti A, Lonciari I, Carrozzi M, Montico M, Bravar L, George

F, Pech-Georgel C, Ziegler JC. Extra-large letter spacing improves reading in dyslexi.

Proceedings of the National Academy of Sciences. 2012; 109(28):11455-11459.

4. Chung ST. Reading speeds benefit from increased vertical word spacing in normal

peripheral vision. Optometry and Vision Science Journal. 2004; 81(7):525-35.

5. Kliegl R, Nuthmann A, Engbert R. Tracking the Mind During Reading: The Influence of

Past, Present, and Future Words on Fixation Durations. Journal of Experimental

Psychology: General. 2006; 135(1):12-35.

6. Lubin G, Hudson H. 29 Eye-tracking heat maps reveal where people really look.

Business Insider; [Cited 2014 July 22]

7. Starr Matthew S, Rayner Keith. Eye Movements During Reading: Some Current

Controversies. Trends Cognitive Science; 2001; 5(4):156-163.

8. Dilts Roberts. Eye Movements and NLP. University of Neuro-Linguistic Programming.

[Cited 2014 July. 29]

9. Mitchell J, Macrae C, Gilchrist I. 2002. Working memory and the suppression of

reflexive saccades. Journal of Cognitive Neuroscience. [Cited 2014 Jul 31] 14(1): 95-103.

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and Inhibition in the Antisaccade Task. Journal of Experimental Psychology: General.

1994;123(4):374-393

[7-15]

APPENDICES

Appendix A

Table I. CollegeBoard SAT and PSAT passages used for testing.

Passage A PSAT, Section 5 (2007-2008)

Passage B SAT, Section 4 (January 2006)

Passage C SAT, Section 7 (January 2007)

Passage D SAT Practice Test #1, Section 7 (2011-2012)

Passage E SAT, Section 4 (May 2012)

Passage F SAT, Section 2 (March 2005)

Table II. Line spacing raw data. Average fixation duration and comprehension score of each

individual.

Figure A1. Individual

Fixation Duration. Average

fixation duration of each

participant in single- and

double-spaced reading

passages. As shown, most

participants fixate longer on

double spaced passages than

single-spaced passages. Even

so, the marginal difference is

very small in all cases.

[7-16]

Figure A2. Individual

Comprehension Scores. Average

comprehension scores of each

participant for single- and double-

spaced passage readings. Eight of

ten participants performed better on

the double-spaced readings than on

the single-spaced reading. However,

the remaining two participants

scored significantly higher on

single-spaced readings than on

double-spaced readings.

Appendix B

Figure A3. Average fixation time per PSA. Each subject’s fixations were averaged for each PSA

in the test.

Table III. PSA Images Used.

http://www.novabucks.org/images/ChildAbuseImageWithHand1

http://www.aceshowbiz.com/news/view/00018761.html

http://www.mobilemarketer.com/cms/news/television/5964.html

http://osocio.org/message/you_will_receive_more_than_you_can_ever_give/

http://i.huffpost.com/gen/1093787/thumbs/o-ANOREXIA-ADS-570.jpg?15

[7-17]

http://3.bp.blogspot.com/MmPqaX1Bs3U/UWRK2t3EdlI/AAAAAAAAACo/wX

kr7XdzxH8/s1600/Unzip_Print_Ad_PSA_Concept_by_misterbedhead.jpg

http://adsoftheworld.com/sites/default/files/styles/media_retina/public/images/w

wfblood.jpg?itok=cp_9fXrW

http://www.mybrandfriend.com/wp-content/uploads/2013/10/Innocence-in-

Danger_girl_16-1200x520.jpg

http://adsoftheworld.com/sites/default/files/styles/media_retina/public/kkf-

wmens-abuse-english.jpg?itok=ttU9E3Lf

http://tanushri-guchhait.blogspot.com/

http://nursingclio.files.wordpress.com/2012/07/anti-domestic-violence-facing-

the-wall-small-56548.jpg

http://171.67.24.121/tobacco_web/images/antitobacco/makes_you_ugly/stinky/la

rge/stink_1.jpg

http://www.mybrandfriend.com/wp-content/uploads/2013/10/Innocence-in-

Danger_girl_16-1200x520.jpg

Table IV. PSA Comprehension Raw Data

Picture P01 (A) P02 (A) P03 (B) P04 (B) P05 (A) P06 (B) P07 (A) P08 (B)

Total

Comprehension

Top 1 ---- ---- Yes Yes ---- Yes ---- Yes 4/4

Top 2 No No ---- ---- No ---- No ---- 0/4

Top 3 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

Top 4 ---- ---- Yes Yes ---- No ---- Yes 3/4

Top 5 ---- ---- Yes Yes ---- Yes ---- Yes 4/4

Top 6 ---- ---- No Yes ---- No ---- Yes 2/4

Top 7 ---- ---- No No ---- No ---- No 0/4

Top 8 Yes No ---- ---- No ---- Yes ---- 2/4

Top 9 ---- ---- Yes Yes ---- Yes ---- Yes 4/4

Top 10 No No ---- ---- Yes ---- Yes ---- 2/4

Top 11 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

Top 12 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

Bottom 1 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

Bottom 2 ---- ---- No No ---- No ---- No 0/4

Bottom 3 ---- ---- No Yes ---- Yes ---- Yes 3/4

Bottom 4 No Yes ---- ---- Yes ---- No ---- 2/4

Bottom 5 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

Bottom 6 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

[7-18]

Bottom 7 No Yes ---- ---- No ---- No ---- 1/4

Bottom 8 ---- ---- No Yes ---- Yes ---- Yes 3/4

Bottom 9 Yes Yes ---- ---- Yes ---- Yes ---- 4/4

Bottom 10 ---- ---- Yes Yes ---- No ---- No 2/4

Bottom 11 ---- ---- No Yes ---- Yes ---- No 2/4

Bottom 12 ---- ---- Yes Yes ---- Yes ---- Yes 4/4

Total

Comprehension 8/12 9/12 6/12 10/12 9/12 7/12 9/12 8/12 8.25/12.00

Figure A4. Average PSA Fixation Duration by subject.

Appendix C

Code used to parse Lying Experiment data

Sub FixationDuration()

Dim x(0 To 10) As Long

Dim asd(0 To 10) As Long

Dim order As Integer

Dim size As Integer

Dim vid(0 To 10) As Integer

Dim checker As Integer

Dim start(0 To 10) As Integer

Dim switcher As Integer

Dim total(0 To 10) As Integer

Dim inc(0 To 10) As Integer

size = ActiveSheet.Cells.SpecialCells(xlLastCell).Row

checker = 1

For i = 4 To size

If Cells(i, 3) <> Cells(i + 1, 3) And Cells(i, 3).Value <> "" Then

[7-19]

vid(checker) = Cells(i, 3).Row

checker = 1 + checker

End If

Next

switcher = 4

For y = 1 To 10

For i = switcher To vid(y)

If Cells(i, 9).Value = "Fixation" Then

x(y) = Cells(i, 10).Value + x(y)

End If

If Cells(i, 9).Value = "Saccade" Then

asd(y) = Cells(i, 10).Value + asd(y)

End If

If Cells(i, 13).Value <> "" And Cells(i, 14).Value <> "" Then

total(y) = total(y) + 1

If ((Cells(i, 13).Value - 320) ^ 2 + (Cells(i, 14).Value - 240) ^ 2) ^ (1 / 2) > 150 Then

inc(y) = inc(y) + 1

End If

End If

Next

Cells(y, 19).Value = x(y) / (vid(y) - switcher)

Cells(y, 20).Value = asd(y) / (vid(y) - switcher)

If total(y) <> 0 Then

Cells(y, 21).Value = 100 - (inc(y) / total(y) * 100)

End If

switcher = vid(y)

Next

End Sub

Table V. Lying Experiment Raw Data, organized by participant

Participant Average

Fixation

Duration:

Truth

Average

Fixation

Duration:

Lie

Average

Saccade

Duration:

Truth

Average

Saccade

Duration:

Lie

Percent of

Gaze Time

on Face:

Truth

Percent of

Gaze Time

on Face:

Lie

1 249 476 31 23 84 92

2 336 303 49 28 91 88

3 458 527 138 170 97 98

4 441 354 111 255 90 92

5 593 461 168 147 95 92

6 1035 1417 132 133 97 98

[7-20]

Appendix D

Figure A5.

Antisaccade task

success rates by

subject in each

subject in the

control (static

fixation point),

when the cue was

in the same

direction as the

fixation point

movement, and

when the cue was

in the opposite

direction of the

fixation point

movement.

Table VI. Subject antisaccade task success rates in the control, same direction cue, and opposite

direction cue.

Subject Control Same Direction Opposite Direction

1 96.70 68.75 68.75

2 86.70 71.88 75.00

3 76.70 43.75 68.75

4 73.33 37.50 9 0.63

5 73.33 43.75 78.13

6 70.00 25.00 62.50

7 70.00 15.63 71.88

Average 78.11 43.75 73.66