Download File - In the Mind`s Eye: Studying the Gaze Events of

In The Mind’s Eye:
Studying the Gaze Events
of Dyslexic Adults
Molly Niemczyk
Rockdale Magnet School for
Science and Technology
930 Rowland Road
Conyers, GA 30012
Table of Contents
ABSTRACT .......................................................................................................................................................... 2
INTRODUCTION ................................................................................................................................................ 3
LITERATURE REVIEW .................................................................................................................................... 5
RESEARCH METHODOLOGY ......................................................................................................................... 8
DATA ANALYSIS & INTERPRETATION PLAN ............................................................................................. 9
DISCUSSION AND CONCLUSION ................................................................................................................. 15
ACKNOWLEDGEMENTS ................................................................................................................................ 16
LITERATURE CITED ...................................................................................................................................... 17
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Abstract
Dyslexia tests are generally expensive, time-consuming, and tedious. This experiment
attempted to use video as a diagnostic tool for dyslexia, as this would be more appealing, less
expensive, and more accurate than a written test that’s results are ultimately based on test-taking
skills, rather that quantitative numerical data. It was expected that, if both dyslexics and those
without dyslexia watched the same video, dyslexics would display different eye movements than
those without dyslexia. The average gaze event duration of the eyes of 20 participants (10 with
primary dyslexia, 10 without) was analyzed by a T120 while they watched a 5 minute video
displaying randomly moving objects. An ANOVA test was performed, and the data showed a
very significant difference between dyslexic and nondyslexic eye movement (F=52976.1; df=1;
p<.05). Dyslexic gaze durations were shorter more of the time than nondyslexic gaze durations.
In addition, the overall gaze of dyslexic participants was preferential to the top right corner of the
screen; nondyslexics focused more on the middle. Based on a preliminary bell curve, primary
dyslexia can be diagnosed 95% of the time within two standard deviations of 53,827 ms. This
information could lead to the utilization of a universal test for dyslexia.
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Introduction
Dyslexia is the “impaired ability to understand written language: a learning disorder
marked by a severe difficulty in recognizing and understanding written language, leading to
spelling and writing problems” (Soukhanov, 1999).
“Common characteristics among people
with dyslexia are difficulty with phonological processing (the manipulation of sounds), spelling,
and/or rapid visual-verbal responding” (National institute of, 2011). Usually, someone being
checked for dyslexia has the following examined: his or her ability to read, write, spell, and do
math. His or her memory, sequencing skills, and hand/eye coordination are also looked at. If the
patient is still in school, doctors may look at school reports and speak to his or her teachers. The
patient may be asked about any family disorders (ADHD/ADD, Autism, Dyslexia, etc.) While
this is a good way to diagnose someone with dyslexia, it is based only on the patient’s
performance completing certain tasks, and the likelihood of the patient having the disorder.
Technically, there are three types of dyslexia: developmental dyslexia, trauma dyslexia,
and primary dyslexia (Disabled World, 1997). Developmental dyslexia is caused in the early
stages of fetus development, is found mostly in boys, and decreases with age. Trauma dyslexia
is caused by an injury. The most prominent form of dyslexia, however, is primary dyslexia,
which does not change with age; it is caused by a malfunction in the left side of the brain. The
type of dyslexia examined in this study will be primary dyslexia.
There are many specific tests that are used to examine a patient who possibly has dyslexia.
The Test of Visual-Perceptual Skills, Third Edition (TVPS-3) is commonly utilized. The
TVPS-3 uses black-and-white designs for all of the perceptual tasks completed during the
examination. During each task, everything is organized in a progressing order and shown in a
multiple-choice arrangement.
The following are examined during a TVPS-3: Visual
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Discrimination, Visual Memory, Visual-Spatial Relationships, Form Constancy, Visual
Sequential Memory, Visual Figure-Ground, and Visual Closure. Patients answering any of the
questions either say the letter of the response choice or point. The test is laid out in such a way
that allows the doctor administering the test to determine the patient’s perceptual abilities
separate from motor skills. The TVPS-3 also provides relatively new data concerning the average
perceptual abilities of children.
It may be administered to one person, or a small group. The
untimed examination takes around 30 to 40 minutes to finish. Scoring a child only takes about 5
minutes (Martin, N.).
Other tests include the Decoding Skills Test (DST), the Comprehensive Assessment of
Spoken Language (CASL), and the Decoding-Encoding Screener for Dyslexia (DESD). The
DST is for those who read at a 1st through 5th grade level. It tests for dyslexia by measuring the
person’s ability to recognize words taught in basal reading programs, decode words using phonic
patterns, and comprehend story passages. Although it only takes 15 to 30 minutes to complete
the test, it is primarily useful when the patient is already known to have a reading disability. The
CASL comes in the form of 15 stand-alone multiple choice tests. It generally lasts about 45
minutes, and is used for people ages 3 to 21. The DESD is only 5 to 10 minutes. It measures
sight-word recognition in three sections titled Decoding, Encoding, and Letter Writing. Though
the test is quick and easy, it is available only for 1st through 8th graders (Martin, N.). Though
different in many ways, each test has a setback, whether it is geared toward a particular age
group, or lasts an excessive amount of time, or is based on how well a person takes a test, which
could be affected by a test’s length or the patient’s test-taking skills.
Dyslexics have been known to exhibit erratic eye movement patterns compared to other
readers, and durations of holding phases between saccades (fast, jerky eye movement) have been
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shown to be significantly longer in dyslexics (MacKeben et al., 2013). That supports the theory
that dyslexics can be diagnosed by examining their eye movements. Because traditional dyslexia
tests can be dull and time-consuming for people, especially children, a dyslexia test using
something more entertaining, such as television, would be the perfect solution for doctors. They
would then be able to subject their patients to a more enjoyable, low-cost, accurate test, instead
of simply making a diagnosis based purely on observation.
The objective of this research is to see if there is a distinct difference in the eye movement
of dyslexics when compared to non-dyslexics. The research hypothesis is: If both dyslexics and
those without dyslexia watch the same video, dyslexics will display different eye movements than
those without dyslexia. The null hypothesis is as follows: If both dyslexics and those without
dyslexia watch the same video, dyslexics will not display different eye movements than those
without dyslexia.
Literature Review
In the 1920s, a man named Samuel Orton furthered the study of reading disabilities with
clinical studies that tested the hypothesis that “reading deficits were a function of a delay or
failure of the left cerebral hemisphere to establish dominance for language functions” (Mash &
Barkley, 2002). Orton stated that children with reading disabilities reversed letters like “b/d” and
“p/q”, and words such as “saw/was” and “not/ton”, attributing the cause to a lack of lack of lefthemispheric dominance in the brain for processing linguistic symbols (Orton, 1928). Though his
observations were only scratching the surface, and in no way completely accurate, his writings
became highly influential, bringing much attention to the disorder. Because of this, Orton’s
contribution to dyslexia research is primarily linked to the development in scientific interest in
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reading disabilities. However, he was also the first to stress that dyslexia did not strictly co-occur
with low intelligence.
Today, much more is known about primary dyslexia, though there is much more to be
discovered. It is now known that people are born with primary dyslexia; it is not contagious or
developed after birth. Often times it is passed down genetically. People are usually diagnosed at
a young age. Although it is commonly thought that a symptom of dyslexia is writing letters and
words backwards, this is common for regular children in their early years. It is an indication that
orthographic representations (letter forms and spellings of words) have not yet been established,
and does not mean someone has dyslexia (Adams, 1990). Dyslexia has been found to affect
spelling as well as reading. People with and without reading disabilities generally have different
brain structures. Booth and Burman found that people with dyslexia have less gray matter in the
left parietotemporal area of the brain (which controls sensory perceptions, and spoken and
written language) than non-dyslexics (Booth & Burman, 2001). Gray matter is responsible for
processing information. Many dyslexics also have less white matter in the same area, and more
white matter is associated with more efficient reading skills (Deutsch, et. al, 2005). Other
differences have also been discovered. Most brains of right-handed, nondyslexic people are
asymmetrical with the left hemisphere being larger than the right’s, but dyslexics show right
being larger than the left (Heim & Keil, 2004). The reason for the size differences is currently
not known, but it may have to do with the spelling and reading problems dyslexics currently
face. Dyslexics have been found to exhibit erratic eye movement (EM) when reading that differs
from the average reader. It has been shown that dyslexics' erratic EMs are present not just when
reading, but also in the simple chronological task of following light sources, each of which is
illuminated sequentially (Pavlidis, 1981). A study has also come out suggesting that examining
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how people move their eyes while watching television could help identify those who have
ADHD, FASD, and Parkinson’s disease, because each of these conditions involve “ocular
control and attention dysfunctions” (Janice, 2012). The eye movements of 108 subjects were
recorded by an eye-tracking device while they watched television for 20 minutes. Researchers
were able to distinguish those with Parkinson’s disease with an almost 90 percent accuracy.
Children with either ADHD or FASD were identifiable with 77 percent accuracy. Autism has
also been shown to affect eye movement, even during infancy. A study done by researchers led
by the Emory University School in Atlanta had 110 infants from two months to two years of age
watch a video of women acting like caregivers. The children were reassessed when they turned
three. It was found that children diagnosed with autism at the age of three had shown diminished
eye contact towards the people in the video they had watched as babies (Jones & Klin, 2013).
This shows that certain diseases/disorders can be sought out using eye movement tests.
The effects of dyslexia have indeed been studied before. One research article discusses
an experiment that had dyslexics and non-dyslexics read while eye movement was examined.
According to the paper, a significant difference was shown between dyslexics and non-dyslexics
(De luca, et. al, 2002). However, a study has not been done on the eye movements of dyslexics
and non-dyslexics when watching a video. As reading from left to right and focusing on the
interesting points in a video are quite different, the information gathered from this research could
be very different than that of the research article’s.
This paper discusses how patients with dyslexia have been known to exhibit erratic eye
movement patterns compared to other readers. However, this project had subjects with and
without dyslexia try to follow light sources with their eyes. Though this is applicable to subjects
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watching a video, it does not indicate whether or not dyslexics focus on other things at different
times, when there is more to be seen and more distractions, as opposed to non-dyslexics.
Research Methodology
The main goal of this experiment was to determine if there is a distinguishable difference
in the eye movement of dyslexics when compared to non-dyslexics. The subjects of this study
were dyslexic and non-dyslexic adults. To be eligible, non-dyslexics simply had to be adults
over 18 years of age.
The dyslexic subjects had to have previously been professionally
diagnosed with primary dyslexia. The dyslexic adults were chosen from a local dyslexia support
group. Nondyslexic adults were the parents of children participating on a recreational baseball
team. The participants were sorted into those with dyslexia, and those without (the control
group). Each subject’s personal information was not used, released, or required for this
experiment. The two groups of subjects were instructed to watch the same video for five
minutes (No information was found suggesting that what type of media is viewed affects the
patients’ overall results.). Nothing was done to any of the subjects without their consent.
The video the subjects watched was filmed beforehand. A video camera, set on a tripod,
had previously paned at a constant speed back and forth, or had followed particular people or
objects (a ball, a yo-yo, a car, or similar moving objects) in different places (parks, parking lots,
forests, or other locations). A total of ten 30-second videos were filmed. The ten filmed videos
were randomly cut to clip snippets (5 seconds each), producing a total of 60 snippets. A 5
second snippet length was chosen because, in the United States, Hollywood films have an
average of 5 seconds shot length, or continuous footage between two snippets (Tseng, Cameron,
Pari, Reynolds, Munoz & Itti, 2012).
The snippets were then reassembled to create one 5
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minute video, and were made black and white to prevent color from being a factor in where the
subjects choose to look during the experiment.
As each person watched this video, his or her eye movements were recorded (Janice,
2012). Specifically, the average gaze duration of the left and right eyes was tracked. The eye
movement data was then examined by the Tobii 120.
The independent variable is dyslexia, and the levels of the independent variable are
whether or not the subject has dyslexia. The dependent variable is eye movement, which was
measured by horizontal and vertical distance of the pupil as time progressed, and by the event of
each saccade, or gaze duration.
Data Analysis & Interpretation Plan
The purpose of this experiment was to see if dyslexics and nondyslexics’ eye would
respond differently to the same video. The research hypothesis states: If both dyslexics and those
without dyslexia watch the same video, dyslexics will display different eye movements than those
without dyslexia. The null hypothesis is as follows: If both dyslexics and those without dyslexia
watch the same video, dyslexics will not display different eye movements than those without
dyslexia. An ANOVA statistical test was performed, and its results support that there was a very
significant difference between the eye movements between the dyslexics and nondyslexics;
therefore the research hypothesis was supported (F=52976.1; df=1; p<.05).
The Gaze Event Duration (ms) was analyzed by a T120, used to track the eye movements
of 20 participants (10 with dyslexia, 10 without). The data was then separated by dyslexia and
no dyslexia, and compiled into two groups.
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Visuals 1 and 2 are gaze plots that show the averaged fixation points of the left and right
eyes of every participant. Each color represents a different person, each circle represents a new
fixation point, and the size of the circle represents the duration of that fixation. Visuals 2 and 4
are heat maps that show the averaged focus of the left and right eyes of every participant. Red
means that the area was focused on the most; green means that the area was focused on less.
Nondyslexic eye movement, as can be seen in Visuals 1 and 3, is primarily focused in the
middle of the screen. Dyslexic eye movement (Visuals 2 and 4), however, is not only focused on
the middle, but is also shifted somewhat to the upper right corner of the screen. The duration of
the gazes also appears to be longer near the middle and bottom of the screen for both dyslexics
and nondyslexics. The two heat maps (3 and 4) both show a yellow and red perpendicular
“cross” in the center of the screen, where the participants focused the most. The nondyslexic
heat map’s “cross” has a red area in its center that is close to a perfect circle. The dyslexic heat
map’s red section is also contained near the center, but it is spread out, and not as contained.
Figure 1 displays the gaze event duration in milliseconds (ms) of the dyslexic and
nondyslexic subjects. As can be seen in the histogram, dyslexics’ gaze durations were shorter
more often than nondyslexics’ gaze durations. Nondyslexics also had gaze durations that lasted
much longer than dyslexics’ ever did throughout the entire experiment.
As the purpose of this project was to see if a video can be used as a diagnostic tool for
dyslexia, a bell curve was created by finding the average gaze duration +/- two standard
deviations in an attempt to see analyze how well dyslexia could be diagnosed using this method.
It seems that, based on the results of the first bell curve, dyslexia occurs 95% of the time within
two standard deviations of 53,827 ms.
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Visual 1: This gaze plot portrays the averaged fixation points of the left and right eyes of each nondyslexic
participant. Each color represents a different person, each circle represents a new fixation point, and the size
of the circle represents the duration of that fixation- the longer the person focused on that area, the bigger the
circle is.
Visual 2: This gaze plot portrays the averaged fixation points of the left and right eyes of each dyslexic
participant. Each color represents a different person, each circle represents a new fixation point, and the size
of the circle represents the duration of that fixation- the longer the person focused on that area, the bigger the
circle is.
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Visual 3: This heat map portrays the averaged focus of the left and right eyes of each nondyslexic participant.
Red means that this area was focused on the most; green means that this area was focused on less.
Visual 4: This heat map portrays the averaged focus of the left and right eyes of each dyslexic participant.
Red means that this area was focused on the most; green means that this area was focused on less.
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Figure 1: This histogram shows the gaze event duration (ms) of dyslexics and nondyslexics. Lines closer to
the y-axis indicate shorter gaze event durations (how long the person focused on one area). Lines further
away from the y-axis indicate longer gaze event durations.
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Boxplot of Gaze Event Duration by Condition
350000
Gaze Event Duration
300000
250000
200000
150000
100000
50000
0
dyslexia
Non-dyslexia
Condition
Figure 2: This boxplot shows the gaze event duration (ms) of dyslexics and nondyslexics
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Discussion and Conclusion
Dyslexia had a significant impact on the eye movements of the participants when
watching a video. Although this was anticipated based on previous research, the ways in which
they were different were unexpected. It has already been shown that dyslexics and nondyslexics
read differently (De luca, et. al, 2002), and it has been revealed that dyslexics exhibit erratic EMs
when following light sources with their eyes (Pavlidis, 1981). However, although it has been
found that the gaze durations of dyslexics are usually significantly longer than nondyslexics
when reading (MacKeben et al., 2013), the results of this experiment show that dyslexics’ gaze
durations were shorter more often than nondyslexics’.
Nondyslexics had the longest gaze
durations of the two groups. This may have to do with the constant movement of objects during
the video, and the quick, 5-second transitions between snippets.
Unfortunately, the same number of men and women with dyslexia or without dyslexia
were unable to be obtained, and therefore could have affected the data.
In addition, the
experiment was completed on two different days instead of the same day, so the procedures had
to be revised. However, this likely did not affect the results of the data significantly.
Only primary dyslexia was examined in this experiment. In future research, all three
major types of dyslexia could be examined (primary, trauma, and developmental). Larger groups
of people are needed to further indicate the implications of using video as a diagnostic tool for
dyslexia. As less than thirty people were used in this study, a bell curve with the normal three
standard deviations could not be made, and so only two standard deviations were used. In
addition, children could be tested instead of adults, as most people diagnosed with dyslexia are
diagnosed at a young age.
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Understanding how dyslexia affects eye movement when watching a video has great
implications. Using this information, people could be diagnosed with dyslexia as early as
infancy.
Acknowledgements
Thank you to the Rockdale Magnet Research teacher Mr. John Hendrix for supervising
this research and providing the tools necessary to make this project possible. Thank you to Mr.
Scott Bolen of The Rockdale Magnet School for Science and Technology for providing guidance
and assistance during this research project. Thank you to the Tobii Company for providing the
T120 and software. Thank you to Ms. Michelle Faraj of the Tobii Company for helping to
provide the T120. Thank you to Ms. Ann Marie Lewis of the International Dyslexia Association
for finding an Adult Dyslexia Program for this project. Thank you to Ms. Foster Soules of The
Schenck School for granting permission to use volunteer subjects from the school. Thank you to
Mr. Sherman Johnson for allowing me to use his baseball players’ parents as test subjects.
Thank you to Mr. Vijar Patel of Tobii Company for providing technical support for the T120 and
Tobii Studio.
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