Transcript Document

What can eye tracking tell us about
reading, writing, and dyslexia?
What can eye tracking tell us about
reading, writing, and dyslexia?
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A range of literacy schemes are highly successful
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Estimated that between 1–33% of the population has reading difficulties
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Educational practice must continue to be informed by research
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Eye movement research can inform our knowledge of children’s reading progress
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Understand what a child must learn to become a skilled reader
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Will enable a children to transition from learning to read, to reading to learn
Highly sensitive research tool
“a window to the mind”
What can eye tracking tell us about
reading, writing, and dyslexia?
What do eye movements look like?
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Your may have the
impression that we scan
smoothly over text when we
read making very smooth eye
movements
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“Saccade”: ballistic eye
movement between words
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“Fixation”: eyes are relatively
still and the majority of
lexical processing occurs
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Eye movements provide a
highly sensitive index of the
cognitive processing during
reading
What can eye tracking tell us about
reading, writing, and dyslexia?
Rapid decline in visual acuity on the retina
What can eye tracking tell us about
reading, writing, and dyslexia?
What can eye tracking tell us about
reading, writing, and dyslexia?
What can eye tracking tell us about
reading, writing, and dyslexia?
What can eye tracking tell us about
reading, writing, and dyslexia?
Characteristics of skilled reading
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What can eye tracking tell us about
reading, writing, and dyslexia?
A series of saccades and fixations - most fixation duration ~200ms less than a ¼ of a second
*
The beautiful girl was feeding the birds
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Aim to land a saccade close to centre of a word - 85% forward saccades,15% backwards saccades
The beautiful girl was feeding the birds
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Not all words are fixated (especially short words)
The beautiful girl was feeding the birds
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Some words are refixated
The beautiful girl was feeding the birds
- 15% content words, 65% function
Linguistic influences on children’s eye movements
•
gaze
duration (ms)
Word length – how many letters
The beautiful girl was feeding the birds
The
kind
What can eye tracking tell us about
reading, writing, and dyslexia?
girl was feeding the birds
438
- 88 ms
350
Joseph, Liversedge, Blythe,
White, & Rayner, 2009
Linguistic influences on eye movements
•
gaze
duration (ms)
Word length – how many letters
The beautiful girl was feeding the birds
The
kind
What can eye tracking tell us about
reading, writing, and dyslexia?
girl was feeding the birds
438
- 88 ms
350
Joseph, Liversedge, Blythe,
White & Rayner, 2009
•
Word frequency – how often the word is read
The kind girl was feeding the birds
459
+ 67 ms
The kind girl was feeding the eagle
526
Joseph, Nation, &
Liversedge, 2013
Linguistic influences on eye movements
•
gaze
duration (ms)
Word length – how many letters
The beautiful girl was feeding the birds
The
kind
What can eye tracking tell us about
reading, writing, and dyslexia?
girl was feeding the birds
438
- 88 ms
350
Joseph, Liversedge, Blythe,
White, & Rayner, 2009
•
Word frequency – how often the word is read
The kind girl was feeding the birds
459
+ 67 ms
The kind girl was feeding the eagle
526
Joseph, Nation, &
Liversedge, 2013
•
Word predictability – how much a word is expected
The kind girl was feeding the viper
539
+ 80 ms
Joseph, Liversedge, Blythe, White,
Gathercole, & Rayner, 2008
Linguistic influences on eye movements
•
What can eye tracking tell us about
reading, writing, and dyslexia?
Eye movements are driven by cognition
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We move our eyes to subsequent areas of the text once the fixated word is fully processed
Reichle, Pollatsek, & Rayner, 2006
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As long as reading is progressing well, eye movements move from left-to-right (English)
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But if comprehension breaks down, eye movements are directed back to previously read text
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These backwards eye movements are known as regressions
While Mary bathed the baby slept
Frazier & Rayner, 1982
Reading progress influences on eye movements
Individual differences are important in understanding how children read
Most people score about average
We usually refer to these children
as “typically developing readers”
Number of people
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What can eye tracking tell us about
reading, writing, and dyslexia?
Skill ability
Reading progress influences on eye movements
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What can eye tracking tell us about
reading, writing, and dyslexia?
Individual differences are important in understanding how children read
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Sentence reading in a typically developing reader
Reading progress influences on eye movements
Individual differences are important in understanding how children read
Most people score about average
Number of people
•
What can eye tracking tell us about
reading, writing, and dyslexia?
Some children struggle or excel in
reading ability beyond the typical range
Skill ability
Reading progress influences on eye movements
•
What can eye tracking tell us about
reading, writing, and dyslexia?
Individual differences are important in understanding how children read
∙
Sentence reading in a reader with developmental dyslexia
Reading progress influences on eye movements
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How difficult is the reading process for children compared to adults?
Typically developing reader
Skilled adult reader
What can eye tracking tell us about
reading, writing, and dyslexia?
What can eye tracking tell us about
reading, writing, and dyslexia?
Reading progress influences on eye movements
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How difficult is the reading process for children compared to adults?
Children typically show longer reading times, make more and longer
fixations, shorter saccades, more regressions and refixations and skip less
words than adult readers; as age increases, and alongside reading ability,
less fixations are required and reading becomes easier and quicker.
Kirkby, Blythe, Drieghe, & Liversedge, 2011
Reading progress influences on eye movements
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How difficult is the reading process for a dyslexic reader?
Typically developing reader
Reader with developmental dyslexia
What can eye tracking tell us about
reading, writing, and dyslexia?
Reading progress influences on eye movements
•
What can eye tracking tell us about
reading, writing, and dyslexia?
How difficult is the reading process for a dyslexic child?
Comparison between TD readers and readers with developmental
dyslexia, eye movement recordings highlight lexical processing
difficulties. With more and longer fixations, more regressions, rarely
skipping words, longer total reading times
Kirkby, Blythe, Drieghe, & Liversedge, 2011
What can eye tracking tell us about
reading, writing, and dyslexia?
Eye movements clearly highlight lexical processing difficulty
But how do we isolate dyslexia from reading ability?
What can eye tracking tell us about
reading, writing, and dyslexia?
Matching comparison groups
Dyslexic Group
Age matched controls
Reading-age matched controls
Word reading
84.5
110
103
Pseudoword reading
87.5
110
103
RAN letters
90
105.5
95
RAN numbers
91
107
102
Chronological age
10y 8m
10y 8m
8y 0m
Reading age
8y2m
11y2m
8y2m
IQ
113
115
112
What can eye tracking tell us about
reading, writing, and dyslexia?
Basic characteristics of eye movements for child groups
Dyslexic readers
Chronological-age match
Reading-age matched
307 ms
245 ms
294 ms
Saccades amplitude
1.92°
2.31°
2.11°
Number of fixations
24
16
20.5
7818 ms
4080 ms
6711 ms
32%
26%
29%
Fixation duration
Total sentence reading time
Regression frequency
Reading progress influences on eye movements
500
450
400
350
300
250
200
150
What can eye tracking tell us about
reading, writing, and dyslexia?
454
398
282
Dyslexic readers
Chronological-age
Reading-age
matched TD readers matched TD readers
Gaze durations
Reading progress influences on eye movements
What can eye tracking tell us about
reading, writing, and dyslexia?
Landing position probability
0.3
0.25
0.2
Dyslexic Group
0.15
Chronological-age
matched TD readers
0.1
Reading-age matched
TD readers
0.05
0
Space
1
2
3
4
Position within target word
5
What can eye tracking tell us about
reading, writing, and dyslexia?
We know that dyslexic readers are processing text differently
We have seen that eye tracking can detect these small differences
So why would there be a difference?
Listening vs. reading
Listeners
receive
information
one
word
at
a
time
What can eye tracking tell us about
reading, writing, and dyslexia?
• Readers can potentially access all the information in the fovea and
parafovea.
• But do they use all of it?
• Only information from the line they are reading
• Mostly information to the right of fixation
Measuring the extent of parafoveal processing
What can eye tracking tell us about
reading, writing, and dyslexia?
Preprocessing: Gaze-contingent boundary paradigm (Rayner, 1975)
Fixation
There was a magic dragon in the kingdom.
There was a magic dragon
rdagon in the kingdom.
There was a magic dragon
jvagon in the kingdom.
Preview benefit effect
Calculating preview benefit
What can eye tracking tell us about
reading, writing, and dyslexia?
Preview identical condition: fixation time on dragon = 315
511 ms
There was a magic dragon in the kingdom.
552 ms
Preview transposed letters: Fixation time on dragon = 347
There was a magic rdagon in the kingdom.
Preview substituted letters: Fixation time on dragon= 387
616 ms
There was a magic jvagon in the kingdom.
Preview benefit = 72
95 ms
64 ms
Transposed letter effect = 40
What can eye tracking tell us about
reading, writing, and dyslexia?
We know that dyslexic readers are using all the same
information to the right of fixation compared to reading-age
and chronological-age matched readers
So something else must be going on, what are dyslexic readers
doing differently?
What can eye tracking tell us about
reading, writing, and dyslexia?
The Magnocellular Theory: Binocular coordination
(Kirkby, White, & Blythe, 2011)
What can eye tracking tell us about
reading, writing, and dyslexia?
Testing the Magnocellular Theory
 If dyslexia caused by impaired binocular coordination
 Increased binocular disparity - in dyslexic individuals during
reading and non-linguistic task
 If dyslexia causes disruption to binocular eye movements during
reading
 Increased binocular disparity should occur only during reading
What can eye tracking tell us about
reading, writing, and dyslexia?
Eye Movements
(Kirkby, Blythe, Drieghe, & Liversedge, 2011)
What can eye tracking tell us about
reading, writing, and dyslexia?
Binocular coordination
During Dot Scanning
During Reading
What can eye tracking tell us about
reading, writing, and dyslexia?
The Results Showed
 Children with dyslexia have increased disparity during reading
compared to dot scanning
 Binocular coordination was affected by the task
 Fixation disparity was significantly greater for dyslexic readers
 Adults’ & typical child readers’ binocular coordination equivalent
What can eye tracking tell us about
reading, writing, and dyslexia?
Conclusions
Poor binocular coordination is unlikely to play a causal role in dyslexia
Our data suggests that when dyslexic readers look at words there is
something different about their binocular coordination
How can we help dyslexic readers access text
•
•
What can eye tracking tell us about
reading, writing, and dyslexia?
Increasing inter-letter spacing found to •
improve legibility of text –shown in
French, Spanish, Italian child readers
(Perea et al., 2012; Zorzi et al., 2012)
Our pattern of effects suggest this is
especially effective for children with
dyslexia
•
Appling this simple technique to
eBooks for example, can potentially
improve the accessibility of text for
dyslexic readers
We find similar benefit in English
dyslexic readers
The beautiful girl was feeding the birds
T h e b e a u t i f u l g i r l w a s f e e d i n g t h e b i r ds
What can eye tracking tell us about
reading, writing, and dyslexia?
Dyslexia Friendly Classroom
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BDA – Dyslexia Friendly Classroom - difficulty in copying from the board
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Classroom learning relies heavily on copying and note-taking
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Copying from a board presents serious difficulties to almost all learners with dyslexia
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Psychologically complex task, involving visual-encoding, construction and maintenance of a mental
representation in working memory, production in written form
Do children engage in meaning or
just pattern copying?
Visual-encoding
How much can children accurately
remember and write?
lexical access
Do children read and fully
understand
information they copy?
mental representation
written production
Using mobile eye tracking
What can eye tracking tell us about
reading, writing, and dyslexia?
The Dikablis mobile eyetracker allows us to record eye movements during a task in which children are
not required to keep still!
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The mobile eye tracker links the location of the eye with the objects in the environment to work out
what children are looking at and how long they spend processing
Study
•
skilled adult readers
•
children aged 7-10
Task
∙
To copy individually
presented words from a
whiteboard in a classroom
What can eye tracking tell us about
reading, writing, and dyslexia?
What did this look like in practice?
What can eye tracking tell us about
reading, writing, and dyslexia?
What can eye tracking tell us about
reading, writing, and dyslexia?
Initial encoding time
Adults
•
Lexical influence on long words,
advantage for high frequency
•
Similar trend in short words
1800
Lexical influence on short words,
advantage for high frequency
No lexical influence on long
words
Gaze Time (ms)
•
Adults
1600
Children
•
Children
2000
1400
1200
1000
800
600
400
200
0
tiny
ruin
treasure
portrait
Word type
stable
fixation
initial
encoding
writing
onset
secondary
encoding
end
writing
verification
end
trial
What can eye tracking tell us about
reading, writing, and dyslexia?
Initial encoding time
Adults
•
Lexical influence on long words,
advantage for high frequency
•
Similar trend in short words
1800
Lexical influence on short words,
advantage for high frequency
No lexical influence on long
words
Gaze Time (ms)
•
Adults
1600
Children
•
Children
2000
1400
1200
1000
800
600
400
200
0
tiny
ruin
treasure
portrait
Word type
stable
fixation
initial
encoding
writing
onset
secondary
encoding
end
writing
verification
end
trial
What can eye tracking tell us about
reading, writing, and dyslexia?
Initial encoding time
Adults
•
Lexical influence on long words,
advantage for high frequency
•
Similar trend in short words
1800
Lexical influence on short words,
advantage for high frequency
No lexical influence on long
words – if anything, there is a
reverse frequency influence
Gaze Time (ms)
•
Adults
1600
Children
•
Children
2000
1400
1200
1000
800
600
400
200
0
tiny
ruin
treasure
portrait
Word type
stable
fixation
initial
encoding
writing
onset
secondary
encoding
end
writing
verification
end
trial
What can eye tracking tell us about
reading, writing, and dyslexia?
Written production
Both adults and children showed
very similar patterns in writing
•
Word length influences writing
processing time
There is no robust influence of
word frequency in processing
writing
10000
Children
Adults
8000
Gaze Time (ms)
•
6000
4000
2000
0
C1: short, high
stable
fixation
initial
encoding
writing
onset
secondary
encoding
C2: short, low
C3: long, high
Condition: length, frequency
end
writing
verification
C4: long, low
end
trial
Summary of copying findings
•
What does this mean?
∙
In sentence reading, children are capable of reading long, low frequency words
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But during copying, children do not always process these words as whole words
∙
•
•
What can eye tracking tell us about
reading, writing, and dyslexia?
Break them down into clusters of letters to make the task easier
Why is this important?
∙
Children can write accurately and efficiently without processing the meaning of the words
∙
Impact on learning
Even if children do read the whole word, during written production, smaller sublexical units seem
more important during the writing process
Summary
What can eye tracking tell us about
reading, writing, and dyslexia?
•
Eye movements provide a highly sensitive index of the cognitive processing during reading
•
Eye movements clearly highlight lexical processing difficulty in dyslexic readers
•
We know that dyslexic readers are processing text differently
•
We know that dyslexic readers are using all the same information to the right of fixation compared
to reading-age and chronological-age matched readers
•
We know that when dyslexic readers look at words there is something different about their binocular
coordination
•
A simple technique of adding spaces between letters can, potentially, make text more accessible for
dyslexic readers
•
But during copying, even typical readers do not always read words as whole words, instead they
break them down into clusters of letters to make the task easier but may not access the meaning