1. What can eye tracking tell us about reading, writing, and dyslexia?
A range of literacy schemes are highly successful
Estimated that between 1–33% of the population has reading difficulties
Educational practice must continue to be informed by research
Eye movement research can inform our knowledge of children’s reading progress
Understand what a child must learn to become a skilled reader
Will enable a children to transition from learning to read, to reading to learn

2. Highly sensitive research tool “a window to the mind”
To examine developmental changes in the processes associated with reading.
Therefore, ideal to study progression from beginner to skilled reader.
But also sensitive enough to detect subtle differences in children with dyslexia

3. What do eye movements look like?
Your may have the impression that we scan smoothly over text when we read making very smooth eye movements
“Saccade”: ballistic eye movement between words
“Fixation”: eyes are relatively still and the majority of lexical processing occurs
Eye movements provide a highly sensitive index of the cognitive processing during reading

4. Rapid decline in visual acuity on the retina
Why do we need to make eye movements? Because of the rapid resolution decline from the fovea out on the retina.

5. This is the area of most detail you would see during a fixation.

6. Visual acuity is limited to the

7. Parafovea 15 letters Fovea 8 letters
The fovea, which extends about 8 letters during reading
If you hold your thumb up, you fovea is the size of your nail.
Then slightly less acuity from the parafovea which extends about 15 letters.
So eye movements serve to bring the high acuity area to fixate one word after an other when we read.
By measuring eye movements we are able to understand the processes involved in reading.

8. Characteristics of skilled reading
A series of saccades and fixations
Aim to land a saccade close to centre of a word
Not all words are fixated (especially short words)
Some words are refixated
- most fixation duration ~200ms less than a ¼ of a second
The beautiful girl was feeding the birds *
- 85% forward saccades,15% backwards saccades
The beautiful girl was feeding the birds
- 15% content words, 65% function
Reading involves a series of highly stylised movements
The time when the eyes are still, called a fixation, range between 100 ms and 500 milliseconds, but on average fixations last around 200ms for a skilled adult readers that is less than ¼ of a second.
We aim to land a saccade in the middle of a word
Around 85% of saccades, move the eyes to right when we read English, but 15% are backward movements, perhaps due to miscomprehension where we want to reread a section of text
But not all words are fixated, some words are skipped, this is especially true for short words, around 15% of content words and 65% of function words
But some words are fixated more than once.
The beautiful girl was feeding the birds
The beautiful girl was feeding the birds

9. Linguistic influences on children’s eye movements
gaze
duration (ms)
Word length – how many letters
The girl was feeding the birds
beautiful
438
- 88 ms
The girl was feeding the birds
kind
350
Joseph, Liversedge, Blythe, White, & Rayner, 2009
So what are the main influences on eye movements?
There are a range of linguistic influences on eye movements, for example word-length,
In a typical study a target word is embedded in the same sentence
Child readers typically take longer to read long words than short words, they may also make more fixations on a longer word.

10. Linguistic influences on eye movements
gaze
duration (ms)
Word length – how many letters
Word frequency – how often the word is read
The girl was feeding the birds
beautiful
438
- 88 ms
The girl was feeding the birds
kind
350
Joseph, Liversedge, Blythe, White & Rayner, 2009
The kind girl was feeding the
birds
459
+ 67 ms
eagle
The kind girl was feeding the
526
Other factors like word frequency, or the amount of time a word appears in books
Control for length this time in our target word, and manipulate frequency
The time spend reading “birds” a highly frequent word is shorter than reading “eagle” a low frequency
Joseph, Nation, & Liversedge, 2013

11. Linguistic influences on eye movements
gaze
duration (ms)
Word length – how many letters
Word frequency – how often the word is read
Word predictability – how much a word is expected
The girl was feeding the birds
beautiful
438
- 88 ms
The girl was feeding the birds
kind
350
Joseph, Liversedge, Blythe, White, & Rayner, 2009
The kind girl was feeding the
birds
459
+ 67 ms
eagle
The kind girl was feeding the
526
And another influence is word predictability,
Notice that these differences are less than 100 milliseconds, but eye tracking offers us a highly sensitive tool to understand these influences
Joseph, Nation, & Liversedge, 2013
viper
The kind girl was feeding the
539
+ 80 ms
Joseph, Liversedge, Blythe, White, Gathercole, & Rayner, 2008

12. Linguistic influences on eye movements
Eye movements are driven by cognition
We move our eyes to subsequent areas of the text once the fixated word is fully processed
As long as reading is progressing well, eye movements move from left-to-right (English)
But if comprehension breaks down, eye movements are directed back to previously read text
These backwards eye movements are known as regressions
Reichle, Pollatsek, & Rayner, 2006
Frazier & Rayner, 1982
While Mary bathed the baby slept
These backwards eye movements are known as regressions, the example is called a garden path sentence, typically children will take longer to fixate on slept and then make a regression back to an earlier part of the text
So naturally a child’s prior knowledge of the world also plays a role in reading

13. 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
Skill ability

14. Reading progress influences on eye movements
Individual differences are important in understanding how children read
Sentence reading in a typically developing reader
Here is a sample of eye movements during a simple sentence reading task.

15. Reading progress influences on eye movements
Individual differences are important in understanding how children read
Most people score about average
Some children struggle or excel in reading ability beyond the typical range
Number of people
Skill ability

16. Reading progress influences on eye movements
Individual differences are important in understanding how children read
Sentence reading in a reader with developmental dyslexia
And so here is a sample of eye movement data from a child with developmental dyslexia during the same sentence reading task.

17. Reading progress influences on eye movements
How difficult is the reading process for children compared to adults?
Typically developing reader
Skilled adult reader
We know that children find reading more difficult to adults, and you can see that in the number of fixations made, the duration of the fixations and the length of the saccade for example.

18. Reading progress influences on eye movements
How difficult is the reading process for children compared to adults?
But also in the number of regressions made, so typically children make more regressions than 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

19. Reading progress influences on eye movements
How difficult is the reading process for a dyslexic reader?
Typically developing reader
Reader with developmental dyslexia
But there are also differences between groups children of the same age, with and without developmental dyslexia.

20. Reading progress influences on eye movements
How difficult is the reading process for a dyslexic child?
Eye movement recordings highlight lexical processing difficulties in children with Developmental dyslexia
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

21. Eye movements clearly highlight lexical processing difficulty But how do we isolate dyslexia from reading ability?

22. Matching comparison groups
Dyslexic Group
Age matched controls
Word reading
84.5
110
Pseudoword reading
87.5
RAN letters  90
105.5
RAN numbers 91
107
Chronological age
10y 8m
Reading age
8y2m
11y2m IQ
113
115
Reading-age matched controls
103 95
102
8y 0m
8y2m
112
As reading ability influences eye movements we really need to include another group.
So we now include a reading age matched comparison group so that we can see if these differences between groups is a function of dyslexia or a function of reading ability?

23. Basic characteristics of eye movements for child groups
Dyslexic readers
Chronological-age match
Reading-age matched
Fixation duration
307 ms
245 ms
294 ms
Saccades amplitude
1.92°
2.31°
2.11°
Number of fixations 24 16
20.5
Total sentence reading time
7818 ms
4080 ms
6711 ms
Regression frequency
32%
26%
29%
So then when we add in this third group we still see small but significant differences in the characteristics of eye movements during reading

24. Reading progress influences on eye movements
Gaze durations

25. Reading progress influences on eye movements
So there are substantial differences in foveal word recognition between these groups

26. 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?

27. Listening vs. reading
Listeners
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
receive
information
one
word at
But readers can poten a
time

28. Measuring the extent of parafoveal processing
Preprocessing: Gaze-contingent boundary paradigm (Rayner, 1975)
There was a magic dragon in the kingdom.
There was a magic rdagon in the kingdom.
There was a magic jvagon in the kingdom.
Preview benefit effect
Fixation
dragon
dragon

29. Calculating preview benefit
Preview identical condition: fixation time on dragon = 315 ms
There was a magic dragon in the kingdom.
Preview transposed letters: Fixation time on dragon = 347 ms
There was a magic rdagon in the kingdom.
Preview substituted letters: Fixation time on dragon= ms
There was a magic jvagon in the kingdom.
Preview benefit = 72 ms Transposed letter effect = 40 ms
511
552
616
Transposed-letter effect in skilled reading taken as evidence for a language processing system that extracts letter identity information independent to absolute letter position (Johnson, Perea, & Rayner, 2007)
Under specification of letter position encoding, however, has been causally linked to developmental dyslexia (e.g. Friedmann & Rahamim, 2007)
These results and comparable results for adult dyslexic readers showed disruption in reading for previews with transposed letters and substituted letters compared to baseline identical previews
With less disruption from transposed letter previews compared to substituted letter previews
The typical transposition effect observed in dyslexic readers has important implications for the causal role of letter position encoding in dyslexia therefore, there seems to be processing occuring prior to fixation for readers with dyslexia and the typical flexibility of letter position encoding. 95 64

30. 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?

31. The Magnocellular Theory: Binocular coordination
(Kirkby, White, & Blythe, 2011)

32. 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

33. Eye Movements
(Kirkby, Blythe, Drieghe, & Liversedge, 2011)

34. Binocular coordination
During Dot Scanning During Reading

35. Binocular coordination was affected by the task
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
The results from the study showed: (i) children with dyslexia have an increased magnitude of fixation disparity when they are reading compared to dot scanning – within the same group of children, binocular coordination was affected by the task; (ii) in comparison with other participant groups, when reading, the magnitude of fixation disparity was significantly greater in the dyslexic children; and (iii) adults’ and typically developing children’s binocular coordination was equivalent, and this was the case during both reading and dot scanning.

36. 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
Importantly, however, poor binocular coordination is unlikely to play a causal role in these children’s reading difficulties. Clearly, our data represent a stimulus specific-deficit in regard to binocular coordination.

37. How can we help dyslexic readers access text
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)
We find similar benefit in English dyslexic readers
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
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 d s

38. Dyslexia Friendly Classroom
BDA – Dyslexia Friendly Classroom - difficulty in copying from the board
Classroom learning relies heavily on copying and note-taking
Copying from a board presents serious difficulties to almost all learners with dyslexia
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
mental representation
Do children read and fully understand
information they copy?
written production

39. Using mobile eye tracking
The Dikablis mobile eyetracker allows us to record eye movements during a task in which children are not required to keep still!
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

40. Study skilled adult readers children aged 7-10 Task
To copy individually presented words from a whiteboard in a classroom

41. What did this look like in practice?

42. Initial encoding time Adults
Lexical influence on long words, advantage for high frequency
Similar trend in short words
Children
Lexical influence on short words, advantage for high frequency
No lexical influence on long words
stable
fixation
initial
encoding
writing
onset
secondary
end
verification
trial

43. Initial encoding time Adults
Lexical influence on long words, advantage for high frequency
Similar trend in short words
Children
Lexical influence on short words, advantage for high frequency
No lexical influence on long words
stable
fixation
initial
encoding
writing
onset
secondary
end
verification
trial

44. Initial encoding time Adults
Lexical influence on long words, advantage for high frequency
Similar trend in short words
Children
Lexical influence on short words, advantage for high frequency
No lexical influence on long words – if anything, there is a reverse frequency influence
stable
fixation
initial
encoding
writing
onset
secondary
end
verification
trial

45. 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
stable
fixation
initial
encoding
writing
onset
secondary
end
verification
trial

46. Summary of copying findings
What does this mean?
In sentence reading, children are capable of reading long, low frequency words
But during copying, children do not always process these words as whole words
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

47. Summary
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