Thursday 28 February 2013

Phonological processing or Visual processing? Which is in control when you read?


Phonological processing or Visual processing? Which is in control when you read?

This is a very important question. Possibly it is the most important as we move towards enabling more people to have more access to text.
It is obvious that reading is a ‘phonological output.’ Text is a ‘substitute for the spoken word, our thoughts are speech based.
A second question that needs considering is this.
What controls phonological processing?

I ask you this one question.
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?

If your answer is yes then you are saying that  
‘My phonological output is controlled by my visual processing.’
 If it does not then perhaps your phonological processing might not be being controlled by visual processing.  You would need to check more carefully.
If a colour or screen brightness makes it easier or harder to read then again Visual processing is in charge.

If the reading of the person in front of you is at all affected by the way the text is presented then again you are agreeing that...
‘Their phonological output is controlled by my their processing’

So anyone out there been in denial?
For those that replied ‘Yes’ 
Please answer the following question.  Why?

I am not sure yet but there are some pretty good hypotheses and some good theories, good biology.

Crowding effects, foveal diameter, magnocellular deficit, visual attention span, uncorrected refractive/focussing problems, and Binocular muscle management/cerebellum problems?

There may be many other problems that the person is having that exacerbate their studying or access to text. BUT that is not the cause of their present reading performance.

Just a bit of logic.

Respond in comments on the blog.

First remove, if possible any visual barriers to phonological processing.
I do not try and motivate my car to run better. I make sure what can be accurately adjusted is.

Phonological processing or Visual processing? Which is in control when you read?


Phonological processing or Visual processing? Which is in control when you read?

This is a very important question. Possibly it is the most important as we move towards enabling more people to have more access to text.
It is obvious that reading is a ‘phonological output.’ Text is a ‘substitute for the spoken word, our thoughts are speech based.
A second question that needs considering is this.
What controls phonological processing?

I ask you this one question.
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?
Does the font you are reading affect how easy it is to read?

If your answer is yes then you are saying that  
‘My phonological output is controlled by my visual processing.’
 If it does not then perhaps your phonological processing might not be being controlled by visual processing.  You would need to check more carefully.
If a colour or screen brightness makes it easier or harder to read then again Visual processing is in charge.

If the reading of the person in front of you is at all affected by the way the text is presented then again you are agreeing that...
‘Their phonological output is controlled by my their processing’

So anyone out there been in denial?
For those that replied ‘Yes’ 
Please answer the following question.  Why?

I am not sure yet but there are some pretty good hypotheses and some good theories, good biology.

Crowding effects, foveal diameter, magnocellular deficit, visual attention span, uncorrected refractive/focussing problems, and Binocular muscle management/cerebellum problems?

There may be many other problems that the person is having that exacerbate their studying or access to text. BUT that is not the cause of their present reading performance.

Just a bit of logic.

Respond in comments on the blog.

First remove, if possible any visual barriers to phonological processing.
I do not try and motivate my car to run better. I make sure what can be accurately adjusted is.

Tuesday 26 February 2013

Comments on the discussion section of the Snowling et al article Questioning the benefits that coloured overlays can have for reading in students with and without dyslexia


Comments on the discussion section of the Snowling et al article Questioning the benefits that coloured overlays can have for reading in students with and without dyslexia


This Blog contains HTML points where I have made comments on the discussion taken from the original article.
These points are at the base of the blog.

This does get a bit detailed. The article was brought to my attention yesterday. I can send the Urll for the original article as well.


Discussion
This study addressed three important questions relating to visual stress: (1) Are undergraduate students with dyslexia more likely to experience visual stress[P1]  during reading than undergraduate students without dyslexia? (2) Does the benefit shown by overlays[P2]  in reading unconnected text extend to reading rate and comprehension of meaningful connected text? (3) Does the improvement shown by coloured overlays on WRRT have good reliability?
All participants in the present study chose an overlay in comparison to 84% of participants in Kriss and Evans (2005). Overall, students read the unconnected text faster with overlays than without, consistent with previous studies (Evans and Joseph, 2002Kriss and Evans, 2005Singleton and Trotter, 2005Wilkins et al., 1996; 2001). Over half (58%) of the normal readers and 75% of the dyslexic readers showed more than a 5% increase in their reading rate[P3]  when using the overlays. Therefore, using this criterion, more dyslexics could be classified as having visual stress than controls.
Although they reported experiencing symptoms of visual stress on a questionnaire, the students with dyslexia in this sample did not show greater gains in reading rate with an overlay than controls[P4] . This[P5]  finding is inconsistent with Singleton and Henderson (2007b) who reported that children with[P6]  dyslexia showed greater gains in reading rate with overlays than controls.







Singleton and Trotter (2005) reported that only dyslexic adults with visual stress significantly benefited from overlays in contrast to dyslexic adults without visual stress, non-dyslexic adults with visual stress, and adults without either dyslexia or visual stress. However, in the present study, the correlation between total symptoms reported and improvement in reading rate with an overlay was weak for controls and not significant for the dyslexic group. Counter to expectations, this implies that individuals who experience more symptoms of visual stress do not benefit more from overlays than individuals who experience few symptoms of visual stress. This finding sparks concern, suggesting that the two main methods of identifying visual stress may not lead to the same diagnostic conclusions. Indeed, Wilkins (2003) stated that ‘. . . sometimes individuals who show dramatic improvements in reading fluency with a coloured overlay report no symptoms and show no signs of visual stress’ (p. 18). Visual stress questionnaires are problematic because many symptoms can be attributed to binocular vision and accommodative anomalies as well as decoding problems[P7] . Given that increased rates of visual and oculomotor difficulties have been reported in individuals with dyslexia (Evans, 1998; 2001Evans et al., 1999), the higher scores for the dyslexic group on the questionnaire may not reflect susceptibility to visual stress, but rather, the presence of other visual anomalies[P8] . This is problematic since overlays are frequently distributed[P9]  solely on the basis of symptom questionnaires or subjective beneficial reports of coloured overlays or lenses without a formal assessment of optometric function[P10] .













Consistent with Ritchie et al., 2011, we found that neither reading comprehension nor rate of reading connected text was improved by overlays in either group. This[P11]  finding questions the value of overlays for reading naturalistic texts. While it is important for the present results to be replicated using a wider variety of passages of varying difficulty, the results question the value that overlays can[P12]  have for undergraduate students with or without dyslexia.
The dyslexic group showed slower reading rate overall. Moreover, there was a significant negative correlation between reading rate without an overlay and the improvement shown in reading rate with an overlay for both groups. A linear relationship has been reported between baseline latency and difference scores (Chapman, Chapman and Curran et al., 1994), suggesting that the size of improvement in reading rate with an overlay on WRRT is confounded by baseline reading rate. Thus, individuals with dyslexia who have a slower reading rate without an overlay have more ‘room for improvement’ than individuals who start out with faster baseline reading rate. This may inflate the improvement scores and account for previous findings that dyslexics show larger improvements in reading rate with an overlay than controls[P13] . Hence, caution should be taken when using such difference scores as a diagnostic indicator, particularly with dyslexic readers.







We also carried out a preliminary investigation of the reliability of overlay testing using the WRRT in undergraduates with and without dyslexia. This issue is particularly important given that overlay testing with WRRT is often used as a means to identify visual stress[P14]  as well as being the primary treatment method. Both groups read more words per minute in Phase 2 than in Phase 1, suggesting that reading rate on WRRT increases with practice. Although the test–retest reliability of reading without an overlay was strong for both groups, consistent with Wilkins et al., 1996Wilkins et al., 2001, the reliability coefficients for the improvement in reading with overlays were weak. Mean overlay improvement did not significantly differ in Phase 1 and 2 for the controls[P15] , but was significantly reduced for the dyslexic group in Phase 2. These results suggest that this means of testing for the benefit of overlays is not reliable when used with young adults. Although the present sample may have contained only a handful of individuals with visual stress, the test–retest reliability of assessment procedures[P16]  should be high regardless of the sample to be tested.








None of the previous studies that have used the immediate benefit criterion have examined the same participants twice in a month as in this study. Wilkins et al. (2001) examined children after 8 months of sustained use, and Jeanes et al. (1997) tested children after 3 and 10 months of sustained voluntary use[P17] . Therefore, these participants had been using overlays for prolonged periods which could have increased the test–retest reliability. Nevertheless, any measure which is used as a diagnostic tool should strive for strong reliability. Although it is important to emphasise the preliminary nature of the present findings and that the reliability coefficients reported here must be replicated in studies with larger samples, one would have anticipated greater agreement between the improvement scores in Phase 1 and 2.
The benefit shown from overlays on WRRT significantly decreased in Phase 2 for the dyslexic group but not for the control group. The improvement scores may have been inflated at Phase 1 because of the lower baseline reading rate in this group (Chapman et al., 1994). An alternative explanation could be that individuals with dyslexia are more prone to novelty effects than controls and that these decrease with repeated exposure. This is particularly likely if the students with dyslexia were aware that overlays are known to aid reading fluency. Indeed, a large proportion (56%) of the dyslexic students had previously been provided with coloured overlays. In the light of the present results, this practice raises concern[P18] .
In conclusion, visual stress remains[P19]  a controversial subject. The dyslexic undergraduates in this study reported experiencing significantly more symptoms of visual stress than undergraduates without dyslexia. However, it remains unclear whether these symptoms were solely attributable to visual stress, or rather to other visual anomalies. All participants read faster with an overlay than without, however, in contrast with previous findings, undergraduates with dyslexia did not benefit from coloured overlays to a greater extent than undergraduates without dyslexia. Furthermore, benefit in reading rate with an overlay did not extend to reading connected text or to reading comprehension, questioning the practical value of coloured overlays as[P20]  a remediation for reading difficulties. Finally, the improvement in reading rate with an overlay was not consistent over time and can therefore not be regarded as a reliable indicator of visual stress[P21]  for dyslexic students. The findings from this study question the use of coloured overlays as a means of identifying or treating visual stress[P22]  as a remediation for reading difficulties. A limitation of our study was the small sample size and the possibility that the students tested were not representative of all those studying in higher education. Although our findings are in need of replication with a larger sample, our results, together with the lack of causal evidence highlighted by previous reviews, suggest that great care should be taken before recommending coloured overlays in the remediation of dyslexia[P23] .






 [P1]Jim Gilchrist at Bradford Optometry would have  prefer to distinguish between ophthalmic originating visual stress and pattern-related visual stress. I tend to agree with this although it is difficult to identify causation at a ‘sympton identification stage.


 [P2]This relates to the use of Intuitive Overlays and the forced choice protocols to identify a ‘preference’ These overlays were designed for research purposes not clinical purposes. And I would suggest too coarse anyway.


 [P3]Reading rate is an interesting concept. Assuming this to be a reading aloud rate of Random text as in the Wilkins rate of reading?


 [P4]If we take a ‘Limiting factors model’ for a person reading, this suggests that even if it did help there were other limiting factors at play in most individuals. I.e. the reported and presumably reduced visual stress symptoms were not affecting rate. Though it may hav affected reading stamina. Very important I studying.


 [P5]


 [P6]It is now understood that automaticity develops with age . With children below say 10 years old the visual span is most likely limiting speed in those with slow reading development.Perceptual span increases with automaticity.. I think. SoI would suggest that this is a likely outcome.


 [P7]As above there is an overlap in causality likely here. Also so many people do not identify the symptoms as ‘stress’ they think of them as norma;’mor have developed strategies associated with reading which avoids getting to the point where their systemdoes not reach ‘tipping points’ and the symptoms are triggered.


 [P8]Using an eye tracker a common response to ophthalmic issues is to suppress an eye so the person effectively becomes monocular. This gives rise to dyspraxic type symptoms associated with reading although it can also give rise to attention management problems since the ‘suppressed eye may well drift sideways away from the text target. Then any image movement on the retina of the suppressed eye will give a reflexive saccade to the moving object  and could suppress the image from the reading eye.


 [P9]To be honest the protocols used  rarely follow those recommended. It takes about 20minutes to 30minutes to follow the protocols carefully and can be very confusing to the tester. So there is a tendency to almost randomness in my opinion.  That was the reason I went over to a measurement based system rather than intuitive much to the annoyance of colleagues at the time.


 [P10]Most dyslexic undergraduates have a long history of optometric/ophthalmic support ( from our data) but in my opinion not sufficiently rigorous on too many occasions.


 [P11]This is like comparing chalk and cheese as they say!  The protocols and materials are not comparable. Arnold designed the |Intuitive overlays because of questions of design and functionality with the Irlen approach.   Perhaps we should have compared the use of Sharps toffee papers, they have different coloured sellophane too!


 [P12]I agree I think that the question is more about what value the protocols used in this study have.


 [P13]I am more interested in the distribution of the ranges of reading ratemin the populations in that a biophysics perspective can kick  in. For example there are certain speeds that are consistent across studies.
134/8.. reading rates for dyslexic undergraduates
158… reading rates for dyslexic undergraduates
184.. reading rate for non=dyslexioc undergraduates and optimised dyslexic undergraduates.. our data
217/219.. reading aloud rates for optimised dyslexic undergraduates and non dyslexic adult undergraduates/graduates/
I can develop this further.


 [P14]I honestly cannot understand this statement. Why on earth do this? Who does?


 [P15]That was the reason why in 1999 IO decided to move to an objective choice process rather than the forced choice protocols. and then to more precise computer based identification in 2000. We were racking students longitudinally. Some students returning four or five times.


 [P16]This does depend on the assumption that there is no ‘therapeutic component. Not that I am claiming there is. But with an objective approach for many students that appears to happen which could well be a consequence , if everything is done well, of increased visual span, possibly from a reduction in crowding ( jury is out on that at the moment.) or from increased perceptual span as a consequence of serial processing of more visual spans within a fixation and a consequential or associated reduction in demand on working memory with a release of more resources in the central executive for other function.. My hypothesis  J


 [P17]This is a very important point Although test-retest is a study of the protocols rather than the concept behind the idea. So perhaps this should be reflected in the title of the report.


 [P18]The longitudinal aspects of this study as compared with studies with  younger people  are so different that placebo effects could not be ruled out. Or indeed any Thompson effects ( I think I know what I mean there,, correct me if I am wrong.)


 [P19]On that the many people involved in using the term have little or know idea about the biology of reading and as such this is a problem of Hegelian Dialectics.  There is not a real conversation taking place. Each person or group of people has their own mental construct of the concept and as such cannot understand or agree with each other. So this discussion is fundamentally flawed and we need a real symposium on the issue. Hopefully a rational consensus might emerge. In Biology a ‘stressed system’ can be defined. This is not really psychology though.


 [P20]No. This  questions the value of the protocols and materials used in this study.


 [P21]I really cannot get my head around this sort of statement. It is really a nonsense to think it was in the first place!


 [P22]The word #treating’ implies that ‘visual stress’ this is a disorder. a disease. To me this is the same as saying a person running in shoes that are the wrong design, finding running difficult or slow is experiencing a disability/ disorder which is called ‘running stress’


 [P23]Now this final conclusion I am in total agreement with.
It is about time that interventions of all sorts were properly audited for benefit.  It got me into trouble though  on many times.

Sunday 24 February 2013

Rapid Digit Naming. A phonological processing measure? Uta Frith Research


Today I was listening to Uta Frith on the radio. 

 Twelve years ago, on the suggestion of a colleague of hers. I used rapid digit naming as an alternative to rapid automatic naming of text to find out how the dyslexic students were performing compared with non-dyslexic adults. As Uta reported the mean for the dyslexic students was around 135  digits per minute.

The same as for rapid  word naming.  The inference in her research was that this was evidence for a phonological deficit.

However when the students were asked to undertake RDN using their optimal settings on the computer screen their performance average 184 digits per minute which was the same s the RAN mean of non-dyslexic students.

 It was also the same as reported for RDN by Uta for the non-dyslexic students at University College.

The question I ask is this.

If the Phonological processing is apparently controlled by the visual image, which one is controlling the reading performance?

Anyone has any answers other than the obvious one which I inferred?




Friday 22 February 2013

Results from yesterday


Yesterday’s  work with ‘John’ (not his name)  was very interesting. With his agreement I shall simply report the data we obtained.

This data was collected using a binocular eyetracker.

Silent reading of basic text on a default computer screen taken gave a reading speed of 49.6 words per minute.

Font size 12, background 255/255/255   Dell Inspiron laptop. Factory setting background full luminance.

Characters per fixation……… 1.4
Words per fixation…………….0.24

Silent reading on his optimised computer screen gave a reading speed of 183 words per minute

Font size 12, background settings… Red 43  Green 161  Blue 162
( I could not get the font size correct when I copied this onto the blog. Sorry.)

Characters per fixation…….6.0
Words per fixation…………..1.0

After reading on his optimised background for 20 seconds these performance figures had changed to the following.

Reading speed had increased to  216 words per minute.
Characters per fixation…..7.48
Words per fixation…………1.3


Thursday 21 February 2013

Anecdotal evidence? Or case studies?


Anecdotal evidence? Or case studies?

As some of you have already seen, yesterday I was working with a fellow professional, taking her reading performance ‘to another level’.

Sandra was in a way very typical of many dyslexic adults, in that she had been taught and had learnt strategies to enable her cope and thrive despite the world appearing to be a very unfriendly place for someone who had to live with a contrast between the way she was seen by others and her own inner feelings about her capability.

In Sandra’s case this has led to explore, to and to assist many other adults. As she has navigated her way through, she has been able and is able to help others on the journey.
Today I shall work with a young man who from what I understand, has not been as successful yet. He has sort of accepted the world’s view of him, or at least that is what I think is so. I shall find out this afternoon.

With his permission, I hope, we shall all be able to understand where he is and where he could go to.  Well I hope so.  We not make any progress.

What fascinates me is how few other professionals in this area really seem to want to know about this stuff.

I like the fact that I can audit progress and benefit. I like the fact that the biological model being applied is so consistent in its outcomes. I can conjecture on mechanisms and to some extent can explore them further, but this work is driven by a ‘technological loop’ rather than a science loop.  The mathematics of the model is complex in that it is about a complex system where cause, correlation and effect can get confused. A typical biological system.

It reminds me of agriculture. Farming appears to be a mixture of science and art.  The desired output can be seen simplistically as ‘tons of product per acre’. Farmers vary the inputs based on what is perceived to be the ‘limiting factor’ controlling the output. But across a field there are huge variations in conditions. The needs of individual plants can be lost.

Short term need by society might be in conflict with long term need, such as maintenance of soil structure, soil fertility, reduction in the fossil fuel energy investment needed to get the food produced.

The evidence base on which farmers make their decisions is a mix of science and experience. The science research usually originated from observations, anecdotal evidence which then gets investigated ‘scientifically’.  For example we know that fungi and bacteria associate with plant roots to provide nutrients to the plant such as Nitrates, Phosphates and trace elements. But it is easier to do ‘the science’ of how much of these fertilisers we add every year rather than how do we nurture the fungi and bacteria which will provide the crops with their needs. The latter will probably give us a better, bigger crop without the massive investment in fossil fuels of the present ‘science based’ methods. If you are interested google ‘permaculture’ and find out more.

What I do and many others is to gather and apply evidence from case studies which can feed back to science based research. This all occurs within the context of ongoing research and at present seems to not be on conflict with the outcomes of research.
So another one today. 

Perhaps I am a bit like a motor racing engineer checking if the technology will work today in another grand prix?

I think I know what the outcomes will be. 

Wednesday 20 February 2013



What can really be done to enable a dyslexic adult? Today’s report on Sandra Fox

Sandra is a professional supporting disabled students. We decided last year to see just what can be done to enable a severely dyslexic adult.

Last September we had a preliminary meeting which showed that there was a correctible ophthalmic component to her difficulties. This was despite the prescription she already had. It was a clear issue which showed up with discussion, minimal testing and from use of the binocular eye tracker.

In September we calculated an optimal computer background setting and decided that we would arrange for Sandra to be seen by an ophthalmologist I have been collaborating with.

Today 6 months later Sandra saw my colleague and we had confirmation about her condition and calculation of what prescription was needed.

I then retested her for optimal computer settings.

Below are some details about the outcomes. We wait excited to find out what happens when we finally have the correct glasses for her. 

Watch this space.

There is a video on U-Tube showing the original consultation.
There will be  detailed report coming soon

___________________________________________________________




The graph below shows Sandra’s reading on a default computer screen on September 14th 2012.
37.575 seconds for 85 words 494 characters 120 fixations.

4.11 characters per fixation

313 milliseconds per fixation
136 words per minute





The graph below shows Sandra’s reading using her optimal conditions but without her optimal glasses on February 20th 2013.
12.84 seconds for 88 words.  515 characters. 50 fixations

10.03 characters per fixation.
257 milliseconds per fixation

411 words per minute



What will happen when she has her perfect pair of glasses?

Please keep in mind my comments on crowding, visual attentions span and perceptual span in the last blog.

More details to come.


Tuesday 19 February 2013

Effective reading performance,dyslexia and lessons from AMD.



Effective reading performance, dyslexia and lessons from AMD.

What is controlling the reading performance in adults? Crowding? Visual attention span?

Ok so what really controls how well an adult can read?

‘Reading well’ is an interesting idea.
 Is it….
·         How fast a person can read?

·         How long a person can read for?

·         How well they understand what they have read?

·         How well they enjoy what they read?

Research on reading performance it is often reduced down to  the number of words which can be read correctly per minute. But many people can read faster than people who understand the ideas in the reading better than them. So the idea of intelligence gets drafted in. But the meaning of the word ‘intelligence’ is not really fixed so we have discussions and research using lots of imprecise words.

I want to use an idea of ‘effective reading performance’.(ERF) I want this ERF to somehow be independent of the level of education , culture or language sophistication of the person.

ERF needs to be a measure of how fast a person can read a set of instructions to correctly undertake a simple task.  So the ERF will involve the effective interpretation of text to as quickly as possible .

So what will control how fast and accurately the reading will take place?  There appears to be strong evidence that in adults their ‘reading speed’ is no longer dependent on phonological processing unlike when they were young. 


Visual attention span (VAS) 
Visual attention span (VAS) is a measure of the number of letters which can be processed / identified at the same time as each other when a person looks at a string of letters, a word

In young children there appears to be evidence building up that visual attention span (VAS) may have a controlling effect on the development of their phonological understanding, rather than the other way round, which has been argued in the past.
.
Perceptual span  (PS).

This is the number of letters you can see without moving your eyes when looking at a string of letters
This is not quite the same as VAS when looking at a string of letters.  You could describe it as how many VAS you can process in one fixation.

Crowding effects

The way the presence of letters and proximity of letters nearby, affect the speed and correct of recognition of a letter.

Evidences

1.   That how large the letters are in words can affect how easily the letters in words are identified
2.   That how easily the letters in words are identified can be affect ed by how close they are to each other. .
3.   The proximity of lines of text above and below the one being read can affect how easily the line being read is identified.
4.   The proximity of words to each other (the gap between words) can affect how easily the word will be identified.
5.   The  spatial regularity (pattern nature) of the words  around the word affects how easily the word will be identified. (pattern related visual stress.. PRVS)
·         .
·         .
These are just five variables that are fixed in printed text. Evidence suggests that what each person (the distances/proximities/size) needs to maximise their reading speed is personal to them.  The phenomenon being referred to here is crowding.

Here the word ‘easily’ is being used to mean how many milliseconds to identify the word. A measure of speed of processing or perhaps a measure of how little ‘computing power’ or memory us needed.


So let’s think about the way crowding and VAS and PS may interact when reading.

When using a binocular eyetracker to study the way an adult’s eye move when they are reading certain things become obvious.

1.    An accomplished reader needs fewer stops/fixations/photographs to get through a sentence than a ‘poor reader’.

2.    An accomplished reader processes more characters/letters per stop/fixation/photograph than an accomplished reader.


3.    An accomplished reader takes a shorter time to process each letter/character than a poor reader.

4.    Everyone’s eyes appear to stop/fixate/photograph around 4 times a second.


So what we need to do is to find out if it is possible increase the speed of processing of the letters.

 Either as more letters processed at a time (VAS) or/and fewer milliseconds to process each group (VAS) of letters so that more letters can be processed in each fixation. An increased perceptual span (PS)

The VAS will control how big a word is (number of letters) which can be parallel processed. VAS will then influence the ability to recognise and blend the phonemes within a word. Giving rise to a sense of fluency and then intonation.

 If VAS is very restricted then the person is unlikely to achieve a fluency of delivery when reading aloud or in their ‘inner voice’ when reading silently.
If the VAS is processed very quickly then it may be possible to hold in memory (Increased PS) the phonemic components of a word and still blend them hence achieving a higher level of fluency/intonation.

The time needed to process each group of letters (The VAS) is appears to be  associated with automaticity. The greater the reading experience the lower the amount of spatial (edge) detail needed to identify the letter string.

Crowding affects VAS and probably PS.  This is particularly obvious in people with age related macular degeneration (AMD). Loss of function in the centre of the retina, the fovea and macular, creates an increasing need to use the parafovea and peripheral retina to process text. The cells and and organisation of the connectivity between cells get larger away from the fovea.

 As such the crowding effect on the VAS gets bigger and bigger, reducing the VAS AND increasing the time needed to process the VAS reducing the PS.  These difficulties lead to a gradual but persistent reduction in reading speed/performance with the person taking on some of the characteristics of a person with ‘developmental dyslexia’.

Raising the font size which is a common response ends up counterproductive, since that will itself constrain the VAS and the PS ( perceptual span) ultimately needing a fixation per letter. The person reverts to a reading style reminiscent of the beginner reader in terms of the eye movement management demand,

Those working with colour, with adults know that the phonological components of the reading performance of their clients increases in a step like way., without any training. The use of a binocular eyetracker can show the increased number of characters processed per fixation and hence per second.

The issues to be addressed are these.
Does the colour (chromaticity) affect….
1.            The VAS?

2.            The crowding which controls the VAS?


3.            The time taken to process each VAS?

4.       The perceptual span as a consequence of affecting the VAS and the time to process the VAS?

If we can investigate / answer these issues we will be starting to make sense of the mechanisms.