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.

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.


 [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.

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