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, 2002; Kriss and
Evans, 2005; Singleton
and Trotter, 2005; Wilkins
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; 2001; Evans
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., 1996; Wilkins
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.
[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.
[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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