In A Second Study, Again Reported In Wilkins Et Al. (2001), 378 Children

In a second study, again reported in Wilkins et al. (2001), 378 children were given an overlay of a random colour which they used for a few months before being given an overlay of their preferred colour. Those children who, by chance, were given an overlay that matched their preference were more likely to carry on using that overlay than those that did not. There was a negative proportional relationship between the difference in the colour of the randomly selected overlay and the preferred overlay with the time for which they used the randomly assigned overlay. The choice of colours by different children showed remarkable variability in these studies - the most frequently chosen colours were rose and aqua and these were selected by only 10% of the children. Recent work by Simmers, Grey & Wilkins (1999) has found some connection between the colour chosen and what is termed 'ocular accommodation'. Still, this relationship was very weak and can be largely discounted as providing a basis for theorising about the connection between the individual child and the colour of overlay they prefer to use. Again it was the case in this research that it was the poorer readers who tended to benefit most from the use of coloured overlays. In summarising the findings in this line of research, Wilkins (2002) states that overlays provide a very cheap way of improving reading ability that has received scientific support. In addition there is no reason why adults cannot benefit in the same way as children. Coloured glasses are often found to be more effective than coloured overlays as it is the colour rather than the reduction in contrast that has been found to be the most important factor in increasing reading fluency.
While this line of research has found some benefit for the use of coloured overlays, more questions immediately arise, researchers are keen to know more about the type of tints that are being used and how the use of tints tie into the theories about dyslexia. Wilkins, Sihra & Smith (2005) theorise that the perceptual distortions that are seen in dyslexics, amongst others with specific learning difficulties, are a result of the hyperexcitability of the visual cortex. The tints are hypothesised in this theory to redistribute the visual stimulus across the cortex more evenly so as to make reading more comfortable. As this hyperexcitability varies across individuals it is necessary to use different tints to gain the same effect. The research reported by Wilkins et al. (2005) asked how the speed of reading was affected by the variations in the colour provided and the number of tints that are required. They found, as previous research had, that moving away from the tint specifically selected by an individual resulted in a slowing of reading speed. They also found that the amount of illumination was important.