Monday, 3 June 2013

Dyslexia, Reading fluency, Colour, parafoveal processing and logic

This weekend I was talking with a relative who is also a teacher.  She told me that the new school she is working at was using colour overlays to help the pupils.

The school has a high proportion of students with ‘Special educational needs’.
They are aiming to get around 90% of their pupils into the 5+ GCSE grades ABC.  
Most SEN pupils have relatively low reading speeds, and there are good arguments to think that the low reading speeds are really about limited visual attention span, the number of letters that can be processed in parallel as they read. (see previous posts) or the number of milliseconds it takes to compute  the visual data this block of letters and others that are in the parafovea; how many letter can be processed within affixation…the perceptual span.

If this is true, and it is looking increasingly certain as more research comes out, then the gains that are experienced when using a coloured filter, has to be caused by.
  1. A decrease in the retinal data compute time … increased data transfer rate per millisecond
  2. Better spatial and temporal data integration as the ‘lines’ or edges’ move across the centre-surround arrangement of the cone cells of the retina; leading to reduced crowding effects.

Research into this is totally possible, but I do not have the resources. All published research seems to treat 'colour' as anything other than white or grey.

Usually 'red' , 'green',  'blue'  or yellow. With no real thought about the biochemistry of pigments and the metrics of pigment bleaching in the cone cells or the edge detection process.

My own work tells me that it is not actually really about ‘colour’ anyway.  Unfortunately, it requires a different mindset about ‘colour’ than appears to be dominant.

The filters that most schools use are from a very restricted palette. For example there is one cyan usually.  Cyan is not really a colour. It is what is perceived when the red cone stimulation is reduced compared with the green cone cells.

About half the population tested by my colleagues and me (from a sample of around 12,000) actually benefit from the use of ‘a cyan’.

But there are thousands of ‘cyans’; If the filter takes out too much red then it may be worse than a white background.

There may be other limiting factors not checked properly.

  • It may be that unless the font size is big enough, then the changing the amount of red will have no effect. It is not the controlling factor.

  • It may be that the ambient lighting is too bright and again the Cyan filter will have no effect.

  • Perhaps they need ophthalmic glasses first  to get any benefit.

The danger is that many young people at this school and other colleges and universities, will actually get minimal or no benefit when they could have got a great deal by teachers/schools/support staff not really understanding what they are doing.

A few will gain a great deal, and will be what spurs people on to use this very ‘cheap’ approach. Many, the majority, will get a ‘false negative’ and will have their failures reinforced.

 This costs them and our country a fortune unnecessarily.  The false negatives, and minimal benefits  that most children get is actually very expensive.

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