Colour Overlays and Visual Stress

What is a coloured overlay?

A coloured overlay is a semi-transparent overlay to be placed over text based materials.  Each overlay has a specific tint colour which can improve a number of aspects, including attention span, reading speed, fluency and comprehension.

How should a coloured overlay be used?

The text should be positioned with the sheet over the page to avoid reflections from the surface of the overlay caused by lighting. The overlays have a matt coating on one side, which most users prefer. The overlay should not be creased, and it is a good idea to keep it in an envelope when it is not in use, although users should nevertheless feel free to touch the overlay when reading. Coloured overlays should simply be seen as a type of reading aid, like ordinary glasses, that makes the words clearer for some people. Alternatively reading rulers can be used instead of full page overlays. (For more detail, see separate article: coloured overlays care and use.)

Are reading rulers better than coloured overlays?

Reading rulers are less intrusive than larger overlay sheets, easier to handle, cheaper, and provide additional tracking support. They are particularly useful when referring to a printed document while word-processing. Many people prefer them. Research comparing reading rulers with A4 overlays has shown that the size of the overlay does not make any difference to reading speed.

For an abstract of the research on this topic. see Visual Stress and Coloured Overlays: does size matter?

How long should overlays be used before coloured glasses are considered?

There are many factors involved. First, are the overlays obviously beneficial? If so, only a short trial period, say six weeks, is necessary, particularly if headaches have been reduced but not eliminated, and if something like untidy writing continues to be a problem and tinted paper is not practical. Under these circumstances glasses may further reduce the headaches and may well improve the handwriting. If, on the other hand, the response to overlays is less marked, it seems sensible to take a little longer before considering coloured glasses. Coloured glasses are more expensive than overlays, and it may be wise to wait before incurring the cost.

Some of this information has been adapted from the Essex University FAQ page on Visual Stress.  Click  here  for more information about coloured overlays and visual stress.