* A table with a large surface.
* Lighting that is similar to that of the patients classroom or office.
* Overlay Assessment Pack, including Visual Materials 1 and 2, and 20 A5-sized overlays.
* Overlay Score sheet, including Chart
There are ten different colours of overlays, two A5-sized overlays for each colour. Arrange the two overlays of each colour in 10 piles on the surface of the desk where you can reach them easily.
NOTE that each overlay is matte on one side and gloss on the other.
NOTE that the Chart refers to single overlays and combinations of two overlays. The outer ring in the Chart and the lower half of the central circle refer to double overlays. Double overlays are formed by placing one overlay on top of the other (it does not matter which overlay in the pair goes on top).
There are 18 colours formed from double overlays (19 including the double grey). These colours are darker and stronger (more saturated) than those provided by single overlays.
NOTE that the 19 combinations of overlays shown in the Chart are the only combinations that need to be tested. Other colour combinations are possible, in fact there are 90 possible combinations of the 10 overlays, but the combinations shown in the Chart are sufficient to sample colours systematically and efficiently. You do not need to try other combinations. The chances of any of these other combinations being preferable are very slight.
There are two passages of text labelled Visual Material 1 and Visual Material 2. Use Visual Material 2 (the smaller text) unless the child finds the text very uncomfortable to look at, or cannot see the letters or the spaces, in which case use Visual Material 1 (the large text).
* Take a single overlay and place it over half the page of text. Start with Number 1, which is Rose. Cover the left side or right side of the page with the overlay, choosing the side at random. Ask which side is clearest and most comfortable to see. (Comfort is more important than clarity.)
* Mark the Chart box with a +, 0 or -. If the side on which the overlay is placed is chosen as the clearest, then place a + in the box in the Chart corresponding to that overlay. If the overlay makes little difference to the clarity or comfort of the page, enter a 0 in the Chart. If the overlay makes the text more difficult to look at, enter a -.
* Chose which way up. If the overlay makes the text clearer or more comfortable, check which way up (matte or gloss uppermost) is best. Use this orientation subsequently for all overlays.
* Repeat the process. Continue until you have tried each of the 10 single overlays once.
* Check. If none of the overlays has been marked + then stop testing now.
* Continue with the double overlays. If any of the overlays has been marked +, then try each of the double overlays, shown in the outer ring. If you present them in the order shown you will reduce the confusing effects of colour adaptation. To save time, you need only try double overlays with boxes that touch those of boxes already marked +.
*Compare good overlays beside one another. Take one of the single overlays marked with a + and place it over half of the text (left or right side). Take another of the single overlays marked with a + and place it over the other half of the text. The overlays should be placed side by side, so that they abut one another and there is no gap between the two. One overlay should cover the left side of the text and the other the right. Vary which one goes on the right and which on the left from trial to trial.
NOTE During testing you may need to compare single overlays with a pair of overlays of the same colour You do not need three similarly coloured overlays to do this. Simply place one overlay over the entire text, then place the other overlay on top so that it covers just one side of the text (the left or the right at random). For example, simply by placing the Rose overlay over the entire text, and placing the appropriate overlay on top, over one half of the text, you can compare a Rose overlay with: 1. a combination of two Rose overlays, one on top of the other; 2. a Rose overlay with a Rose and Orange combination; 3. a Rose overlay with a Rose and Pink combination.
* Annotate the chart. Ask the child which side is the
clearest and most comfortable to look at, as before. Then take all overlays off
the page, replacing them in their piles, and put an oblique line (/) through
the box in the Chart corresponding to the colour that was not preferred. If the
child was uncertain, leave both boxes unmarked, and return to them later.
* Repeat the process. Take another pair of colours (single overlays or combinations of overlays) marked with a +, place them side by side as before, and ask the child to choose the better of the two. Then replace the overlays in their piles and put a / through the box of the colour that was not preferred. Repeat this process, until there is only one box that has not been lined through. By successive elimination you have chosen the best overlay colour.
NOTE that it is advisable to vary at random the side of the text on which the overlays are placed.
* Prepare the overlays for the patient. If the patient consistently prefers a particular combination of two overlays rather than a single overlay, the overlays should be adhered to one another by adhesive tape along both short sides. This will ensure that they are used as a pair, and the tape does not mask the overlay.
It is a good idea to check the consistency of the choice if there is any doubt. You can do this by taking the overlay or overlay combination that has been selected as best in Stages 2 or 3, and comparing it in turn with all the overlays you originally marked +.
A childs responses may be equivocal. They may appear to be inconsistent. If you are uncertain, it is helpful to arrange for a weeks trial usage of the best overlay or combination of overlays to see whether the child spontaneously uses the overlay.
You can assess whether the overlay has a beneficial effect on reading speed using the Rate of Reading Test (IOO Marketing Ltd). Individuals who use the overlay without prompting and continue to do so long-term usually read faster with the chosen overlay.