You will need:
* 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
Setting up
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).
Stage 1. Identifying good
overlays
* 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 +.
Stage 2. Finding the best of the good overlays.
*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.
Stage 3. Confirmation of
choice
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.
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Additional pictorial instructions under preparation