Orientation discrimination in WS 10
participants had been diagnosed by medical practitioners before the WS genotype had
been identified. This diagnosis was based on their unique cognitive, behavioural and
facial characteristics. All WS participants had been recruited for a previous study
from the records of the Williams Syndrome Foundation UK.
Table 1 about here
Design and Procedure
An A5 card was placed length-ways in front of the participant. This depicted
the 4 target stimuli; 4 black and white squares divided through the centre, each
displayed in one of 4 possible orientations, as shown in Figures 2a and b. In condition
1 the squares were divided by a diagonal line (obliques) and in condition 2 they were
divided by horizontal/ vertical lines (nonobliques). A sliding arrow was attached to
the base of card, which was used to point to each of the four targets. The participant
was shown a model image which was made up of the four possible orientations of
stimuli (i.e. the 4 target squares) in a 2 by 2 formation, and example of which is
illustrated in Figure 3 below. Red lines separated the image into the four quadrants.
Participants were asked to match one of the target squares on their card, as indicated
by the red arrow, to one of the 4 quadrants of the stimulus pattern by outlining it with
their finger. The arrow indicated which square to identify sequentially, moving from
left to right across the four possible targets. This sequence was repeated 4 times, thus
there were 16 trials. The position of each of the 4 target squares in the model image
appeared in each of the 4 quadrants once. Presentation of the model images was in a
fixed random order, so that the correct position of the target in the image presented
could not be predicted. Reaction time (RT) was measured using a stop watch. RT was