Orientation discrimination in WS 5
Bellugi, Wang, & Jernigan, 1994) who reported that individuals with WS were able to
choose the correct block faces, but that their solutions were not properly integrated
into a global whole. A control group of individuals with Down syndrome (DS)
showed the opposite pattern, namely greater global than local accuracy. However,
individuals with DS also show an atypical profile of cognitive abilities (Klein &
Mervis, 1999), and one must therefore be cautious when determining the extent to
which group differences can be accounted for by deviance in the WS, as opposed to
the DS, group. Nevertheless, this pattern of performance in WS is mirrored in drawing
tasks, when compared to typically developing controls (Bertrand, Mervis, &
Eisenberg, 1997).
To fully understand the nature of any deficit in Block Design performance in
WS, studies need to isolate the different processing stages, segmentation and
integration. A local processing bias at the level of perceptual segmentation has been
reported in autism by Shah and Frith (1993). When presented with an adapted Block
Design task, in which the model image was pre-segmented into the individual block
faces, individuals with autism showed no or little effect of segmentation, compared to
typically developing controls whose performance was facilitated by segmentation.
This suggests that the group with autism perceive the model image more as a
collection of parts than as a complete image. Following this approach, Farran et al.
(2001) investigated the effects of segmentation in WS using a „Squares construction
task’, a 2D version of the Block Design task (see Figure 1). Participants were given 4
squares, which resembled the block faces of the Block Design task but which were
divided through the centre, either diagonally (oblique), or along the vertical/
horizontal axis (nonoblique). They were then shown a model image, which they were
asked to copy by placing the squares in a 2 by 2 formation within a square frame. The