Orientation discrimination in WS 2

Orientation discrimination in WS 7

WS on the Performance subtests of the WISC. The results showed that the variance
uniquely associated with verbal ability was significantly correlated with those tasks in
which performance was relatively elevated. This did not include the Block Design
task, which suggests that although individuals with WS can employ a verbal strategy
for some tasks with a positive effect, this is not the case for Block Design.

In addition to examining the effects of segmentation on Block Design
performance, Farran et al. (2001) also explored the second factor noted above, mental
imagery. In the Squares construction task, Farran et al. (2001) manipulated whether
squares were divided by oblique or non-oblique lines; evidence from typical
development shows that oblique lines are more difficult to discriminate between than
nonoblique lines (Cecala & Garner, 1986). Farran et al. (2001) found that their WS
group showed the same pattern of errors on the Squares construction task as typically
developing (TD) controls matched for non-verbal ability, but performed at a lower
level of accuracy overall. Both groups showed an effect of obliqueness; with
significantly longer RTs and reduced accuracy on oblique compared to nonoblique
trials. However, the effect on RTs was larger in the controls than the WS group. This
might have reflected the mental and manual manipulation strategies available to each
group. Mental and manual manipulation abilities were measured independently by
Farran et al. (2001) using a mental and a manual rotation task. The TD controls
performed well on both of these tasks, while the WS group showed high levels of
performance on the manual, but not the mental rotation task. Farran et al. (2001)
suggested that the TD controls used a mental rotation strategy to complete the
relatively easier nonoblique trials, and a less advanced manual rotation technique for
the harder, oblique trials in the Squares construction task. In contrast, the WS group,

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