Orientation discrimination in WS 2

Orientation discrimination in WS 8

who were unable to perform mental rotation, may have used a manual strategy
throughout.

Although the difference in performance on the Squares construction task
observed between WS and TD individuals might well reflect differential use of mental
and manual rotation strategies in preparing to construct the stimuli, perceptual
differences in the groups’ ability to discriminate between different block patterns and
orientations might also contribute to this effect. The perception of orientation in WS
has been addressed by employing the Benton Line Orientation task (Benton, Varney,
& Hamsher, 1978) in which the participant is asked which of 11 lines (oriented 18
degrees apart) matches the orientation of two target lines. Individuals with WS have
consistently been found to be at floor in their performance on this task (Bellugi et al.,
1988a; Rossen, Klima, Bellugi, Bihrle, & Jones, 1996; Wang, Doherty, Rourke, &
Bellugi, 1995). Although this may indicate that orientation discrimination is poor in
WS, it may also reflect the fact that the task is not pitched at the appropriate level to
properly test individuals with WS (Farran & Jarrold, 2003). Stiers, Willekens,
Borghgraef, Fryns, and Vandenbussche (2000) designed the Pre-school Judgement of
line Orientation task (PJLO), which has fewer lines in the display set than the Benton
task. They found that the level of ability shown by individuals with WS on this task
was not significantly different from their overall level of non-verbal ability, measured
by the nonverbal subtests of the WPSSI (Wechsler, 1989). These mixed findings leave
open the question of whether poor performance on the Squares construction might be
attributed to problems of orientation perception.

Consequently, to further our understanding of the pattern of performance
observed in the Squares construction task, the first experiment presented here directly
examines the perceptual processing of oblique and nonoblique lines in WS. The

<<   5   6   7   8   9   10   11   >>

More intriguing information