Orientation discrimination in WS 22
A difference between same and different response patterns is not an
uncommon finding in the literature on size transformation (e.g., Besner, 1983; Besner
& Coltheart, 1976; Kubovy & Podgorny, 1981). We also found a linear decrease in
accuracy with increasing size ratio from responses to the „same’ trials only.
Responses to the „different’ trials were not affected by increasing size ratio. This
difference in response patterns for same and different trials suggests that the increased
difficulty experienced with increasing size ratio, must relate to the act of size
transformation itself, rather than a general difficulty caused by an overall increase in
cognitive demands. We suggest that this difference in response patterns is best
explained by response uncertainty, which could cause participants to adopt strategic
response patterns. The pattern of performance in the present study appears to indicate
that as trials became more difficult, individuals became less able to perform the size
transformation accurately and, when unsure defaulted to a „different’ response. On the
„same’ trials, this default response was incorrect, which can explain why accuracy
decreased with increasing size ratio and why, on „different’ trials accuracy did not
decrease with increasing size ratio, but stayed constant across the five size ratios (see
Besner, 1983; and Jolicoeur & Besner, 1987 for alternative accounts).
The results of Experiment 2 contrast sharply with those in our previous study
(Farran et al., 2001) where level of performance of the group of individuals with WS
on a mental rotation task, also a measure of mental image transformation, was
significantly poorer than that of a control group who were again matched by score on
the RCPM. The Z-score analysis demonstrated a significant difference in the level of
ability of the individuals with WS on the two tasks, relative to matched controls;
performance was superior on the size transformation task in WS than on the mental
rotation task. It appears that the ability to mentally transformation images is available