Orientation discrimination in WS 2

Orientation discrimination in WS 19

response type was significant, F(1, 40)=19.09, p<.001, partial η²=.32, due to
increased accuracy on the „different’ responses. There was also a significant
interaction between size ratio and response type, F(4, 160)=5.85, p<.001, partial
η²=.13, which is investigated below. The interaction between response type and group
was not significant, F(1, 40)=2.43, p=.13, partial η²=.06, and the 3-way interaction
between response type, size ratio, and group was also not significant, F(4, 160)=1.14,
p=.34, partial η²=.03.

Table 4 and Figure 6 about here

To investigate the interaction between ratio and response type, two one-way
ANOVAs were employed, one for each response type, with size ratio as a within
participant factor (5 levels). Analysis of the „same’ responses showed a significant
main effect of ratio for „same’ responses, reported in terms of the linear contrast, F(1,
41)=44.28, p<.001, partial η²=.52. This contrasted to the results of the analysis of the
„different’ response, where the main effect of size ratio was not significant, reported
in terms of the linear contrast, F<1.

Response times

Response times were averaged for each participant across the 4 target shapes.
A three way ANOVA was carried out with one between participant factor of group (2
levels: WS, TD) and two within participant factors: size ratio (5 levels: 1:1, 1:2, 1:3,
1:4, 1:5), and response type (2 levels: same, different). Empty cells were replaced by
the mean RT, across both of the groups, for responses to the largest (1:5), and
arguably the hardest size ratio. As incorrect responses reflect a high level of difficulty,
this value most closely represents performance on these trials. Due to the small
number of empty cells replaced (<1%), the reduction in variance was minimal.

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