Orientation discrimination in WS 2

Orientation discrimination in WS 18

Results

A one-way ANOVA, with RCPM score as the dependent variable, and group
as the independent variable (2 levels: WS, TD) revealed that the group matching was
satisfactory: F(1, 41)=.08, p=.79. Data for the size transformation task were analysed
in terms of the number of correct responses and in terms of response time (RT) for
correct responses only. Preliminary analysis of correct response and RT data, using
the Kolmogrov-Smirnoff one-sample test, showed that response distributions were
approximately normal and not in need of transformation prior to further analyses.
ANOVA results are reported in terms of the between and within participant main
effects for the factors of group and response type respectively, and in terms of within
participant linear contrasts for the within participant factor of size ratio. Within
participant contrasts are of interest due to previous evidence demonstrating that size
ratio has a linear effect on speed and accuracy.

Correct responses

Figure 6 illustrates the level of performance of the two groups at each size
ratio. For this analysis, the correct response data was partitioned into the responses to
„same’ and „different’ trials. A 3 way ANOVA was employed on the number of
correct responses with group (2 levels: WS, TD) as the between participant factor, and
size ratio (5 levels: 1:1, 1:2, 1:3, 1:4, 1:5) and response type (2 levels: same, different)
as the within participant factors. Descriptive statistics of these data are shown below
in Table 4. The results showed that there was no significant main effect of group,
F(1, 40)=1.14, p=.29, partial η²=.03. There was a significant main effect of size ratio,
reported as a linear trend: F(1, 40)=40.39, p<.001, partial η² =.50, which indicates
that the number of correct responses decreased linearly as size ratio increased. The
interaction between size ratio and group was not significant (F<1). The main effect of

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