In the spatial context task, a two-way repeated-measures ANOVA was performed on the mean PSE. The two factors were “flanker condition” (intact and scrambled flankers), and “flanker direction” (−45°, −30°, −15°, +15°, +30°, and +45°). The main effect of “flanker condition” was not significant, F(1, 29) = 0.917, р = 0.346, ηp2 = 0.031. The main effect of ‘flanker direction” was significant, F(5, 145) = 6.05, р = 4 × 10−5, ηp2 = 0.173. Most importantly, the interaction was highly significant, F(5, 145) = 5.28, р = 1.8 × 10−4, ηp2 = 0.154. Post hoc comparisons, Holm–Bonferroni corrected, showed that for three flanker directions the mean PSE was significantly stronger for intact flanker condition than scrambled flanker condition: for −30°, mean difference = 2.83°, SD = 0.682°, p = 2.6 × 10−4; for +30°, mean difference = −1.63°, SD = 0.734°, p = 0.034; for +45°, mean difference = −3.39°, SD = 1.17°, p = 0.007. The results indicate that the effect of flanker condition on the mean PSE varied depending on the flanker direction. We further conducted four paired-samples t-tests to compare the effect between +15° with +30°/+45° and −15° with −30°/−45° flanker directions. The data were calculated as the difference between intact and scrambled flanker conditions for each of the six flanker directions. The results showed a significantly stronger effect for the −30° flanker direction compared with −15°: mean difference = −2.30°, t(29) = −2.62, р = 0.014, Cohen's d = −0.553, indicating tuning of the effect across flanker directions within the range of −15° to −30°.
We performed one-sample t-tests to test whether the effect under the scrambled condition differed significantly from zero. The results indicate that there was no significant effect for any of the six directions. The outcomes demonstrate that the spatial context effect depends more on global rather than local processing of the surrounding stimuli.
In the adaptation task, a one-sample
t-test was first performed to test whether the aftereffect was significantly different from zero. The aftereffect data used here were generated by calculating the average repulsive aftereffect produced by the adaptation direction of +30° and the repulsive aftereffect produced by the adaptation direction of
−30°. The results showed a significant effect:
t(29) = 2.49,
р = 0.019, Cohen's
d = 0.456. This result is consistent with the result we obtained in our previous study on smaller samples (
Chen et al., 2023).