Fig. 2.

(A) Example psychometric functions for one observer. The green curve shows data from the condition in which the standard Gabor patch is 8 c/deg and the oddball Gabor patch is 2 c/deg. The red curve shows data from the condition in which the standard is 2 c/deg and the oddball is 8 c/deg. Arrows show the shift in the psychometric functions from veridical and the corresponding PSEs. The middle plot (B) shows PSE data for all observers (colour-coding identical to A). Error bars for individuals show the error of the PSE extracted from the logistic function fit to the data. Error bars for the group show the standard deviation. The right-hand plot (C) shows that temporal expansion occurs when the oddball is lower in spatial frequency than the standard (green), while temporal contraction occurs when the oddball is a higher spatial frequency than the standard (red). The direction of the effect is modulated according to the spatial frequency relationship of the stimuli, not their ‘differentness’.