Fig. 3.

Sample psychometric functions for compound stimuli on the left (filled symbols) and right (open symbols) of fixation (observer SH, contour adaptation, 1 Hz, synchronous components). Symbol size indicates the relative number of responses underlying each data point (actual numbers vary from 1 to 46 responses per point). The horizontal grey line indicates the point of 50% probability of responding on the compound side. The vertical grey line (100° on x axis) represents the point of veridical equality. The PSE is calculated from the average of the points where the left and right side functions cross the 50% probability line.