Figure 12.

Experiment 2: Size, letters. Both critical spacings are mostly conserved (red and blue). 65% thresholds are estimated from each observer's psychometric functions. Thresholds for center spacing (red) and edge spacing (blue) are compared for conditions with small and large flankers. Targets are always small. Centroid spacing (not shown) is practically the same as center spacing. Thresholds do not differ significantly when measured in terms of center spacing. Error bars indicate plus or minus one standard error about the mean (three observers). Linear fits are shown.