Comparison of peak-to-peak contrasts for stimuli matched for surface brightness

Results of perceptual matching for two subjects. (A) Comparison of peak-to-peak contrast of the test Cornsweet (red) or Narrow Real (blue) stimulus, versus the matching Real contrast chosen by the subject. Results of Cornsweet versus Real are comparable to that of Burr (1987). Error bars indicate +- 1 s.d. (n=8). (B) The actual peak-to-peak contrasts tested for the stimuli in cat visual cortex (white bars), versus the average matching real contrasts (dark bars) based on the human subjects. Negative contrast indicates that, to match the surface contrasts, the sign of the border contrast was reversed for the two stimuli. Based on these results, the magnitude of edge induction effects to the Real and Cornsweet stimuli should be comparable, and the magnitude of effect to the Narrow Real stimulus should be weaker.

Burr, D. C. Implications of the Craik-O'Brien illusion for brightness perception. Vision Res. 27, 1903-1913 (1987).