Two competing mechanisms underlying neon color spreading, visual phantoms and grating induction

Neon color spreading is closely related to the photopic visual phantom illu sion. since these two completion phenomena are characterized by in-phase li ghtness induction, and the only difference in the stimulus configuration is the difference in the inducer height. This idea was supported by the prese nt study. Neon color spreading showed almost the same function of critical spatial frequency as photopic visual phantoms (Experiment 1), and the criti cal spatial frequency was constant as the inducer height was changed (Exper iment 2). We also examined the relationship between neon color spreading an d grating induction (characterized by counterphase lightness induction) in critical spatial frequency (Experiment 3) and in magnitudes of lightness in duction (Experiment 4) as a function of the inducer height. The inducer hei ght at which in-phase (neon color spreading) appearance gave way to counter phase (grating) induction was approximately 0.1 deg. These results suggest that neon color spreading shares a common neural mechanism with the photopi c visual phantom illusion and that this mechanism is different from, and co mpetes with, the mechanism of grating induction. (C) 2001 Elsevier Science Ltd. All rights reserved.