Afterimage oscillation after a brief light flash

Abstract: To investigate whether oscillation might appear not only in brightness but also in color dimension, we performed the following two experiments. In Experiment 1 subjects were asked to observe a moving dim light slit in the darkness with their right eye focused on a fixation point, which resulted in an afterimage appearing like a comet’s trail after the slit. The trail oscillated rapidly in brightness (four/five times), and soon disappeared. In Experiment 2, an afterimage generated by an intense color disc (S1) was projected onto a dim white disc (S2) after a controlled period of interstimulus interval. The white disc appeared oscillating slowly between the similar color and the complementary color, at least twice in approximately 40 s. The results of these experiments led us to infer that afterimage oscillations occur in both brightness and in color dimension. These oscillations are closely correlated with those caused by two physiological mechanisms: the magnosystem generating the brightness oscillation, and the opponent‐color site of the parvosystem generating the color oscillation.