Figure 3.

(a) Schematic illustration of the pattern onset/offset stimulation mode. Here a patterned field is alternated with a uniform field of the same mean luminance. (b) Schematic illustration of the pattern-reversal stimulation mode. Here the same pattern is presented in both phases, but with a 180° shift of spatial phase that causes bright bars to be exchanged for dark ones and vice versa. (c) Schematic illustration of one cycle of the response to pattern onset/offset consisting of a large response at pattern onset and a smaller response at offset. (d) Schematic illustration of one cycle of the response to pattern reversal. Here the response to each reversal event in the display is accompanied by an equal response. Note that the period of the response is now one half of the full stimulus cycle in (b). (e) The response spectrum of the pattern onset/offset response contains both odd (1f, 3f, etc.) and even (2f, 4f, etc.) harmonics of the stimulus frequency. (f) The response spectrum of the pattern-reversal response contains only even harmonics (2f, 4f, etc.) of the stimulus frequency.