cSIFE is sensitive to high-frequency flicker. A, The response of cSIFE as a function of temporal frequency of a full-screen, full-contrast sinusoidal grating (6° wavelength, red, N = 11, except at 0.5 Hz where N = 4). The arrow indicates 5 Hz, which was used in Figure 1. The green data show the response to full-screen, sinusoidal flicker at a subset of these frequencies (N = 8, except at 2 and 40 Hz where N = 6). B, The mean response to full-screen, full-contrast sinusoidal flicker at 5 Hz (N = 7). C, The data from B plotted as a function of the luminance change between two frames, 20 ms previously (N = 7). D, The mean response to full-screen, full-contrast square-wave flicker at 20 Hz. The luminance flickered between mean luminance (0.5) and white (1 on the scale bar, N = 4). E, The mean response to a full-screen, full-contrast square-wave flicker at 20 Hz. The luminance flickered between mean luminance (0.5) and black (0 on the scale bar, N = 4). F, The power after FFT of the data in D, E, quantified at 20 and 40 Hz.