Abstract
Images with Fourier amplitude spectra that deviate from the natural (1/f) statistical characteristics, or that have excessive energy at medium spatial frequencies are generally uncomfortable to look at (Fernandez & Wilkins, 2008; Juricevic et al., 2010). Recently we observed analogous effects of amplitude spectra in the temporal domain for flickering patterns, but found that the discomfort for flicker is also strongly affected by the phase spectra (Yoshimoto et al., 2017). Here we examined how discomfort from flicker is affected by adaptation to different temporal spectra. Participants rated the discomfort from a flickering uniform field (17°) before or after 3 min of adaptation. The flicker comprised luminance transitions filtered by increasing (blurring) or decreasing (sharpening) the slope of the amplitude spectrum relative to 1/f, and had either a fixed (squarewave) or random phase spectrum. The pattern of aftereffects depended on the phase spectrum. For the random phase, adaptation to blurred flicker caused all test slopes to appear less comfortable, while the sharpened adaptor reduced discomfort at all slopes. For the squarewaves, the blurred adaptor again increased the discomfort from all test spectra, but the sharpened adaptor had little effect (except at 1/f). Moreover, there was little cross-adaptation between the two phase spectra. These results thus further point to the importance of phase-selective processes in the perception of discomfort from flicker. They also suggest that in general adaptation to temporal blur may lead to greater discomfort by perceptually sharpening the stimulus spectrum.