Visual Search against Uncomfortable Noise Patterns

Visual discomfort consists of the adverse effects of viewing certain visual stimuli such as stripes and particular filtered noise patterns. Noise patterns with amplitude spectra differing from those typical of natural images are judged as uncomfortable. Specifically, noise filtered to have 1/f2 amplitude a spectrum is judged to be more uncomfortable than 1/f noise (Juricevic et al 2010, Perception 39, 884–899). In the present study, we investigated whether stimuli with amplitude spectrum slopes previously judged to be uncomfortable affect performance on visual tasks. In the first part of the experiment, contrast detection thresholds for a target against 1/f and 1/f2 backgrounds were measured using a staircase procedure, in order to determine performance-matched contrast levels for the target. Our hypothesis is that, in the visual search task, observers will have a shorter reaction time for target absent responses for the 1/f2 trials if they are visually uncomfortable, when conditions are matched for accuracy. With low-contrast targets, no significant differences in reaction times or accuracy were found. With high-contrast targets, reaction times were shorter with the 1/f2 background compared to the 1/f background, but there was no reduction in accuracy. Eye-movement data showed there to be no differences in either saccade length or fixation duration for the two backgrounds. Therefore, although stimuli with atypical amplitude spectrum slopes have previously been shown to increase visual discomfort judgments, we found no evidence that this is associated with impaired performance in a visual search task