Abstract
While the effects of degraded visual input on visual processing have been studied extensively, there is a dearth of knowledge in how degraded visual input interacts with higher-level cognitive processes such as attention and working memory (WM). This is particularly relevant to people with visual impairment. Here we investigate the effects of visual noise on selective attention and working memory separately using the EEG indices of selective attention (alpha lateralization) and working memory storage (contralateral delay activity; CDA) and a within-subject task design. EEG data was recorded from 19 participants as they performed three visual tasks in which they reported the orientation of a Landolt C embedded in one of three different levels of 1/f visual noise. The first visual task was with a single target. The second task required participants to selectively attend to one target among three distractors under valid or neutral cues. The last task was identical to the second except for additional WM component. All tasks used a continuous response paradigm from which response errors were calculated. First, behavioral results showed differential effects of visual noise across tasks, though, overall, response errors tended to increase with noise level. Second, EEG results showed significant differences in the posterior CDA amplitude (WM storage) between valid and neutral trials and between the second and third tasks reflecting the difference in WM demands. Surprisingly, the CDA was not modulated by visual noise per se. Alpha lateralization (i.e., attention), however, was modulated by visual noise level. Interestingly, this alpha modulation was observed after the retro-cue, thus reflecting the internal attentional processes related to reducing the interference of visual noise with maintaining the target representation. Our findings suggest that sensory deprivation affects cognitive functions beyond the level of basic visual processing, which may be an overlooked source of difficulty in visual impairment.