Abstract
Expectations play a critical role in guiding vision during everyday life. In some cases, expectation is directly relevant to the currently relevant stimulus, while in other cases, expectation is not directly relevant but is instead tied to some other contextual aspect of the task (termed contextual expectation). Information about what target features are relevant (e.g., target orientation and location) has been shown to improve visual discrimination by enhancing the efficiency of sensory processing. However, less is known about how task-irrelevant contextual performance are similar to those induced by information about task relevance. Here, we presented subjects with a bilateral visual display of square-shaped and circle-shaped cues; these cues were presented 0-450ms before a bilateral stimulus array containing a horizontal (non-target) or a slightly tilted vertical grating (target). Task-irrelevant contextual expectation was manipulated by changing the relationship between the color of the left and right cues (e.g., in 70% of trials, left and right cue were presented in red and blue respectively, while in 30% of trials the left and right cue were presetned in blue and red respectively). We found that information about target location increased behavioral performance by reducing reaction times, specifically when the target array appeared 50-450ms after cue onset. In contrast, contextual expectation only had an effect on accuracy at the 0ms cue-to-target onset asynchrony such that an 'unexpected' context increased discrimination accuracy. Taken together, these results suggest that task-irrelevant contextual expectation and task-relevant information can have opposing effects on perceptual performance with distinct temporal dynamics.
Meeting abstract presented at VSS 2016