The role of stimulus uncertainty on attractive and repulsive biases in perception

Abstract

As the visual environment offers us an overload of visual information embedded in an abundance of noise, we are able to use previous visual experience to facilitate processing and perception of current scenes. Rather than attending to all items in our surroundings, the perceptual system filters out and prioritizes items that are more important to us. In order to make more accurate predictions about our visual environment, the attractive bias of previously attended targets pulls perception of subsequently attended targets towards their specific features, while distractors seem to have an opposing, repulsive effect on perception.While these biases generally reduce uncertainty and stabilize our perception of the world, they can also distort it from the real visual environment. While these biases are considered automatic processes, little is known as to how they affect the metaperception of one’s ownperformance – confidence.This bachelor thesis contains two similar, but separate experiments investigating whether these perceptual biases are modulated by stimulus uncertainty. Both experiments contained an odd-one-out search task of an oddly oriented line within 35 distractor lines. In Experiment 1 uncertainty was produced by higher standard deviations in the distribution of distractor orientations, increasing difficulty in target detection. Uncertainty in Experiment 2 was manipulated by changing the contrast of all items, and therefore increasing overall item discrimination. Attractive bias – also known as serial dependence – was apparent in all conditions of both experiments, while the repulsive bias of distractors was rather weak. Uncertainty had little to no effect on the biases, but more so on observers’ confidence judgments of their own task performance.