Serial dependence in higher-level visual processing

Abstract

Visual perception is not always veridical from moment to moment and can be biased by the recent history of visual input: a phenomenon called serial dependence. In this thesis, I present three studies that add to the further understanding of serial dependence, particularly in relation to higher-level visual processing. Study 1 tested whether aesthetic judgments of various artworks are subject to serial dependence. The task was to rate the attractiveness of serially presented paintings. The results indicate that attractiveness ratings of artworks are positively biased toward the recent past. In Study 2, the mechanism of serial dependence was investigated by dissociating low and higher stages of visual processing using binocular rivalry. In the experiment, two orthogonal gratings were briefly presented in a rivalry trial, followed by a monocular test grating. The results showed that the perceptually dominant grating, but not the suppressed one, exerted an attractive orientation bias on the test grating. Study 3, using face attractiveness ratings and identification as tasks, investigated whether the mechanism of serial dependence established with a low-level visual task would generalise to higher-level visual processing. Sensory uncertainty was manipulated on a trial-by-trial basis by overlaying various levels of random noise masks onto the face stimuli. The results indicated that bias magnitude toward the past was modulated by both previous and current sensory uncertainty, given that the noise modulation was appropriate. In summary, these empirical findings suggest that: i) serial dependence occurs for a task that requires a higher-level visual evaluation of a complex stimulus, ii) priors on which serial dependence is based are updated at a post-perceptual stage of visual processing, and iii) the underlying mechanism of serial dependence generalises across multiple visual stages.