Retinotopic serial dependency in visual perception

Abstract

Previously seen stimuli can influence the current content of perception. Examples of such history effects abound (aftereffects, hysteresis, masking). Recently, renewed interest has been sparked by studies on serial dependencies: the percept reported on one trial is pulled towards the stimulus seen on the previous trial (e.g. orientation, Fisher & Whitney, 2014; facial expression, Liberman et al., 2018; position, Manassi et al., 2018). These serial dependencies are proposed to be the result of a domain-general mechanism (“continuity field”) that describes how the visual system deals with variability in the input, be it due to changes in lighting, perspective, or retinal location across eye movements. If serial dependencies are related to object recognition, then they should occur in a spatiotopic reference frame, since mechanisms that support the recognition of objects (that make up our subjective experience) must be spatiotopic (like our visual experience). The current experiment tested in what reference frame serial dependencies occur by asking subjects to report the perceived orientation of a Gabor. Both fixation and Gabor position could change across trials, giving rise to four types of two-trial sequences: identity repetitions (Gabor and fixation at same locations), spatiotopic repetitions (Gabor at same location on the screen but different fixation locations), retinotopic repetitions (Gabor and fixation at different locations, Gabor at same retinal location) and control repetitions (none of the previous). Responses were pulled towards the previously-seen orientation in the identity condition, replicating previous reports. Serial dependencies were larger in the retinotopic relative to the spatiotopic condition. These results suggest that serial dependencies might occur at multiple levels of visual processing, both early (retinotopic) and late (spatiotopic).