Individual differences in attractive and repulsive context effects on shape categorization

Abstract

How we perceive a visual form not only depends on the currently presented shape, but also on the temporal context in which it is shown. Earlier research found both attractive and repulsive context effects in perception. Tendencies to see the current stimulus similar to how the previous stimulus was seen (i.e., hysteresis, attraction) co-exist with tendencies that repel the current percept away from the organization for which there was most evidence in the previous stimulus (i.e., adaptation, repulsion). While previous research focused on group-level effects of temporal context, this study investigated whether everyone shows effects of the previous percept and the previous stimulus in the expected direction, and whether possible individual differences in these attractive and repulsive temporal context effects are consistent. Participants (N=209) conducted a perceptual categorization task with two series of abstract morph figures as stimuli, for which average temporal context effects were identified before. A Bayesian multilevel logistic regression analysis on the current percept was conducted to get estimates for the size of the hysteresis and adaptation effect per participant. Results indicate that almost everyone showed an attractive effect of what was perceived in the previous trial, while a repulsive effect of the previously shown stimulus was less universal. The size of the individual hysteresis and adaptation effects were strongly correlated: participants with a more outspoken attractive effect of the previous percept also showed a stronger repulsive effect of the previous stimulus. Furthermore, individual differences in the strength of the adaptation effect were heavily correlated with individual differences in the sensitivity to perceptual differences between the different morph levels. The study provides evidence for different percepts in different individuals even when presented with the same stimulus in the same context and thereby increases insight in how different individuals differentially combine previous and current input in their perception.