Beyond Uniform Perception: Individual and Stimulus-Specific Differences in Visual Working Memory

Working memory is crucial for short-term information processing, but its limited capacity means items are not represented with perfect fidelity to the external world. Many systematic patterns of error exist that are thought to be telling of the underlying mechanisms that process and maintain information in memory. Here we suggest that the processes governing some of these patterns of errors are interrelated and highly individual. Specifically, we look at how perceptual structure relates to stimulus-specific biases in color, and further explore the possible implication of this connection for contextual biases like serial dependence and repulsion between concurrently presented items. In Experiment 1, using a novel within-participant serial reproduction method, we reveal reliable attractors in color space across individuals, as well as individual differences that significantly influence these stimulus-specific biases. Simulations based on an independently measured perceptual structure of the stimulus space reproduce the group-level differences but do not capture the observed individual variation. In Experiment 2, we investigate how contextual biases – serial dependence when remembering 1 item and inter-item repulsion when remembering 2 items – interact with stimulus-specific biases. We identify color-specific properties of these contextual biases, suggesting they may depend on the stimulus-specific biases. We argue that because stimulus-specific biases are connected to perceptual structure, this same latent structure may impact the contextual biases. Overall, we show a strong connection between stimulus-specific biases, contextual biases, and perceptual structure, as well as rich individual differences in these biases.