Efficient Coding in Visual Working Memory Accounts for Stimulus-Specific Variations in Recall.
The Journal of neuroscience : the official journal of the Society for Neuroscience
Society for Neuroscience
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Taylor, R., & Bays, P. (2018). Efficient Coding in Visual Working Memory Accounts for Stimulus-Specific Variations in Recall.. The Journal of neuroscience : the official journal of the Society for Neuroscience, 38 (32), 7132-7142. https://doi.org/10.1523/jneurosci.1018-18.2018
Recall of visual features from working memory varies in both bias and precision depending on stimulus parameters. While a number of models can approximate the average distribution of recall error across target stimuli, attempts to model how error varies with the choice of target have been ad hoc. Here we adapt a neural model of working memory to provide a principled account of these stimulus-specific effects, by allowing each neuron's tuning function to vary according to the principle of efficient coding, which states that neural responses should be optimised with respect to the frequency of stimuli in nature. For orientation this means incorporating a prior that favours cardinal over oblique orientations. While continuing to capture the changes in error distribution with set size, the resulting model accurately described stimulus-specific variations as well, better than a slot-based competitor. Efficient coding produces a repulsive bias away from cardinal orientations - a bias that ought to be sensitive to changes in the environmental statistics. We subsequently tested whether shifts in the stimulus distribution influenced response bias to uniformly sampled target orientations in human subjects (of either sex). Across adaptation blocks we manipulated the distribution of non-target items by sampling from a bimodal congruent (incongruent) distribution with peaks centred on cardinal (oblique) orientations. Pre-adaptation responses were repulsed away from the cardinal axes. However, exposure to the incongruent distribution produced systematic decreases in repulsion that persisted post-adaptation. This result confirms the role of prior expectation in generating stimulus-specific effects and validates the neural framework.
Humans, Likelihood Functions, Statistical Distributions, Photic Stimulation, Memory, Short-Term, Mental Recall, Visual Perception, Adaptation, Physiological, Fixation, Ocular, Models, Neurological, Adolescent, Adult, Female, Male, Young Adult, Orientation, Spatial
WELLCOME TRUST (106926/Z/15/Z)
External DOI: https://doi.org/10.1523/jneurosci.1018-18.2018
This record's URL: https://www.repository.cam.ac.uk/handle/1810/282825
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/