A matter of availability: Sharper tuning for memorized than for perceived stimulus features.

Poster Presentation 43.435: Monday, May 22, 2023, 8:30 am – 12:30 pm, Pavilion
Session: Visual Working Memory: Neural mechanisms

Samson Chota1 (), Surya Gayet1, J. Leon Kenemans1, Christian N.L. Olivers2, Stefan Van der Stigchel1; 1Utrecht University, 2Vrije Universiteit Amsterdam

Our visual environment is relatively stable over time. An optimized visual system could capitalize on this by not devoting any representational resources to objects that are still physically present. The vividness of subjective experience, on the other hand, suggests that externally available (i.e., perceived) information is more strongly represented in neural signals than memorized information. To distinguish between these opposing predictions, we use EEG multivariate pattern analysis to quantify the representational strength of task-relevant features (color or spatial frequency) in anticipation of a change-detection task. Perceptual availability was manipulated between experimental blocks by either keeping the stimulus available on the screen during a two second delay period (perception) or removing it shortly after its initial presentation for the same time period (memory). We find that task-relevant (i.e., attended) memorized features are more strongly represented than irrelevant (i.e., unattended) features. More importantly, we find that task-relevant features evoke significantly weaker representations when they are perceptually available compared to when they are unavailable. These findings demonstrate that, contrary to what subjective experience suggests, vividly perceived stimuli elicit weaker neural representations (in terms of detectable multivariate information) than the same stimuli maintained in visual working memory. We hypothesize that an efficient visual system spends little of its limited resources on the internal representation of information that is externally available anyway.