Cyclic reactivation of distinct feature dimensions in human visual working memory

Area of Science:

• Cognitive Neuroscience
• Psychology

Background:

• Behavioral studies show 4-10 Hz rhythmic fluctuations in attention-related performance.
• Rhythmic attentional sampling has been primarily studied for external visual attention.
• The sampling of concurrent internal representations in working memory remains largely unexplored.

Purpose of the Study:

• To investigate how attention samples from concurrent internal representations of different feature dimensions in working memory.
• To determine if internal working memory representations exhibit rhythmic fluctuations.
• To explore the temporal dynamics of feature representation in working memory.

Main Methods:

• A human behavioral dense-sampling experiment was conducted.
• Participants held representations of two distinct feature dimensions (color and orientation) in working memory.
• WM contents were queried at 72 time-points to estimate activity time courses.

Main Results:

• An oscillatory component at 9.4 Hz was found in the joint time courses of both representations, suggesting early perceptual sampling.
• An oscillatory component at 3.5 Hz was observed in the time course difference, indicating later attentional sampling.
• Distinct internal features were activated in an alternating manner.

Conclusions:

• Internal working memory representations of distinct features undergo cyclic reactivation.
• Behavioral fluctuations at distinct frequencies are associated with internal perceptual and attentional rhythms.
• Findings challenge strict parallel processing models in visual search, suggesting potential sequential mechanisms for multi-feature search.