Similarity-driven compression during encoding supports biased but more precise working memory.

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Perception

Background:

• Visual working memory (VWM) is crucial for navigating complex environments.
• Inter-item similarity can impair encoding but enhance memory maintenance.
• Prior research suggests similarity benefits memory maintenance, but the mechanism is unclear.

Purpose of the Study:

• To investigate if inter-item similarity enhances VWM by compressing similar items into summary representations.
• To determine if this similarity-based compression occurs during encoding or active memory maintenance.
• To examine the timing of similarity-based compression within a trial.

Main Methods:

• Participants encoded visual displays with varying color similarity.
• Retrospective cues were used to probe memory for specific items.
• Experiments manipulated inter-item similarity and cue timing.

Main Results:

• Higher memory precision and attractive biases were observed between similar items, supporting compression.
• The similarity benefit and attractive bias occurred even without cues.
• Compression effects were consistent regardless of cue validity or timing, indicating early occurrence.

Conclusions:

• Inter-item similarity enhances VWM performance through early compression into summary representations.
• This compression mechanism operates before active memory maintenance or cue presentation.
• Findings clarify the role of item similarity in VWM and its underlying neural processes.