Simple and Complex Working Memory Tasks Allow Similar Benefits of Information Compression

Area of Science:

• Cognitive Psychology
• Neuroscience

Background:

• Working memory span tasks measure cognitive capacity.
• Complex span tasks limit chunking strategies, resulting in lower average spans (4±1 items) compared to simple span tasks (7±2 items).
• Chunking, or grouping items, is a mnemonic strategy that can inflate simple span performance.

Purpose of the Study:

• To investigate the role of chunking and information compressibility in simple versus complex working memory span tasks.
• To test the hypothesis that chunking is primarily beneficial in simple span tasks.

Main Methods:

• Developed a compressibility metric to quantify stimulus list chunkability.
• Manipulated task type (simple vs. complex span) and stimulus chunkability.
• Measured performance across four conditions: simple span with chunkable items, simple span with non-chunkable items, complex span with chunkable items, and complex span with non-chunkable items.

Main Results:

• Contrary to predictions, information compressibility influenced performance in both simple and complex span tasks.
• The effect of compressibility was similar across both task types, not exclusive to simple spans.
• The difference in performance between simple and complex span tasks may not solely stem from the prevention of chunking in complex tasks.

Conclusions:

• Complex span tasks might overestimate general working memory storage capacity.
• The distinction between simple and complex span performance likely involves mechanisms beyond the mere prevention of chunking strategies in complex tasks.
• Information compressibility is a significant factor influencing working memory performance across different task designs.