The influence of expertise and of physical complexity on visual short-term memory consolidation

Abstract

We investigated whether the expertise of a perceiver and the physical complexity of a stimulus influence consolidation of visual short-term memory (VSTM) in a S1–S2 (Stimulus 1–Stimulus 2) change detection task. Consolidation is assumed to make transient perceptual representations in VSTM more durable, and it is investigated by postexposure of a mask shortly after offset of the perceived stimulus (S1; 17 to 483 ms). We presented colours, Chinese characters, pseudocharacters, and novel symbols to novices (Germans) or experts of Chinese language (Chinese readers). Physical complexity was manipulated by the number of strokes. Unfamiliar material was remembered worse than familiar material (Experiments 1, 2, and 3). For novices the absolute VSTM performance was better for physically simple than for complex material, whereas for experts the complexity did not matter—Chinese readers memorized Chinese characters (Experiment 3). Articulatory suppression did not change these effects (Experiment 2). We always observed a strong effect of SOA, but this effect was influenced neither by physical complexity nor by expertise; only the length of the interstimulus interval between S1 and the mask was relevant. This was observed even with short stimulus onset asynchrony (SOA) of 100 ms (Experiment 2) and in comparing colours and characters (Experiment 5). However, masks impaired memory if they were presented at the locations of the to-be-memorized items, but not beside them—that is, interference was location-based (Experiment 6). We explain the effect of SOA by the assumption that it takes time to stop encoding of information presented at item locations with the offset of S1. The increasing resistance against interference by irrelevant material appears as consolidation of S1.

Keywords:

• Consolidation
• Visual short-term memory
• Expertise
• Physical complexity
• Perceived complexity

Acknowledgments

Most of the experiments were planned and run while the first author stayed as visiting scientist of the Brain and Cognition Unit within the International Research Training Group (IRTG 1457) “Adaptive Minds: Neural and Environmental Constraints on Learning and Memory” at Saarland University. The IRTG is supported by the German Research Foundation under Grant GRK 1457/1. The exchange visit was granted from 973 Program (2006CB303101) and the National Natural Science Foundation of China (90820305).

Notes

¹ We want to thank the reviewer who explicitly asked for this clarification.

² A part of these data was also presented at the 6th International Conference on Natural Computing (ICNC'10), Yantai, China.