Bound feature combinations in visual short-term memory are fragile but influence long-term learning

Abstract

We explored whether individual features and bindings between those features in VSTM tasks are completely lost from trial to trial or whether residual memory traces for these features and bindings are retained in long-term memory. Memory for arrays of coloured shapes was assessed using change detection or cued recall. Across trials, either the same colour-shape (integrated object) combinations were repeated or one feature was repeated while the other varied. Observers became sensitive to the repetition of bindings, but only if it occurred on every trial. Repetition of single features only led to learning in the cued-recall task, and was weak compared to whole-object repetitions. Results suggest that representations in visual short-term memory comprise integrated objects rather than individual features. These representations are readily displaced by new representations formed on subsequent trials. However, when a given representation is not displaced, longer term residual traces can be generated to support long-term learning, and any learning that does occur is based on integrated objects, not individual features.

Keywords:

• Visual short-term memory
• Feature binding
• Learning

Acknowledgements

This research was supported by British Academy grant SG-43564 awarded to JRB and RHL. This study was conducted while AREV was visiting the University of Edinburgh. We thank Graham Hitch and an anonymous reviewer for helpful comments on a previous version of this paper.

Notes

¹Many vision researchers use the terms visual working memory and visual short-term memory interchangeably, whereas researchers in working memory view the latter as comprising one of a range of functions of the former (e.g., Logie & van der Meulen, in press). In this paper, we are primarily concerned with representations stored over the short term (within trials) and long term (across trials), and hence we will refer to visual short-term memory without implying a theoretical contrast with visual working memory.