Comparing the prioritisation of items and feature-dimensions in visual working memory

Abstract

Selective attention can be directed not only to external sensory inputs, but also to internal sensory representations held within visual working memory (VWM). To date, this has been studied predominantly following retrospective cues directing attention to particular items, or their locations in memory. In addition to item-level attentional prioritisation, recent studies have shown that selectively attending to feature dimensions in VWM can also improve memory recall performance. However, no study to date has directly compared item-based and feature-based attention in VWM, nor their neural bases. Here, we compared the benefits of retrospective cues (retro-cues) that were directed either at a multi-feature item or at a feature-dimension that was shared between two spatially segregated items. Behavioural results revealed qualitatively similar attentional benefits in both recall accuracy and response time, but also showed that cueing benefits were larger following item cues. Concurrent EEG measurements further revealed a similar attenuation of posterior alpha oscillations following both item and feature retro-cues when compared to non-informative, neutral retro-cues. We argue that attention can act flexibly to prioritise the most relevant information - at either the item or the feature-level - to optimise ensuing memory-based task performance, and we discuss the implications of the observed commonalities and differences between item-level and feature-level prioritisation in VWM.