Neural reinstatement tracks attentional selection of object features in working memory

Abstract

Working memory (WM) is the ability to hold information in mind in the short-term and use it flexibly for behaviour. Not all items are represented equally in WM. Attention can be allocated to select and privilege relevant WM content. It is unclear whether attention selects individual features or whole objects in WM. Here, we used behavioural measures, eye-tracking and electroencephalography (EEG) to test the hypothesis that attentional selection spreads between an object’s features in WM. Twenty-six participants (male and female) completed a WM task that asked them to recall the angle of one of two oriented, coloured bars after a delay while EEG and eye-tracking data was collected. During the delay, an orthogonal ‘incidental task’ cued the colour of one item for a match/mismatch judgement. On congruent trials (50%), the cued item was probed during memory recall; on incongruent trials (50%), the other memory item was probed. As predicted, selecting the colour of an object in WM brought other features of the cued object into an attended state as revealed by EEG decoding, oscillatory α-power, gaze bias and improved subsequent orientation recall performance. Together, the results build a case for object-based attentional selection in WM. Analyses of neural processing at recall revealed that the selected object was automatically compared with the probe, whether it was the target for recall or not, providing a potential mechanism for non-predictive cueing benefits in WM.SIGNIFICANCE STATEMENTEveryday behaviour depends on working memory (WM)—the ability to hold information in mind for an upcoming task. Attention can be focused to prioritise the most relevant object in WM. Most objects consist of multiple features, such as shape and colour. It is unclear whether attention selects entire objects in WM or only enhances the currently relevant feature. Here, we show that when people focus on a single feature of an object in memory, such as its colour, other features of that object are shifted into the focus of attention and become prioritised for subsequent decision-making. The results show that well-known object-based attention mechanisms exist for internal attention and highlight objects as a key unit of selection in WM.