The role of spatial attention in visual short-term memory and visual consciousness: an ERP change detection study

In the framework of visual consciousness theories, visual short-term memory has been divided in different stages with different characteristics in terms of capacity, duration of the trace, and dependency from attentional resources. To date, it is still debated which is the role of attention in visual short-term memory, and which could be the electrophysiological activity related to visual consciousness. The present study had a twofold aim: to better understand the contribution of focused spatial attention on maintenance in short-term memory and trying to disentangle electrophysiological correlates related to attention, maintenance and visual consciousness. We tested 20 subjects during execution of a change detection task while recording EEG. Spatial attention was manipulated using an endogenous pre-cue which could predict (i.e., valid condition) or not (i.e., invalid condition) the side of appearance of the probe. An uninformative pre-cue was used as baseline (i.e., neutral condition). Behavioral results showed differences in accuracy between neutral and invalid conditions in all selected visual short-term memory intervals (150ms, 600ms, 1200ms), and between valid and neutral conditions for both 600ms and 1200ms intervals. The difference in accuracy between neutral and valid condition for 150ms interval was not significant. Electrophysiological results showed interesting attentional effects related to the retro-cue and probe appearance. Our findings suggest that focused spatial attention can affect maintenance of representations in visual short-term memory in a time dependent manner. Taken together with electrophysiological measures, our findings provide further insights on the role of attention in short-term memory maintenance and their implications in visual consciousness.