Working memory signals in early visual cortex are present in weak and strong imagers

Abstract

It has been suggested that visual images are memorized across brief periods of time by vividly imagining them as if they were still there. In line with this, the contents of both working memory and visual imagery are known to be encoded already in early visual cortex. If these signals in early visual areas were indeed to reflect a combined imagery and memory code, one would predict them to be weaker for individuals with reduced visual imagery vividness. Here, we systematically investigated this question in two groups of participants. Strong and weak imagers were asked to remember images across brief delay periods. We were able to reliably reconstruct the memorized stimuli from early visual cortex during the delay. Importantly, in contrast to the prediction, the quality of reconstruction was equally accurate for both strong and weak imagers. The decodable information also closely reflected behavioral precision in both groups, suggesting it could contribute to behavioral performance, even in the extreme case of completely aphantasic individuals. Our data thus suggest that working memory signals in early visual cortex can be present even in the (near) absence of phenomenal imagery. Working memory signals in early visual cortex are thought to arise because people engage in vivid imagery to maintain visual information. We test this by measuring working memory signals in visual areas of people with strong and weak imagery abilities. We observed strong working memory signals irrespective of imagery ability, and signal strength was equally predictive of task performance in both groups. Thus, working memory in visual cortex is not necessarily linked to imagery. image