Consciousness and working memory (WM) have been thought to be closely
related, but their exact relationship has remained unclear. The present
study focused on the question whether visual awareness, the subjective
experience of seeing, depends on resources of WM. Three dual-task
experiments were run. The participants were asked to report their
awareness of a low-contrast target stimulus while their WM was loaded by
a requirement to concurrently maintain verbal information (Experiment
1) or visuo-spatial information (Experiment 2) in WM, or by a concurrent
executive task (Experiment 3). Behavioral responses and event-related
brain potential (ERP) correlates of visual awareness in response to the
targets were examined. Experiments 1 and 2 revealed that maintenance of
information in WM did not have any effect on reported visual awareness
and its electrophysiological correlates. Experiment 3 found that
executive load decreased reported visual awareness, which was reflected
in ERPs around 350–550 ms after stimulus onset as a reduction in the
amplitudes of P3 to detected stimuli. The earlier, posterior correlate
of visual awareness in N200 time window (180–280 ms) was not affected by
load in any of the conditions. The results suggest that visual
consciousness and WM share resources at a relatively late stage of
conscious processing, which involves active manipulation of contents.
The findings are in line with a recent view suggesting that a posterior
“hot zone” is responsible for visual awareness, while frontal regions
contribute to higher-level cognitive processes that occur after visual
awareness has arisen.