Working memory load and search efficiency in conventional monitor-based 2D versus 3D virtual settings: analysis of response times and parietal induced alpha activity in a modified Sternberg task

In psychophysiological research on memory encoding and retrieval, Virtual Reality (VR) allows for meaningful insights into mnemonic processing under realistic conditions, yet its effects on working memory (WM) processing and performance remain inconclusive. The present study investigates how information search processes in WM differ when stimulus material is encoded in a conventional monitor-based context or in a more realistic virtual setting, and whether complex, naturalistic stimulus properties facilitate or challenge WM processing and task performance. Participants performed a modified Sternberg task with everyday objects presented either on a 2D monitor or in photorealistic VR. To investigate the search mechanism and WM load, response times, accuracy, and parietal induced alpha activity during retention were analyzed. Across both modalities, response times, error rates, and parietal alpha activity increased with setsize, consistent with serial WM search up to capacity limits. Reaction times were faster for target than non-target probes, suggesting that complex object stimuli engage familiarity- or priming-based components in WM search, particularly in VR. Critically, 3D presentation yielded faster response times across setsizes and lower WM load, reflected by reduced parietal alpha activity during retention, while accuracy was preserved. Moreover, response times in the 2D condition deviated earlier from linearity at higher setsizes, whereas 3D presentation resulted in a more gradual increase, indicating delayed capacity-related saturation. Together, the behavioral and electrophysiological findings indicate that more realistic presentation in VR supports more efficient utilization of WM capacity, likely by facilitating access to stored representations, without altering the fundamental serial nature of WM search.