Comparative analysis of early visual processes across presentation modalities: The event-related potential evoked by real-life, virtual reality, and planar objects

Characteristics of real-life objects, such as binocular depth, potentially yield visual processes going beyond what examinations of planar pictures as experimental cues can reveal. While virtual reality (VR) is used to approximate real-life features in experimental settings, this approach fundamentally hinges on whether the distinct modalities are processed in a similar way. To examine which stages of early visual processing depend on modality-specific characteristics, our study compares the electrophysiological responses to 2D (PC), VR, and real-life (RL) objects. To this end, participants passively explored abstract objects in one of these modalities followed by active exploration in a delayed matching-to-sample-task. Our results indicate that all modalities fundamentally yield comparable visual processes. Remarkably, our RL setup evoked the P1-N1-P2 complex corresponding to the well-established ERP morphology. However, the magnitude of the ERP response during real-life visual processing was more comparable to the response to VR than to PC. Indicating effects of stereoscopy on the earliest processing stages, the P1 differentiated only between PC and RL, and the N1 differentiated PC from both other conditions. In contrast, the P2 distinguished VR from both other conditions, which potentially indicated stereoscopic visual fatigue. Complementary analysis of the alpha-band response revealed higher attentional demands in response to PC and VR compared with RL, ruling out that the ERP-based results are exclusively driven by attentional effects. Whereas comparable fundamental processes are likely occurring under all modalities, our study advises the use of VR if the processes' magnitude is of relevance, emphasizing its value to approximate real-life visual processing.