Electrophysiological correlates of sustained conscious perception.

Sustained visual awareness is associated with a negative event-related potential (ERP) that persists for the entire duration a stimulus is consciously perceived. In a visual task, participants viewed line stimuli presented for 500 or 1000 milliseconds. Some participants were informed that the lines sometimes contained a face, enabling them to see the face through visual one-shot learning, while uninformed participants did not perceive the face. Comparing brain activity between groups showed an enhanced negativity over occipitotemporal electrodes that lasted as long as the stimulus was presented. This sustained visual awareness negativity (SVAN) indicates that awareness-related brain signals correspond to the duration of a conscious percept, not just a transient onset response.

Study at a glance

Abstract

Previous research on the neural correlates of consciousness (NCC) in visual perception revealed an early event-related potential (ERP), the visual awareness negativity (VAN), to be associated with stimulus awareness. However, due to the use of brief stimulus presentations in previous studies, it remains unclear whether awareness-related negativities represent a transient onset-related response or correspond to the duration of a conscious percept. Studies are required that allow prolonged stimulus presentation under aware and unaware conditions. The present ERP study aimed to tackle this challenge by using a novel stimulation design. Male and female human participants (n = 62) performed a visual task while task-irrelevant line stimuli were presented in the background for either 500 or 1000 ms. The line stimuli sometimes contained a face, which needed so-called visual one-shot learning to be seen. Half of the participants were informed about the presence of the face, resulting in faces being perceived by the informed but not by the uninformed participants. Comparing ERPs between the informed and uninformed group revealed an enhanced negativity over occipitotemporal electrodes that persisted for the entire duration of stimulus presentation. Our results suggest that sustained visual awareness negativities (SVAN) are associated with the duration of stimulus presentation.