Neural correlates of consciousness in the sound-induced flash illusion.
Theresa Rieger, Josefine Feuerstein, Niko A Busch, Thomas Straube, Maximilian Bruchmann
Scientific Reports November 28, 2025 DOI: 10.1038/s41598-025-28068-5 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Event-related potential (ERP) study Peer reviewed |
|---|---|
| Sample size | 47 |
| Population | Human participants |
| Intervention | sound-induced flash illusion (SIFI) |
| Keywords | Consciousness EEG/Erp Illusions Ncc Van Visual awareness |
| Key points | The visual awareness negativity (VAN) is enhanced during illusory perceptions of a second flash in the sound-induced flash illusion, supporting its role as a neural correlate of consciousness. |
Abstract
The visual awareness negativity (VAN) has been identified as a potential neuronal correlate of consciousness (NCC). The VAN is typically found when comparing experimental trials in which a stimulus was perceived with trials in which the same stimulus was not perceived. However, if the VAN represents a reliable NCC, it should also be observed under conditions in which participants report conscious perception despite the absence of a corresponding visual stimulus, i.e., a visual illusion. Our event-related potential (ERP) study (N = 47) aimed to investigate this question by using a suited stimulation design, the sound-induced flash illusion (SIFI), for which a visual stimulus is presented once together with two short beeps, leading - on about half the trials - to the illusory perception of a second flash, with graded levels of reported awareness of these trials. When comparing illusory with non-illusory trials, we found an enhanced negativity over posterior electrodes between 250 and 300 ms. Frequency analyses additionally revealed lower pre-stimulus alpha power in illusion trials, aligning with prior work linking alpha dynamics to perceptual variability. Our findings suggest that even illusory perceptions enhance negative potentials over posterior regions during the VAN interval, supporting the interpretation of the VAN as a NCC.