Many event-related potential (ERP) studies have tried to find out which brain processes are responsible for the subjective experience of seeing. The contribution of these studies has been crucial in order to identify the temporal and spatial dynamics of visual awareness. The negative difference wave named visual awareness negativity (VAN), observed around 200 ms after the stimulus onset, has been claimed by many as a plausible candidate for reflecting the processes correlating with conscious visual perception. Other studies argue instead that only the P3 wave, a positive wave observed around 300-400 ms, correlates with visual awareness. The aim of the present study was to shed light on the issue of the presence of VAN even when using an experimental procedure that allows to dissociate the ERP correlate of subjective awareness from those of unconscious perception, allowing a separate analysis. Data from 24 participants was collected in the present study. The experimental framework included a forced-choice localization task of a low-contrast stimulus, followed by the subjective rating of awareness. The results of the study support the idea that the VAN is the earliest electrophysiological correlate of subjective visual awareness and that the phenomenon of visual awareness emerges early in the visual area.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-104606 |
| Date | January 2015 |
| Creators | Grassini, Simone |
| Publisher | Umeå universitet, Institutionen för psykologi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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