Abstract
Everyday life requires monitoring of changes in the environment even without paying attention to it. Numerous EEG-studies have revealed that we are able to detect visual changes pre-attentively. Here we asked, whether also changes in visually simulated self-motion (heading) are processed automatically, i.e. without necessarily paying attention to it. We studied event-related potentials (ERPs) in a visual oddball paradigm. ERPs as observed in response to standard (80% occurrence) and deviant (20% occurrence) stimuli were compared in order to test for the occurrence of visual mismatch negativity (MMN). The MMN is a component of an event-related brain potential that reflects a pre-attentive mechanism for change detection. In this study the subject's attention was drawn off the self-motion stimuli by one of two different unrelated secondary tasks which they had to perform during stimulus presentation. Subjects viewed a random dot pattern that simulated self-motion across a ground plane. The self-motion stimuli (37° x 11°) were presented on a computer monitor in front of them. Standard and deviant trials lasted 400 ms each and differed only in their simulated heading direction (forward-left vs. forward-right). Each trial consisted of a stationary and a following self-motion phase (800 ms and 400 ms, respectively). EEG-data were aligned to the onset of the simulated self-motion. Analysis of the evoked ERPs revealed a MMN between 100 ms and 170 ms after self-motion onset. Topographic analysis of this difference revealed a typical N2-component topography across occipital and parietal areas, which was lateralized, i.e. contralateral with respect to the simulated heading direction. Occurrence of the MMN was not dependent on the specific secondary task. The occurrence of MMNs as observed in our study provides evidence for a pre-attentive processing of visually simulated self-motion direction.
Meeting abstract presented at VSS 2016