12/24/2023 0 Comments Inform target chances![]() ![]() Rather than locking EEG to stimulus onset, we lock EEG to fixation onset and examine whether we can distinguish target from nontarget fixations on a single-fixation basis. Here we try to infer from EEG whether individuals look at a target object or not in situations with natural eye movements. We expect that the brain's electrophysiological response to perceiving a target among nontargets will be similar regardless of whether the eyes are static and targets and nontargets are presented at a fixation location or whether an observer fixates a set of nontargets individually in search for a target (Kamienkowski, Ison, Quiroga, & Sigman, 2012). However, in natural visual search tasks, observers sample their visual environment by self-initiated fixations and saccades instead of fixating a location where the visual stimulus is known to appear. For example, they fixate a fixation cross that is subsequently replaced by a particular visual stimulus, or they fixate a target among nontargets and count the number of times it is flashed. Usually, participants using a P300 BCI or taking part in an experiment in which the P300 is investigated, are asked not to move their eyes around the time that the P300 occurs. These results are the first step to practical applications such as covertly monitoring observers' interests and supporting search tasks. It was possible to classify single FRPs into target and nontarget FRPs above chance (on average 62% correct, where 50% would be chance). As expected, an FRP component consistent with the P300 reliably distinguished between target and nontarget fixations. After each search display, they indicated whether and where target Cs had been presented. Participants systematically scanned search displays consisting of six small Landolt Cs in search of Cs with a particular orientation. We investigated the possibility to differentiate between single target and nontarget fixations in a target search task involving eye movements by using EEG epochs synchronized to fixation onset (fixation-related potentials: FRPs). Common practice in P300 experiments and applications is that observers are asked to fixate their eyes while stimuli are presented. Abstract The P300 event-related potential (ERP) can be used to infer whether an observer is looking at a target or not. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |