Distinguishing between target and nontarget fixations in a visual search task using fixation-related potentials

Abstract

The P300 event-related potential (ERP) can be used to infer whether an observer is looking at a target or not. Common practice in P300 experiments and applications is that observers are asked to fixate their eyes while stimuli are presented. 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). Participants systematically scanned search displays consisting of six small Landolt Cs in search of Cs with a particular orientation. After each search display, they indicated whether and where target Cs had been presented. As expected, an FRP component consistent with the P300 reliably distinguished between target and nontarget fixations. It was possible to classify single FRPs into target and nontarget FRPs above chance (on average 62% correct, where 50% would be chance). These results are the first step to practical applications such as covertly monitoring observers' interests and supporting search tasks.

EEG correlates of active visual search during simulated driving: An exploratory study

“…Despite the existence of a large amount of studies describing EFRPs, almost all of them are performed in well-controlled laboratory studies using simple stimuli [11]. More important, even those studies using more natural stimuli typically employ static images, avoid gaze shifts or instructed subjects to fixate during long periods (>300ms) [8], [12], [13].…”

“…More important, even those studies using more natural stimuli typically employ static images, avoid gaze shifts or instructed subjects to fixate during long periods (>300ms) [8], [12], [13]. This has allowed to identify discriminat late EFRP components [8], even at a single subject level [11]. Nonetheless, this leaves unanswered the question of how these signals are during realistic conditions and natural behaviour.…”

Combining EEG and eye movement recording in free viewing: Pitfalls and possibilities

“…We reserve ''amplitude" for EEG measures, thereby avoiding confusion in the description of EEG and eye movements. Reuderink, Vincent, van Gerven, & van Erp, 2013;Dandekar, Ding, Privitera, Carney, & Klein, 2012;Kamienkowski et al, 2012; but see Dias et al, 2013 for an opposite conclusion) and N400 (Dimigen et al, 2011). In free viewing, the latencies of the early components most likely lie within the duration of a single fixation, whereas the latencies of the late components may only appear after two or even three subsequent saccades.…”

Quality control of geological voxel models using experts' gaze

“…Another route of improving the model would be to add information from brain signals. It has been shown that by relating EEG traces to eye fixations, it is possible to distinguish above chance whether an observer is looking at a looked-for target (which in this case would be a geological model error) or not (Brouwer et al, 2013(Brouwer et al, , 2014Kamienkowski et al, 2012).…”

“…It is generally accepted that errors will draw experts' attention and visual attention is closely intertwined with gaze location (Rizzolatti et al, 1987;Corbetta et al, 1998;Carpenter, 1988;Land and Furneaux, 1997) and gaze duration (e.g., Brouwer et al, 2013). We devised an experiment that captures eye gaze behavior of 12 geological experts who were asked to visually check a geological voxel model for errors, and then also manually mark the errors they identified.…”