Fixation-related potentials in visual search: a combined EEG and eye tracking study

JUAN E KAMIENKOWSKI; MAIAS J ISON; RODRIGO QUIAN QUIROGA; MARIANO SIGMAN

JOURNAL OF VISION

ASSOC RESEARCH VISION OPHTHALMOLOGY INC

Lugar: Rockville, MD 20852; Año: 2012 vol. 12 p. 1 - 20

1534-7362

We report the study of concurrent eye movements and electroencephalographic (EEG) recordings whilesubjects freely explored a search array looking for hidden targets. We describe a sequence of fixation-event related potentials (fERPs) which unfolds during ~400 ms following each fixation. We show that this sequence highly resembles the event-related responses in a replay experiment in which subjects kept fixation while a sequence of images simulating the spatial and temporal patterns occurring around the fovea during the free viewingexperiment. Similar responses were also observed in a second control experiment where the appearance of stimuli was controlled by the experimenters and presented at the center of the screen. We observed a relatively early component (~150 ms) that distinguished between targets and distractors only in thefreeviewingcondition. We present a novel approach to match the critical properties of two conditions (targets/distractors) which can be readily adapted to other paradigms to investigate EEG components during free eye-movements.