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

J Vis. 2012 Jul 9;12(7):4. doi: 10.1167/12.7.4.

Abstract

We report a study of concurrent eye movements and electroencephalographic (EEG) recordings while subjects freely explored a search array looking for hidden targets. We describe a sequence of fixation-event related potentials (fERPs) that unfolds during ∼ 400 ms following each fixation. This sequence highly resembles the event-related responses in a replay experiment, in which subjects kept fixation while a sequence of images occurred around the fovea simulating the spatial and temporal patterns during the free viewing experiment. 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 also observed a relatively early component (∼150 ms) that distinguished between targets and distractors only in the freeviewing condition. 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Attention / physiology
  • Electroencephalography / methods*
  • Evoked Potentials, Visual / physiology*
  • Eye Movements / physiology*
  • Female
  • Fixation, Ocular / physiology*
  • Form Perception / physiology*
  • Fovea Centralis / physiology
  • Humans
  • Male
  • Photic Stimulation / methods
  • Reaction Time / physiology
  • Space Perception / physiology
  • Young Adult