High-density scalp EEG in perception of Gestalt stimuli in an inattentional blindness paradigm

Thirty participants performed a demanding, attention-capturing task in which they had to detect an occasional decrement in the luminance of small discs. Crucially, numerous white segments in the background were presented either in random orientations or configuring a contour shape of a square or a diamond.

EEG was recorded using a Geodesic Sensor Net with 256 Ag/AgCl scalp electrodes with a high input impedance amplifier (EGI, a Philips company, Eugene, OR, USA). The participants’ awareness about these background configurations was tested with a questionnaire after the first and second sessions. On the basis of the questionnaire test, participants were divided into “aware” and “unaware” groups.