Abstract
Purpose. Facial adaptation — induced by prolonged exposure to an individual face — can bias the perceived identity of a subsequently presented faces. The goal of the present study is to uncover the mechanisms of neural plasticity underlying face adaptation using ERP. Methods. We used computationally derived facial morphs of female and male faces. Subjects' task was to discriminate the gender of the given face (ET:200 msec) without any adaptation or using a given female face, a building, Fourier randomised face or a scrambled face as adaptor for 5 seconds. During the experiments we tested if the face specific N170 component of the ERP (recorded from 23 channels, positioned according to the 10–20 system) reflects the change of perceptual decisions. Results. We found that facial adaptation increases the latency and decreases the amplitude of the N170 significantly. Results of control experiments suggest, that this effect of the previous presentation of a given stimulus is specific to face processing: adapting with an image of a house resulted in increased latency and amplitude, while adapting with scrambled or Fourier randomised faces resulted significantly less modification of the N170 component. Conclusions. While adaptation with faces had a strong effect on both the early and late components of the ERP responses to faces, when controlled for the low level visual properties of the stimuli it is the decrease of the amplitude of the N170 component that emerged as a specific ERP correlate of face adaptation.
This work was supported by grants from the Hungarian National Research and Development Program: 5/0079/2 to G.K. and 2/035 to Z.V.