Abstract
In everyday life, we are constantly presented with a large amount of different faces that we need to discriminate. Recently, we used a face adaptation paradigm to investigate the extent to which this process is modulated by the temporal rate at which faces are presented, both with electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) (Alonso Prieto E and B Rossion, 2011; Gentile F and B Rossion, 2012, respectively). In these studies, participants were presented with sequences of different and identical faces at several temporal frequencies ranging from 1 Hz (1face/second) to 12 Hz (sinusoidal contrast modulation, as in Rossion B and A Boremanse, 2011). In both studies, neural adaptation (signal difference between different and identical faces) peaked at 6Hz and decreased for higher frequency rates. Even though we ensured that an individual face was never repeated consecutively, the amount of different faces presented in the different condition for all temporal frequencies was fixed. Therefore, the number of face repetitions was larger at higher frequency rates of presentation. In order to control for such a potential confound we ran an EEG (N = 8) and fMRI (N =4) experiment with variable amounts of different faces in each block of stimulation (10, 20, 50, 100 in EEG; 18, 36 in fMRI), at two different frequencies (6 and 12 Hz). For both frequencies tested, neither the fMRI nor the EEG signal was modulated by the number of different faces presented in a block. This result indicates that the decrease of neural adaptation between 6 and 12 Hz cannot be explained by an increase of individual face repetitions at high frequency rates.
Meeting abstract presented at VSS 2013