Figure 1

Experimental design. A) An illustration of the fast periodic oddball stimulation during EEG recording: a base face (A) is presented 4 times followed by a different oddball face (B) during each trial, thus there are 2 embedded frequencies: at a rate of 5.88 Hz facial images are presented (base frequency) and at a rate of 1.18 Hz a face with a different identity is shown (oddball frequency). B) Varying image size conditions as used in the present study (1st row: 0% image size change, 2nd row: 10% image size change, 3rd row: 20% image size change, 4th row: 40% image size change, 5th row: 80% image size change). Please see also the Additional files 1, 2, 3, 4 and 5 for short movie clips. All variations were implemented in 6 steps, thus the number of possible size changes across the conditions was equal. During each trial the order of size variations was random.