Fig. 2

a Log–log plots of the average amplitude spectra in all types of the stimuli, i.e. Face-only, Black dots on the face, Gray dots on the face, and Black dots and gray dots on the face. b Log–log plots of the average amplitude spectra in Black dots on the face versus Black and gray dots on the face. c Log–log plots of the average amplitude spectra in Black dots on the face versus Gray dots on the face. d Log–log plots of the average amplitude spectra in Gray dots on the face versus Black and gray dots on the face. Gray zones in b–d indicate the spatial frequency bands at which there were significant differences between the two functions (p < .05). Dashed lines indicate the medium spatial frequencies (37.5–150 cycles per image) reported in a previous study [22]