Women are better at seeing faces where there are none: an ERP study of face pareidolia

Abstract

Event-related potentials (ERPs) were recorded in 26 right-handed students while they detected pictures of animals intermixed with those of familiar objects, faces and faces-in-things (FITs). The face-specific N170 ERP component over the right hemisphere was larger in response to faces and FITs than to objects. The vertex positive potential (VPP) showed a difference in FIT encoding processes between males and females at frontal sites; while for men, the FIT stimuli elicited a VPP of intermediate amplitude (between that for faces and objects), for women, there was no difference in VPP responses to faces or FITs, suggesting a marked anthropomorphization of objects in women. SwLORETA source reconstructions carried out to estimate the intracortical generators of ERPs in the 150-190 ms time window showed how, in the female brain, FIT perception was associated with the activation of brain areas involved in the affective processing of faces (right STS, BA22; posterior cingulate cortex, BA22; and orbitofrontal cortex, BA10) in addition to regions linked to shape processing (left cuneus, BA18/30). Conversely, in the men, the activation of occipito/parietal regions was prevalent, with a considerably smaller activation of BA10. The data suggest that the female brain is more inclined to anthropomorphize perfectly real objects compared to the male brain.

Keywords: ERPs; face processing; perception; sex differences; social cognition.

Fig. 1.

Examples of stimuli used in the study, as a function of category: faces (upper row), faces-in-things (middle row) and objects (lower row).

Fig. 2.

(Top) Face-likeness ratings (along with standard deviations) obtained for a set of 400 pictures of real objects. Validation was performed to select the 130 objects more likely (FITs) and less likely (objects) to be perceived as faces. (Bottom) Validation data showing a clear bias toward face-likeness in women compared to men. (0= non-face; 2= face).

Fig. 3.

Grand-average ERPs recorded from all scalp sites as a function of stimulus category.

Fig. 4.

Close-up of ERP waveforms recorded at left and right posterior temporal sites as a function of stimulus category. The N170 response over the right hemisphere was larger to faces and faces-in-things.

Fig. 5.

Mean amplitude of the N170 response recorded as a function of stimulus type and relative scalp distribution. Isocolor topographical maps show the N170 surface voltage distribution over the right hemisphere.

Fig. 6.

Close-up of ERP waveforms recorded at left and right prefrontal sites as a function of stimulus category. Overall, the VPP response was larger to faces than to objects, while the N250 was larger to objects than to faces or FITs.

Fig. 7.

Sex difference in the amplitude of the VPP component recorded at midline frontocentral sites. Isocolor topographical maps show the VPP surface voltage distribution (top view) recorded regardless of the sex of the viewer. The number indicates the peak latency of the component.

Fig. 8.

Coronal, axial and sagittal views of active sources during the processing of FIT patterns (150–190 ms) in women and men. The different colors represent differences in the magnitude of the electromagnetic signal (in nAm). The electromagnetic dipoles are shown as arrows and indicate the position, orientation and magnitude of the dipole modeling solution applied to the ERP waveform within the specific time window. The numbers refer to the displayed brain slice in sagittal view: A = anterior, P = posterior. The images highlight the strong activation of social and affective area (STS and cingulate and orbitofrontal cortices) in female participants, suggesting how they are more inclined to anthropomorphize objects.