Abstract: Human faces provide important social information about others. The response to faces is modulated by factors such as attention, visual imagery, and emotions. Some behavioral and imaging studies suggest that human adults prefer to look at attractive faces of the opposite sex than attractive faces of the same sex. However, electrophysiological studies on differences between opposite vs. same sex face perception are sparse. The aim of the present study was to investigate whether and how early a bias occurs in the processing of the opposite-sex in comparison with the same-sex faces. Particularly, we were interested in detecting electrophysiological indexes specific of opposite-sex and same-sex face processing. ERPs were recorded from 128 channels in 40 (20 males) right-handed volunteer university students engaged in a secondary perceptual task. Face stimuli consisted of 130 pictures of attractive adult male and female faces (ranging from 18 to 50 years of age) and target stimuli consisted of 44 pictures without humans representing landscape and urban sceneries. Stimuli were balanced in terms of picture size and average luminance and were presented for 800 ms with an Inter Stimuli Interval (ISI) of 1200 ms. The amplitude and the latency of the ERP components of interest were analysed using analysis of variance. Source reconstruction analyses by swLORETA algorithm were also computed. Two main ERP components were found, one specific for oppositesex face perception and the other one for same-sex face perception. In particular, ERP data showed a larger and earlier centro-parietal N400 (350-500 ms) in response to faces of the opposite than of the same sex. At a later stage, between 590 and 720 ms, an occipitotemporal LP was found to be larger for faces of the same than of the opposite sex. The swLORETA linear inverse solution showed a greater activation of the face-related areas (FG, BA37, BA20/21) and of the limbic areas (the Parahippocampal Gyrus and the Cingulate Gyrus) in response to the opposite-sex faces than the same-sex faces. Thus, the results of this study showed how faces of the same sex and of the opposite sex are differently processed. Indeed, we found two different electrophysiological indexes for the two category of stimuli. The N400 component, found to be earlier and of greater amplitude for opposite-sex face perception, is indicative of a faster and deeper processing of this category. Therefore, this suggests that faces of the opposite sex draw more attention and probably have a higher emotive impact. Data derived from the source reconstruction analyses support this interpretation, as a greater activation of the face-related brain areas and of the limbic areas were found in response to the opposite-sex faces than to the same-sex faces. The subsequent LP component, of greater amplitude in response to same-sex faces, indicates that the processing of these faces occurs at a later stage. Finally, the present study provides evidence of two electrophysiological indexes, the N400 and the LP, specific for opposite-sex vs. same-sex face processing.
Electrophysiological indexes of opposite vs. same sex face processing
Zani A;
2011-01-01
Abstract
Abstract: Human faces provide important social information about others. The response to faces is modulated by factors such as attention, visual imagery, and emotions. Some behavioral and imaging studies suggest that human adults prefer to look at attractive faces of the opposite sex than attractive faces of the same sex. However, electrophysiological studies on differences between opposite vs. same sex face perception are sparse. The aim of the present study was to investigate whether and how early a bias occurs in the processing of the opposite-sex in comparison with the same-sex faces. Particularly, we were interested in detecting electrophysiological indexes specific of opposite-sex and same-sex face processing. ERPs were recorded from 128 channels in 40 (20 males) right-handed volunteer university students engaged in a secondary perceptual task. Face stimuli consisted of 130 pictures of attractive adult male and female faces (ranging from 18 to 50 years of age) and target stimuli consisted of 44 pictures without humans representing landscape and urban sceneries. Stimuli were balanced in terms of picture size and average luminance and were presented for 800 ms with an Inter Stimuli Interval (ISI) of 1200 ms. The amplitude and the latency of the ERP components of interest were analysed using analysis of variance. Source reconstruction analyses by swLORETA algorithm were also computed. Two main ERP components were found, one specific for oppositesex face perception and the other one for same-sex face perception. In particular, ERP data showed a larger and earlier centro-parietal N400 (350-500 ms) in response to faces of the opposite than of the same sex. At a later stage, between 590 and 720 ms, an occipitotemporal LP was found to be larger for faces of the same than of the opposite sex. The swLORETA linear inverse solution showed a greater activation of the face-related areas (FG, BA37, BA20/21) and of the limbic areas (the Parahippocampal Gyrus and the Cingulate Gyrus) in response to the opposite-sex faces than the same-sex faces. Thus, the results of this study showed how faces of the same sex and of the opposite sex are differently processed. Indeed, we found two different electrophysiological indexes for the two category of stimuli. The N400 component, found to be earlier and of greater amplitude for opposite-sex face perception, is indicative of a faster and deeper processing of this category. Therefore, this suggests that faces of the opposite sex draw more attention and probably have a higher emotive impact. Data derived from the source reconstruction analyses support this interpretation, as a greater activation of the face-related brain areas and of the limbic areas were found in response to the opposite-sex faces than to the same-sex faces. The subsequent LP component, of greater amplitude in response to same-sex faces, indicates that the processing of these faces occurs at a later stage. Finally, the present study provides evidence of two electrophysiological indexes, the N400 and the LP, specific for opposite-sex vs. same-sex face processing.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
