Neural stimulants to N170 event related potential (ERP) component of Hijab covered faces: An ERP study

Has Hijab covered face (Hijab-face) any special neural stimulants to persons of the similar traditions? To address this question we performed Event Related Potential (ERP) (128 channels) study by using the Wavelet Transform (WT), a time frequency representation in 9 healthy volunteers in the same culture during the presentation of bared head face and hijab wearing face with randomly presented cross and house picture as two other neutral stimuli within the face presentation. There had two experiments, Face-target and Hijab-face target experiment. In Face-target experiment, subjects pressed `1' button when saw bared head face and in Hijab-target experiment, subjects pressed the same button when saw Hijab wearing face. The stimuli were presented for 1 s with 1.5 s interstimulus interval (ISI). Upon the stimulus types, event-related responses in the 0 Hz-30 Hz range were distributed mainly in the Fz, Cz, Pz, O1 and O2 locations. Data formed visual ERPs. The cue stimuli evoked posterior N170 ERP components both in the face-target and hijab-target experiments at O1 and O2 locations. Both face and hijab-picture stimuli were analyzed in both face and hijab-target experiments. Amplitude was higher of N170 at face-picture stimuli in both experiments. But significantly higher (P= 0.03) in hijab-target experiment. Latency had no significant change in both experiments in all areas. In the face-target experiment, face-picture gave significantly (P= 0.03) higher beta power at O1 area comparing the hijab-picture, where as remarkable decreased (P=0.03) theta power was found in the same stimuli at O2 area. Results suggest that in the same culture, hijab did not give any special neural stimulants. Increased Beta activity and decreased theta waveform indicate that similar society facial picture give the face-picture impression at O1 and O2, respectively and subjects give more attention to face-picture than hijab-picture where O1 and O2 locations are the crucial for this case.