Background: In daily life, visual information plays an important role to improve accuracy
of auditory perception, and such phenomenon might be explained by audio-visual integration. However,
audio-visual integration differs between genders, i.e., female tends to perceive voice with mouth
movement more accurately. In this study, we examined gender differences of cerebral processing of
audio-visual information. Methods: Cerebral processing was examined in male and female participants
under different audio-visual conditions: 1) Auditory (A) condition: presentation of white-noise (noise)
or a vowel (/a/ or /i/) pronounced by a male; 2) Visual (V) condition: presentation of a face image pronouncing
a vowel ([a] or [i]), 3) Audio-Visual (AV) condition: simultaneous presentation of auditory (noise or vowel) and
visual stimuli. Participants were asked to press a button when the vowel /a/ or noise was presented in the A or AV condition.
Subtracted auditory ERPs in the AV condition (congruent: /a/ with [a]-[a] and incongruent: /a/ with [i]-[i]) were
compared to ERPs in the A condition (auditory /a/). Results: In the AV condition, amplitude of auditory P2 in the male
participants was smaller than that in the females, whether the stimulus set was congruent or incongruent. The lower P2
amplitude in males may have been caused by overlapping of negative components, which may be related to selective attention.
Subtracted visual ERPs in the AV condition (congruent: [a] with /a/-/a/ and incongruent: [a] with /i/-/i/) were
compared to ERPs in the V condition (visual [a]). Amplitude of visual N170 to congruent stimuli was smaller than that for
alone visual stimuli only for the females. Conclusion: Lower amplitude of the N170 may reflect enhanced facial processing
in females. Gender differences in audio-visual information processing were discussed.