Voice gender categorization in the connected and disconnected hemispheres.

Area of Science:

• Neuroscience
• Auditory Perception
• Cognitive Psychology

Background:

• The hemispheric role in voice gender processing remains debated, with conflicting evidence for bilateral versus right-hemisphere dominance.
• Understanding hemispheric specialization is crucial for comprehending auditory perception and cognitive functions.

Purpose of the Study:

• To investigate the involvement of the left and right brain hemispheres in categorizing voice gender.
• To compare voice gender processing in healthy individuals and a split-brain patient using a dichotic listening paradigm.

Main Methods:

• A dichotic listening task presenting natural female or male voices to one ear and white noise to the other.
• Inclusion of healthy participants and a male split-brain patient to assess hemispheric processing.
• Measurement of response times and accuracy for voice gender categorization.

Main Results:

• Healthy participants exhibited faster voice categorization for stimuli presented to the left ear compared to the right ear.
• No significant accuracy differences were observed between ears for either healthy participants or the split-brain patient.
• Healthy participants were more accurate with female voices, and an opposite-gender bias (faster categorization of opposite-gender voices) was noted, particularly in females.

Conclusions:

• Findings support bilateral hemispheric involvement in voice gender categorization, with a potential right-hemisphere advantage in healthy individuals when stimuli are directly presented.
• The split-brain patient's results suggest that inter-hemispheric communication may be necessary for certain processing asymmetries.
• An evolutionary basis for an opposite-gender bias in voice categorization, facilitated by integrated hemispheric function, is proposed.