How brain asymmetry relates to performance - a large-scale dichotic listening study

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psycholinguistics

Background:

• Major mental functions like language are lateralized, but the degree and direction vary significantly between individuals.
• Understanding the relationship between the strength of brain lateralization and functional performance is crucial but remains underexplored.

Purpose of the Study:

• To investigate the association between the degree of lateralization and performance accuracy in a language processing task.
• To determine if the strength of hemispheric specialization impacts cognitive function efficiency.

Main Methods:

• Utilized data from 1839 participants performing a dichotic listening task involving consonant-vowel syllables.
• Calculated the degree of lateralization based on ear advantage and correlated it with overall response accuracy.
• Employed reference models to account for statistical interdependencies between ear reports.

Main Results:

• A U-shaped relationship was observed between the degree of lateralization and overall accuracy.
• Both stronger left-hemispheric (right ear advantage) and right-hemispheric (left ear advantage) specialization were associated with higher accuracy.
• This pattern was consistent across different demographics, including sex, handedness, and age groups.

Conclusions:

• The performance of lateralized language functions is contingent upon the strength of their lateralization.
• The findings highlight the importance of considering the degree of brain asymmetry when studying performance.
• Statistical control for interdependencies is essential for accurate asymmetry-performance relationship analyses.