Factor analysis and the cerebral hemispheres: temporal, occipital and frontal functions

Area of Science:

• Cognitive Neuroscience
• Neuropsychology
• Brain Lateralization

Background:

• Individual differences in cognitive task performance are often linked to brain lateralization.
• Previous research has proposed various models to explain these differences, including lateralization strength, hemisphericity, and independence.

Purpose of the Study:

• To investigate the underlying functional architecture of cognitive asymmetries.
• To determine the number and nature of independent lateralized functions.
• To test the consistency of findings with neurodevelopmental theory.

Main Methods:

• Three experiments were conducted using a battery of lateralized tasks targeting temporal, occipital, and frontal lobe functions.
• Oblique factor analyses were applied to the measured asymmetries.
• Correlations between identified lateralized functions were examined.

Main Results:

• Factor analysis revealed nine distinct lateralized functions: auditory lexical, facial figural, facial motive, spatial attentive, spatial positional, spatial quantitative, tactile figural, visual lexical, and visual phonetic.
• Most of these functions were uncorrelated.
• Both positive and negative correlations between certain functions were observed.

Conclusions:

• The identified nine lateralized functions provide a more nuanced view of cognitive asymmetry.
• The observed patterns of correlations support neurodevelopmental theories of brain lateralization.
• Findings contradict simpler models such as lateralization strength, hemisphericity, and independence views.