A directional bias for studies of laterality

Area of Science:

• Neuroscience
• Cognitive Psychology
• Human Lateralization Research

Background:

• Cerebral lateralization, the brain's functional asymmetry, is a well-established phenomenon.
• Directional bias (D), the tendency to favor certain directions in movement or perception, was previously considered independent of cerebral lateralization.

Purpose of the Study:

• To investigate the relationship between directional bias (D) and cerebral lateralization.
• To determine if the direction of D influences lateral asymmetries in cognitive tasks.

Main Methods:

• Studied a group of consistent right-handed individuals (dextrals) with no family history of left-handedness (familial sinistrality).
• Assessed lateral asymmetries in performance on linguistic and spatial tasks.
• Correlated these asymmetries with the direction of the individuals' directional bias (D).

Main Results:

• The direction of lateral asymmetries was found to depend on the direction of D.
• Left-directed dextrals exhibited typical visual field advantages for linguistic and spatial processing.
• Right-directed dextrals did not show these usual visual field advantages.

Conclusions:

• Directional bias (D) is intimately associated with cerebral lateralization, contrary to previous assumptions.
• The direction of D acts as a moderator variable influencing cognitive task performance related to lateralization.
• Future studies on laterality should incorporate directional bias (D) as a key variable.