Handedness is not a unidimensional trait.

Area of Science:

• Neuroscience
• Human Behavior
• Genetics

Background:

• Current theories often view handedness as a single, continuous trait.
• This perspective simplifies the complex nature of manual preference inheritance.

Purpose of the Study:

• To investigate whether hand preference is a unidimensional trait or comprises independent dimensions.
• To explore the neural basis of hand preference across diverse manual activities.

Main Methods:

• Surveyed 290 adults (180 right-handed, 110 left-handed) on their hand preference for 55 activities using a five-point scale.
• Applied Varimax Factor Analysis to identify underlying dimensions of hand preference.

Main Results:

• Four distinct factors emerged, explaining 80% of the variance in hand preference.
• Factor 3, associated with strength and axial musculature, showed less lateral bias compared to dexterity-focused factors (e.g., writing, drawing).
• This suggests independent lateralization for different types of manual tasks.

Conclusions:

• Hand preference is a multidimensional trait, not a singular continuum.
• Multiple, independently lateralized neural systems likely govern distinct aspects of manual preference.
• This challenges traditional unidimensional models of handedness inheritance.