End-state comfort trumps handedness in object manipulation

Area of Science:

• * Human Perception and Performance
• * Motor Control
• * Cognitive Psychology

Background:

• * Research on action selection investigates the relative importance of various constraints.
• * Two key constraints are the tendency for comfortable final postures and hand dominance.
• * These constraints have not been directly contrasted in previous studies.

Purpose of the Study:

• * To determine the relative importance of comfortable posture versus hand preference in action selection.
• * To investigate whether individuals prioritize comfort or dominant hand use when grasping objects.
• * To understand the underlying factors influencing hand selection during motor tasks.

Main Methods:

• * Participants reached and grasped a horizontal rod, with conditions manipulating hand choice and grasp type (overhand/underhand).
• * A second experiment assessed comfort levels for different postures (thumb-up vs. thumb-down).
• * A third experiment linked participant choices to objective performance metrics.

Main Results:

• * Participants prioritized achieving a comfortable, easy-to-control thumb-up posture over using their dominant hand.
• * Comfort was objectively higher for thumb-down postures compared to thumb-up postures.
• * Choice data correlated with objective performance differences, supporting comfort's role.

Conclusions:

• * Comfort and ease of control are significant factors in action selection, often outweighing hand preference.
• * Hand preference may reflect sensitivity to performance differences rather than a simple bias for the dominant hand.
• * Understanding constraint weightings is crucial for explaining action selection mechanisms.