Bimanual reaches with symbolic cues exhibit errors in target selection

Area of Science:

• Neuroscience
• Cognitive Psychology
• Motor Control

Background:

• Symbolic cues in bimanual reaches increase reaction times compared to spatial cues, suggesting higher cognitive load.
• Previous research indicates symbolic cues demand more cognitive visuomotor translation than spatial cues.

Purpose of the Study:

• To investigate if bimanual movements show greater spatial coupling with symbolic cues than spatial cues.
• To differentiate the impact of cognitive load on response selection versus movement execution in bimanual reaches.

Main Methods:

• Participants performed symmetric and asymmetric bimanual reaches to targets indicated by symbolic or spatial cues.
• Movement trajectories and reaction times were analyzed for symmetric and asymmetric reaches.
• Errors in target selection and trajectory modulations were recorded.

Main Results:

• The reaction time cost for symbolically cued asymmetric movements was replicated.
• A subset of asymmetric reaches showed trajectory errors, indicating switched arm movements, but only with symbolic cues.
• Little evidence of increased spatial coupling was found with symbolic cues during correct movement execution.

Conclusions:

• Cognitive visuomotor translation demands during response selection elevate bimanual coupling at the selection level (reaction time, errors).
• These demands do not increase spatial coupling at the movement execution level for correctly targeted movements.