Continuous reports of sensed hand position during sensorimotor adaptation

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Psychology

Background:

• Sensorimotor learning involves both volitional and automatic processes.
• Implicit learning is difficult to isolate from explicit control.
• Previous studies show motor adaptation to visual perturbations, but awareness remains unclear.

Purpose of the Study:

• To investigate participants' awareness of behavioral changes during sensorimotor adaptation using a clamped visual feedback method.
• To quantify sensitivity to adaptive changes in hand position.
• To explore the influence of feedforward and feedback signals on subjective experience during adaptation.

Main Methods:

• Utilized a "clamped" visual perturbation paradigm where visual feedback followed an invariant trajectory offset from the target.
• Instructed participants to ignore the cursor and report their perceived hand position after each reach.
• Analyzed hand reports to quantify awareness of motor behavior shifts during adaptation.

Main Results:

• Observed robust motor deviations (∼18°) consistent with motor adaptation.
• Hand position reports showed systematic deviations, initially toward and then away from visual feedback.
• Perceived hand position shifts were subtle (∼2° at asymptote), indicating limited awareness of adaptation.

Conclusions:

• Sensorimotor adaptation is an obligatory process with limited conscious awareness.
• Participants exhibit a subtle sensitivity to adaptive changes, influenced by feedback signals.
• The study highlights the dissociation between automatic motor adjustments and subjective experience.