Task goals shape the relationship between decision and movement speed

Area of Science:

• Cognitive Neuroscience
• Human Motor Control
• Decision Science

Background:

• The relationship between decision speed and movement speed is not fully understood.
• Existing research presents conflicting findings, suggesting either joint invigoration or a speed-accuracy trade-off.

Purpose of the Study:

• To investigate the existence of a shared process linking decision and movement speed.
• To test if this link is suppressed when it negatively impacts reward rate.

Main Methods:

• 62 human subjects performed the Tokens task across two experiments.
• Experiment 1 examined how decision speed influences movement speed.
• Experiment 2 manipulated movement speed to assess its effect on decision speed, with groups incentivized for decision speed or accuracy.

Main Results:

• A coregulation of decision urgency and movement speed was observed in Experiment 1 and the fast-decision group of Experiment 2.
• This coregulation was absent in the slow-decision group of Experiment 2, despite their capacity for coregulation shown in Experiment 1.
• Findings suggest coregulation is a default but can be overridden by a trade-off when maximizing reward rate.

Conclusions:

• Decision and movement speeds are coregulated by default.
• This coregulation is modulated by task demands and reward rate optimization.
• Multiple control processes likely shape the speed of both decisions and movements.