Linking cognitive and reaching trajectories via intermittent movement control

• We recorded arm movements and button press responses to random dot kinematograms.
• We described how to fit a Wiener diffusion model to intermittent arm movements.
• We predicted arm movements assuming intermittent access to the decision process.
• This offers the potential for early access to the decision process.

Theories of decision-making have traditionally been constrained by reaction time data. A limitation of reaction time data, particularly for studying the temporal dynamics of cognitive processing, is that they index only the endpoint of the decision making process. Recently, physical reaching trajectories have been used as proxies for underlying mental trajectories through decision space. We suggest that this approach has been oversimplified: while it is possible for the motor control system to access the current state of the evidence accumulation process, this access is intermittent. Instead, we demonstrate how a model of arm movements that assumes intermittent, not continuous, access to the decision process is sufficient to describe the effects of stimulus quality and viewing time in curved reaching movements.