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"Using arm movements to study consciously and unconsciously perceived stimuli in decision making" Dr. Jason Friedman (Sagol School of Neuroscience, Tel Aviv University)

Tuesday, September 20, 2022, 02:00pm - 03:20pm

152 Frelinghuysen Rd, Psych Bldg. Room 105

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Abstract: Simple two-alternative choices in humans (e.g., are these dots moving left or right) are often modeled using the drift-diffusion model, where evidence is accumulated in a noisy process until a bound is reached. This bound then determines which choice will be made. Often button press (reaction time) responses are used to fit these models, as the button press is assumed to occur at the conclusion of the process (when a bound is reached). In this talk, I will describe an alternative method, where we use arm movements instead of button presses to fit a model, when subjects reach out and touch a target and the arm movements are recorded using a motion capture system. Importantly, we force the subjects to begin moving very early (< 350 ms), likely before a final decision has been made. The benefit of this technique is that we can then observe through the kinematics of the arm movements the unfolding decision-making process. I will detail how we can decompose continuous movements into a small number of temporally overlapping movement primitives, and how we can use this technique to probe the status of the decision variable before a final decision is made. I will provide examples of how we used this technique to quantify the decision process in a number of different tasks, and how we can use this technique to determine the temporal dynamics of consciously and unconsciously perceived stimuli.

Bio: Dr. Jason Friedman is a senior lecturer in the Dept. Physical Therapy and a member of the Sagol School of Neuroscience, at Tel Aviv University. His research focuses on human motor control – understanding how the brain controls movement. Originally from Melbourne, Australia, Jason moved to Israel after completing a B.Sc degree in Computer Science at Monash University. In Israel, he completed an M.Sc and Ph.D in Computer Science at the Weizmann Institute of Science, examining questions related to arm movements and grasping. Following postdoctoral research at Penn State University, USA in the Dept. Kinesiology, and in the Dept. Cognitive Science at Macquarie University in Sydney, Australia, he returned to Israel to take up a position at Tel Aviv University in the Department of Physical therapy. Jason combines his computational background with a clinical approach, where he works on better understanding the basic processes of how we coordinate our movements and learn to produce new movements, how and why movements differ in movement disorders, and what are the optimal strategies for learning new movements and movement rehabilitation.