Poster F127, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Choosing to make an effort: the effect of reward on performance speed under risk
Xingjie Chen1, Youngbin Kwak1; 1University of Massachusetts Amherst
Reward and risk are two main variables of everyday decision making including whether or not to exert motor efforts. We investigated how reward and risk influenced decision to make a speeded response during a Go/NoGo task. At the beginning of each trial, participants were presented with reward points at stake (high vs. low) and the probability that a Go signal would follow (Go-probability) (Trial Information), followed by a Go/NoGo signal. Faster responses to a Go signal resulted in larger proportion of the rewards at stake, whereas false alarm resulted in losing rewards. In a behavioral study of 110 participants, we found a significant effect of reward magnitude on response time, which was modulated by Go-probability. Reward magnitude influenced response time when the Go-probability was 50% or above (i.e. when the assessed risk level was low). In order to investigate the neural underpinnings of these effects, an EEG study was conducted in 20 participants. We focused our analysis on beta frequency oscillations in the sensorimotor cortex, which is known to be associated with motor processing. In particular, we analyzed the time period in between Trial Information and Go/NoGo signal during which motor planning takes place. Consistent with the behavioral data, there was a significant effect of reward magnitude on beta oscillations and this was modulated by Go-probability. Reward effect on beta oscillations was greater with high vs. low Go-probability. These findings provide a mechanistic understanding of the effect of reward and risk on decisions for exerting motor efforts.
Topic Area: THINKING: Decision making