Poster E131, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Influence of other’s choice behavior on observational learning
Nadège Bault1, Tobias Larsen1, Mehdi Khamassi2, Luca Polonio1, Alexander Vostroknutov1, Giorgio Coricelli1,3; 1Center for Mind/Brain Sciences (Cimec), Trento, Italy, 2Institute for Intelligent Systems and Robotics, CNRS, Paris, France, 3University of Southern California, Los Angeles, USA
When making decisions in an uncertain environment, individuals may learn by observing the choice behavior of others. The goal of this study was to investigate whether we discriminately imitate other individuals based on their choice behavior, in order to optimize our own learning. We tested the prediction that learning from observation relies on two signals: the reward prediction error derived from direct experience and a prediction error related to the value of imitation. We measured brain activity of 30 participants using functional MRI while they made decisions in a repeated two-armed bandit task, with varying reward probabilities. In some trials, the participants observed the choice of one of two individuals before making their own choice. One observed individual was switching options more often than the other. We found that the type of observee influenced the observer participants both in their ability to choose the best option and in the probability that they would switch options. We tested a model of choice in which a value of imitation was incorporated in a standard Q-learning model. The value of imitation increased with successful imitation and with unsuccessful anti-imitation and was updated using an imitation prediction error. Activity of the striatum was positively modulated both by the reward and the imitation prediction errors. During the choice phase, the striatum and dorsolateral prefrontal cortex showed a parametric modulation by the chosen and imitation aggregated value. This mechanism supports optimal imitation (choosing whom and when to imitate) in social environments.
Topic Area: THINKING: Decision making