The study aimed to understand how payoffs for others influence perceptual decision making. The research consists in testing how varying monetary payoffs for another modify the perceptual decision making processes. The use of drift diffusion models on a random dots task enable the characterization of the decision parameter(s) that are modulated when a decision is made to win payoffs for others as compared to decisions for self-benefits. Once the parameter revealed through behavioral experiment, neuroimaging is applied to find the neural correlates of the effects of taking others into account in the decision making process.