Reward, value, and salience

Value and salience are key variables for associative learning, decision-making, and attention. In this chapter we review definitions of value and salience, and describe human neuroimaging studies that dissociate these variables. Value increases with the magnitude and probability of reward but decreases with the magnitude and probability of punishment, whereas salience increases with the magnitude and probability of both reward and punishment. Moreover, salience may be particularly enhanced in situations with probabilistic as opposed to safe outcomes. At the behavioral level, both value and salience independently accelerate behavior. At the neural level, value signals arise in striatum, orbitofrontal and ventromedial prefrontal cortex, and superior parietal areas, whereas magnitude-based salience signals arise in the anterior cingulate cortex and the inferior parietal cortex. By contrast, probability-based salience signals have been found in the ventromedial prefrontal cortex. In conclusion, the related nature of value and salience stresses the importance of disentangling both variables experimentally.