Motivation for reward as a function of required effort: Dissociating the 'liking' from the 'wanting' system in humans

Recent studies investigating the neurobiology of reward motivation in animals have begun to deconstruct reward into separable neural systems involving the 'liking' of a reward (hedonic enjoyment of consumption) versus the 'wanting' of a reward (incentive salience to obtain reward). To date, however, it is unclear whether these systems are also separable in humans. We examined this question by manipulating the effort (clicking on a moving square) required for participants to obtain a reward (humorous versus non-humorous cartoon). Overall, as the required effort to view a humorous cartoon increased, participants were less likely to choose this reward. Moreover, individual differences in cartoon preference predicted cartoon choice at low levels of required effort, but not at high levels of required effort. These findings suggest that manipulating effort may be a valid method for dissociating the 'liking' from 'wanting' components of reward motivation in humans.