Measuring the motivational influences of reward and habits on human motor behavior

Previous research has shown that motor actions are strongly influenced by two major motivational pathways which either process reward or trigger habitual responses. It is via these pathways that environmental cues can gain influence over human behavior, which can become maladaptive and even pathological. Previous work has proposed that the responsiveness to motivational cues is subject to large individual differences. Revealing new insights into these mechanisms is, however, currently hampered by the lack of psychophysical paradigms that quantify the “subjective value” of a rewarded versus a habitual action on a common scale. Here, we propose a new behavioral paradigm making use of the strong link between motivational drive and the motor system. We will use an an approach motivated by Neuroeconomics, which experimentally reduces the subjective costs. In this way, subjective motor costs represent a common “currency” to measure and compare the influence of different incentives.