Pavlovian-to-instrumental transfer (PIT) refers to the process of a Pavlovian reward-paired cue acquiring incentive motivational proprieties that drive choices. It represents a crucial phenomenon for understanding cue-controlled behavior, and it has both adaptive and maladaptive implications (i.e., drug-taking). In animals, individual differences in the degree to which such cues bias performance have been identified in two types of individuals that exhibit distinct Conditioned Responses (CR) during Pavlovian conditioning: Sign-Trackers (ST) and Goal-Trackers (GT). Using an appetitive PIT procedure with a monetary reward, the present study investigated, for the first time, the extent to which such individual differences might affect the influence of reward-paired cues in humans. In a first task, participants learned an instrumental response leading to reward; then, in a second task, a visual Pavlovian cue was associated with the same reward; finally, in a third task, PIT was tested by measuring the preference for the reward-paired instrumental response when the task-irrelevant reward-paired cue was presented, in the absence of the reward itself. In ST individuals, but not in GT individuals, reward-related cues biased behavior, resulting in an increased likelihood to perform the instrumental response independently paired with the same reward when presented with the task-irrelevant reward-paired cue, even if the reward itself was no longer available (i.e., stronger PIT effect). This finding has important implications for developing individualized treatment for maladaptive behaviors, such as addiction.

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Gender differences in social cognition are a long discussed issue, in particular those concerning Theory of Mind (ToM), i.e., the ability to explain and predict other people’s mental states. The aim of this randomized, double-blind, placebo-controlled study was to test the hypothesis that anodal tDCS over the medial prefrontal cortex (mPFC) selectively enhances cognitive ToM performance in females. In the first experiment we administered to sixteen females and sixteen males a cognitive ToM task during anodal or placebo tDCS over the mPFC. In the second experiment further sixteen females completed the task receiving anodal or placebo tDCS over the vertex. The results showed that anodal tDCS over the mPFC enhances ToM in females but not in males, an effect indicated by enhanced ToM in females that received anodal tDCS over the mPFC compared with females that received tDCS over the vertex. These findings are relevant for three reasons. First, we found evidence of gender-related differences in cognitive ToM, extending previous findings concerning affective ToM. Second, these differences emerge with anodal stimulation of the mPFC, confirming the crucial role of this area in cognitive ToM. Third, we show that taking into account gender-related differences is mandatory for the investigation of ToM.