Coordinated decision-making boosts altruistic motivation-But not trust.

In the current study, we separately tested whether coordinated decision-making increases altruism and whether it increases trust. To this end, we implemented a paradigm in which participants repeatedly perform a coordinated decision-making task either with the same partner on every trial, or with a different partner on each trial. When both players coordinate on the same option, both are rewarded. In Experiment 1 (N = 52), participants were sometimes presented with tempting opportunities to defect. In Experiment 2 (N = 97), participants sometimes had to decide whether or not to trust that their partners had resisted such tempting opportunities. The results show that repeatedly coordinating with the same partner increased participants' resistance to temptation (Experiment 1) but did not increase trust (Experiment 2). These findings support the hypothesis that coordinating with a partner increases altruistic motivation towards that partner; they do not support the hypothesis that coordinating boosts trust.

Probing commitment in individuals with borderline personality disorder.

Interpersonal problems are a core symptom of borderline personality disorder (BPD). In particular, patients with BPD exhibit a heightened sensitivity to cues of acceptance or rejection in their relationships. The current study investigated the psychological processes underpinning this heightened responsiveness. In a between-subjects design, we implemented a reactivity induction designed to trigger either acceptance or rejection of a partner in two separate groups, and measured the effects which this manipulation had upon 49 patients with BPD, as well as 52 control participants. The experimental paradigm required participants to repeatedly choose whether to coordinate with their partner on a decision-making task. When both players coordinate on the same option, both are rewarded. The experiment probed participants' commitment to their partners: participants were sometimes presented with tempting opportunities to unilaterally defect from the coordination. The results show that participants in the BPD group were less committed than participants in the control group when exposed to the rejection manipulation.

Effort and performance in a cooperative activity are boosted by perception of a partner's effort.

In everyday life, people must often determine how much time and effort to allocate to cooperative activities. In the current study, we tested the hypothesis that the perception of others' effort investment in a cooperative activity may elicit a sense of commitment, leading people to allocate more time and effort to the activity themselves. We developed an effortful task in which participants were required to move an increasingly difficult bar slider on a screen while simultaneously reacting to the appearance of virtual coins and earn points to share between themselves and their partner. This design allowed us to operationalize commitment in terms of participants' investment of time and effort. Crucially, the cooperative activity could only be performed after a partner had completed a complementary activity which we manipulated to be either easy (Low Effort condition) or difficult (High Effort condition). Our results revealed participants invested more effort, persisted longer and performed better in the High Effort condition, i.e. when they perceived their partner to have invested more effort. These results support the hypothesis that the perception of a partner's effort boosts one's own sense of commitment to a cooperative activity, and consequently also one's willingness to invest time and effort.