Purpose <p>Competence and prosociality of the person being helped are important indicators for ensuring a return on help, as reciprocity would not be possible if the person being helped lacked either the competence or the inclination to reciprocate in the future. A previous study that measured compassion using a Likert scale found that the controllability of the cause of the difficulty and the level of the sufferer’s prosociality independently influenced the degree of compassion. In this study, we aimed to examine how the probability of reciprocity affects physiological responses (such as heart rate), as well as psychological responses, to the suffering of others.</p> Methods <p>Participants’ heart rates were monitored while they watched a video of a man monologuing about his difficulty. Compassion was also measured using a Likert scale. In Study 1, we investigated the effect of the controllability of the difficulty on heart rate. In Study 2, we provided participants with additional information about the prosociality of the man in the video.</p> Results <p>Controllability affected compassion ratings, replicating the results of previous studies. Although participants’ heart rates decreased when they learned that the man was suffering, the controllability of the cause did not influence the degree of decline.</p> Conclusion <p>The results suggest that people experience compassion at a physiological level, while the controllability of the difficulty (i.e., a cue for reciprocity) is processed subjectively and reflected only in consciously reported psychological measures, which may reflect the evolutionary history of compassion.</p>