Attribution of responsibility for the causes of suffering is one of the main factors that influence responses to individuals in distress. While the role of attributional processes on prosocial motivation has been widely investigated in social psychology, only few attempts have been made to characterize their behavioural and neurophysiological underpinnings. This is partly due to the lack of stimuli that can facilitate within-subject experimental designs. To overcome this problem, we created a set of stimuli consisting of videos depicting people in different situations of distress. Each video is paired with short stories that aim to manipulate the perceived degree of responsibility of the main character. To validate the stimuli, we investigated the effect of different context-video pairs on self-report measures of participants’ subjective experience. We found that different contexts preceding the same video can influence blame and responsibility judgments, affective responses and willingness to help. In a complementary analysis, we replicated previous findings on the influence of empathy and responsibility on willingness to help, showing how the latter is mediated by moral judgments. Finally, we observed a general increase in responses times when videos were paired with responsible contexts. We provide interpretations of this finding that can relate attribution accounts to prominent theories in moral psychology. Overall, this study highlights the possibility of expanding existing theories on prosocial motivation by implementing a set of stimuli that includes multiple scenarios and allows for the collection of third person measures in within-subject designs.