Oxytocin makes individuals more averse to deliberately harming others when considering moral dilemmas, according to findings published yesterday in Molecular Psychiatry. Vasopressin, another hormone involved in social behavior, has no such effect.
Individuals with disorders that are associated with social behavior problems—such as autism, borderline personality disorder, psychopathy, and obsessive-compulsive disorder—also tend to show differences in moral behavior compared with neurotypical individuals, wrote Xiaoxiao Zheng, M.S., Ph.D., of the University of Electronic Science and Technology of China and colleagues. Both oxytocin and vasopressin (neuropeptides that are expressed throughout the central nervous system) play roles in social cognition and motivation, the authors continued, but their influence on moral behavior is unclear.
Zheng and colleagues recruited 180 participants (50% male) aged 18 to 26 who did not have medical or psychiatric disorders. Participants were randomized to receive oxytocin, vasopressin, or a placebo intranasally 45 minutes before completing two tasks designed to assess moral emotions and moral judgment.
The moral emotions task presented the participants with 28 scenarios involving cartoons in different situations that depicted the figures causing either deliberate or accidental harm to others. Participants rated their feelings of guilt or shame in reaction to each scenario, imagining themselves as the agents or victims.
In the moral judgment tasks, participants were asked if they endorsed certain actions in response to moral dilemmas. For example, one scenario asked participants if, as the captain of a submarine, it is appropriate to kill a crew member who is fatally wounded if such an action would ensure that there is enough oxygen for the rest of the crew to survive.
Participants who received oxytocin reported significantly increased feelings of shame and guilt when they imagined deliberately harming others compared with the vasopressin and placebo groups. There was no significant difference between the treatments in response to scenarios involving accidental harm. Additionally, participants in the oxytocin group were less likely to endorse moral choices that involved deliberately harming others, even for the greater good, compared with those in the other two groups.
“[Oxytocin] may be acting to strengthen deontological moral decision-making where it is the morality of the action performed rather than its consequence which is important,” the authors wrote. They concluded that their findings suggest oxytocin has much more influence than vasopressin in promoting altruism and empathy, and that only oxytocin “may have therapeutic potential for disorders where moral behavior is influenced.”
For related information, see the American Journal of Psychiatry article “Neural Responses to Intranasal Oxytocin in Youths With Severe Irritability” and the Psychiatric News article “Oxytocin May Promote Empathy in BPD Patients.”
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