The cost of social punishment and high-lethality suicide attempts in the second half of life.

Age-related cognitive changes may contribute to impairments in making complex social decisions. Interpersonal conflict is a key factor behind suicidal behavior in old age, with suicidal motivations ranging from escape to revenge. Such conflicts may prove catastrophic for people prone to suicide, in part because of their tendency to make disadvantageous decisions. Yet, little is known about social decision making in older suicidal individuals. We assessed economic bargaining behavior using the Ultimatum Game, where players decide whether to accept or punish (reject) unfair monetary offers from another player. Our sample included depressed older adults with a history of high-medical-lethality suicide attempts, low-medical-lethality suicide attempts, nonsuicidal depressed older adults, and those with no psychiatric history who served as control groups. Participants in all groups punished their counterparts in response to unfair offers. However, low-lethality attempters, nonsuicidal depressed, and nonpsychiatric controls punished less as the cost of punishment increased, accepting more unfair offers as the stakes grew large. High-lethality attempters did not adjust their choices based on stake magnitude, punishing unfair offers without regard to the cost. Two thirds of the difference between the high-lethality attempters and nonpsychiatric controls was explained by individual differences in fairness judgments: the comparison group judged offer fairness as a joint function of inequality and magnitude, whereas the high-lethality attempter participants judged offer fairness on the basis of inequality. In real life, high-lethality attempters' relative insensitivity to the cost of retaliation may lead to uncompromising, catastrophic responses to conflict.