The 89th Annual Meeting of the American Association of Physical Anthropologists (2020)

Is depression an evolved costly signal of need?


Anthropology, Washington State Univeristy

April 16, 2020 , Platinum Ballroom Add to calendar

Major depression is considered to be a pathological response to stress that elicits aversive responses towards depressed individuals. Alternatively, depression might involve honest signals of need in response to stress and help to bargain for increased support from reluctant others. To test this hypothesis, we examined responses to a wide range of emotional signals in a vignette study in which we also manipulated information about the signaler’s need and her levels of conflict with the social partner (participant) in a between-subjects factorial design. Specifically, a fictional sister asked the participant to help pay for medical treatment. The sister’s true need for money was either clear or questionable, and her level of conflict with the participant was either high or low. The sister’s signals were either verbal request, crying, depression, or, as a control, schizophrenic symptoms.

In our sample of 1,447 participants recruited from Amazon Mechanical Turk, depression increased belief in need and elicited more help than all the other proposed signals of need on our four outcome measures across all conditions. Simple crying and verbal requests were generally less effective. We also found evidence for the predicted interaction between signal type and conflict on relationship outcomes. Because signals comprising symptoms of schizophrenia caused a dramatic reduction in support, we can discount the hypothesis that help was provided due to symptoms of mental illness. Our results suggest that depression, an apparent human universal, is a relatively successful way of signaling honest need and eliciting support, consistent with costly signaling explanations.