Hidden tears and scrambled joy: On the adaptive costs of unguarded nonverbal social signals

Abstract

The ability to correctly assess the internal states of another is assumed to have clear adaptive advantages. Yet, the balance of evolutionary costs and benefits appears less obvious for the sender. Rather than to indiscriminately maximize the ratio of signal to noise, human nonverbal signaling is finely tuned to its situational context. We smile naturally and without flinching, out of politeness, to signal positive intentions, or to distract an opponent. Careless displays of fear may draw a predator’s attention, or they may reveal a readiness to abandon resources without a fight. Emotional tears result in blurred vision and reduce visual acuity, akin to a self-imposed handicap. This chapter re-examines socially intelligent nonverbal communication while focusing on the evolutionary costs of signaling too clearly and indiscriminately.