Threatened by the unexpected: physiological responses during social interactions with expectancy-violating partners.

Individuals who violate expectations increase uncertainty during social interactions. Three experiments explored whether expectancy-violating partners engender "threat" responses in perceivers. Participants interacted with confederates who violated or confirmed expectations while multiple measures were assessed, including cardiovascular reactivity, task performance, appraisals, and behavior. In Experiments 1 and 2, participants interacted with White or Latino confederates who described their family backgrounds as either high or low socioeconomic status. In Experiment 3, participants interacted with Asian or White confederates who spoke with expected accents or southern accents. Participants interacting with expectancy-violating partners (e.g., Asians with southern accents) exhibited cardiovascular responses consistent with threat, poorer task performance, and manifested negative and defeat-related behavior. Implications for decreasing prejudicial responses via uncertainty reduction are discussed.