Adverse caregiving experiences are thought to bias internal representations of self and others, giving rise to negative expectations that generalize to new encounters. However, few studies examine whether cues signaling resemblance to caregivers selectively increase the odds of generalization. In this preregistered study, 133 participants were assessed for maltreatment at two waves (n = 65 maltreated; ages 4–16 and 11–24 years). At the second wave, participants played Cyberball. Following social exclusion, participants re-engaged with two novel co-players, who ostensibly introduced themselves via self-descriptive blurbs: The Target implicitly resembled the participant’s caregiver, whereas the Control resembled someone else’s caregiver. The co-players threw the ball to participants (re-inclusions) or not (re-exclusions) at equal rates. We assessed event-related cardiac slowing, a correlate of expectancy violation. Cardiac slowing to Target was most pronounced in younger participants and declined with age, suggesting that caregiver cues exert a stronger influence on peer interactions at younger ages. Supporting our pre-registered hypotheses, during re-exclusions, maltreated participants showed greater cardiac slowing to Control vs. Target, whereas nonmaltreated participants exhibited the opposite pattern. We conclude that, for maltreated individuals, re-exclusion violates expectancies less when stemming from caregiver-like targets, implying that resemblance cues trigger selective generalization during early psychophysiological processing.