Horn effect (devil effect)

Biological Parallel

Brood parasites like cuckoo chicks evoke rejection from host birds if a single feature—like mismatched egg color—triggers categorical recognition of "foreign." Once labeled as parasite, the host treats the entire clutch with suspicion even if other eggs are genuine. The horn effect evolved as conservative threat detection: when one negative signal correlates with danger, organisms evolved to generalize negativity across the entire entity because false negatives (accepting a threat) cost more than false positives (rejecting something safe).