Mere exposure effect

Biological Parallel

Sticklebacks prefer to mate with individuals from familiar visual backgrounds—repeated exposure without negative outcomes signals safety and compatibility. This familiarity preference evolved because in territorial animals, neighbors who haven't attacked represent known, manageable threats, while strangers might be dangerous competitors. The mere exposure effect is adaptive learning: ancestral environments where repeated encounters didn't result in harm provided Bayesian evidence of low threat, making familiarity itself a fitness cue worth approaching.