Observational Conditioning of Snake Fear in Unrelated Rhesus Monkeys

It was the results of two experiments that demonstrate rapid, strong, and persistent observational conditioning of snake fear in unrelated rhesus monkeys, extending the findings of Mineka, Davidson, Cook, and Keir (1984), who reported similar results using related monkeys that were living together. In Experiment 1, two wild-reared adult monkeys with a strong fear of snakes served as models, and 10 laboratory-reared adult monkeys with no initial snake fear, who were "acquainted" with, but not related to their models, served as observers. The observers showed asymptotic levels of fear in another context (the Sackett Self-Selection Circus) after only 8 min of watching their models behave fearfully in the presence of snake stimuli in the Wisconsin General Test Apparatus. In Experiment 2, two observers from Experiment 1 who had acquired snake fear vicariously served as models for 8 other unrelated, and for the most part unacquainted, laboratory-reared adult monkeys. The results were similar to those for Experiment 1, except that the level of acquired or maintained fear was slightly lower in Experiment 2. Possible reasons for the differences in level of fear in the two experiments are discussed, in conjunction with possible mechanisms underlying such observational conditioning.