de Lima Rocha, A. D., Menescal-de-Oliveira, L., da Silva, L. F. S. 2017. Effects of human contact and intra-specific social learning on tonic immobility in guinea pigs, Cavia porcellus. Applied Animal Behaviour Science 191, 1-4.
Social learning is the capacity of animals to acquire adaptive information from others. In the case of fear responses, animals can learn fearful or non-fearful responses by observing the behavior of conspecifics. Tonic immobility (TI) is an anti-predatory behavior elicited during intense fear situations. Studies have revealed that regular contact with humans can reduce TI responses in animals. In our study, we evaluated the effect of human contact on the TI responses in guinea pigs. We also evaluated the effect of cohabitation (non-fearful animals with fearful animals) on their TI responses. To achieve this, we measured the TI responses induced by postural inversion and restraint in guinea pigs as a result of different treatments. In our first experiment, we determined the effect of human contact on TI responses by establishing 3 treatment groups: no contact, handled, and habituated. In our second experiment, we addressed the effect of social learning on TI response by testing TI response in habituated, and unhabituated animals that had cohabitated for 10days. In the first experiment, 10days of either handling or habituation did not prevent TI in guinea pigs, but habituation did increase latency [F(2,119)=14.19; p<0.0001] and handling or habituation decrease duration [F(2,119)=15.01; p<0.0001] of the TI behavior in the guinea pigs. In the second experiment, the cohabitation of unhabituated and habituated animals reduced TI duration [F(2,93)=5.058; p<0.008]. These data suggest that both forms of human interaction can reduce experimenter fear in guinea pigs. It therefore seems that unhabituated guinea pigs learn not to fear the experimenter by cohabitating with habituated guinea pigs.