Social learning strategy in Macaca nemestrina : a two-actions test

The existence of an imitative learning ability (i.e. learning to do an act by seeing it done) can be evaluated only by distinguishing between different social learning mechanisms, and the so called two-action procedure has proved highly effective in this respect. In this research, the Two-Action Test paradigm was employed to investigate which social learning mechanism was involved in the acquisition of a new behaviour by pig-tailed macaques (Macaca nemestrina nemestrina). Ten subjects hosted at Parco Natura Viva, Bussolengo, I, were assigned to two different experimental groups and their ability to solve a problem after observation of a human model was assessed. The subjects were presented with the same object (a winged-box) that could be opened in two simple but different ways to reach a reward: by pushing down the lid on the one side of the box or by lifting it up on the other side. Each group was shown only one of the two possible solutions. All the subjects touched and manipulated the same part of the equipment touched by the demonstrator when opening the box to retrieve the reward. However, they used an individual strategy to solve the task. These findings show that macaques learned something through observation, i.e. which part of the box should be manipulated to open it, but did not imitate the behaviour witnessed (pushing/ lifting). The process underlying the acquisition of the new behaviours via observation, therefore, seems to be stimulus/local enhancement plus individual learning. All the subjects tried to open the box by lifting the lid up and none of them pushed it down. As during a previous study, the macaques were shaped to open a box by lifting up the lid from the front side, thus, a priming effect could have interfered with the acquisition of the new response.