Aversion‐related changes in the call structure of Squirrel monkey vocalizations Free

It is generally assumed that the variation in primate calls is, to a certain extent, correlated with the internal state of a caller. However, it remains difficult to describe this relationship because it is difficult to get reliable information of the internal state of a caller. Therefore, the vocalizations given by Squirrel monkeys were analyzed in a self‐stimulation study done by Uwe Jürgens (1978). In this study it was measured how certain intracerebral stimulations were experienced by the subject. The Squirrel monkeys were in a cage with two compartments. Presence in one compartment was followed by a stimulation, whereas presence in the other compartment was stimulus free. As the animals were free to move from one compartment to the other, they could decide whether they wanted to avoid the stimulus or not. The multiparametric analysis revealed significant correlations between call parameters and the degree of aversion. Whereas single call types showed partly different parameter correlations, a shift in call pitch was found for all call types. In other words, the more intense the aversion was, the higher the frequency parameters (e.g., peak frequency or frequency range) were. =20