The importance of auditory stimulation for captive rhesus monkeys (Macaca mulatta) was assessed through three studies. The first study allowed three groups of monkeys to control the onset and offset of a series of 5 types of auditory stimulation over 10 weeks. Using an ABA design, the behavioral effects of this manipulation were examined. A significant increase in affiliative behavior was seen during the test phase. This was accompanied by a decrease in self directed behaviors, notably stereotypes.
The second study allowed the monkeys to control the onset and offset of two types of sound. Operant response rates, duration of music exposure, and activations of the music indicated that there was a preference for Jazz and Dixieland music over Animal Sounds.
The final study examined the behavioral responses of the monkeys to music under two conditions; (a) normal home-cage or (b) heightened arousal. The arousal condition was accomplished through the introduction of novel and/or threatening objects. To assess whether responses were truly as result of a stimulus with tonal and rhythmic components, white noise was used as a control. Significant interactions between sound type and arousal condition suggested that music has a calming effect under conditions of heightened arousal. Levels of tension related behaviors were lower during the Music and Arousal condition than the Noise and Arousal condition. In addition, higher levels of social contact were evident.
The results of these studies indicate that monkeys will play music when given the opportunity. Interest in the music is maintained for longer when they are presented with a simultaneous choice between two stimuli than when presented with only one type to turn on or off. As the presentation of music was accompanied by increases in affiliative behavior and decreases in self directed behavior, the manipulation was said to have a beneficial and calming effect.
