Discrete or graded variation within rhesus monkey screams? Psychophysical experiments on classification
Gouzoules et al. (1984, Animal Behaviour,32, 182-193) presented evidence that semifree-ranging rhesus monkeys, Macaca mulatta, produce acoustically distinctive classes of scream vocalizations that carry different functional messages. To determine the perceptual validity of these vocal classes, we conducted psychophysical experiments on captive rhesus monkeys. We trained two monkeys to maintain contact with a metal response […]
Chimpanzees communicate to two different audiences during aggressive interactions
Conflict and aggressive interactions are common phenomena in group-living animals and vocal behaviour often plays an important role in determining their outcomes. In some species, vocal signals seem to provide bystanders with information about the nature of an ongoing aggressive interaction, which can be beneficial for the victims. For example, in chimpanzees and some other […]