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 […]