A Search for Tonal Pattern Perception in Cebus Monkeys: Why Monkeys Can't Hum a Tune

This article reviews a series of experiments aimed at assessing the capacity of cebus monkeys and rats for tonal pattern perception (sensitivity to frequency contour). The animals' ability to differentiate between two tunes (structured sequences of tones) that shared several component notes and were similar in their average frequency suggested tonal pattern perception in both species. Detailed analysis of the basis of their discriminative behavior revealed, however, that the latter was completely controlled by local cues. Additional studies confirmed this finding and showed that the cognitive limitation was not, in the case of the monkeys, due to a generally impoverished capacity for processing acoustic stimuli or to an unduly truncated auditory short- term store. Many species of songbirds also seem remarkably deficient in their ability to perceive the tonal patterns of non-species-specific acoustic stimuli, which may be widespread among animals. Some implications of this striking difference in the auditory processing capacities of animals and humans are briefly discussed.