Perception and Generalization of Frequency Contours by a Bottlenose Dolphin (Tursiops truncatus)

A single adult female bottlenose dolphin was tested in a series of perceptual studies. On each trial, 4 sine-wave tones were presented that contained a falling frequency contour or some other contour. There were several frequency-transposed exemplars of each contour type in each experiment. The dolphin discriminated contours at a level significantly greater than chance in all experiments. In the 1st 2 experiments, the dolphin demonstrated only modest transfer to novel stimuli and a sensitivity to the absolute frequency of stimuli. In the 3rd experiment, there was no effect of the absolute frequency of stimuli; in the 4th experiment, the dolphin successfully transferred the discrimination to novel stimuli drawn from the octave above the previously heard range. These results demonstrate dolphins\u27 capability to perceive frequency contours, which may underlie the recognition of conspecific whistles. © 1995 American Psychological Association