James V. Ralston
Kathryn F. Gage
Jeffrey G. Harris
Sean P. Brooks
Dept. of Psychol., Ithaca College, Ithaca, NY 14850
Louis M. Herman
Kewalo Basin Marine Mammal Lab., University of Hawaii
It was previously reported [Ralston et al., J. Acoust. Soc. Am. Suppl. 1 84, S77 (1988)] that a dolphin appeared to perceive relative pitch in sequences of four pure tones. At any point in those studies, all stimuli were pitch transpositions of one of two contours. The dolphin generally whistled after presentation of one contour and remained silent after presentation of the other contour. Recent analyses have examined whistle probability, whistle latency, and whistle duration as a function of the absolute pitch of stimuli. Generally, as the absolute pitch of the stimuli increased, the probability of whistling increased and the whistle latency decreased. The combined results suggest that the dolphin judged both the absolute and relative pitch of the stimuli. Consistent with Ridgway et al. [J. Acoust. Soc. Am. 89, 1967 (A) (1991)], the present results also suggest that whistle responses provide a sensitive index of perceptual processing and are an appropriate modality in choice response paradigms with dolphins.