Perception of temporal acoustic patterns by the goldfish (Carassius auratus)

The perception of temporal acoustic patterns was studied in the goldfish using classical respiratory conditioning in combination with a stimulus generalization paradigm. Stimuli consisted of a bandpass filtered pulse repeated in various periodic and aperiodic temporal patterns. In each of 14 experiments, animals received 40 conditioning trials to a given stimulus pattern and were then tested for generalization to eight novel stimuli differing only in temporal pattern. In experiments 1-5, animals were conditioned to a periodic pulse train with a particular interpulse interval (IPI) and then tested to novel periodic pulse trains with various IPIs. Generalization gradients were substantially symmetric and monotonic with repetition rate, suggesting a perceptual continuum in goldfish that is similar to periodicity pitch or roughness in human listeners. Several additional experiments indicated that the perceptual qualities of simple and complex temporal patterns are not primarily determined by spectral structure or pulse rate, but rather are determined by the distribution of IPIs. A model for the central analysis of IPIs was successful in accounting for the results of experiments in which animals were conditioned to simple, periodic stimuli. However, the model failed when animals were conditioned to more complex stimuli having aperiodic temporal patterns. These experiments demonstrate the potential usefulness of the stimulus generalization paradigm for investigating aspects of complex sound source perception in non-human animals.