Perception of sinusoid ‘‘ramps’’ and ‘‘damps’’ by the goldfish

Abstract

A stimulus generalization paradigm combined with classical respiratory conditioning investigated the perceptual tonal qualities of repeated, asymmetrically shaped tone bursts (‘‘ramps’’ and ‘‘damps’’) in the goldfish. Ramps are tone bursts with a slow rise and a relatively fast fall envelope (raised cosine-shaped). Damps are ramps played backward. Human listeners report that ramps sound more tonelike than damps, in spite of their identical spectra. Groups of animals were given 40 classical conditioning trials to 6 s trains of either ramps or damps (400-Hz carrier) repeated at 20/s, and then tested for generalization to eight continuous pure tones above, below, and including 400 Hz. A relatively large generalization response in the region of 400 Hz indicates a perceptual similarity between the ramp or damp conditioning stimulus and a sinusoid. Differences in the magnitude of generalization between groups conditioned to ramps or damps indicate that goldfish perceive ramps as slightly more tonelike than damps. Implications for the mechanisms underlying human perception of ramps and damps are discussed. [Work supported by the NIH, NIDCD.]