Perception of the missing fundamental by cats

Abstract

Two cats were tested on their ability to perceive the missing fundamental through the use of an avoidance technique. The animals were trained to discriminate between rising and falling pitch sequences first with single and then with multiple tones. They were then tested by presenting them with tone triads known to produce the perception of the missing fundamental in humans. In these traids the pitch of the frequencies composing the triad either remained the same or shifted in the direction opposite the shift of the missing fundamental. The animals'' response to these triads was not in conformity with that expected from the direction of change of the component frequencies, but could be accounted for if it were assumed that the cats were responding on the basis of the missing fundamental. A further test given one of the cats indicated that this phenomenon declined progressively as the center frequency was raised, until at 6 kHz it was apparently completely absent. A similar decline in the strength of the fundamental pitch occurs over the same range in humans. Cats may perceive the missing fundamental.