CATEGORICAL PERCEPTION OF MOUSE-PUP ULTRASOUNDS IN THE TEMPORAL DOMAIN

Mouse-pup ultrasounds emitted from outside the nest area are releasers of maternal pup searching and retrieving behaviour. House mouse, Mus domesticus, mothers were tested in a situation with two alternative choices for their unconditioned preference of 50 kHz tone bursts of various durations (models of mouse-pup ultrasounds). Categorical perception in the temporal domain was established by labelling and discrimination tests. Two categories occurred: one of non-preferred short-duration tones (25 ms and shorter) and the other of preferred long-duration tones (30 ms and longer) with a sharp boundary between 25 and 30 ms. Stimuli from the two categories were discriminated, however, only if they differed in duration by at least 20-25ms, which may be the threshold of duration discrimination. The discussion concentrates on the biological significance of categorical perception of communication sounds and possible mechanisms of boundary formation. © 1992 The Association for the Study of Animal Behaviour.