Development of a frequency dimension in chickens (Gallus gallus)

Multidimensional scaling is used to examine the consistency of neonates' responses to frequency changes. Chickens at 0 and 4 days of age were presented with all possible transitions between pairs of five pure tones at 500, 525, 551, 578, and 608 Hz. Subjects were habituated to one stimulus, and the duration of an unconditioned delay in their otherwise ongoing peeps was measured after the frequency of the stimulus was changed. Durations of these delays can be used as measures of how different animals perceive two frequencies to be. Scaling solutions show that a nonrandom, adult-like ordering of frequencies emerges between 0 and 4 days of age.