Tune discrimination in monkeys ( Cebus apella ) and in rats

Monkeys and rats were trained on an operant discrimination employing structured auditory stimuli (tunes). The rats acquired the tune discrimination very rapidly and considerably faster than the monkeys. Both species generalized the discrimination across intensity and octave transformations. Discriminative performance remained at a high level when only the first halves of the tunes werepresented, but substantially less generalization occurred to the second halves. Rats trained with tones (brokenor steady) required three to four times more training to reach criterion than did the rats trained with tunes. The potential of structured auditory stimuli for investigations of information-processing mechanisms in animals is pointed out.