VOCAL LEARNING INDUCED WITH OPERANT TECHNIQUES - AN OVERVIEW

Operant-conditioning techniques originally developed by B. F. SKINNER (1938) have had a strong impact on our understanding of learning mechanisms. Recent interest in the extent to which non-human animal vocalizations, like any other motor response, can be shaped by such procedures has generated a number of studies which are reviewed in this article. The modification of vocal behaviour by instrumental learning requires two conditions which have been fulfilled in various species of birds and mammals: (1) the physical parameters of calls such as the rate, pitch, duration and amplitude can be altered by conditioning and extinction; (2) these acoustic features as well as the form of the vocalization can be brought under the control of stimuli. These findings provide some support for the hypothesis that a precursor of human speech, namely the ability to control vocal utterances, can be found in higher vertebrates. Beside this, a new line of research undertaken by the author shows that Skinnerian techniques can be used to induce imitative learning in a songbird species for which tape-tutoring had been found inadequate. When song presentation was made contingent upon key pressing, young male zebra finches copied to a greater extent than controls receiving the same stimulation in a passive way. In this species, the effectiveness of the contingency for initiating song imitation is greater when key pressing rather than hopping on a reinforcing perch provides the reward.