Schusterman R J, Feinstein S H
Science. 1965 Dec 24;150(3704):1743-4. doi: 10.1126/science.150.3704.1743.
A captive vea lion (Zalophus californianus) which had never before produced clicking sounds in the laboratory was first conditioned to vocalize in air and subsequently learned to emit underwater clicks. clicking was brought under control by differential reinforcement procedures. Vocalization as an indicator response may be useful in the comparative study of discriminative behavior.
一只圈养的加州海狮（Zalophus californianus）此前在实验室中从未发出过咔哒声，它首先被训练在空气中发声，随后学会了发出水下咔哒声。咔哒声通过差别强化程序得到控制。发声作为一种指示反应，在辨别行为的比较研究中可能有用。
