1) A unit of behaviour with a clear beginning and end. Responses can be operant or respondent, depending on whether they are controlled by; stimuli which follow them or by stimuli which precede them. How much behaviour constitutes "a response" is largely arbitrary. We can talk about the response or saying one word or of giving a whole lecture.

2) An instance of an identifiable part of behavior. A class of such instances. In this sense, response is equivalent to operant . See also behavior.

3) The use of the term response has been limited in this text to the reflex. Operant behaviours are designated as performances. Other writers, however, use the term response interchangeably with operant and reflex behavior.

4) A directly measurable behavior. Used interchangeably in this book with behaviour and performance.

5) An single instance of a response class or behavior.

6) A unit of behavior, a discrete and usually recurring segment of behavior.