Journal of the experimental analysis of behavior
-
The operant conditioning of response variability under free-operant and discrete-response procedures was investigated. Two pigeons received food only if their pattern of four pecks on two response keys differed from the patterns emitted on the two immediately preceding trials. Under the free-operant procedure, the keys remained illuminated and operative throughout each trial. ⋯ Variability increased under this procedure, and the pigeons obtained three fourths of the available reinforcers. Previous successes and failures to produce response variability may have been due to the use or failure to use, respectively, a discrete-response procedure. Respondent effects inherent in the free-operant procedure may encourage the development of response stereotypy and, in turn, prevent the development of response variability.