Operant conditioning must solve the “problem of the first instance”: How and why do responses occur before they have been reinforced?
The problem was solved in part by the evolution of processes through which individuals take advantage of behavior already acquired by others. Imitation is an example. It often brings the imitator into contact with the reinforcing consequences responsible for the behavior imitated. The behavior of the imitator is “primed” in the sense of made to occur for the first time and usually when it is likely to be reinforced. (pp. 664-665)