Whenever Tommy has a babysitter and asks to stay up past his bedtime, the babysitter lets him. Whenever Tommy asks his parents to let him stay up past his bedtime, they do not let him. As a result, Tommy only asks the babysitter if he can stay up past his bedtime. The presence of the parents at bed time is referred to as a(n) __________ for asking to stay up late:

Early behaviorists were interested in

A) ensuring that elements of the unconscious mind were more measurable. B) making psychology more objective and scientific. C) understanding children's thought processes. D) helping psychology align itself more with theories of evolution.

Whenever Tommy has a babysitter and asks to stay up past his bedtime, the babysitter lets him. Whenever Tommy asks his parents to let him stay up past his bedtime, they do not let him. As a result, Tommy only asks the babysitter if he can stay up past his bedtime. The presence of the babysitter at bed time is referred to as a(n) __________ for asking to stay up late:

a. stimulus class b. S-delta c. reinforcer d. discriminative stimulus