Reading focus
Syllabus: How Do Consequences Shape Action?
Trace the baseline ranking, the imposed dependency between activities, and the different clarity of results across monkeys.
Why you’re reading it. Turn the broad selection argument into a prospective prediction about which consequence should reinforce which response.
A question to consider. If activity B is more probable than C but less probable than A, what does Premack predict when access to B follows C versus A? What would a test of both arrangements add to observing just one?
Why this reading
What makes an activity reinforcing for another activity? Premack tests a prediction based on independently measured behavior, making the explanation more demanding than simply calling any effective consequence a reward.
Before you read
A manipulandum is an object an animal can operate. The instrumental response gives access to a contingent response. Baseline measurements estimate how often each activity occurs before that dependency is imposed. A reinforcer is defined by its effect on the behavior it follows, rather than by whether it seems pleasant to an observer.
Read for
- Follow the measurements with objects presented separately and in pairs before access to one is made dependent on operating the other.
- Compare the individual monkeys. Identify why the clearest test comes from the animal with consistent differences among its baseline activities.
- Examine the intermediate-probability activity: its different effects on higher- and lower-probability activities challenge the idea that an activity is always reinforcing.
Consider afterwards
- Two activities occur equally often, but one lasts much longer each time. Would response counts alone support the same prediction as time spent? Explain what needs measuring before testing the contingency.
Editorial context
The four monkeys did not provide four equally clear confirmations. Much of the discriminating evidence came from one animal; the others had smaller, absent, or unstable baseline differences. The discussion also acknowledges difficulties defining comparable response units. Timberlake and Allison (1974) later argued that restricting access relative to baseline, together with the schedule requirement, is more informative than a probability ranking alone. Treat Premack’s proposal as a testable account, not an unrestricted rule for choosing rewards.