Examination for Professional Practice of Psychology (EPPP) Practice Test

A pigeon is placed in a cage that has two levers. Lever 1 delivers reinforcement on a VI-30-second schedule, while lever 2 delivers reinforcement on a VI-60-second schedule. What proportion of the pigeon's pecks will be on lever 1?

1. One-third

2. Two-thirds

3. One-half

4. Three-fourths

The correct answer is: Two-thirds

The question examines how the rates of reinforcement on two different schedules influence the behavior of the pigeon. The pigeon is presented with two levers that provide reinforcement on variable interval (VI) schedules, with one lever offering reinforcement every 30 seconds on average and the other every 60 seconds. The key factor here is the relative frequency of reinforcement available for each lever. Since Lever 1, with a VI-30-second schedule, provides reinforcement more frequently than Lever 2, with a VI-60-second schedule, the pigeon is more likely to peck Lever 1. To understand the proportion of the pecks, consider how often each lever is expected to provide reinforcement over time. In a simplistic view, if we consider a 60-second period, Lever 1 would provide reinforcement approximately twice (once every 30 seconds), while Lever 2 would provide reinforcement once in that same time frame. Thus, in 60 seconds, there would be a total of three reinforcements: two from Lever 1 and one from Lever 2. The proportion of pecks on Lever 1 would therefore be two out of three total reinforcements, which simplifies to approximately two-thirds of the total pecks. This reasoning supports why the correct choice