On the First Trial, a Rat in a Skinner Box

Multiple Choice

On the first trial, a rat in a Skinner box receives reinforcement for the first bar press it makes after 50 seconds have elapsed. On the second trial, the rat receives reinforcement for the first bar press it makes after 70 seconds. Although it varies from trial to trial, on average the rat's behavior is reinforced once every 60 seconds. The rat is on a _____ schedule of reinforcement.

A) fixed-ratio
B) fixed-interval
C) variable-interval
D) variable-ratio