The image at the top shows a stopwatch with a picture of a pigeon in the center. The introduction reads as follows; Continuous reinforcement is ideal for establishing new behaviors. But once learned, a behavior is best maintained through partial reinforcement. Partial reinforcement can be delivered according to four schedules; fixed-ratio, variable-ratio, fixed-interval and variable-interval.
There are four sequences of illustrations, titled, Timing is Everything.
The first sequence is titled, Fixed-Ratio, and shows a sketch of a bird with the word peck written five times around it. An arrow labeled Reinforcement points to the bird, with the caption reinforcement with food pellet on 5th peck. There are three instances of the bird pecking. The callout reads, Fixed Ratio; Subject must exhibit a predetermined number of desired responses before a reinforcer is given.
The second sequence is titled, Variable-Ratio, and shows a sketch of a bird with the word peck written three times around it in the first illustration, eight times in the second illustration, and four times in the third illustration. An arrow labeled Reinforcement points to the bird, with the caption reinforcement with food pellet on 3rd peck; reinforcement with food pellet on 8th peck; and reinforcement with food pellet on 4th peck respectively. The callout reads, Variable-Ratio; Reinforcement is unpredictable, that is, the number of desired responses that must occur before a reinforcer is given changes across trials and is based on an average number of responses to be reinforced.
The third sequence is labeled Fixed-Interval, and shows three illustrations of the bird and the word peck written once, thrice, and twice from left to right on a timeline with arrows indicating 40 second time intervals. An arrow labeled Reinforcement points to the timeline at the end of each 40-second interval, with the caption Reinforcement at 40-second intervals as long as there is at least one peck during the interval. The callout reads, Fixed-Interval; The reinforcer comes after a pre-established interval of time; the target response is only reinforced after the given time period is over.
The fourth sequence is labeled Variable-Interval and shows three illustrations of the bird and the word peck written twice, once, and three times from left to right on a timeline with arrows indicating 41, 43, and 40 second time intervals. An arrow labeled Reinforcement points to the timeline at the end of each interval, with the caption Reinforcement at variable intervals as long as there is at least one peck during the interval. The callout reads, Variable-Interval; Reinforcement follows the first target response after the time interval has elapsed. The length of the time interval changes from trial to trial.