7/4/84, Updated 6/29/01

Every Once in a While

David A. Gershaw, Ph.D.

How often and when should we reinforce desired responses? Last week, we discussed two schedules of partial reinforcement fixed ratio and fixed interval. In contrast to rewarding every desired response, both schedules produced slower learning and are slower in going to extinction. However, the fixed ratio schedule leads to a high, consistent response rate, while the fixed interval schedule produces a low response rate that only increases near the end of the time interval.

The third schedule of partial reinforcement is random reinforcement. It rewards the organism on an unpredictable, chance basis. Whether rewarded according to the number of responses or the time intervals, the frequency of rewards is randomly varied. In other words, although the organism may expect a reward it never knows exactly when the reward is coming.

If a pigeon's pecking is randomly rewarded, the pigeon will show a high, consistent response rate similar to fixed ratio. In addition, random reinforcement is extremely hard to bring to extinction. For example, a pigeon was randomly reinforced for pecking at a dot for only one minute. Once this occurred, no more rewards were given. It took over 3.5 hours, before the pigeon gradually stopped pecking. In other words, for one minute of training, it took the pigeon 210 minutes to go to extinction!

This is one reason why praising other people's desired behavior is so effective. Typically, people get praised only "every once in a while." Because this verbal reinforcement is random and unpredictable, there is a strong tendency to continue the praised behavior.

However, gamblers are also reinforced randomly. This contributes to the problem of compulsive gambling. Let's say that a man wins a great deal of money over his first day of gambling but never wins after that. Although it may not take 210 days similar to the pigeon above to go to extinction, it will take a very long time. However, in real life, the gambler will continue to win "every once in a while," even though he may be losing most of the time. For example, he may win $1200 but lose $8000 during that same period. In other words, even though the gambler is on a losing streak, he is still being randomly reinforced! Under these conditions, the gambling may continue indefinitely.

Because supetstitions are reinforced randomly,
they are very hard to bring to extinction.

Various superstitions may also stem from random reinforcement. One of the most familiar examples is the behavior of baseball players, when they come up to bat. Have you ever noticed the rituals they go through, before they are ready for the pitch? How does behavior begin?

Suppose a batter goes into a slump. He tries all he has been taught but with no success. Before the next pitch, he happens to pull the visor of his cap down. He hits that pitch! While on base, he ponders the reason for his hit. Possibly pulling the visor down helped. Just in case it did, he continues this habit. Every once in a while, he gets another hit. In this way, pulling his cap down becomes randomly reinforced and part of a superstitious ritual. Similarly, other acts like tapping home plate with the bat, knocking mud off of his cleats (even under dry conditions), or chewing tobacco can be added to become parts of a complex ritual.

Primitive religious rituals may also be due to random reinforcement. Suppose a group of natives believes that a "shark god" is responsible for making their fishing successful. To insure the cooperation of their deity, they regularly throw it a pig as a sacrifice. Sure enough, every once in a while their catch is especially good. However, what if the catch is poor? The pig sacrifice would tend to continue, because it is being randomly reinforced. They may believe that the first offering was a "bad" pig, so an additional one should be sacrificed. Even if the additional pigs did not help, the natives may think, "Who can question the ways of the shark good?"

Although you may smile at the baseball player and native examples, you are less likely to be so jovial when you realize that the same principles of random reinforcement apply to your religious rituals. Have you ever prayed for something you wanted? Have you done some other religious ritual fasting, chanting or lighting candles to help you achieve some goal? If so, you probably could not predict if or when you would get what you wanted. Every once in a while, you might obtain your goal. Like the native, getting rewarded on a random schedule made you likely to continue your religious ritual, even after it has outlived its usefulness.

This is not an attempt to argue that there is no God. Instead, it is a reminder that we are all human. Thus even in our religious rituals we respond according to basic principles of human behavior.

Go back to listing of additional articles.

Go back to "A Line on Life" main page.