(a) A disturbed child who must wear eyeglasses to see properly keeps taking them off and throwing them on the ground. An acceptable reinforcer is found (say, the child likes a particular kind of...

(a) A disturbed child who must wear eyeglasses to see properly keeps taking them off and throwing them on the ground. An acceptable reinforcer is found (say, the child likes a particular kind of candy). When hungry, the child is given a piece of this candy for touching the eyeglasses gently while they are on a table. When this response has been well learned, the child is reinforced for picking up the eyeglasses carefully, then for bringing them nearer to his face, then for trying them on, and so on until he routinely wears the eyeglasses without incident. The reinforcement provided by his improved vision eventually replaces that provided by the candy. (b) A gambler continues to play a slot machine, even though it only pays off once in a great many trials. (c) I go to the supermarket to buy a loaf of my favorite bread. The loaf I see on the shelf is not exactly the same as the bread I bought yesterday; no two loaves are identical. But it is very similar, so I am able to emit the behavior of placing it in my shopping cart. (d) During a bridge tournament, I make a play that works out badly and fails to provide any reinforcement. On another occasion, the same play succeeds brilliantly. So I decide that the fi rst situation is different from the second one and requires a different strategy. When I next encounter the former situation, I use my new strategy. My plan succeeds, and this reinforcement increases the probability that I will continue to behave differently in these two situations. (e) After 20 years of playing tournament bridge, I give up this avocation permanently. Skinner would argue that I did not lose interest in bridge, but rather that external contingencies of reinforcement were too poorly designed for me to continue to emit the behavior of playing.