This is the 2007 version. Click here for the 2017 chapter 05 table of contents.

Extinction-Induced Resurgence (the "extinction burst")

During an extinction period, animals usually show a great variety of behaviors. The animal appears to test variations of behavior to see if anything will make the reinforcers start again. Epstein (1985) called this "extinction-induced resurgence." Others call it an extinction burst.

What is extinction-induced resurgence? How is it useful to animal trainers? How was it shown by some dolphins?

Extinction-induced resurgence is a handy phenomenon for animal trainers. If they want animals to learn new tricks, instead of repeating old ones, they put the animals temporarily on an extinction schedule (stop delivering reinforcers). This results in an increase in the activity level and variability of behavior. Then the trainer can pick out a new behavior to be reinforced.

In 1992 two trained porpoises escaped from an enclosure and swam out to sea. A few weeks later they turned up in a waterway next to a golf course, performing tricks for amazed golfers. The porpoises had been trained to perform tricks for fish, but by escaping they put themselves on an extinction schedule (except for catching their own fish). Their behavior at the golf course was lively and variable...and it worked. Before long some golfers bought a load of fresh fish, and the porpoises were feasting.

Porpoises are social animals that often make eye contact before and after a trick. Attention is a powerful reinforcer for most social animals-including humans. Suppose you were on a golf course by the ocean, and you saw a porpoise close to the shore, doing what appeared to be a show trick (such as swimming on its tail, with its head high out of the water) while looking you straight in the eye. Wouldn't you feel the urge to go buy some fish?

In short, it was not just the porpoises that were being reinforced! This brings to mind the old cartoon in which a rat is sitting in a cage telling another rat, "Boy, have I got that human trained...every time I hit this bar, the human gives me a food pellet." Humans think they are training the animals, but the animals are just as surely training the humans.

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