Title/Introduction
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1. Defense and the Conditional Reflex
Page 1
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2. Flight, Locomotion and Image Memory
Page 2
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3. Olfactory Familiarity and Imprinting
Page 3
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Neophobia and Object Memory
Page 4
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Learning of "Wildness"
Page 5
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Habituation to Handling
Page 6
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Learning of Visually-Released Boxing
Page 7
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Conclusion
Page 8
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Bibliography
Page 10
A number of years ago in our laboratory, we raised a generation of highly inbred laboratory rats in a large earth-filled tank where they could construct a burrow system. To our surprise, these animals, when adult, acted like wild rats. They fled wildly in response to the slightest noise or movement, quite unlike the laboratory rats which we normally raise in wire cages. A similar phenomenon was reported by Rasmussen [50] who came to the conclusion that a short period of "freedom" for a domesticated rat was sufficient to make it wild.
Although this phenomenon is obviously of great importance in the process of domestication, and must represent an important form of learning, it was not investigated systematically until the last few years. In May, 1977 Clark and Galef [15] reported in Animal Behavior that Mongolian gerbils, given as little as 24 hours of experience with a burrow environment, show much greater defensiveness than controls. They also found that there was a critical period in this learning. Unless the experience was gained before the age of 60 days, the adult gerbil did not become wild [14]. Furthermore, they reported that the provision of a cliff or a hole was not sufficient; the young animal required the experience of running from an open, lighted area into an enclosed darkened area of "safety".
The converse finding, that young animals exposed to sounds and movements without any chance for escape, then fail to show defense to similar stimuli when adult, may be a special case of habituation. Unlike most habituation which has been studied in other behavioral systems, however, it would appear that certain types of early experience "lock-in" the defense response so that habituation cannot occur.
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