Inborn and Acquired Aspects of Offense and Defense Motivational Systems in Muroid Rodents: Role of Memory
6. Habituation of Defense to Handling Page 6

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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Figure 1
Page 9

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Bibliography
Page 10


The habituation of defense to human handling is well known in laboratory animals. It is regularly used by psychologists engaged in learning experiments, who handle their test animals before they begin the experiment in order to reduce the confounding effects of defensiveness. The strongest effects of handling habituation, however, are upon young wild animals. Galef [25] has systematical documented the taming effect of handling upon both domestic and wild rats; his experiments used animals reared in large cages with externally attached next boxes to which they could escape. Thus, he could show that the effects of handling were separate from the effects of "wildness" derived from opportunity to flee. Galef's results confirm those of many previous studies on the taming effect of handling on wild rats [59, 50, 23, 11]. In mice, similar data have been obtained by Connor [16] who showed that wild mice vocalized less when tested in repeated sessions of handling. Contact with conspecifics may also serve to habituate the defensiveness of muroid rodents in response to tactile stimulation. This is indicated by the fact that socially-isolated laboratory rats become "irritable" and show escape and biting in response to human handling [30, 42], but housing with conspecifics then reduces the irritability [30].

Habituation to handling is most effective if it occurs when the animal is young, but it may also occur in adults. If wild rats are captured as adults they are more difficult to tame by handling [59, 11]. The rats successfully tamed with handling by Galef [25] and the mice tamed by Connor [16] were young animals. However, Hatch et al. [30] found that the adult rats who were difficult to handle after three months of post-weaning isolation could still be tamed by placing them in group cages with conspecifics for three weeks.

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