HOPELESSNESS-INDUCED SUDDEN DEATH IN RATS ANTHROPOMORPHISM FOR EXPERIMENTALLY INDUCED DROWNINGS?

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Abstract
A series of experiments with wild and laboratory Rattus norvegicus were conducted to re-examine the reports of hopelessness-induced sudden death in the Richter swimming cylinder. Alternative behavioral and physiological interpretations of this phenomenon were supported in rats without invoking psychological stages of hopelessness. Deaths in wild and domestic rats were dependent upon: the jet pressure of water shooting into the swimming cylinder and depth of the water, both of which handicapped swimming; kinesthetic cues of the vibrissae; genetic variation in swimming ability; stock differences in emotionality and perhaps as a result of rearing and handling conditions; body size and sex; and differences in behavior leading to susceptibility to anoxia-induced drownings. Sudden death occurred in those animals either unable to keep their nostrils above the water surface or those who spent a great deal of time diving below the surface and exploring the bottom of the cylinder. Both were more susceptible to anoxia and drowning in this difficult swimming task. Bradycardia previously associated with these hopelessness-induced deaths proved to be the well-known dive or O2-conserving reflex and only occurred when the animal was below the surface. The need to carefully re-examine certain infrahuman experiments that purported to show a connection between psychological states such as helplessness and hopelessness, and psychosomatic pathology was suggested.

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