Species Specific Defensive Reactions and Avoidance Training

Some interesting speculation on avoidance learning has advanced the idea that animals undergoing aversive stimulation respond in species-specific ways, thereby facilitating some forms of avoidance learning while impeding others (Bolles, 1970, 1973). According to Bolles (1970), animals are innately prepared to react to novel or startling stimuli with a limited set of defensive behaviors. These species-specific defensive reactions (SS-DRs) do not depend on learning for their expression: they are motivationally and topographically stereotypic, possess an evolutionary significance, and exhibit a low threshold for expression:

What keeps animals alive in the wild is that they have very effective innate defensive reactions which occur when they encounter any kind of new or sudden stimulus. ... The mouse does not scamper away from the owl because it has learned to escape the painful claws of the enemy; it scampers away from anything happening in its environment, and it does so merely because it is a mouse. The gazelle does not flee from an approaching lion because it has been bitten by lions; it runs away from any large object that approaches it, and it does so because this is one of it species-specific defensive reactions. Neither the mouse nor the gazelle can afford to learn to avoid; survival is too urgent, the opportunity to learn is too limited, and the parameters of the situation make the necessary learning impossible. The animal which survives is one which comes into its environment with defensive reactions already a prominent part of its repertoire. (1970:33)

Bolles has argued that SSDRs can either facilitate or impede avoidance training. Depending on the species involved, aversive stimulation evokes varying degrees of immobilization, flight, or active defensive reactions.

Avoidance or escape responses that are similar to an animal's natural defensive repertoire are most easily learned; in the language of Seligman (1970), the responses are prepared, whereas those avoidance responses that are dissimilar or incompatible with the animal's natural defensive repertoire are either unprepared or contraprepared for such training. For instance, teaching rats to lever press to avoid shock is relatively hard to accomplish. In comparison, training rats to jump over a low hurdle or to run to the opposite side of a training compartment is much more easily attained. Ostensibly, jumping and running are high-priority defensive reactions in rats, whereas lever pressing is not. The latter response may be more directly associated with appetitive-consummatory activity associated with the search for food and eating it.

Hineline and Harrison (1979) challenged Bolles's theory of prepotent species-specific avoidance responding. In a series of experiments, they compared the differential acquisition of lever pressing with that of lever biting in rats. The operative assumption was that lever biting should prove innately prepotent over lever pressing and, therefore, be learned more rapidly. Instead, they found that rats actually learned lever pressing more rapidly than lever biting. Their findings, however, are not inconsistent with predictions based on Bolles's SSDR theory of avoidance learning. The study simply demonstrates that lever biting is not prepotent over lever pressing in rats. The researchers appear to have been misled by a presumption that defensive aggression ought to be prepotent over other escape-avoidance actions, such as lever pressing. In fact, under conditions of aversive stimulation, attack may not be prepotent over other escape possibilities. Azrin and colleagues (1967) found that escape was typically dominant over attack in rats and was only likely to occur when (1) escape was otherwise not possible or (2) when the escape requirements were too difficult. Also, although attack behavior tended to interfere with escape behavior during the acquisitional phases of training, this early attack behavior quickly diminished as the escape response was mastered.

In dogs, many competing SSDRs occur during the early stages of obedience training. According to Bolles, "The trick in the avoidance situation is to punish all of the wrong responses so that the right response will occur" (1973:299). Dogs being trained with forceful methods typically react by systematically experimenting with various defensive postures and reactions that are prepotent to the dog as a species. These defensive behaviors range from bolting and jumping up, to dropping down and freezing; balking and struggling to pull away, or biting the leash. Some dogs exhibit a wide variety of passive submissive displays or, in the opposite extreme, occasionally threaten or snap at the handler. The early stages of avoidance training (really punishment training) involve systematically suppressing these innate defensive reactions and replacing them with forcefully prompted alternatives. Only once all defensive reactions are punitively suppressed or reduced to the obedient target response does systematic and formal avoidance training begin.

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  • Benjamin Cameron
    What are speciesspecific defensive reactions?
    6 years ago

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