Two experiments investigating. the effects of chronic vs. acute insulin-induced hypoglycemia on attack and biting behavior elicited by tailshock are reported. Chronic-injection subjects had blood-sugar level experimentally reduced by insulin for 29 days, including the day of shock testing. Acute-injection subjects received an insulin injection only on the day of testing. High levels of attack and biting behavior were shown in the single-animal shock-elicited aggression situation by the chronic subjects in both experiments. High response levels were shown by the acute-injection subjects only in Experiment 2. The lack of such responding in Experiment 1 was attributed to the different injection procedures used in the two experiments. The data are supportive of the proposed negative relationship between hypoglycemia and aggressive responding.
This experiment assessed the ability of rats to learn uncued free operant single-and double-alternation tasks. Each of six male albino rats was trained to single and double alternate responses between two levers in an operant conditioning chamber. All rats. quickly mastered the single-alternation task. Accuracy improved with increased double-alternation training and was above the level predicted by chance. However. double-alternation accuracy was higher when extra responses were allowed (e.g.• LLLRR was reinforced as was LLRR). The rats in this experiment were totally unable to perform two correct double alternations in sequence (i.e., LLRRLLRR or RRLLRRLL).
Two studies relating extended insulin-dosage level to attack and biting elicited by tailshock are reported. In Experiment 1 four groups of rats received subcutaneous injections of 12, 16, 20, or 24 units of regular zinc insulin, respectively, prior to shock testing. A fifth group served as an injection control. Response level for the 12-unit insulin group was significantly higher than for all other groups. Surprisingly, the response level of the 24-unit group was higher than that of the 16-and 20-unit groups. Dosage levels of 12, 28, and 32 units were employed in the second study to investigate this elevated responding. High and virtually identical response levels were shown by the 12and 28-unit groups, with an extremely low response level being shown by the 32-unit group.
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