Effects of Drugs on Conditioned “Anxiety”

THE behavioural phenomenon known as conditioned suppression was first demonstrated by Estes and Skinner 1 . They maintained the bar-pressing activity of rats by a schedule of food reinforcement and found that this behaviour decreased in frequency during a stimulus which ended with an unavoidable shock. Estes and Skinner suggested that the suppression of responding was an indirect measurement of “anxiety”. Subsequent workers 2 have argued that the temporal relationships between the shock and the stimulus which precedes it satisfy the requirements for classical (respondent) conditioning to occur. After a number of pairings, the conditioned stimulus (pre-shock stimulus) elicits the respondents which were formerly elicited only by the unconditioned stimulus (shock).