SHOCK INTENSITY AND DURATION INTERACTIONS ON FREE‐OPERANT AVOIDANCE BEHAVIOR 1

Abstract

Shock intensities (1 to 4 mA) and shock durations (0.3 to 0.75 sec) were concurrently varied over a range commonly used in free‐operant avoidance studies using a lever‐press response. Response rates were a positive linear function of the log of the product of intensity times duration. Shock rates were a negative linear function of that log. The increase in response rates was primarily due to a selective increase in the conditional probability of making responses with long interresponse times. The disproportionality of receiving shocks early in the session (warm‐up) was also a linear function of the log of the intensity‐duration product, with increasing disproportionality as the value of the intensity‐duration product was increased. Thus, with all measures of the avoidance performance, shock intensity and shock duration combine in a multiplicative fashion to determine the avoidance performance.