Effects of sustained avoidance/escape on demand for food

Rats were concurrently exposed to a sustained avoidance/escape (SAE) procedure and a procedure for assessing demand for food. In the sustained SAE procedure, signalled shock avoidance/escape trials were presented at varying intervals averaging five minutes. The shock could be avoided by pulling on a ceiling chain early in the trial, or escaped by pulling on the chain later in the trial. Demand curves for food were generated by requiring 1, 5, 10, 20, 40, 80, 160, and 320 lever presses for each food pellet on successive days. The demand curve procedure was introduced after either brief (3 or 5 days) or extended (21 or 23 days) exposure to SAE. Following brief exposure to SAE, SAE animals showed decreased food intake and less elasticity of demand relative to non-SAE controls. Following extended exposure to SAE, these effects were diminished or absent.