Applicability to foraging simulation of a reinforcement schedule controlling the response energy of pigeons

In optimal foraging theory (OFT), energy expenditure is an important variable for predicting foraging behavior. However, early studies, including operant simulations of foraging, did not measure energy expenditure. In the present study, an adjusting energy (AE) schedule was developed to control energy expenditure. Interresponse energy (IRE), a measure of the energy expenditure during a response, was calculated by dividing the square of the elapsed time between two consecutive responses by the square of the straight-line distance between the locations of the same two responses. An adjusting procedure was employed to estimate the indifference point between the requirements of the AE schedule and a fixed ratio (FR) schedule, which has been used in many operant simulations. In the adjusting procedure, pigeons adjusted the requirement of the AE schedule to that of the FR schedule. The results showed a systematic relationship between the requirements of the AE and FR schedules. Moreover, the total IRE per reinforcement systematically increased with the AE requirement. Thus, the present study demonstrates the utility of the AE schedule as a procedure for testing the validity of OFT.