Abstract
Pigeons on concurrent variable-ratio variable-ratio schedules usually, though not always, maximize reinforcements per response. When the ratios are equal, maximization implies no particular distribution of responses to the two alternatives. When the ratios are unequal, maximization calls for exclusive preference for the smaller ratio. Responding conformed to these requirements for maximizing, which are further shown to be consistent with the conception of reinforcement implicit in the matching law governing relative responding in concurrent interval schedules.