The appearance of matching

•A computer model of concurrent variable interval schedules was used to investigate the matching law.•The schedule dictates the form of the relation between behavior and reinforcement ratios.•Matching law graphs of optimal behavior are sigmoidal.•Matching- like behavior only appears when reinforcement generation efficiency is high. A computerized version of Houston and McNamara’s (1981) model of concurrent variable time schedules was used to generate large data sets consisting of behavior inputs and the corresponding reinforcement outputs. The data was analyzed to assess the hypothesis that matching behavior observed with CONCVTVT (or CONCVIVI) schedules is an inevitable product of the operation of the schedule. The results suggest that the generalized matching law does not provide the best description of the results obtained with CONCVTVT schedules; that the parameter value of schedule components determine the framework of the reinforcement efficiency maps of behavior choices; and that by random chance alone matching-like behavior is likely to appear if the reinforcement generation efficiency of the behavior is high.