| Abstract: Behavioral variability was characterized as an operant dimension of behavior (Page & Neuringer, 1985). Three studies examined the effects of reinforcement and extinction on three-response sequences under lag reinforcement schedules. Resistance to change of each response position was measured under lag 3 and lag 5 schedules. Variability increased under lag schedules as expected. However, contrary to what would be expected based on temporal contiguity of each response position with the reinforcer, backward progression of extinction was observed, as the first and not the last response was the most resistant to change. As responding did not cease, it was concluded that an interaction between both reinforcement and extinction is involved in the variability observed under lag schedules. |