Resistance to extinction of lever-pressing rates maintained by different wheel-running reinforcement durations

- First assessment of resistance to extinction with wheel-running reinforcement.
- Lever press on response-initiated VI schedule for 5 s, 30 s, and 90 s of running.
- Assumed resistance to extinction would vary with duration.
- Found resistance to extinction varied inversely with duration.
- Explanation-response deprivation varies inversely with duration.
- Explanation - discriminability of extinction varies directly with duration.

Previous research using resistance to extinction to assess response strength has shown slower attenuation of responding maintained by larger than smaller reinforcement magnitudes. The current study sought to generalize this reinforcement-magnitude effect to extinction of lever-pressing rates maintained by wheel-running reinforcement of different durations. Rats responded on a response-initiated variable interval 20-s schedule for the opportunity to run in a wheel for 5 s, 30 s, and 90 s. Following training on each reinforcement duration, lever pressing for wheel running was placed on extinction. Results showed that responding maintained by 5 s of wheel-running reinforcement declined slower in extinction than for the 90-s duration, while 30 s of wheel-running reinforcement produced inconsistent effects on attenuation of response rates. These results suggest that shorter periods of wheel-running reinforcement have higher reinforcement value than longer durations-findings incompatible with the earlier research showing more resistance to extinction with large reinforcement magnitudes. We offer an interpretation based on response deprivation arising from restriction of the wheel-access interval and its motivational impact on wheel running as a reinforcing consequence and on responding for wheel-running reinforcement. An alternative analysis proposes that discrimination of the shift to extinction is more salient for the long wheel-running duration-accounting for the rapid attenuation of responding in extinction with the long periods of wheel-running reinforcement.