Temporal discrimination and delayed reinforcement

• Delayed reinforcement lengthens the acquisition of discrimination similar to longer signals.
• Delayed reinforcement reduces overall stimulus control, increase Weber fraction but not affect bisection point and Difference Limen.
• Delayed reinforcement reduces stimulus control on time discrimination similar to reduction of motivation in other discrimination procedures.
• Delayed reinforcement seems to produce flatter generalization gradients.

We attempted to determine the effect of reinforcement delay on time discrimination in an interval bisection task. Three groups of rats were exposed to immediate, delayed reinforcement and longer signals with immediate reinforcement in acquisition and test. Results show differences in the amount of training necessary to reach the acquisition criteria, the Weber fraction and the range or overall stimulus control. The results suggest an increased difficulty to discriminate the difference among durations rather than an increase in estimated time as main effect of delayed reinforcement.