Effects of extended fixed-interval training on reversed scallops

Two groups of pigeons were used to determine if different amounts of fixed-interval training with an added clock resulted in different local response rates when the clock was reversed. One group of seven pigeons received 120 reinforcements on a fixed-interval 90-sec schedule, while the other group received 1200 reinforcements. Following training, the added clock was reversed in extinction. Reversed scallops were obtained for both of the groups. Only the group with extended training showed an increase in responding during the previously reinforced segment of the interval. This suggests the development of greater temporal control with extended training.