Extinction

The last two days of training Swanson consisted of extinction--ceasing the rewards in order to stop the behavior. I put Li'l Swanson in the operant box, and for the full 30 minutes she was not rewarded one single time that she pressed the bar. The chart below shows how many times she pressed the bar in each 5-minute interval:

	Time (min)	Bar presses
Extinction Day 1	5	79
	10	57
	15	31
	20	13
	25	5
	30	13
Extinction Day 2	5	30
	10	25
	15	11
	20	23
	25	18
	30	3

As you can see, as time went on, she pressed the bar fewer and fewer times. She often exhibited odd behaviors during extinction--hopping around the cage, chewing on the bar, sniffing the bar then the magazine then the bar again, etc., as if she was frustrated that there were no rewards appearing in the magazine. During day 2 of extinction, at the 20 minute mark, her number of bar presses doubled (from 11 to 23) after almost constantly decreasing in each 5-minute interval. This could be considered an example of extinction burst, albeit a weak example. I did not see any examples of spontaneous recovery.

In the video below, notice how Li'l Swanson searches inside the (empty) magazine for food, then presses the bar repeatedly, then chews on the bar (probably in frustration), then continues pressing the bar.