To place Shirley on extinction, and have the number of bar presses to decrease over the two days. Pressing the bar should occur no more than it did during training.
Procedure:
Extinction is a process that is defined as a decrease in instrumental responding because the response is no longer followed by a reinforcement. Shirley was placed on extinction on the last two days of training. The extinction process started at 2:30 p.m. and both sessions lasted 30 minutes. We observed her behavior and watched for any signs of extinction burst and spontaneous recover, as well as any strange behavior she was displaying.
Results and Discussion:
Shirley did not respond to extinction very well. Once placed in the box she went straight to the bar and started pressing. She had been on a VR-5 training schedule before extinction, so it took her a few minutes to figure out that she was not receiving any reinforcements for her behavior. When Shirley realized that she was no longer reinforced she became very aggressive toward the bar and started biting down on it and chewing it at certain points. There was an extinction burst (an immediate increase in behavior on extinction) on the first day with in the first 10 minutes of training Shirley had pressed the bar 246 times and at 30 min she had pressed the bar 475 times which is more than she had pressed the bar during any training session. Shirley was trying everything she possibly could to get a reinforcement, she would bite the bar, push the bar up instead of down, and hold the bar down and gnaw on it. As the session reached the end Shirley did interact with the bar less but I would not say that she was fully extinct.
On the second day of extinction when Shirley was placed in the box she started pressing the bar again. Because a small amount of time had passed since her last training session this could be an example of spontaneous recovery. At the beginning of the session, after pressing the bar down Shirley would still check the food hopper for pellets. However, overall the behavior occurred much less today, the total number of presses after 30 minutes was 247. She was still showing signs of aggression today by biting the lever and rolling in front of the food hopper when trying to get the pellets out, however, she is much less aggressive than yesterday. I also assume that she probably would not have pressed as many times or continued pressing for so long had she not been placed on the variable ratio schedules.
Shirley trying to dig the food pellets out, this is right before she rolled over in front of the hopper.
This is Shirley trying to push the bar down while also biting it
Number of bar presses every five minutes on extinction day 1
Number of bar Presses every 5 minutes on extinction day 2
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