Schedules VR-3 and VR-5

Goal 1: The goal today is to place Shirley on a Variable Ratio schedule with the average number of presses to receive a reward being 3 presses.
Goal 2: The goal today is to place Shirley on a Variable Ratio schedule with the average number of presses to receive a reward being 5 presses.

Procedure:
A Variable Ratio schedule of reinforcement is also known as a VR schedule. This is defined as a schedule on which every nth performance of a behavior is reinforced. The first VR schedule is the VR-3. The session started at 2:25 p.m. and Shirley weighed 221.8 grams which is 13.8 grams above her goal weight. On the VR-3 schedule Shirley will not be able to predict how many responses it will take before she is rewarded, on average though it will be after 3 responses. This should result in a more steady pattern of extinction. There should also be less predictable pauses in this training session.
The second VR schedule is the VR-5; on this day the session started at 2:24 p.m. and Shirley weighed 220.2 grams which is 12.2 grams above her goal weight. On the VR-5 schedule Shirley will still not be able to predict how many responses it will take before she is rewarded, on average though it will be after 5 responses. This should also result in a more steady pattern of extinction. There should also be less predictable pauses in this training session.

Results and Discussion:
The VR-3 schedule seems to capture Shirley's attention more than the fixed ratio schedules. Shirley has been very active today and hardly leaves the bar. Carolyn and I discussed and chose to put Shirley on a VR schedule of reinforcement because we thought we would have more interesting results during extinction. Even on the VR schedule Shirley takes breaks in the front left corner that she always goes to during the training sessions. Shirley has so much energy today and darts from one side of the cage to the bar and presses down on it as many times as she possibly can. She is also biting the bar more and trying to push herself further into the magazine to get as many pellets as possible. I think that her biting the bar is a frustration response and being on this schedule causes her to press down on the bar and bite more, thinking she can be rewarded more by doing this. She pressed the bar a total of 503 times during this session.

Shirley on a VR-3 schedule

On the VR-5 schedule Shirley is even more aggressive toward the bar and she is even more energetic than she was yesterday on the VR-3 schedule. She is pressing much more than she has ever done in the past, but is displaying strange behaviors in-between pressing the bar and receiving a reward. At one point Shirley was trying to use the light in the cage to climb, so she was hanging from it at one point. She is also throwing herself at the walls of the cage. If she is displaying this much aggression today I can not even imagine what she will try to do during extinction when she does not receive any rewards. Shirley has become increasingly more frustrated and shown more aggressive behavior as the schedules have changed, but this is by far the worst she has been.  She has spent less time taking a break in the front left corner and stayed very engaged with the bar the entire session. She pressed the bar a total of 779 times today, which is by far the most presses of any training day.