Something New...VR3 and VR5

Our Goal:
On September 30, our original goal was to put Peaches on a VR5 reinforcement schedule, but we realized that we needed to put her on a VR3 schedule first in order for her to get use to this new schedule.  On October 1, our goal was to put Peaches on a VR5 reinforcement schedule.

In a variable ratio schedule of reinforcement, instead of providing a reinforcer when a behavior has occurred a fixed number of times, it makes it possible to vary the requirement around some average.  For example, instead of reinforcing every fifth lever press, it might reinforce after the second, the eighth, the sixth, the forth, or so on.  So in a VR5 schedule, reinforcement might occur after one to ten lever presses, but the overall average will be one reinforcement for every five presses.

Procedure:
On September 30, VR5 session started at 8:47 A.M, after we realized the light above the lever was not on we put her on a VR3 schedule so she could get used to it.  The VR3 session started at 9 A.M and lasted 21 minutes.  Peaches pressed the lever 286 times and received 95 reinforcements.  She weighed 217.7 grams, 5.7 grams above her target weight.

On October 1, the VR5 session started at 8:52 A.M and lasted 22 minutes and 17 seconds.  Peaches pressed the lever 496 times and received 99 reinforcements.  She weighed 220 grams, 8 grams above her target weight.

Results:
During the VR3 session, Peaches immediately had a quick rapid run rate, pressing the bar until the magazine was heard.  When she was pressing the lever, she would look up at the light above it and it wasn't on (which is why we switched her from VR5 to VR3).  Megan and I needed her to get used to pressing the lever without having to look at the light above it.  The house light would blink when the magazine went off so after a couple minutes in the operant box she began to focus on that instead.  She continued to have long PRPs (post-reinforcement pauses), just like in the last couple of session on the FR schedule.  Her longest PRP was when we switched her from the VR5 to VR3 schedule, but once she was reinforced she began to continuously press the lever in order to get more reinforcements.

Peaches During VR3

For the VR5 session when she was placed in the operant box, Peaches immediately went to the lever and began pressing it rapidly until she heard the sound of the magazine.  While she was pressing she would place her head on the lever and keep it there for a couple of seconds then begin to press the lever with her paws again.  Megan and I weren't sure why this was happening, but we believe that she might be doing it as a way to apply more pressure to the bar hoping that it would provide a reinforcement.  During the session we ran into a little problem, when Peaches had pressed the lever enough times to get a reinforcement, the magazine sound would go off but no food pellet would appear.  When Megan and I realized this, we began to listen to the "ping" of the food pellet and if we didn't hear it we would have to manually turn the magazine in order to reinforce Peaches.  This could have been an issue because the sound of the magazine and the food pellet dropping weren't happening at the same time, which is what Peaches was used to.  It ended up not effecting Peaches, because even after the reinforcement was in the food hopper she continued to press the lever.  Another thing Peaches was doing today was pressing the lever twice and then would go to the food hopper to see if there was a reinforcement waiting for her.  If there wasn't a reinforcement there, Peaches would immediately go back to the lever and begin pressing it until she heard the magazine.  Megan and I thought this might have something to do with Dr. Trench using her for an example on September 30th for one of her classes and put her on an FR2 schedule.

Peaches Learning VR5

VR5 schedule (you can see Megan having to manually provide Peaches with a reinforcement)

Cumulative Record for VR3

Cumulative Record for VR5

Discussion:
Both days of training were successful.  Although we ran into a few issues, once we realized that the light above the lever that would flash on the FR schedule wasn't working we moved her from the VR5 schedule to the VR3 schedule so she could get used to it.  Today she didn't even look at the light above the lever, she focused on the house light that would flash when she was reinforced.  For the VR3 schedule she seemed to take much longer PRPs compared to when she was on VR5, but that could be due to the fact that she was getting used to the new schedule.  Even with the issues we faced, Peaches seemed to be able to adjust to the variable ratio schedule of reinforcement.