Shaping Peaches (day 2)

Our Goal:
To shape Peaches to press the lever in the Operant box in order to receive a pellet of food.  Megan and I decided that we were going to put Peaches on a manual shaping schedule because she was biting the lever on Shaping Day 1.

Shaping is a training procedure in which the rat is provided a reinforcement of successive approximations of a desired behavior.  Shaping makes it possible to establish a behavior in a few minutes that rarely or never occur spontaneously.  Manual shaping means that instead of Peaches automatically getting a pellet every time the lever was pressed or pulled down, we would have to reward her by pressing the hand switch.

Procedure:
The shaping session started at 8:45 A.M and lasted 30 minutes.  Peaches pressed the lever 36 times and received 56 reinforcements. She weighted 212.8 grams, .8 grams above her target weight. Megan was the trainer today and I was the observer.

Results:
When we put Peaches in the operant box she went straight to the lever, she would rear up over the lever and put her paws on it instead of her head. Although, when she wasn't reinforced right away she seemed to go back to her habit of biting the bar out of desperation to get food.

Peaches biting the lever

Peaches underneath lever, trying to bite it

It was interesting to see how she knew that the lever was where she needed to be in order to get food, but we just had to get her to put her paw on the bar instead of biting it down.  With 10 minutes left in the session she began to consistently press the lever to get food, a couple of those times she would bite the lever, but she would continuously have her paws on it.  Towards the end of the session she seemed to have lost some focus because she was wondering around the box more instead of staying in the area with the lever.  Peaches was reinforced 59 times and pressed the bar 36 times.

Cumulative Record of Shaping Day 2

Peaches pushing lever down

Discussion:
Although Peaches still tended to bite the lever down occasionally, she always seemed to have her paw on the bar.  This could be due to higher number of reinforcements given today than on day one.  She seemed to be able to understand that the lever is where she needed to go to get food and the only way to get it was to move the lever down.  We still need to work on not getting her to bite the bar, so on day 3 we will continue to reinforce her paws on the bar, but today was a vast improvement.