Extinction

Our Goal:
On October 4, our goal was to extinct the previously reinforced behavior of pressing the lever.

Extinction means that a previously reinforced behavior is never followed by reinforcers, therefore the overall effect is to reduce the frequency of the learned behavior.

Procedure:
The extinction session started at 8:47 A.M and lasted 30 minutes.  Peaches weighed 210.4 grams, 2.4 grams below her target weight.  She pressed the lever a total of 314 times and received 0 reinforcements.

Results:

Within the first minute of the session Peaches pressed the lever 39 times meaning she experienced an extinction burst, an immediate effect of extinction which entails an abrupt increase in behavior.  Megan and I counted the number of times Peaches' pressed the lever every 5 minutes of the 30 minute session.  After 10 minutes and 165 lever presses, Peaches began climbing the operant box and hanging on to the house light.  After 15 minutes, Peaches rolled over, a behavior she had shown in previous VR sessions.  By the end of the session, Peaches would walk past the lever and not press it.

Peaches During Extinction

 (This video displays Peaches continuously pressing the lever, pausing to see if a reinforcement has appeared then continuing to press the lever again.  When she sees that no reinforcement appears she presses the lever more vigorously.)

Peaches Climbing the Box 

(This video shows Peaches climbing the wall of the operant box and hanging onto the house light, which is placed above the food hopper.  You can see Peaches even try to climb on the ceiling of the operant box, but she reaches too far and falls.)

Extinction Graph

(This graph shows how many times Peaches pressed the lever every 5 minutes during the session.  It starts at a high number, decreasing, increasing and gradually decreasing in the second half of the session.)

Cumulative Record of Extinction

(From this picture you can see the extinction burst Peaches experienced at the beginning of the session)

Discussion:

Through out the session, Megan and I measured the number of times Peaches pressed the lever every 5 minutes of the 30 minute session.  As the session went on, Peaches gradually began to press the lever less frequently.  Therefore, the extinction session was successful.  It might have been more successful if we had continued extinction for a second day and gotten to the point where Peaches was pressing the lever no more than 5 times every minute.