FR Schedule of Reinforcement and Chart of Responses per 30 Minutes

After Li'l Swanson had been successfully shaped, I began putting her on different schedules of reinforcement. Because rewarding an organism every single time for performing a desired action is not particularly practical, you can reward the organism in different patterns, which elicit different amounts of behavior in the organism. I began Li'l Swanson on the FR2 (fixed ratio 2) schedule of reinforcement, which means that I reinforced her for every two times she pressed the bar. At the beginning of this training session, she would look for a pellet in the magazine after every single time she pressed the bar, even though there would only be a pellet there every other time she pressed the bar. 

However, as time passed, Li'l Swanson eventually stopped checking the magazine every single time (although occasionally she returned to that behavior) and would only check it after she had pressed the bar twice. At the end of this session, Li'l Swanson had pressed the bar about 86 times.

The next day, I put Li'l Swanson on an FR3 schedule of reinforcement. This schedule works the same way the FR2 schedule does--reinforcing the behavior after a certain number of times the behavior is performed--except Swanson was reinforced for every three times she pressed the bar. Notice how the cumulative record below differs from the cumulative record above:

Reinforcing Swanson less often led to her pressing the bar many more times. On the FR3 schedule of reinforcement, Swanson pressed the bar a total of 184 times, more than double the number of times she pressed the bar on the FR2 schedule.

The next training day I moved Swanson up to a FR5 schedule, where she was reinforced for every 5 times she pressed the bar, and she pressed the bar 272 times. The next day I put her on the FR7 schedule, where she was reinforced every 7 times she pressed the bar, and she pressed it 276 times. The day after that (my 10th day of training, including the magazine training and shaping), I moved Swanson up to the FR10 schedule of reinforcement, where she was reinforced for every 10 times she pressed the bar. If she had continued in her pattern of pressing the bar more when she was on a higher schedule of reinforcement, I would have expected her to press the bar more than 270 times. However, this was not the case. Li'l Swanson only pressed the bar 94 times when I put her on the FR10 schedule (see graph below)

As you can see, Swanson pressed the bar fairly consistently (albeit not too often) during the first 15 minutes or so, but after that she only pressed the bar a few more times. I ended the session early because she seemed to have "given up." Because of her low performance, the next training day I put her back on the FR10 schedule of reinforcement, and she did much better, with a total of 252 bar presses:

Because Li'l Swanson had not increased her number of bar presses much from FR5 to FR7 to FR10, I decided to put her on a different schedule for my last two days of reinforcement--a variable reinforcement schedule. In this schedule, the organism gets reinforced every time they perform an action for a varying number of times. For example, in a VR3 schedule of reinforcement, Swanson would get reinforced about every 2, 3, or 4 times she pressed the bar, but the average number of times she would have to press the bar for a reward would be 3 times. I used the VR3 schedule next, and she did well--232 bar presses. The next day, however, was her personal best: on the VR 5 schedule, she pressed the bar 407 times:

So looking back at the number of bar presses Li'l Swanson did on each schedule, the VR5 schedule elicited the most.

The following is a chart of the number of bar presses per 30 minutes for each of the different schedules (and each day of shaping) that I used with Li'l Swanson:

Schedule	Number of Responses per 30 minutes
Shaping 1	7.2
Shaping 2	2.6
Shaping 3	7
Shaping 4	67
FR2	107.5
FR3	204.4
FR5	272
FR7	276
FR10	141
FR10 pt. 2	252
VR3	257.8
VR5	407