Sniffy, The Virtual Rat

Project 3: Chapter 11: Exercise 30

The Effects of Punishment on Response Elimination

This exercise is based on the materials in the Sniffy Pro manual. To get a feel for the software download the Sniffy Demo software available on this site, and print off this document to follow step by step. Some users may find it helpful to run the Tutorial, and see Project 3 before they try it by themselves.

Exercise 30: The Effect of Repeated Mild Punishment

Reinforcing a response makes the response more likely to occur under similar circumstances in the future, while, punishment makes a response less likely to occur. In Exercises 25 and 26, you saw that discontinuing reinforcement of a previously reinforced response (extinction) causes the response to occur less often until eventually the response occurs no more often than it did originally.

In chapter 11 you will examine the effect of mildly or severely punishing the first response that Sniffy makes at the start of an extinction session and of mildly punishing each response that Sniffy makes during extinction. If the effect of punishment is opposite to the effect of extinction, then punishing Sniffy for responding during extinction should lead to more rapid elimination of bar pressing. In Exercise 29 you likely found that a single severe shock is enough to produce very rapid, nearly complete elimination of the response.

In Exercise 28 we found that a single mild punishment administered at the beginning of extinction briefly suppresses bar pressing but has little effect on the total number of bar presses required to produce extinction. Most of the time the cumulative record will resemble that shown next.

After receiving the single mild shock, Sniffy doesnât press the bar again for a couple of minutes, after which he begins to press it more or less as if he had not been shocked at all. As the behavior extinguishes Sniffy barpresses less often until eventually the response occurs no more often than it did originally.

The extinction criterion, on an eye-ball estimate basis, is no more than 2 presses within a 5-minute period. The lab Assistant window reports the rate of bar-presses per minute, calculated over the last 10 presses. When the rate drops below .5 presses per minute (i.e., 2.5 presses in 5 minutes) we shall consider bar pressing extinguished. Sniffyâs rate of pressing has returned to within the normal pre-training level (.25 to .50 per minute). When that point is reached you should mark the cumulative record by executing the Mark Record command in Experiment menu. Save your extinction file by selecting the Save command from the File menu.

When the extinction criterion is reached, you should estimate the number of responses that Sniffy made between the onset of extinction and the time when the criterion was reached. You should also estimate the time required to reach the extinction criterion.

When estimating the number of responses and the time elapsed during extinction, remember that:

The thin alternating dotted and solid vertical lines on the cumulative record mark off 5-min periods in program time.
Sniffy always makes 75 responses between two successive pen resets.

Determining how many responses Sniffy has made during extinction and the time that extinction required will typically require you to estimate fractional parts of 75-response vertical pen excursions and fractional parts of 5-min time intervals. You can elect either to make precise measurements or to do ãeyeballä estimates.

In the current experiment, you will examine the effect of repeated mild punishment. If the effect of punishment is opposite to the effect of extinction, then punishing Sniffy for responding during extinction should lead to more rapid elimination of bar pressing.

Thus we will want to know how long does he continue pressing, and how many presses until he stops.

Follow these steps:

Open your trained Sniffy file from Exercise 23. This is the file that we recommended you save under the name Ex23-ShapeBP. If you no longer have the file, you can use the file called ShapeBP from your Sample Files folder.
Use the Save As command in the File menu to save the file under a new name (e.g., Ex28-1MildPun in the Sniffy Files folder. This step preserves your original trained Sniffy for future use. You will need this file in several further experiments.
If the most recent cumulative record is not visible, make it visible by selecting it from the Windows menu.
If Sniffy is hidden, make him visible by selecting Show Sniffy from the Experiment menu.
Execute the Design Operant Conditioning Experiment command by selecting it from the Experiment menu.
In the dialogue box that appears:
- Select Extinction.
- Click on the box titled Punish Bar Press.
- Make sure that a check mark appears next to First Press Only.
- Make sure that a check mark also appears next to Mute Pellet Dispenser.
- Click OK.
You will note that the first time Sniffy presses the bar, he leaps in the air, indicating that he has been shocked.
If you want to speed up the experiment, you may do so by selecting Hide Sniffy (Accelerate Time) from the Experiment menu.
When Sniffy meets the extinction criterion: Save the file

Now the experiment is running. A further boost in speed is available if you put the program in background mode, E.G., select Hide Sniffy under the Sniffy menu. (this will vary depending on the speed of your computer).

Repeated mild shocks cause Sniffy not to press again for a couple of minutes after each bar press.

You should see that Sniffy presses infrequently for a very long time. The start of the cumulative record will resemble that shown next.

When Sniffy meets the extinction criterion: Save the file

To measure the effect on behavior calculate two measures; how long did Sniffy keep pressing, and how many presses has he made. You can estimate this to nearest minute and the nearest 10 bar presses using the 5-minute vertical lines, and the pen resets that occur on the Cumulative Record every 75 presses.

Compare the number of bar presses that Sniffy makes prior to reaching the extinction criterion in this experiment with the results of Exercise 25, in which Sniffyâs bar pressing was extinguished without shocking the first bar press.

The result of the comparison will likely be that when Sniffy is shocked after each bar press, he will reach the extinction criterion after fewer bar presses. However, repeatedly shocking Sniffy may not reduce the amount of time before he meets the extinction criterion. In fact, the amount of time required to meet the criterion may be longer.

See the Sniffy Pro manual for more details on these phenomena. Thank you for exploring Project 3 with us! See Projects 4 and 5 for more advanced exercises with Sniffy, the Virtual Rat.