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Experiment 2: Bar Press Response
Purpose:
To train the rat to lever press for food.
Procedure:
- Do an equipment test.
Notify the TF when you are ready to begin the experiment.
Click Food Trials: Give the rat 15 click food trials by pressing the hand switch once
for the delivery of each pellet. This will serve as a reminder to the subject that food is
available in the food cup. At the end of the 15 click food trials the external light will
flash. This will indicate the transition into the next phase.
Baseline: The purpose of this phase is to establish your subject’s operant
baseline, which is the number of bar press responses your subject makes per minute prior
to reinforcement training. Baseline responses will be recorded for a period of three
minutes. During this time responses will not be rewarded with food. At the end of the
three minutes, the external light will flash indicating transition into the next phase.
You will record the number of responses per minute from the beginning of baseline to the
end of the experiment.
Bar Pressing: Ideally at this stage your animal will be begin bar pressing for food. If
so, then the next hundred bar-presses made by the subject will be reinforced. The external
light will flash at the end of every minute, and you will continue to record the number of
responses made by your subject per minute.
If your animal does not bar press for a period of three minutes after the end of
baseline, then it will be necessary to shape your animal using the technique of successive
approximations.
Shaping: Shaping will require the manual delivery of pellets by pressing the hand
switch. Deliver a pellet when the animal approaches either one of the levers. Slowly make
the criteria more stringent e.g. he must get closer to the lever, look at the lever, smell
the lever, put his paw on the lever etc. Discontinue shaping your animal once he begins to
lever press. Pellets will automatically be dropped when the animal lever-presses.
The experiment will end and the house light will go off once 100 responses have been
reinforced. If this does not occur within two hours, then the experiment will terminate
regardless of the number of responses.
Data Collection:
Before coming to class, prepare a data sheet. You will
be recording the number of responses per minute from the beginning of baseline until the
end of the experiment.
Group Data:
Submit your group data before leaving class.
The number of
responses per minute for all subjects in your lab section are required |
# of
responses during the 3 minutes of baseline |
# of
responses during the last 3 full minutes of reinforcement |
1 |
2 |
3 |
1 |
2 |
3 |
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Lab Report # 1:
You will be required to present the data from this laboratory
graphically with a view to answering the following questions:
- What was the pattern of responding displayed by your subject during this experiment? You
will be given a computer generated cumulative record of your subject’s responses.
Describe this figure, beginning with baseline condition.
- Was there a change in the number of responses by minute that your subject made during
this experiment?
- How does your subject differ from the group? Use the group data to compare your subject
to the group during baseline and during the last three minutes of responding.
Statistical Analysis:
Is there a significant difference between the average number of responses for the group
from baseline to the last three minutes of responding?
MED-PC Output
Array C – used to generate a cumulative record
Array D –number of bar press responses per minute.
Bar Press Response Program.
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