Transcript Operant Conditioning Sniffy the Rat

Operant Conditioning:
Sniffy the Rat
210 Lab Assignment #2 – 2014
Due: Friday April 4th (last day of classes)
Today
1) Brief background: Operant conditioning and the reinforcement
schedules we’ll use
2) Using the Sniffy Program
3) Steps to completing the assignment
4) Walkthrough of CRF training (and brief explanation of how to start
PRF training)
5) Assignment Outline – lab report
Purpose
• The Sniffy program will help you understand operant
conditioning and give you first-hand experience with these
concepts:
• Magazine training
• Shaping behavior
• Partial Reinforcement (PRF) schedules
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Continuous Reinforcement (CRF)
Fixed Ratio (FR)
Variable Ratio Schedule (VRF)
Fixed Interval (FI)
Variable Interval (VI)
• Acquisition
• Extinction
Operant Conditioning
• Increases the rate of a desired behavior by
reinforcing that behavior when it occurs
• In our case, we want Sniffy to bar-press
• We will reinforce him with food pellets
Schedules of Reinforcement –
Main Types:
Continuous Reinforcement
(CRF)
Partial Reinforcement
(PRF)
• Rewarded every time the
desired behavior occurs
• Every time Sniffy presses
the bar, he will get a
food pellet
• Rewarded some times
when behavior occurs;
not every time
• e.g. Sniffy might press
the bar 5 times and only
get rewarded once.
PRF Schedules – 4 Types:
Fixed
Variable
- Reward happens after a
set number of responses or
time
- Reward happens around a
certain average
Ratio
Fixed Ratio (FR)
Variable Ratio (VR)
- Bar-pressing is the
determinant for reward
- Pellet is delivered after a
set number of bar-presses
- Pellet is delivered after an
average number of barpresses
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Interval
Fixed Interval (FI)
Variable Interval (VI)
- Amount of time is the
determinant for reward
- Pellet is delivered after a
set amount of time passes
- Pellet is delivered after an
average amount of time
passes
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Materials needed
• The lab manual (on Moodle)  read this before you start
• Sniffy Program
• On any campus lab computer:
• Click My Computer  Apps on Caesar (‘S:’ drive)  Sniffy folder 
double click the Sniffy icon to open the program
• Stop watch, or stop watch app on your phone
• Paper & pen
Project components
• Shaping an Operant Response:
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Observe Sniffy’s base-line behavior for 10 mins
Magazine Training
Shaping Bar-Pressing by Successive Approximation
Extinction
Spontaneous Recovery
• PRF Schedules:
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Fixed Ratio 20  extinction
Variable Ratio 20  extinction
Fixed Interval 20  extinction
Variable Interval 20  extinction
Observing baseline behavior
• For 10 minutes, observe Sniffy’s behavior
• Pay attention to what he does and get an idea of what kind of
behaviors you’ll be reinforcing later on
• Planning ahead a bit will help with the next part
• Record how many times Sniffy bar-presses on his own in the 10
minutes
• DO NOT reinforce him
bar
water
The
cumulative
record (CR)
will show you
how Sniffy’s
training is
progressing
magazine/hopper
These dotted lines show you 5minute increments
The ticks on the cumulative record show when Sniffy bar-presses. The line also moves
up when he presses the bar, allowing you to track training progress. Sniffy may bar
press a few. My Sniffy bar-pressed twice during the 10 min observation time.
Magazine Training
• Using the spacebar or your mouse, drop a pellet from the
hopper
• When Sniffy approaches and eats it, give him another pellet
• Consider Sniffy magazine-trained when he approaches the
hopper as soon as you drop a pellet (10-15 reinforcements)
• You can test his training by waiting until he is far away from
the hopper (nearest to you) and dropping a pellet: if he goes
to eat it, he’s magazine-trained
Training Sniffy to bar-press
• Training by successive approximation
• Reinforce behavior that is closer and closer to the desired
behavior
• Reinforce: drinking, rearing on the rear wall, going near the food
hopper, passing in front of it
• Fixation
• If you reinforce one behavior too frequently (e.g. reinforcing
rearing on the rear wall too many times in a row), Sniffy will fixate
on that behavior, rather than what you are trying to shape
• Note
• I cannot stress enough how important it is to devote your FULL
attention to this part of the assignment.
• Training Sniffy to bar-press takes about 30 to 45 mins if you pay
attention and reinforce him appropriately. It can take several
hours if you aren’t giving it your full attention.
Bar-pressing cont.
• Slowly wean reinforcement down to only when he is rearing near
the bar, or in front of the magazine
• Sniffy will start to bar-press by himself more and more frequently 
stop reinforcing him manually and let him continue to bar press until
the CR resets two times. Time him to make sure he’s bar-pressing at a
frequency of 4-5 presses per minute. If he is, your training was
successful!
Immediately save Sniffy to your H:
drive, USB drive, etc.
• Go to File  Save As  Name him something appropriate
(SniffyCRF.sdf, etc.). You’ll be working from this saved Sniffy file
several more times, so saving is vital. You don’t want to have to train
a new Sniffy later.
My CR has resent by going back to the bottom twice.
At this point he’s bar-pressing 4-5 times per minute.
Extinction Trials
• Click Parameters menu  Training Schedules  Extinction 
Click OK
• Sniffy will no longer be on a CRF schedule – He won’t get a
pellet when he presses the bar
• Time and Record:
• Number of non-reinforced bar presses in the first 2 minutes of
extinction
• Time to complete extinction
(if he presses 3 times or less in 5 minutes we’ll consider that
extinction)
Spontaneous Recovery
• Next we’re going to test spontaneous recovery after a ‘time out’
(think of this as an overnight break from the chamber)
• Click Parameters  Remove Sniffy for Time-Out  OK
• After Sniffy is placed back in the chamber, time and record:
• Number of bar presses in first 2 minutes
• Amount of time required for Sniffy to completely extinguish a second
time
• Save this Sniffy (e.g. SniffyEXT.sdf) and print your results
• You’re finished with CRF training!
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Time out
Note on Cumulative Records
• You will print a copy of CRF, extinction, and spontaneous recovery
cumulative records to turn in with your report
• Label the printout (in pen):
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When was acquisition complete?
When was extinction instituted?
When was extinction complete?
When was spontaneous recovery instituted?
When was extinction complete the second time?
• Print and make notes as you go through the steps, not after you’re
finished everything – it might be hard to remember later.
• Check the manual for more info on what you’ll need to print as you move
through the steps, and what you’ll need to label on the printout for each
training schedule
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PRF Training
• I’ll show you how to do the one PRF training schedule
• Fixed Ratio (FR) 20
• Teach Sniffy to bar-press 20 times for a food pellet
• The procedure to carry out this training schedule applies to all
the others
• First, open your original CRF Sniffy
• We can’t start out with FR20, we have to start out with a
lower ratio
• Remember how fast extinction occurred? If we start out at FR20,
or FR15, or FR10, it’s likely that he won’t learn the new schedule
Use for interval schedules
Use for fixed schedules
What I’ve selected means Sniffy
will get a pellet after 4 barpresses (FR4)
Sniffy’s response rate will be lower at
first
Looks like he’s learned the
new schedule
Wait until Sniffy has been reinforced 15 times, then increase the
# of responses before reinforcement (by 3 or 4 responses)
Repeat these steps until you’re up to FR20
Tips
• Give yourself lots of time to complete training – start as early as you
can
• I can give you rough estimates of how long each part will take:
• Observing behaviour and magazine training: 30 mins
• CRF – from 30 mins to an hour
• Assuming you’re paying attention! I’ve been told it can take several hours
if you’re not.
• The PRF schedules (+ extinction) take about an hour each
• If you forget to start your stopwatch, you can tell 2 minutes (or
whatever time you need) using the CR and a ruler
• Print the CR and label it before moving on to a new step.
• Read the instructions fully before starting – it’s hard to do it as
you’re working on training
• Saved full labs from last term
Lab Assignment #2
• Due April 4th (in class)
• After you’ve trained Sniffy and printed your CRs, write a lab report
detailing your findings
• More info on lab report requirements are in the manual
• Components:
• Title page
• Partial Intro
• Outline hypotheses for each training schedule (how do you think they
will they compare to one another?)
• Method
• Results
• Report your observations made during steps outlined in the manual
(acq/ext times, behavioural observations, etc.)
• Discussion
• Address questions listed in the manual
• Refs (textbook, chapter 5)
• CR printouts (labelled and with required notes)