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Classical Conditioning

To clarify some key terms, a stimulus is some environmental event that we hear, see, feel, smell or taste.  A response is something that we do after detecting a stimulus.  So, for example, when you smell a food that you really like (stimulus) your mouth starts to produce more "mouth-waterin" saliva (response).

Some stimuli naturally induce a response without any learning necessary.  For example, a loud scary noise (stimulus) naturally causes animals to retreat (response) because, from a sociobiological perspective, loud things are dangerous.  We call these responses "unconditioned" because they are caused by the stimulus naturally.  Classical conditioning involves learning that a stimulus that would otherwise have no biological meaning is associated with something that does.

Ivan Pavlov (1849-1936), a Russian scientist studying the biological processes involved with digestion, is widely considered the father of classical conditioning because he scientifically demonstrated that a biological response (drooling) could be triggered by a stimulus (sound) if dogs learned to associate the sound with food.

WatchPavlov's Dogs Get Conditioned (https://www.youtube.com/watch?v=NzBDScsHL44)

Now let's see how trainers use classical conditioning to teach an animal to like the sound of a click.  This will come in handy in our next section when we try to influence behavior - but the first step is for the animal to learn an association.

WatchCharging the Clicker (http://youtu.be/7VcvBIfwKPA)

An early and influential (not to mention controversial) demonstration of classical conditioning comes from John Watson (1878-1958).  Watson wanted to show that a child could learn to fear (response) something it previously was not afraid of (stimulus) if it was associated with something naturally scary (unconditioned stimulus).

WatchJohn Watson - Little Albert (http://youtu.be/Xt0ucxOrPQE)

Now let's break this down:

  • Neutral Stimulus (NS) –Albert had no experience with white rats previously, so the presence of the white rat had no particular meaning. Therefore, the white rat was a neutral object to Albert. There is no naturally wired response to the neutral stimulus. It is just, well, neutral.
  • Unconditioned Stimulus (UCS) – A baby, just like an adult or another mammal, will have a startle response to a loud noise.  Albert was not conditioned to have this response to the gong (he did not learn to have that response). It is natural and automatic.  So in this study, the gong is the UCS.
  • Unconditioned Response (UCR) – Crying is the natural and automatic response to a scary noise. In this study, the gong (UCS) triggered the unconditioned response (UCR) of crying.
  • Conditioned Stimulus (CS) – After repeatedly pairing the white rat (NS) with the gong (UCS), the baby learns the association.  What was neutral now has a conditioned meaning, so the rat has gone from a NS to a CS.
  • Conditioned Response (CR) – If Albert sees the rat (or anything else white or fluffy for that matter), he now begins to cry even without hearing the scary sound.  The unconditioned crying response (UCR) has now becomes a conditioned response (CR) to the presences of the rat (CS).

Do you think the same concept could be applied to classically conditioning college students?

WatchRoommate Training (http://youtu.be/Eo7jcI8fAuI) - please note: we do not condone the shooting of roommates!

How about with officemates?

WatchThe Office Classical Conditioning (http://vimeo.com/35754924)

  • NS: reboot chime (pre-learning)
  • UCS: mint
  • UCR: extending hand (an unlearned, natural response to a desirable food)
  • Jim pairs the NS with the UCS repeatedly
  • The reboot chime becomes the CS, extending the hand in response to the CS is the CR

In all of these examples an association was established by pairing two stimuli - a NS and a UCS - with a particular pattern.  The NS (bell, rat, easy button, reboot sound) was presented, and just a moment later, the UCS (food, gong, bullet, mint).  We refer to this as forward short-delay pairing -- the NS becomes useful in predicting the UCS (when I see the rat something scary is about to happen).  In that way animals can quickly see that the two stimuli are associated with each other and, with a few pairings, the NS becomes the CS and we get the CR (Albert sees the rat and starts crying because rats are now bad).  Using the roommate example, consider some other ways we might try this:
  • Simultaneous: We hit the easy button at the exact same time as we shoot the Airsoft bullet
  • Forward long-delay: we hit the easy button and two minutes later we shoot the Airsoft bullet
  • Backwards: we shoot the Airsoft bullet and then we hit the easy button
Psychologists have applied this basic concept in learning to do all sorts of things, including to train bees to keep us safe from terrorist plots.  As a final example…

Watch: Scientists Train Honeybees to Detect Explosives (http://youtu.be/_T7d0bze4kM)

Critical Thinking Question: Why is it easier to learn the association between a NS and a UCS with the forward short-delay pairing?