Educated people know about Pavlov's classical conditioning
studies. But few people realize the pervasive implications that apply even
today.
The key initial observation made by Pavlov was that when
dogs saw objects that looked like (and probably smelled like) food, they
salivated. He immediately seized on the concept of ASSOCATION that somehow
caused nervous systems to learn. He had no way to know if dogs actually "thought"
about the association. It did not matter whether the dogs did or not. The
biological adaptiveness of such a learning system was obvious. Pavlov realized
he needed to pursue this, instead of digestive physiology, as it was something
new and fundamental. He went on to perform experiments that lead to the ideas
of UCS/CS and UCR/CR.
The idea he missed was positive reinforcement. In fact, it
took some 50 years for others to realize that reinforcement was an underlying
mechanism in classical conditioning. This led of course to the idea that you
could produce learning by manipulating reinforcement (i.e., operant
conditioning).
Pavlov's work, old as it is, is still finding applications
today. A couple years ago I got an up-date in
the area of PTSD research at a seminar by Gregory Quick from the Department of
Psychiatry at the University of Puerto Rico. As Pavlov showed, memory
extinction is a basic phenomenon even in simple animals. If you repeatedly
flash a light and then stress a rat, it soon learns to become distressed the
next time it sees the flash, even after you stop the stress. In the lab, this
is manifested by the rat showing freeze behavior. But, if you repeat flash cue
enough times without the stress, the conditioned response (CR) (freeze
behavior) eventually becomes extinguished.
At first, scientists
thought that extinction erases the memory of the CR. But extinction really
creates a new memory that competes with memory of the original CR. Both
memories co-exist. Over time the extinction memory may be lost, and the CR can
return. The implication is that, just as ordinary learning needs rehearsal, so
does extinction learning.
Therapy for emotional trauma
and PTSD might be more effective if therapy were approached like a conventional
learning experience whose memory is affected in all the usual ways. Recall what
was said about extinction being a case of new learning. Re-learning of an
extinguished response occurs much more readily than it does for initial
extinction learning. This is an example of priming. It’s like re-learning a
foreign language. It goes easier the second time and the memory might be even
more dependable.
Since memory of an emotional
CR learning experience and its extinction can co-exist, these two memories
compete for which one is strong enough to survive long-term. Sadly, the CR
memory that causes the PTSD is often stronger. Cues are extremely important to
both forming and retrieving all kinds of memory. It seems likely there are many
more explicit cues for CR memories than for extinction memories. Therapy should
be aimed at enriching the number and variety of cues associated with extinction
learning. Rehearsal is likewise important. So far, nobody seems to have given
that much thought.
There is another aspect to emotional learning: learning to learn. If you have multiple anxieties, they may generalize and "spread" to facilitate learning new anxieties. In other words, the brain is learning to become emotionally dysfunctional. The corollary would be that learning how to promote extinction could also generalize and thus increase the general ability to cope with emotional trauma. Obviously, for one's brain to learn how to do that, one would need to begin with a single relatively easy extinction learning task, and then apply that learning-to-extinguish experience to other situations. Extinction learning needs to be repeated in order to become firmly established.
