Saturday, May 12, 2012

Learning and the persistence of appetite

This week's blog entry is about the most interesting article on eating and learning that I have read up to date. You can find it here.  Unlike my previous posts, it is not based on a specific research study, but about the work of behavior psychologist Mark Bouton, who aims to reach far-ranging conclusions and analyses about various observations and phenomenon that have been encountered with learning and extinction of appetitive behavior.  I was hoping to drift slightly from the extensive blogging about Pavlovian conditioning and move unto a topic that was more recently discussed (in class) - operant conditioning, appetitive behavior, and the return of extinguished behaviors.  To start off - appetitive behavior is a behavior that increases the likelihood of satisfying a specific need (something pleasant), and is a central component of operant behavior.  Extinction is a conditioning phenomenon as well, where a previously learned response to a cue is eliminated when a cue is presented in the absence of the previously paired aversive or appetitive stimulus (
    I wrote an earlier blog entry about how environmental cues are so important in our lives and how they can trigger an eating response, even if we aren't hungry.  This article gets into the effects of extinguishing those learned responses; and how extinguishing those is simply context-specific, likely to resurface when the environment changes.  It has been found that extinction does not erase the original learning, meaning that it is hard to unlearn behavior and habits that have developed over many years, but someone may learn that a CS or behavior is no longer paired with the reinforcer only in the present context.
    The first, major point that is hit upon is renewal of extinguished appetitive behavior.  Simply put, if a CS is associated with a reinforcer in one context (Context A) and then extinguished in a second one (Context B), the CS elicits the behavior again when it is returned to the original context (Context A) or a new context (Context C), these are referred to as ABA renewal or ABC renewal, respectively.  This tells us that simply removing some organism from the context of the extinction will reinstate the conditioned response.  This is a scary thought for people being treated for anxiety disorders or for conditioned fear responses.  The current technique I know of for extinguishing fear and anxiety in patients is exposure therapy.  Patients are exposed to the object or a less threatening form of the object that they fear (void of any actual danger) in slow, successive steps.  For example, someone who is afraid of snakes will be shown pictures of snakes, then touch rubber snakes, then be in the presence of a real snake, then potentially touch a real snake.  This research is suggesting that once that even though the conditioned fear is extinguished, the patient will once again be afraid as soon as he steps into the original context where he learned the fear (like the snake exhibit at the zoo) or in a context different from the therapist's office.  Since my blog is focused on health and eating, I will also give an example of the return of an extinguished behavior and overeating.  Friends of mine at UCLA who actually live there (I am a commuter, so it is not AS STRONG in my case) tell me how happy they are that they have stopped overeating at school and have begun working out and getting in shape.  They were notorious overeaters in their hometowns and were overweight, but have since learned to cut back on their desire to overeat.  When they return home for the holidays, however, that extinguished response seems to reemerge they tell me, as they indulge in the feasts presented during Thanksgiving, Christmas, Easter, etc.  The interesting thing, though, is that they were not just taking advantage of the holidays and rewarding themselves with lots of food and desserts for a great quarter at school.  For the duration of their vacation, they were actually reverting to their old "pre-extinguished" way of life, and unable to preserve their patterns of healthy eating and working out.  In other words, they were able to stop overeating in the setting of UCLA, but were unable to transfer that behavior over to another context that they had not trained themselves in.
    The other, important topic I wanted to dive into is the resurgence of extinguished appetitive behavior.  Bouton talks about this in terms of learning one operant response (pressing a lever in a Skinner box) and then, while that behavior is being extinguished, a second, replacement behavior is reinforced (pressing a second lever in the box).  In a third phase, the second behavior is then extinguished, and the first response recovers.  The extinction in this case is not erasing the original memory, but only suppressing it.  I have experienced similar, in my own life, with the reinforcement of "other" behavior during the extinction of a target behavior.  During the summer after 10th grade, while I was 15 years old and looking to start working out, I experienced this exact thing.  I was a little overweight and decided that I was at the right age to get myself a gym membership... so I did.  I was taking one summer class at Santa Monica College and going to the gym after class, every day.  I was extinguishing my regular behavior or overeating and replacing it with a new, reinforcing behavior of working out.  So now, rather than getting pleasure from eating, I was getting pleasure (reinforcement) from working out, and even eating less reinforcing and pleasurable foods (such as vegetables instead of junk food).  I felt myself losing weight, I was building muscle tone and feeling pretty good about myself.  This continued for months (so you would think it would stick pretty strongly with me) until school started and my workload in high school became hectic again.  I was taking 3 AP classes, the rest of them honors classes, and the extra time that I had to dedicate (to the gym) shrunk drastically.  I was no longer able to utilize my YMCA gym membership 5 times a week as I had done during the summer, but was now going maybe once a week if I was lucky and not building muscle nearly as efficiently or effectively as I had done before.  As Bouton puts it, once that secondary behavior becomes extinguished, it could allow the bad habits to resurge... and they did.  I began overeating again to counteract the stresses of school and I was not able to get the reinforcement from working out at the gym any longer.  It is as if my original behavior had not been extinguished, and had suddenly resurged onto the surface.
   With the examples that I have given above, it is important to note a few things as take-home messages.  Extinction is not the same as erasure; the tendency to respond can return at any time.  Sometimes just by changing the context (ABC renewal), or the passage of time (Spontaneous recovery), a behavior that was thought to be extinguished and erased could end up resurfacing.  Also,  conditioning generalizes more than extinction does to a new context.  So just because you extinguished a behavior does not mean that there will not be resurgence if someone is placed in a different environment.  It also turns out that the second thing learned about a stimulus is often more context-specific than the first thing learned.  It is as if the memory system treats something that is learned second as conditional, context-specific and an exception to the general rule that reinforcement will be occurring.  Extinction is thus context-specific because it is the second thing learned.  Renewal, spontaneous recovery, and resurgence all tell us that lapse and relapse are very good possibilities (and perhaps inevitable) to see after extinction.  This can explain why once a behavior is learned it is so persistent.  This also tells me why the behavior of overeating is so hard to extinguish (in my case of replacing it with working out, or my friends case of coming to UCLA and training to eat healthier) when it has been a common part of your life for over a decade.

No comments:

Post a Comment