The time has come to post my last blog article about learning and eating behaviors for my Psych 110 class. The quarter has been interesting and educational, both with the work I have done in class and the weekly blogs. I believe the two have complemented each other very well and have given me an expansive realm of knowledge on the subject, which I can now apply to my every day life. I will skim through and recap some of my favorite findings from the experiments in primary literature, online websites and testimonials. Finally, I will aim to connect everything I have learned into a plan for me and my dad to start losing weight over the summer.
I started the quarter off talking about a Pavlovian approach to conditioning in my first two blog posts. In the first one, I talked about the experiment where foods that are sweet, but low in calories tend to confuse our system into dissociating the sweetness-calorie assocation and causing us to overindulge in sweet foods like cakes and cookies (because we may somehow think that not all sweet foods are calorie-dense). For example, when we drink something with a sweet taste, like diet-coke, and end up getting no calories, we develop a disconnect between two things. Sweetness and calories have been closely associated through time to tell us that we are consuming a lot of calories and that we will be getting full soon. This is a good example to bring to the table in order to discourage diet coke and encourage drinking more water. Not only are you ingesting fewer chemicals, you are drinking something with less taste and definitely less sweetness, so you are slowly restoring the connection that things which are less sweet carry less calories, and those that are more sweet carry more calories (this is a rather general rule, not hard and steadfast).
From here, I moved on to the point of environmental cues triggering our desire to eat. If we (or rats) are very well conditioned to certain environmental cues or signals, then we may eat, even while satiated. To counteract this point, I would recommend disturbing the patterns that we have all developed, by eating based on hunger, and not based on time. If you, let's say, eat your meals at 8 AM, 12PM, and 5PM every day and stick with that routine, you will tend to get hungry around those times as well. As soon as, one day, your routine changes, your mind will be so set on eating at those times that you may eat even while satiated. If you disrupt any type of routine, by eating only when hungry, then you will be more in control of your weight.
Next, I moved on to the idea of aversive images and evaluative conditioning in food choices. The idea behind this study was really interesting as it showed that people who were exposed to aversive images of different diseases, obesity, etc., which were linked to unhealthy food items, would prefer to choose the healthier food than those who were not exposed to the link between images and the aversive conditions. Although this has some implications in billboards and advertisement exposure, I am having a hard time connecting it to a practical application in my daily life. I don't normally lose my appetite when I see something disgusting (as some people do), but I could try conditioning myself over time to associate a link between these aversive images and unhealthy snack items. Perhaps, over time, I will want to avoid them, seeing a direct link between the foods I eat and the potential negative consequences.
I wanted to skip over to my blog on the Shangri-La diet and express how interested I have become in this. From reading the real experiences of people online and doing some research on the diet itself, I strongly believe that it will work out for me and my dad. It is the first book I want to jump into this summer, because it could potentially change my eating habits as I hope to avoid the snacking and overeating during my two months of studying for the MCAT (normally I eat and overeat during times of stress, especially studying). Ever since I published the blog article, I have been telling my parents about the tactics Seth Roberts uses, and how breaking the taste-calorie associations is going to be our solution to a lower weight and healthier lifestyle. As they say, the devil is in the details, so in order to really tackle this, I am going to create an eating schedule and follow Seth Roberts' techniques and advice closely. Of all the topics I learned this quarter, this is the one I am most eager to dive further into, and I want to thank Psychology 110 and professor Blaisdell for introducing me to the concept.
A final blog topic I wanted to discuss about was a look into the future and the possibile benefits of a high-fat diet in renewal and extinction. The results of the study where rats were fed a high-fat diet and were conditioned to a cue showed that this type of exposure may reduce the context-specificity of extinction. Of course, the reason behind this is not immediately apparent, and more research will need to be conducted, but it is an interesting finding to look at. Therapy has always fascinated me and, now, a possible solution to a problem like extinction has captured my attention. Just make sure that you don't use this technique of feeding someone a high-fat diet, if you are trying to extinguish their behavior of overeating!
And that brings me to the end of my weekly blog. I hope that my readers enjoyed reading what I had to say every week and learned a thing or two. I know I did. So much research has been published on the topic of learning and eating, and I feel that only with a combination of different techniques will I begin to see any results of controlling appetite and overeating. I have already begun this process by switching the location that I eat all of my main meals. This is meant to break the associations I have developed with the cues of a location and the desire to eat desserts or to overeat. In addition, as Seth Roberts suggests in his book, I have begun adding more spice to my foods to "confuse my senses" in some ways and to break the taste-calorie association. My next step is to try the olive oils and the nose-pinch techniques. Once I figure everything out, I am going to share my knowledge with my dad and see if he is open to the idea of trying it as well.
I want to, once again, make a shoutout to my professor and the class he has taught so brilliantly, which has definitely changed the way I see things when it comes to learning. So far Psych 120A (Cognition) and Psych 110 have been my favorite psychology classes at UCLA because they have both been analytical in their approach of the world and focused on thinking, connecting dots in life and looking into the reasons behind interesting phenomena that we take for granted on a daily basis.
Thank you for reading! Have a great, relaxing summer!
Monday, June 18, 2012
Wednesday, June 6, 2012
Environmental cues, fear and the BRAIN!
This week's article for my blog is by Gorica D. Petrovich, and it is called "Learning and the motivation to eat: Forebrain circuitry." As the name suggests, some biology will be brought up, as I attempt to connect it to psychological principles and different learning mechanisms and eating habits that I have learned about and blogged about for the past couple of months. Two important topics I will hit upon in this blog are the ideas about cues that cause a subject to eat while sated and fear/anxiety inducing cues that can inhibit eating, even in states of hunger.
This article hits upon multiple different points related to learning/motivation and eating, and as I discuss them they will be a good review of some of the topics I have previously discussed. One of the topics talked about is the environment in which food is consumed. There are always cues associated with certain foods, and the environments in which we sit down to eat, that serve as conditioned stimuli (CS) and trigger our urges to eat, even if we are not particularly hungry. I have talked about this in a previous blog, and I have discussed the importance of trying to limit those cues. I suggest that, the next time you plan on eating lunch or dinner, eat it in a novel environment, so you don't end up showing a conditioned response to the environment and then overeat... you will be able to limit yourself more effectively. If you, as I do, normally eat at the kitchen table, then switch to the dining room or to the living room, so that you don't trigger those usual cues. For example, my kitchen table is right next to the pantry, and after I finish my meal, I usually go digging around there to see what cookies or desserts we have lying around. It has become a habitual behavior, where sometimes I take the few steps over to the pantry with my eyes still glued to the TV and I don't even realize how automatic the behavior has become. It is also important to develop new preferences and reminders for "healthy" foods. One suggestion I have is that you create a vegetable tray at home of different vegetables that you enjoy eating and place that at eye level of your refrigerator... this way you will associate the cue of walking to your refrigerator and opening the door with the vegetables that you are about to consume. In other words, the cue will serve as a constant reminder of the healthy food reward, rather than having high-calorie foods such as cakes in your immediate vicinity and placed at eye-level. Put the cakes further back in the refrigerator or on a different level, just so that you don't see the box from "Gelson's" or "Sprinkle's Cupcakes" and remind yourself of how that high-calorie red-velvet cake is going to taste (these boxes from Gelson's or wherever else are the type of environmental cues we should watch out for and distract ourselves from).
The researchers of the study decided to lesion different parts of the rat brains to see how they affected eating. One discovery they made was that rats with a lesion of the ventromedial prefrontal cortex (vmPFC) ate less food than controls when fed in a novel environment, or when novel food was first presented in a familiar environment. Since the rats in these studies did not have a change in body weight, it suggests that the vmPFC is not responsible for homeostatic control of food intake and body weight, but instead may be important for judging environmental signals and prior experience. Just make sure you don't jump to any rash conclusions with a study like this, as lesion studies are just meant to be informative and responsible for learning about how the different parts of the brain operate. This is, by no means, meant to be a solution to overeating as it would be impractical to go around chopping off slices of the brain of every person who ate too much.
The other major point I wanted to talk about in my blog is the idea of induced fear inhibiting eating. In the wild, this is an evolutionary adaptation because in the event that you are chased by a lion and you are running for your life, there is no time or desire to eat or search for food. During the fight-or-flight response, it is well known that our digestion slows down so that we can divert our energy to more important functions. Rats that receive tone-shock pairings eat a lot less food than rats in a control condition as this article points out. When rats are frightened, their natural response is to freeze. This is because they are not particularly fast animals to run away from danger, so it is more beneficial for them to freeze and try to blend in with their background by not moving, or at least give the appearance that they are dead, with an extremely slow heart rate. Certain experiments referred to in this article talk about the fact that both freezing and inhibition of feeding are indued by the same conditioned stimuli, in other words, the same CS triggers both responses in rats. This is proven by the work of brain lesions of the ventrolateral region of the periaqueductal gray that were able to stop conditioned freezing, but left inhibition of eating intact. Conditioned freezing and inhibition of eating are both part of a motivational system that is important for defensive behavior. Before we jump to any conclusions about their use in overeating, let's remember that prolonged fear is associated with anxiety, and is more likely to result in maladaptive behaviors and disordered eating such as Anorexia nervosa. Very little is known, as of now about the brain circuitry through which fear and anxiety inhibit feeding, so it will be a while until we can lesion out the correct regions.
It may sound far-stretched to say that we should induce fear in people who are trying to lose weight or who are morbidly obese and need to stop overeating, but there are examples of this in real life that may signal otherwise (as long as it is not prolonged fear). Based on an example from my own life, my mother, in some ways, is a fear-inducing cue in my household because of the way she criticizes or gets mad at someone for eating junk food and not eating enough healthy foods. I don't mean, in any way, to make my mom sound like a bad person, but this is the best example that i could think of, which also seems to be pretty accurate. I have come to learn that, in her presence, I can not eat any junk food, I should not be overeating, and I should pull out the vegetable tray if I want to munch on a snack, instead of eating pita chips or candy. Although the prototypical example is the struggle for survival in the wild which inhibits hunger or the fear of a shock inhibiting hunger in mice, my example runs along the same principles. When my mother is in the house and is looking to watch what we eat, I feel myself shift my focus and either stop eating altogether or eat something healthier. I know that she does it for our own good and in many ways this approach has been working because I am eating healthier more often, especially at home. You may not assume that this type of training transfers over to other settings, much like extinction in a therapist's office does not always transfer to the real world, but surprisingly, it is generalizing, and is converting my overall eating behavior. Sometimes that's just the way things happen.
Although there are some advancements being made in the field of brain lesions and figuring out how we can regulate our eating, fear behaviors, etc. we are still a while away from figuring out how fear and anxiety inhibit feeding. I have made some suggestions in this blog about how to change the environment that you eat in, and to adjust the cues that would trigger you to eat. If those do not work out for you, then you can always have someone shock you or scare you every time you are about to overeat, just as long as the fear does not last for too long!
Stay tuned for my final blog next week as I recap many of the topics I have covered and discuss some of the most important lessons I have learned over these 10 weeks!
References:
Petrovich, G.D. (2011, April 28). Learning and the motivation to eat: Forebrain circuitry.
Elsevier, (104), 582-589. Retrieved from http://www.sciencedirect.com/science/article/
pii/S0031938411002186
This article hits upon multiple different points related to learning/motivation and eating, and as I discuss them they will be a good review of some of the topics I have previously discussed. One of the topics talked about is the environment in which food is consumed. There are always cues associated with certain foods, and the environments in which we sit down to eat, that serve as conditioned stimuli (CS) and trigger our urges to eat, even if we are not particularly hungry. I have talked about this in a previous blog, and I have discussed the importance of trying to limit those cues. I suggest that, the next time you plan on eating lunch or dinner, eat it in a novel environment, so you don't end up showing a conditioned response to the environment and then overeat... you will be able to limit yourself more effectively. If you, as I do, normally eat at the kitchen table, then switch to the dining room or to the living room, so that you don't trigger those usual cues. For example, my kitchen table is right next to the pantry, and after I finish my meal, I usually go digging around there to see what cookies or desserts we have lying around. It has become a habitual behavior, where sometimes I take the few steps over to the pantry with my eyes still glued to the TV and I don't even realize how automatic the behavior has become. It is also important to develop new preferences and reminders for "healthy" foods. One suggestion I have is that you create a vegetable tray at home of different vegetables that you enjoy eating and place that at eye level of your refrigerator... this way you will associate the cue of walking to your refrigerator and opening the door with the vegetables that you are about to consume. In other words, the cue will serve as a constant reminder of the healthy food reward, rather than having high-calorie foods such as cakes in your immediate vicinity and placed at eye-level. Put the cakes further back in the refrigerator or on a different level, just so that you don't see the box from "Gelson's" or "Sprinkle's Cupcakes" and remind yourself of how that high-calorie red-velvet cake is going to taste (these boxes from Gelson's or wherever else are the type of environmental cues we should watch out for and distract ourselves from).
The researchers of the study decided to lesion different parts of the rat brains to see how they affected eating. One discovery they made was that rats with a lesion of the ventromedial prefrontal cortex (vmPFC) ate less food than controls when fed in a novel environment, or when novel food was first presented in a familiar environment. Since the rats in these studies did not have a change in body weight, it suggests that the vmPFC is not responsible for homeostatic control of food intake and body weight, but instead may be important for judging environmental signals and prior experience. Just make sure you don't jump to any rash conclusions with a study like this, as lesion studies are just meant to be informative and responsible for learning about how the different parts of the brain operate. This is, by no means, meant to be a solution to overeating as it would be impractical to go around chopping off slices of the brain of every person who ate too much.
The other major point I wanted to talk about in my blog is the idea of induced fear inhibiting eating. In the wild, this is an evolutionary adaptation because in the event that you are chased by a lion and you are running for your life, there is no time or desire to eat or search for food. During the fight-or-flight response, it is well known that our digestion slows down so that we can divert our energy to more important functions. Rats that receive tone-shock pairings eat a lot less food than rats in a control condition as this article points out. When rats are frightened, their natural response is to freeze. This is because they are not particularly fast animals to run away from danger, so it is more beneficial for them to freeze and try to blend in with their background by not moving, or at least give the appearance that they are dead, with an extremely slow heart rate. Certain experiments referred to in this article talk about the fact that both freezing and inhibition of feeding are indued by the same conditioned stimuli, in other words, the same CS triggers both responses in rats. This is proven by the work of brain lesions of the ventrolateral region of the periaqueductal gray that were able to stop conditioned freezing, but left inhibition of eating intact. Conditioned freezing and inhibition of eating are both part of a motivational system that is important for defensive behavior. Before we jump to any conclusions about their use in overeating, let's remember that prolonged fear is associated with anxiety, and is more likely to result in maladaptive behaviors and disordered eating such as Anorexia nervosa. Very little is known, as of now about the brain circuitry through which fear and anxiety inhibit feeding, so it will be a while until we can lesion out the correct regions.
It may sound far-stretched to say that we should induce fear in people who are trying to lose weight or who are morbidly obese and need to stop overeating, but there are examples of this in real life that may signal otherwise (as long as it is not prolonged fear). Based on an example from my own life, my mother, in some ways, is a fear-inducing cue in my household because of the way she criticizes or gets mad at someone for eating junk food and not eating enough healthy foods. I don't mean, in any way, to make my mom sound like a bad person, but this is the best example that i could think of, which also seems to be pretty accurate. I have come to learn that, in her presence, I can not eat any junk food, I should not be overeating, and I should pull out the vegetable tray if I want to munch on a snack, instead of eating pita chips or candy. Although the prototypical example is the struggle for survival in the wild which inhibits hunger or the fear of a shock inhibiting hunger in mice, my example runs along the same principles. When my mother is in the house and is looking to watch what we eat, I feel myself shift my focus and either stop eating altogether or eat something healthier. I know that she does it for our own good and in many ways this approach has been working because I am eating healthier more often, especially at home. You may not assume that this type of training transfers over to other settings, much like extinction in a therapist's office does not always transfer to the real world, but surprisingly, it is generalizing, and is converting my overall eating behavior. Sometimes that's just the way things happen.
Although there are some advancements being made in the field of brain lesions and figuring out how we can regulate our eating, fear behaviors, etc. we are still a while away from figuring out how fear and anxiety inhibit feeding. I have made some suggestions in this blog about how to change the environment that you eat in, and to adjust the cues that would trigger you to eat. If those do not work out for you, then you can always have someone shock you or scare you every time you are about to overeat, just as long as the fear does not last for too long!
Stay tuned for my final blog next week as I recap many of the topics I have covered and discuss some of the most important lessons I have learned over these 10 weeks!
References:
Petrovich, G.D. (2011, April 28). Learning and the motivation to eat: Forebrain circuitry.
Elsevier, (104), 582-589. Retrieved from http://www.sciencedirect.com/science/article/
pii/S0031938411002186
Monday, May 28, 2012
A High-Fat Diet may be beneficial?!
Some researchers have made the discovery that a diet high in saturated fat could impair rats' ability to inhibit responding to stimuli that are reinforced in some circumstances but not in others. This article can be found at this link. This is basically proposing a solution to a problem I had blogged about two weeks ago ("Learning and the persistence of appetite") where if something is extinguished in one context, the same behavior may renew and appear again in a different context (one that it was not extinguished in). The researchers are suggesting that if one consumes a high fat diet that those behaviors will be extinguished for good and will not reappear in a different context (= renewal will not occur). At first glance this sounds preposterous, as it certainly did for me, but if true, the applications are tantalizing. The main examples I think of with extinction and renewal are fear conditioning, extinction of overeating habits, addictions, etc. Imagine if one could finally extinguish these conditions in one setting and have them permanently extinguished and remain that way in other settings as well.
Rats were trained in two contexts, X and Y. They were trained to consume sucrose pellets as reinforcers in two 64-minute sessions with 16 deliveries of two 45-mg sucrose pellets. Then, the rats received training with an auditory cue; in each of eight 64-minute daily sessions rats received sixteen 10 second reinforced presentations of an 80-db white noise. After the acquisition training, half the rats were fed the high fat diet and half were fed the control diet for 7 days. After this phase, rats were kept on a calorie restriction for 7 days, so that they would be motivated for the extinction training. Finally, the rats received extinction training with 16 non-reinforced presentations of noise; half of the rats received extinction in the same context in which they were trained and half received extinction in a different context. The extinction was done with the introduction of a light, which preceded the tone CS, and signaled no food coming. Finally, all the rats returned to the same context and were given four daily tests of renewal of extinguished food cup responding. Responding by the rats was measured as the amount of time they spent with their head in the food cup before or after the time of reinforcer delivery. The results showed that control rats extinguished in a new context showed renewal back in their training context, while rats who were fed a high-fat diet showed considerably less renewal. Therefore, it was concluded that exposure to a high-fat diet reduced the context-specificity of extinction.
An interesting point that the discussion section brings up is the possibility that a high-fat diet may be interfering with normal hippocampus and medial prefrontal cortex learning. They are suggesting that these areas of the brain may be affected, thus leading to a lack of contextual control. This, in turn, is encouraging people to overeat because they ignore the normal cues such as internal satiety signals or external signals (predators is the example given); just like the rats who ignored the light signals that food was not coming. This point actually counters my original thought that overeating could somehow be extinguished (by extinguishing the cues and CS's that cause humans to expect food) and transferred over to multiple settings. In addition to explaining overeating, this article may be helpful for therapeutic extinction of anxieties and fears as well. Imagine a scenario where a fear or anxiety is extinguished in the therapist's office, but rather than renew and reappear in other contexts as these things tend to do, they remain permanently extinguished.
I want to make some critiques of this article that came to my attention as I was reading it and speaking to my professor. What if the rats are simply nosing around the food cup extensively because they like the high-fat food so much and get addicted to it, just as someone gets addicted to candy or potato chips, etc. which are also high in fat. Maybe they choose to ignore the extinction cue of the light simply because the reward (fatty food) is so tantalizing and they can't get enough of it, so they are always in search of it.
An issue that was brought to light in my discussions with Professor Blaisdell was that rats and humans digest fats very differently, which may be the key to the differences in the effects of fats between the two groups. It is well-known that a diet high in fats can cause all sorts of complications in humans such as cardiovascular disease, obesity and an impairment of cognitive functioning, but apparently in rats it shows some positive effects of countering extinction. Lard (pig fat) has a high concentration (almost 50%) of monounsaturated fats, which can be digested better in rats than in humans.
With careful reading of the 'materials and methods' section you can see that there is a disproportionately larger amount of corn starch in the control group as opposed to the high-fat diet group (452.2g vs. 72.8g). Corn starch is a thickening agent, and I wonder if they had to use extra corn starch in order to counter the lower quantity of lard (maybe to give the two groups' foods similar appearances) and if it had any effects on the results of the experiment. In addition, I noticed that there is 20g of lard in the control group as opposed to the 177.5g in the HFD group, which makes sense considering it is a control for this factor, but the researchers never controlled for the amount of kcal/g in the two groups.
Regardless of the critiques of this article, it is an interesting find and definitely something worth blogging about and bringing to the attention of others. If something along these lines can be replicated in humans then, needless to say, it will change the way we think of high-fat foods and may end up appreciating the benefits, especially in a therapeutic setting.
Tuesday, May 22, 2012
Shangri-La Diet: What people have to say about it.
I am going to deviate from the norm of blogging about primary literature
on research articles and dive into a diet regimen introduced and extensively
elaborated on by Seth Roberts. As a disclaimer: I am not recommending
this diet; it is something that should be looked at and analyzed, however.
Also, I have not read the full text of The Shangri-La Diet and
what I am going to write about stems from online research, particularly from
the author's website itself, Sethroberts.net. I am going to look into
what the Shangri-La diet actually is, how it relates to Psychology and what
things people are actually saying about it. The website I got most of my information off of can be found at SethRoberts.net.
Let me start off with a quick background
about the Shangri-La diet. Roberts believes in a “set point” theory of weight control: at any given time, your
body wants to be a certain weight, and it will increase or
decrease feelings of hunger and its metabolic rate in order to achieve that
weight. Any attempt to modify your weight away from your current set point will
meet with failure, or at least will be very difficult to achieve and maintain.
Roberts compares the set point to the temperature setting for a
thermostat. The set point idea
is not new, but Roberts extends it by claiming that the set point can be
modified by diet. This is the second part of his theory: the “taste-calorie
association.” Roberts believes that the “tastiness” of the food you consume
controls your set point. Specifically, tastier food raises your set point
(i.e., makes your body want to get fatter), while bland food lowers your set
point (i.e., makes your body want to adapt to being leaner). According to calorielab.com, the three
major ways of breaking the taste-calorie association is to: consume calories
that have little or no taste, consume calories that have an unfamiliar taste,
consume foods that are only detected by the body after a delay (in order to
dissociate the initial taste from the later calorie hit).
One of my earlier blog posts was also about a taste-calorie association and about how rats would eat more when given a tasty, calorie-dense food because that is how we have come to associate and enjoy the two together. Seth Roberts talks about different techniques of breaking the taste-calorie association and suppressing appetite. The consumption of oils is one thing I came across (in my readings of people's experiences) as a successful technique. Drinking a spoonful of olive oil or canola oil twice a day seems to work in suppressing appetite; people report eating less in a meal after they have consumed olive oil. Seth Roberts recommends drinking the spoonful of oil an hour before or an hour after the meal, long enough so that a connection is not made between the food and the oil, however. The oil is tasteless and relatively odorless and you are still consuming calories (about 200-300 a day), but not associating it to any particular taste or smell in your brain and thus not reinforcing those connections that have been made between taste and calories. One of the reasons why we eat so much is because we feel good after we consume those calories because of the pleasurable associations we have created in our brain between tastes/smells and the foods we consume. By consuming tasteless things like oils, people are cutting down on the amount of food/calories that they want to take in and this reduces junk/snack food consumption tremendously. Another technique to suppress appetite is to drink vinegar-water before a meal. Although that sounds pretty disgusting, it has a purpose in aiming to suppress appetite and prevent you from overeating (and especially snacking on junk and desserts after your meal) which is a big cause of weight gain.
One of my earlier blog posts was also about a taste-calorie association and about how rats would eat more when given a tasty, calorie-dense food because that is how we have come to associate and enjoy the two together. Seth Roberts talks about different techniques of breaking the taste-calorie association and suppressing appetite. The consumption of oils is one thing I came across (in my readings of people's experiences) as a successful technique. Drinking a spoonful of olive oil or canola oil twice a day seems to work in suppressing appetite; people report eating less in a meal after they have consumed olive oil. Seth Roberts recommends drinking the spoonful of oil an hour before or an hour after the meal, long enough so that a connection is not made between the food and the oil, however. The oil is tasteless and relatively odorless and you are still consuming calories (about 200-300 a day), but not associating it to any particular taste or smell in your brain and thus not reinforcing those connections that have been made between taste and calories. One of the reasons why we eat so much is because we feel good after we consume those calories because of the pleasurable associations we have created in our brain between tastes/smells and the foods we consume. By consuming tasteless things like oils, people are cutting down on the amount of food/calories that they want to take in and this reduces junk/snack food consumption tremendously. Another technique to suppress appetite is to drink vinegar-water before a meal. Although that sounds pretty disgusting, it has a purpose in aiming to suppress appetite and prevent you from overeating (and especially snacking on junk and desserts after your meal) which is a big cause of weight gain.
When reading the experiences of a
first time user of the Shangri-La diet on her first day, I became intrigued at
the immediate impact this diet has. The user said she skipped breakfast
and had no appetite to eat and was only getting full off of half a sandwich,
some chips and maybe a fruit later on in the day. It is amazing how
changing your daily regimen can cause you to lose drastic amounts of weight, as
some report losing averages of 2-3 pounds a week over the course of months.
There is a discussion about
bland, unprocessed foods compared to processed foods. The idea behind
this is that processed foods have been added with so many tastes including
spices, salts, fats, etc. and that every piece of the processed food tastes the
same, in any part of the world, that our brain recognizes those tastes, makes
the associations with calories and we eat it non-stop. Things like salts,
fats, sugars are tastes that we are genetically wired to eat because they
signal that we will get full off of that meal (by ingesting calories).
These were cues that our ancestors used to know if a food was going to
fill them up or if they were going to starve. And now in the 21st century,
these are the same cues that are signaling to us that the foods are full of
calories... but since food is so abundant in this day and age we end up
overeating. The blandness argument makes sense because we are not going
to immediately recognize the calories that we are ingesting and therefore, not
overeat. In many ways, the taste of the food is acting as a conditioned
stimulus that signals the unconditioned stimulus - calories. By breaking
that association, or messing with the association and introducing tasteless or
unfamiliarly tasting foods, then we are breaking the CS-US association and we
are less likely to eat as much.
In conclusion, the real successes I see behind the Shangri-La diet are that you do not need to restrict the foods you eat or have an insane amount of will-power in order to keep up the weight-loss or maintain your progress. With the suppression of appetite, you won't feel like eating any more and you will be more inclined to restrict the amount of calories that you consume. As some people posted about, they can still have their cheese and ice creams, but they're not mindlessly eating two bags of M&M's in one sitting at the movie theaters, but rather something like half a bag and being just as satisfied. Humans are intellectual beings that learn and form associations between millions of things. Taste, calories and appetite are just a few examples of the things we make associations between and can learn to break and manipulate!
In conclusion, the real successes I see behind the Shangri-La diet are that you do not need to restrict the foods you eat or have an insane amount of will-power in order to keep up the weight-loss or maintain your progress. With the suppression of appetite, you won't feel like eating any more and you will be more inclined to restrict the amount of calories that you consume. As some people posted about, they can still have their cheese and ice creams, but they're not mindlessly eating two bags of M&M's in one sitting at the movie theaters, but rather something like half a bag and being just as satisfied. Humans are intellectual beings that learn and form associations between millions of things. Taste, calories and appetite are just a few examples of the things we make associations between and can learn to break and manipulate!
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 (Wikipedia.org).
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.
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.
Saturday, May 5, 2012
Aversive images and Evaluative conditioning in food choices
This is the third installment of my weekly blog post; and I am running through the longest article, up to this point. The article is here for anyone with access. The title of the article is "Using aversive images to enhance healthy food choices and implicit attitudes: An experimental test of evaluative conditioning" and I'm excited to talk about the real-world applications that this study portrays. Let me define some terms, just to help clarify the points of the study. Evaluative conditioning deals with how we can come to like or dislike something through an association (Wikipedia.org). So basically, evaluators wanted participants to form an association between energy-dense snack foods and aversive images. The evaluators also wanted to see how this evaluative conditioning would affect implicit attitudes - the positive or negative thoughts, feelings, or actions towards objects which arise due to past experiences which one is either unaware of or which one cannot attribute to an identified previous experience (Wikipedia.org). [Later on I will talk about the problem I see with this definition of implicit attitude and the experiment]. They would assess this using the Implicit Association Test (IAT) which required participants to choose between fruits or snacks to take home with them.
The experiment was conducted with 134 participants (101 females) who were recruited from King's College London staff and students. Participants were randomly assigned to either a control or intervention group which determined what set of pictures they would be viewing. Participants were asked to watch a slideshow of 100 images (five snack images shown 20 times in a random order). Each trial lasted for 2.5s, with the snack image being shown for one second, followed by one of five aversive bodily images (intervention condition) or just a blank screen (control condition). The aversive images were carefully chosen through pilot participants and came to include two images of obesity (in men and women), two images of arterial disease (with the text "artery disease" written on them) and one of heart surgery.
Two outcomes were measured. The primary outcome measure (an index of behavior) involved participants choosing to take fruit or snacks home with them and secondly, a voucher to spend at either a fruit or confectionery stand at the nearby train station. The participants' choices were scored on a 5 point scale from -2 (two choices of snacks) to 0 (no preferences either way) to +2 (two choices of fruit). The secondary outcome measure dealt with the IAT. The assumption with the IAT is that responses to categories that are highly associated in memory are assumed to be faster when they share the same response key, relative to the response to categories not associated in memory. Four categories were laid out, as two targets (fruit, snacks) and two attributes (pleasant, unpleasant). So, in a first task, participants assigned a target with an attribute, so they would assign "fruit" and "pleasant" to the left computer key ("E") and "snacks" and "unpleasant" to the right key ("I"). In the second task, the targets were switched, so the left key was for snacks-pleasant and the right key for fruits-unpleasant. Then, category headings were displayed throughout, in the left and right hand corners of the screen and participants had to press the correct button that corresponded to them. Errors in sorting were pointed out, and an accurate response was necessary to move on to the next presentation. The IAT scores were measured as the average response time between the two versions of the critical combined task. In other words, if responses were faster for when fruit-pleasant were on the same key (than with fruit-unpleasant), then that must have meant that an association had been made in the mind of the participant and a more positive score would be assigned indicating a more positive attitude to fruit, and a more negative attitude to snacks. In addition, explicit attitudes of the participants were also measured. Participants were asked to express their ratings to "For me, eating fruits/snacks is" along 5 semantic differential scales (not at all healthy - healthy; bad - not at all bad; not at all enjoyable - enjoyable; not at all unpleasant - unpleasant; good - not at all good) and their responses were scored to gauge their overall preference for fruit.
The results of the experiment showed that with the primary outcome, participants in the intervention condition preferred to choose fruit over snacks more often than those in the controlled condition. This was predictable, since those in the control group were simply seeing biscuits, cookies, brownies, etc. with no association or link to them being healthy or unhealthy. Those in the intervention group had made an association between the aversive images and the snacks and decided not to choose them when given the chance. With the secondary outcome (test of implicit attitudes) it was shown that there were higher IAT scores than in the control group, indicating a relatively stronger implicit preference for fruit over snacks. In addition, both the implicit and explicit attitudes explained the variance in food choice that was observed. Results were always compared to a baseline in the pre-intervention to see how participants' choices had changed.
One potential problem I see with these results is that there was an overwhelming majority of females in the study who may be more likely to change their attitudes and select healthier snacks, because of an underlying preference to eat healthier. Also, since this study was conducted at a College, it is not representative of the general population and may include participants who are generally more health-conscious and more likely to change their behaviors and eating habits as opposed to older individuals who may be more fixed in their eating preferences and behaviors. Another problem with the study may be the lack of controlling for the aversive images. Maybe it is the aversive stimuli that are causing the participants to choose one way or the other. Ideally, a control group should be established with participants exposed to just the aversive stimuli and see how they respond, or even a control group where fruits are shown with the aversive images to see if participants would prefer to choose the energy-dense snacks over the fruits that were associated with aversive images. These would, potentially, make the experiment a lot more valid and convincing, but there are always costs of money and time associated with recruiting more participants and sorting through the data from all the various experimental conditions. Another point to note in this experiment (not necessarily a problem) was that there was an inability to change the implicit attitudes of those who already held negative attitudes towards the snacks, which could be explained by ceiling effects. As explained in my psychology class, ceiling effects arise when responding to a certain stimulus has already reached its maximum potential, and you are not going to get any increase in responding, as if you had hit a ceiling.
It is interesting to note that in this experiment, the conditioned stimulus (CS) is the food, and the unconditioned stimulus (US) is the aversive images of health consequences (obesity, arterial disease, etc.) This is reversed, where normally we would see food as the US in other experiments because it is enjoyable and biologically essential, and elicits an unconditioned response. The results of the experiment did not say a lot about how explicit attitudes were changed in the participants, but it is noted that implicit attitudes, rather than explicit attitudes have been shown to be changed through the evaluative conditioning when there is a clear, observable link between the CS and the US. In this case there was that strong association between the CS and the US, which is why we saw a large change in implicit attitude in those participants who had stronger implicit preferences for snacks over fruit at baseline.
When I first read through this experiment, I immediately connected it to the real-world applications of advertising and marketing. Imagine billboards with images of sodas and aversive images of obese adults on them, along with a message saying "GOT MILK?" on the bottom? The possibilities are endless with conditioning people to associate two images and change implicit attitudes to the foods/drinks that they previously enjoyed so much. The study itself talks about aversive images used on tobacco packaging (the skull and bones), signaling how this procedure is already underway and will potentially become more widespread as more research is conducted and experiments begin to dive deeper into the underlying mechanisms of behavior change and the best methods of intervention. I believe that implicit attitudes are not going to be changed overnight with a simple experiment linking foods and aversive stimuli; because, even in this study, people are clearly going to remember that they saw hundreds of aversive images next to the snacks that they were later asked to choose from (it is not like they don't remember their past experience, and they suddenly feel a change in their behavior). I believe that implicit attitudes are much harder to change in most people who already have established food preferences and behaviors. This is why I believe the research should have been conducted on more adults. Potentially, the best way to prevent people from choosing energy-dense snacks over fruits is to instill a mind-set from an early age. If people are exposed to aversive stimuli and develop a fear response to certain foods and the possibility of developing obesity and arterial disease, then they will be less likely to choose these foods over healthier alternatives. This brings up ethical issues, however, about manipulating younger children and mentally affecting them (with aversive images), when they are most impressionable. A whole range of convincing research needs to be conducted in order for the full effects of these advertisements to be known and eventually proliferated.
The experiment was conducted with 134 participants (101 females) who were recruited from King's College London staff and students. Participants were randomly assigned to either a control or intervention group which determined what set of pictures they would be viewing. Participants were asked to watch a slideshow of 100 images (five snack images shown 20 times in a random order). Each trial lasted for 2.5s, with the snack image being shown for one second, followed by one of five aversive bodily images (intervention condition) or just a blank screen (control condition). The aversive images were carefully chosen through pilot participants and came to include two images of obesity (in men and women), two images of arterial disease (with the text "artery disease" written on them) and one of heart surgery.
Two outcomes were measured. The primary outcome measure (an index of behavior) involved participants choosing to take fruit or snacks home with them and secondly, a voucher to spend at either a fruit or confectionery stand at the nearby train station. The participants' choices were scored on a 5 point scale from -2 (two choices of snacks) to 0 (no preferences either way) to +2 (two choices of fruit). The secondary outcome measure dealt with the IAT. The assumption with the IAT is that responses to categories that are highly associated in memory are assumed to be faster when they share the same response key, relative to the response to categories not associated in memory. Four categories were laid out, as two targets (fruit, snacks) and two attributes (pleasant, unpleasant). So, in a first task, participants assigned a target with an attribute, so they would assign "fruit" and "pleasant" to the left computer key ("E") and "snacks" and "unpleasant" to the right key ("I"). In the second task, the targets were switched, so the left key was for snacks-pleasant and the right key for fruits-unpleasant. Then, category headings were displayed throughout, in the left and right hand corners of the screen and participants had to press the correct button that corresponded to them. Errors in sorting were pointed out, and an accurate response was necessary to move on to the next presentation. The IAT scores were measured as the average response time between the two versions of the critical combined task. In other words, if responses were faster for when fruit-pleasant were on the same key (than with fruit-unpleasant), then that must have meant that an association had been made in the mind of the participant and a more positive score would be assigned indicating a more positive attitude to fruit, and a more negative attitude to snacks. In addition, explicit attitudes of the participants were also measured. Participants were asked to express their ratings to "For me, eating fruits/snacks is" along 5 semantic differential scales (not at all healthy - healthy; bad - not at all bad; not at all enjoyable - enjoyable; not at all unpleasant - unpleasant; good - not at all good) and their responses were scored to gauge their overall preference for fruit.
The results of the experiment showed that with the primary outcome, participants in the intervention condition preferred to choose fruit over snacks more often than those in the controlled condition. This was predictable, since those in the control group were simply seeing biscuits, cookies, brownies, etc. with no association or link to them being healthy or unhealthy. Those in the intervention group had made an association between the aversive images and the snacks and decided not to choose them when given the chance. With the secondary outcome (test of implicit attitudes) it was shown that there were higher IAT scores than in the control group, indicating a relatively stronger implicit preference for fruit over snacks. In addition, both the implicit and explicit attitudes explained the variance in food choice that was observed. Results were always compared to a baseline in the pre-intervention to see how participants' choices had changed.
One potential problem I see with these results is that there was an overwhelming majority of females in the study who may be more likely to change their attitudes and select healthier snacks, because of an underlying preference to eat healthier. Also, since this study was conducted at a College, it is not representative of the general population and may include participants who are generally more health-conscious and more likely to change their behaviors and eating habits as opposed to older individuals who may be more fixed in their eating preferences and behaviors. Another problem with the study may be the lack of controlling for the aversive images. Maybe it is the aversive stimuli that are causing the participants to choose one way or the other. Ideally, a control group should be established with participants exposed to just the aversive stimuli and see how they respond, or even a control group where fruits are shown with the aversive images to see if participants would prefer to choose the energy-dense snacks over the fruits that were associated with aversive images. These would, potentially, make the experiment a lot more valid and convincing, but there are always costs of money and time associated with recruiting more participants and sorting through the data from all the various experimental conditions. Another point to note in this experiment (not necessarily a problem) was that there was an inability to change the implicit attitudes of those who already held negative attitudes towards the snacks, which could be explained by ceiling effects. As explained in my psychology class, ceiling effects arise when responding to a certain stimulus has already reached its maximum potential, and you are not going to get any increase in responding, as if you had hit a ceiling.
It is interesting to note that in this experiment, the conditioned stimulus (CS) is the food, and the unconditioned stimulus (US) is the aversive images of health consequences (obesity, arterial disease, etc.) This is reversed, where normally we would see food as the US in other experiments because it is enjoyable and biologically essential, and elicits an unconditioned response. The results of the experiment did not say a lot about how explicit attitudes were changed in the participants, but it is noted that implicit attitudes, rather than explicit attitudes have been shown to be changed through the evaluative conditioning when there is a clear, observable link between the CS and the US. In this case there was that strong association between the CS and the US, which is why we saw a large change in implicit attitude in those participants who had stronger implicit preferences for snacks over fruit at baseline.
When I first read through this experiment, I immediately connected it to the real-world applications of advertising and marketing. Imagine billboards with images of sodas and aversive images of obese adults on them, along with a message saying "GOT MILK?" on the bottom? The possibilities are endless with conditioning people to associate two images and change implicit attitudes to the foods/drinks that they previously enjoyed so much. The study itself talks about aversive images used on tobacco packaging (the skull and bones), signaling how this procedure is already underway and will potentially become more widespread as more research is conducted and experiments begin to dive deeper into the underlying mechanisms of behavior change and the best methods of intervention. I believe that implicit attitudes are not going to be changed overnight with a simple experiment linking foods and aversive stimuli; because, even in this study, people are clearly going to remember that they saw hundreds of aversive images next to the snacks that they were later asked to choose from (it is not like they don't remember their past experience, and they suddenly feel a change in their behavior). I believe that implicit attitudes are much harder to change in most people who already have established food preferences and behaviors. This is why I believe the research should have been conducted on more adults. Potentially, the best way to prevent people from choosing energy-dense snacks over fruits is to instill a mind-set from an early age. If people are exposed to aversive stimuli and develop a fear response to certain foods and the possibility of developing obesity and arterial disease, then they will be less likely to choose these foods over healthier alternatives. This brings up ethical issues, however, about manipulating younger children and mentally affecting them (with aversive images), when they are most impressionable. A whole range of convincing research needs to be conducted in order for the full effects of these advertisements to be known and eventually proliferated.
Friday, April 27, 2012
Conditioned Cues Elicited Feeding in Sated Rats
This is the second week of my blog and I have another exciting article to talk about. For anyone with access, the article is here. The title of the article is Conditioned Cues Elicited Feeding in Sated Rats: A Role for Learning in Meal Initiation. The article talks about Pavlovian conditioning influencing rats to eat even while they are full (satiatied), if they have learned the cues that signal food. The procedure for this experiment was to take seven male rats, housed individually and carry out two phases: conditioning and testing. During conditioning a 4.5 minute conditioned stimulus (CS+) consisting of a buzzer and a light presented together, was presented before every meal. The '+' sign in this experiment, as professor Blaisdell taught us, means that the US (the food) will actually be appearing in this experiment, and is signaled by the CS. The meal, which was composed of 8ml of a liquid diet (some type of evaporated milk) was delivered to the mice during the last 30 seconds of the CS+. Rats received six meals in a day, 3.5 hours apart. A CS- of a pure tone was presented at the midpoint of every inter-meal interval. As we learned the '-' sign in this case signals that no food will be paired with the stimulus, and it was meant to condition the rats to learn that feeding had ended, at least for some period of time. Once the rats had been conditioned to a stimuli and knew which stimuli were meant to signal food, they were tested in a subsequent experiment. The conditioned simuli were presented and the responses of the rats measured. The most important observation of this experiment was that feeding responses were made to the CS+ during testing on all 21 days, EVEN WHILE THE RATS WERE SATIATED! In further testing, where rats were tested with the conditioned stimuli and then later allowed to feed on a food bottle for a free period of time, the experimenters discovered some very shocking results. The rats would eat when presented with the previously conditioned stimuli, but they would limit their food intake from a food bottle when the signal was not present. This goes to show that rats had learned to eat only in the presence of specific signals, and did not eat simply because food was readily available; the rats also ate while satiated if the signals were presented. As the text itself has explained: Once an association has been learned between signals for food and a meal, stimuli retain their ability to influence feeding for protracted periods and even under a state, satiation, that might be expected to minimize the impact of such events.
Although it is possible for people to eat when hungry (this experiment has not directly disproved that explanation), it is more logical to think of eating as a complex process that incorporates learned procedures and extenuating circumstances that influence our ability to ingest foods. It is interesting to see that an energy deficiency is NOT the dominating factor in causing someone to eat, contrary to what the major thinking has been for as long as I have known. I mean, most people that I talk to would say that they eat because they think they are hungry, but little do they know that there are external cues and conditioned stimuli that can influence their conditioned response to eat, without them even knowing. In the experiment with rats, the conditioned stimuli to signal food were a light and a buzzer, but in real life the stimuli that have conditioned many of us takes on different forms. Think about when we decide to eat. If you are out with friends, the social cues around us, such as friends ordering food, the smell of food in a restaurant, people enjoying their food, will all elicit cues for you to order food and eat, even if you are not hungry (much like the rats in this experiment).
The example that I think of with my own life, is the time of day that elicits cues for eating. I have associated the time of 12-1 o'clock with eating lunch and 5'oclock with eating dinner. Regardless of what time I wake up, when those times roll around, my brain will be alerted and want to eat a meal... To clarify this point, during the summer I often wake up around 12 o'clock and will start my day off with eating lunch, and then eat a dinner around 5 p.m. On the other hand, during the school year, I wake up at a more respectable time of 10 o'clock and begin my day with a breakfast, eat lunch around 3 p.m., but when 5 p.m. rolls around I immediately begin thinking about eating again even though I am full from eating just two hours ago (much like the satiated rats in the experiment). The same processes are at work with conditioning rats to eat at the sight of a light and the tone of a buzzer, with conditioning humans to eat at cues of time or external signals. Sometimes we both do things that don't make sense based on needs, we do things because we have become accustomed and learned to do them by association.
In rats, much like in real life, once an association has been made, it is hard to counteract those effects and unlearn or extinguish those associations. We often do not eat when we have an energy depletion, mostly because we have associated quicker, easier cues to the desire to eat. I imagine this to be a biological effect, because food was very limited in our ancestors. In other words, since food was not always available for our predecessors, it is easier to learn associations and cues that will make us want to eat even when we are not particularly hungry. Our genetic makeup predisposes us to want to eat and take in nutrients for the possibility (usually a reality in our ancestors) that food would not be available at a later time. In other words: we are predisposed to take advantage of the food that is available now at an earlier time. This explanation, however, is not supported by the finding that rats limit their food intake when presented with a feeding bottle. If it was an evolutionary limitation explanation, as I proposed, then we probably should have seen the rats eat a lot of food, unconditionally, while sated, but even when the learned cues were not presented.
This is just my opinion on the matter. Going out on a limb and saying that there is a biological and genetic basis to the ease of association and learning may be completely incorrect or it may be right on point. That is up to you to let me know in the comments. I would love some feedback.
Thanks for reading! Look out for my next post very shortly!
Although it is possible for people to eat when hungry (this experiment has not directly disproved that explanation), it is more logical to think of eating as a complex process that incorporates learned procedures and extenuating circumstances that influence our ability to ingest foods. It is interesting to see that an energy deficiency is NOT the dominating factor in causing someone to eat, contrary to what the major thinking has been for as long as I have known. I mean, most people that I talk to would say that they eat because they think they are hungry, but little do they know that there are external cues and conditioned stimuli that can influence their conditioned response to eat, without them even knowing. In the experiment with rats, the conditioned stimuli to signal food were a light and a buzzer, but in real life the stimuli that have conditioned many of us takes on different forms. Think about when we decide to eat. If you are out with friends, the social cues around us, such as friends ordering food, the smell of food in a restaurant, people enjoying their food, will all elicit cues for you to order food and eat, even if you are not hungry (much like the rats in this experiment).
The example that I think of with my own life, is the time of day that elicits cues for eating. I have associated the time of 12-1 o'clock with eating lunch and 5'oclock with eating dinner. Regardless of what time I wake up, when those times roll around, my brain will be alerted and want to eat a meal... To clarify this point, during the summer I often wake up around 12 o'clock and will start my day off with eating lunch, and then eat a dinner around 5 p.m. On the other hand, during the school year, I wake up at a more respectable time of 10 o'clock and begin my day with a breakfast, eat lunch around 3 p.m., but when 5 p.m. rolls around I immediately begin thinking about eating again even though I am full from eating just two hours ago (much like the satiated rats in the experiment). The same processes are at work with conditioning rats to eat at the sight of a light and the tone of a buzzer, with conditioning humans to eat at cues of time or external signals. Sometimes we both do things that don't make sense based on needs, we do things because we have become accustomed and learned to do them by association.
In rats, much like in real life, once an association has been made, it is hard to counteract those effects and unlearn or extinguish those associations. We often do not eat when we have an energy depletion, mostly because we have associated quicker, easier cues to the desire to eat. I imagine this to be a biological effect, because food was very limited in our ancestors. In other words, since food was not always available for our predecessors, it is easier to learn associations and cues that will make us want to eat even when we are not particularly hungry. Our genetic makeup predisposes us to want to eat and take in nutrients for the possibility (usually a reality in our ancestors) that food would not be available at a later time. In other words: we are predisposed to take advantage of the food that is available now at an earlier time. This explanation, however, is not supported by the finding that rats limit their food intake when presented with a feeding bottle. If it was an evolutionary limitation explanation, as I proposed, then we probably should have seen the rats eat a lot of food, unconditionally, while sated, but even when the learned cues were not presented.
This is just my opinion on the matter. Going out on a limb and saying that there is a biological and genetic basis to the ease of association and learning may be completely incorrect or it may be right on point. That is up to you to let me know in the comments. I would love some feedback.
Thanks for reading! Look out for my next post very shortly!
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