The Role of Optimism in Neurobiology and Behavior
"Life is Good." It's a motto that appears everywhere: from tee-shirts to water bottles, and even bumper stickers. It's what I say to my friend whenever he mocks me for being an optimistic. It is my belief that having an optimistic outlook on life can lead to a more enjoyable experience of life. And the phrase "Life is Good" is what got me interested in the implications that optimism may have on our neurobiology as humans.
Different individuals have very different outlooks on life, and I'm curious about the impacts that particular outlooks may have on one's brain or their behavior. There is the proverbial water glass to consider. If an 8oz glass contains 4oz of water, there are those that consider the glass to be half full, and those that consider it to be half empty. Recent studies have found that optimists, that is to say, those who see the glass as half full, generally live about twelve years longer than pessimists.(1)  This has interesting biological implications, and I think that the way that neurobiology affects one's ability to be optimistic, and the way that optimism in turn affects human biology is worth investigating. I think that people have the ability to change their experiences of the world by changing their outlook and the way in which they perceive their surroundings, but I believe that there may be something on a neurobiological level that is capable of affecting one's ability to be optimistic.
On a biological level, there have been studies concerning the implications of perception of one's life experiences. For example, studies have shown that it is not the actual amount of stress, but rather one's perception of the amount of stress that correlates to biological responses. (1)  I feel that this provides evidence that the interpretation of experiences plays a strong role in the biological responses to such inputs. If a person is able to change the way that life experiences are input in the brain, or the way that the inputs are interpreted by the brain, they may be able to achieve a more optimistic disposition.
Let me begin with possible ways to change the method of inputting experiences into the brain and the results that may ensue. I think that the most obvious way of changing the input to make more one optimistic is just by changing one's outlook on life. Simply telling one's self positive things may allow them to appreciate the world more. For example, upon looking outside and seeing snow, there are many different outlooks that would result in the input of such information differently. A person could say "This is awful, now I'm going to have to shovel my car out again and trudge through the snow to get to class." On the other hand, one could say "The snow is beautiful, and it really makes the campus appear more peaceful." Such outlooks would then lead to different inputs, resulting in different moods and amounts of enjoyment of the snow. I realize however that a possible objection to this is that there may be a predetermined outlook created by the brain that results in the manner in which the situation is assessed.
Another way to change the way that the information is input into the brain relies on the concept of perceptual accentuation.(2)  That is, while one may acknowledge both the positive aspects and the negative aspects that are associated with freshly fallen snow, they can accentuate those that are positive by focusing on them more. This can be done by spending more time reveling in the pleasantries of the snow than thinking about the difficulties that may also be acquired. I think that this would be possible because selective attention enables people to attend most to what meets their wants and needs. (2) 
An impact of altering the way that information is input could be similar to the results of the Pollyanna Effect, in which you see what you want to see. The Pollyanna Effect results in different cognitive appraisals of information of different types. Input that is pleasing and enjoyable is more greatly cognized, that is to say that it is more detailed in the mind, it is better remembered, and it is given a higher status in the mind than less pleasing inputs.(3)  For example, if a person is given a stack of 100 one dollar bills and a stack of 100 ten dollar bills, they will characterize the stack of ten dollar bills as weighing more than the stack of one dollar bills because it is a more pleasing stimulus and it is given more status, although the two stacks will have the same weights.
Methods of changing the interpretation of inputs are of interest as well. William James believed that an external event results in physical changes in the body, and that the physical bodily responses are then experienced in an individual as emotion. Because, like many of my classmates, James believed in the concept of free will, he accounted for this in his theory as well. He believed that one could change their physical responses by will, thus changing their emotional responses.(4)  This implies that if a person wants to be happier, they simply have to change their body to what it would be if they were happy (for example by smiling), and happiness will follow. There have in fact been experiments to test this hypothesis (called the "facial-feedback hypothesis" (5) ) and the results have supported his theory. In one study, participants read cartoons with a pen in their mouth (without knowing why the pens were in their mouths.) Some held the pen between their teeth, utilizing the facial muscles involved in smiling, and others held the pen directly between their lips, utilizing the muscles involved in expressions of displeasure or disgust. Those that had the "happier" expressions found the comics to be more pleasing than did those with the less happy faces. (5) 
Stanley Schachter and Jerome Singer had a different concept of the way that information is interpreted by the brain. They believed that there was both a physical response and a cognitive response to input. The cognitive response results from the assessment of the situation and what it means to an individual. In one of their studies, people were given injections of adrenaline and exposed to situations that would induce happiness. There was an informed group, which knew that they had been given the adrenaline, and an ignorant group that did not. Because the informed group attributed their physiological responses (such as an increased heart rate) to the adrenaline on a subconscious level and the ignorant group only attributed it to the pleasing situation, the ignorant group had a stronger experience of happiness. (6)  In this way, it seems to follow that people can be more optimistic if they let themselves feel good about a situation, rather than trying to attribute a situation to something greater than their own experiences of it.
Cognitive coping strategies have resulted from concepts of the role of cognition on people's enjoyment of life. It has had very real impacts, particularly in patients suffering from chronic diseases. Under the direction of psychotherapists, such patients were able to lessen the amounts of perceived stress and pain, as well as having physiological impacts. The level of arousal of the sympathetic nervous system decreased, as was the amount of cortisol released internally. Feeling better emotionally enabled these patients to feel better physically and some of them were able to increase their amounts of physical activity and resume some of their daily activities. (7) 
Another example in which altering the assessment of a situation results in physiological changes is that of the Placebo effect. Placebos are substances that are given to patients under the assumption that it is a type of medication that has expected results. However, it is nothing more than a sugar pill, saline solution, or other inert substance that will not cause any physiological side effects. It has been proven time and again that many patients that receive a placebo and expect their physical or emotional ailments to improve have actual improvements.(8)  The mere suggestion that they should get better enables them to do so.
Neurotransmitters also play a strong role in a person's mental processing and thus ability to enjoy life. Dopamine in particular is released in a person's brain when they experience pleasurable occurrences. Dopamine also has great impacts in the pharmaceutical treatment of depression. It acts as a selective serotonin reuptake inhibitor, which results in an increased amount of serotonin in the synapse of neurons in the brain, and has been shown to alter the mental state of those who take it.(9)  In this way, people are able to alter their optimism levels on a chemical and cellular level of the brain.
Optimism is clearly a combination of both biological and cognitive aspects of the brain. But I am still left wondering what role free will plays on the mind and it's interpretation of the world around (or possibly in) it. We know that a person is capable of changing their attitude and the way that they perceive things so as to make their life experiences more enjoyable, but what is it specifically that enables them to do so? Can we will our brains on a chemical level to produce more serotonin or dopamine? Can we change our cognitive process so that information is translated into the brain in a different manner? Or do we simply have to tell ourselves that "today is a good day," and "life is good?"
1)Annie Appleseed Project , an article about Optimism and Longevity
2)The Interpersonal Communication Book 10th Edition , online lecture notes
3)Pollyanna Discussion Homepage , a discussion of the Pollyanna Effect as Experiment Results
4)Classics in the History of Psychology , Writings by William James
5)Grounding Language in Bodily States: The Case for Emotion , contains a description of Strack's experiment, as well as other information concerning emotions and their expression through body language
6)Cognitive, Social and Physiological Determinants of Emotional State , a detailed description of Schachter and Singer's experiment
7)Stress and Health: Psychological, Behavioral, and Biological Determinants , an in-depth discussion of the effects of stress
8)The Placebo Effect , an article in the Skeptic's Dictionary describing briefly the Placebo Effect9)Novel Antipsychotics for Treatment-Resistant Depression , information about several antidepressants and the ways in which depression may not respond to pharmecutical treatment