Biology 202
1998 First Web Reports
On Serendip

Model for Perception

Rachel Mosher

Most people assume everyone sees the world the same way. This can be expected because people are not able to compare what they see to what someone else sees (using language to describe visuals is inherently biased). This widely accepted assumption, however, is inaccurate. There is evidence that each person's perception of the world is different- if only in minor ways. For example, a perception discrepancy can be found when comparing how people suffering from anorexia nervosa see their bodies and how other people see the anorexics' bodies. Even though this distortion is an extreme perception difference that can actually be documented (most perception differences can not even be verbalized), analyzing the distorted body phenomenon can be useful. It can help explain the concept of perception by answering three key questions: 1) what does a different perception entails mentally, 2) what provokes different perceptions to occur, and 3) how does this all fit together on a neurological level. To come to these conclusions with this example, perception must first be defined on a neurological level to use as background information. Next, data from studies of anorexics should be used to learn what having a different perception means on a conscious level. Then an analysis of the typical life experiences of anorectics should be performed to discern what factors led this particular group to a perception distortion. These analysis will t hen be related back to the neurobiology of perception. The result will be a model of perception differences which demonstrates why everyone sees the world differently.

Perception may not be what you think it is. Perception is not just a collection of inputs from our sensory system. Instead, it is the brain's interpretation of stimuli which is based on an individual's genetics and past experiences. The biological process of perception can help explain this definition; what exactly does it mean that the brain interprets stimuli from the environment and makes it into what we see and hear? According to biologists, the process begins with stimuli, usually in the form of photons, vibrations or chemical reactions from the outside world, being picked up by the sensory systems. The stimuli is detected by a sensory neuron located on the surface of the body. This neuron converts the stimuli's light, sound, heat, etc. into action potentials. The action potential changes the membrane permeability of the neuron which allows it to transform into electric signs. The signs are conducted to a primary processing area and elaborated on eventually being converted into corresponding information regarding color, shape, shade, etc. Next, this new information is brought to the thalamus (usually) where it is linked to older data containing similar experiences to form a complete message. The message is carried to its specific cortical center to become perception. Therefore, perception is actually a message constructed using outside inputs, inner-neuron processes and past, relevant information stored in the brain.

Although it is not possible to know the conscience perception of victims of anorexia, there is a wealth of data on these patients allowing experts to make conservative assumptions on their perceptions. Based on this data, anorexics see a distorted image of themselves when compared to their physical construction. How is it known that they are seeing a distorted image when people's perception cannot be compared? Well, there is substantial evidence available from collections of artwork, personal interviews and behaviors of victims of anorexia that make the distorted images authentic. According to these sources, anorexics see themselves as being overweight even though they are severely emaciated (at least 15% below the individual's normal body weight). They draw themselves in pictures as chubby and helpless. They speak of having pouches of fat around their bodies that they want to get rid of. They are scared of eating anything because they think they will just get heavier then they already are. Because of these negative self-images, anorexics will intentionally starve themselves and sometimes require hospitalization in order to be fed interveiniously against their wills. It is obvious that something is going on with these patient's perception of their bodies. Consciously, anorectics see themselves inches bigger than they actually are even though they have the same access to mirrors, scales, pictures and sized clothes as the rest of us.

Investigating the lives of patients with anorexia leads to the discovery of factors that cause this particular perception distortion. This gives an idea of how different perceptions occur in general. The first thing to consider is the relationship between anorexia and body image distortion; which one comes first? It seems that a slight My body distortion perception comes first and then triggers the eating disorder because it makes the patient feel as if she needs to lose weight to get to the 'normal' weight-range category (even when they were probably in the 'normal' weight category already). As the patient loses weight, the distortion between how she sees her body and the physical reality of her body becomes larger. The important question to answer next is: what initially provokes the body distortion that happens before the patients begin to lose weight? It is possible that a body image that went from positive (or neutral ) to negative could lead to this initial distortion.

There are a cascade of experiences that can ruin one's personal body image. A body image is an individual's experience of his/her body. It is the mental picture people have of their body which includes associated thoughts, feelings, judgments, sensations, awareness and behaviors. The common experiences of anorectic patients reveal insights on the specific factors that damage their personal body images leading to a distorted body perception. To sort these experiences out, specific factors can be found in the three main similarities of anorexics: 1) they are female, 2) the onset of symptoms of the disease happens in their early teenage years and, 3) they are members of the middle-upper class. These commonalties will help reveal the shared experiences of anorectic patients. First, the fact that the majority of patients are female makes sex-related experiences probable factors related to poor body image. Such experiences may include physical changes in the body during puberty, menopause and pregnancy, prevailing socio-cultural pressures on women to measure their value with physical-attractiveness, and sex-role stereotyping. Another set of factors is revealed when looking at the age of the onset of the disease (14 years old). This happens to be the age where people are most influenced by others. At this age, kids internalize what they see on TV, in magazines and what pay close attention to what people say to them. They are at the most risk of peer pressure. As a result, the mass media images of women that are underweight and glamorized, of women on diets and looking for ways to lose weight, and of negative stereotypes of 'fat' people are internalized by the kids. These compounding media experiences lead to: the undermining of nutritional and eating habits, "sensory overload" (a condition that alters brainwaves, paralyzes eye movements, and irritates the central nervous system among other things) and deteriorated judgment in their own meaning, dignity and worth in comparison to media portrayals. These al could lead to the weakened reality perception leading to a poor body image. Finally, the majority of sufferers are from middle-upper class families with parents who are successful and try to play a large part in their child's life. Possible experiences the kids might be going through because of this situation include: feeling that they need to be perfect and successful in order to gain respect in their families, thinking that they have to conform to their classes' ideals, and worrying about how they are perceived by others (whereas the lowest and highest income-family kids often have many other things to worry about). The fact that these three broad similarities in the average anorexic exists and that their are numerous related factors that can contribute to having a poor body image helps us to see the connection between distorted perception and specific life experiences.

Now that the link between common experiences of anorexics and poor body image is made it can be related back to body perception and its neurobiological basis. Most likely, the perception distortion occurs after the senses have transformed into action potentials. This is when the information from the preliminary senses processing goes to the thalamus for further processing with 'older data.' This data must consists of those common experiences leading to similar thoughts about their personal body image. This anorexics' 'older data' is filled with negative thoughts based on their experiences which might give them the information: "skinny is the way to go... skinny means you look like the characters in the magazines whose jaw bones pop out... skinny means you lead a perfect, happy life and have an onslaught of admirers... since you don't lead this life, you are not skinny enough... you need to lose more weight..." Combining these negative thoughts with their sensory action potentials leads to specific behaviors; behaviors that will lead the person to lose more weight and not be happy with their body because that is what their previous experience data is telling them to do. In this example, the corresponding behavior is to see their own body as ugly and large when, in reality, it is thin and possibly even emaciated (depending on the stage of anorexia). This is why the perception of body-image is distorted in this limited group of people with similar backgrounds. Now that the process of perception distortion is understood in this example, it can be applied on a larger scale to understand how and why each individual sees the world differently.

WWW Sources:

Dittrich, Liz. Interesting Facts on Eating Disorders.

Lang, Susan. Study links personality and weight. Cornell Chronicles, 9/9/93

National Foundation for Brain Research. Eating Disorders.

Oliveira, Jorge. Perception and Reality, Brain and Mind.

Rice, Carla. Promoting Healthy Body Image, 1995.

Rivers, Karen. Human Values and the Effects of Television on Children.

Shipton, Geraldine. If looks could kill! Women and the Mirror.

University Health Center. Women, Weight and Body Image. 1997

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