The Science of Psychology

Why are some people shy while others are outgoing? What sometimes causes opposites to be attracted to each other and fall in love? Why can we remember a first date which happened long ago while forgetting information necessary for a test which we studied only hours ago? Psychology studies all these and countless other scenarios and subjects alike.

Behaviour and Mind

The definition of psychology is the scientific study of behaviour and of the mind. The term behaviour refers to directly observable actions and responses, while the term mind refers to internal states and processes, such as thoughts and feelings, which cannot be seen directly and need to be inferred from observable, measurable responses.

The complexity of behaviour poses special challenges for scientific studies. As we become familiar with the kind of evidence needed to validate scientific conclusions, we become better informed about the many claims made in the name of psychology. For one thing, this teaches us that many widely-held beliefs are inaccurate, but the most important thing we learn is the habit of critical thinking.

Critical Thinking

Critical thinking involves taking an active role in understanding the world around us, rather than merely receiving information. It's important to reflect upon the meaning of the information, how it fits with our experiences, and its implication on our lives and society. Critical thinking also means evaluating something present to us as fact. For example, when someone tells you a new fact, ask yourself the following questions:

Exactly what do you want me to believe?
How do you know this, and what evidence have you got?
Could there be other possible explanations?
What is the most reasonable conclusion?

This helps us understand to be cautious in accepting psychological claims, making us less likely to form simplistic judgement on the behaviours and thoughts of other people. Thus, critical thinking would help serve us in many areas of our lives.

Psychology as an Applied Science

Science involves two types of research: basic research, which requires the quest for knowledge purely for its own sake; and applied science, which is designed to solve specific problems. For psychologists, the most basic of research is centred around the reasons behind people's behaviour, thoughts, and feelings. Basic research can be carried out in laboratories or outdoors, with participants being either human or from other species.

Psychologists studying other species usually do so in an attempt to discover principles which ultimately would shed light on human behaviour, but some study animal behaviour for its own sake. In the field of applied research, psychologists often use basic scientific knowledge in order to design, implement, and assess intervention programmes.

Robbers Cave Study

How do hostility and prejudice develop between groups, and what can be done to reduce it? In the multicultural world we live in today, where clashes erupt between various religious and ethnic groups, there is great importance in this question.

In order to provide an answer, psychologists have conducted research on factors which increase and reduce inter-group hostility. In one experiment, 11-year-old boys were divided into two groups upon arrival at a summer camp in Robbers Cave, Oklahoma. The groups were named the Eagles and the Rattlers and were put in separate cabins, but took part in all the other activities together. Initially, both teams got along well.

In order to test the hypothesis that competition could breed inter-group hostility, the researchers began to pit the two teams against each other in athletic and other contests. As predicted, hostility soon grew between the two groups. Next, the researchers examined if the conflict could be reduced between the teams by having them share enjoyable activities such as watching movies together, but surprisingly, it caused more taunting and fighting among them.

The researchers then created several small emergencies to test a final hypothesis, placing the hostile groups in situations that required cooperation between one another in order to attain common goals, hoping it would reduce their hostility towards each other. In one emergency, the truck transporting food for the hungry boys supposedly stalled, forcing the two groups to pool their strength and tow it with a rope to get it started. This, as well as other cooperative experiences, gradually reduced the hostility among the boys, causing the development of many new friendships.

Since then, the Robbers Cave Study has become a classic, which is an older but widely-known influential study. It represents basic research as its goal was to discover the general principles of inter-group conflicts and not to solve an existing problem. The prejudice between the two groups did not exist from the outset; rather, it was created by the researchers, which showed that hostility could be bred by competition and reduced by making them dependent on each other to reach a common goal.

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Personality and Crime

On the surface, Charles Whitman seemed as solid and as the University of Texas tower from which he rained death on unsuspecting strangers. He was the son of a wealthy family in Florida. Whitman was an outstanding student, an accomplished pianist, one of the youngest eagle scouts in state history, and a former US marine who was awarded the Medal of Good Conduct, as well as the Marine Corps expeditionary medal. He wedded the woman of his dreams, and the couple was even seen as an ideal couple. Whitman became a student of the University of Texas when he was selected for an engineering scholarship by the marines. In his spare time, he served as a scoutmaster in Austin.

So, what caused such a seemingly exemplary person to commit such horrific acts of violence? On December 18, 2001, the Austin History Centre opened its records on Charles Whitman to public scrutiny. The records provide important insight into the complexities of Whitman's personality and the turmoil which existed within him. Although the Whitman incident had happened decades ago, it has a sad reminiscence to more recent acts of violence in schools, workplaces, and communities across the United States.

Whitman's Confession Letter

On a summer evening in 1966, Whitman wrote the following letter:

I don't understand myself these days. I am supposed to be an average, reasonable, and intelligent young man. However, since of late (I am unable to recall the specific day it all started), I have become the victim of many unusual and irrational thoughts. These thoughts tend to recur constantly, and it requires a tremendous mental effort to concentrate on useful and progressive tasks.

In March, when my parents made a physical break, I noticed a great deal of stress. I consulted a doctor, Cochrum, at the university health centre and requested him to recommend someone that I could consult with about some psychiatric disorders that I felt I had. Once I talked with a doctor for about two hours as I tried to convey my fears that I have been feeling overcome by overwhelming violent impulses. After the first session, I never saw that doctor again. And since then, I have been fighting my mental turmoil by myself, and it seems to be to no avail. I wish an autopsy to be done on me when I am dead to find out if there is any visible physical disorder in me. I have had some tremendous headaches in the past and I have consumed two large bottles of Excedrin (Painkiller for migraine headaches) in the past three months.

Later that night, Whitman murdered his wife and mother, both who was loving and supportive of him. The next morning, he carried a high-powered hunting rifle to the top of a 307-foot tower on the busy University of Texas campus in Austin and opened fire on the persons passing below. Within 90 horrifying minutes, he murdered 16 people and wounded 30 others before he was killed by the police.

What is Personality

The concept of personality derives from the fascinating spectrum of human individuality. According to observations, people differ meaningfully according to the ways they customarily think, feel, and act. These distinctive behaviour patterns help in defining one's identity as an individual. According to the noting of one theoretical group, each of us is, in some respects, like all other people, like some others, and like no other person who lived in the past or will exist in the future.

The concept of personality also rests on the observation that any given person seems to behave somewhat consistently over time, and across different situations. From this perceived consistency comes the notion of personality traits that characterizes an individual's customary ways of responding to his or her world. Although only a modest consistency is found from childhood personality to adult personality, consistency becomes greater as we enter adulthood. Nonetheless, even in adulthood, a capacity for meaningful personality change remains.

With the combination of these notions of individuality and consistency, we can define personality as the distinctive and relatively enduring ways of thinking, feeling, and acting that characterize a person's response to life situations.

The thoughts, feelings, and actions that are seen as reflecting an individual's personality typically have three characteristics. First, they are seen as behavioural components of identity that distinguish that person from others; second, the behaviours are viewed as being caused primarily internal rather than environmental factors; and third, the person's behaviour seems to have organization and structure—they seem to fit together in a meaningful fashion, suggesting an inner personality that guides and directs behaviour.

Studies on personality have been guided by psychodynamic, humanistic, biological, behavioural, cognitive, and sociocultural perspectives. These perspectives provide different conceptions of what a personality is and how it functions. Yet this diversity of viewpoints arises from the fact that theorists have their own personalities, which influence their perception and understanding of themselves and the world.

Dementia & Alzheimer's Disease

Dementia is a reference to impaired memory and other cognitive deficits that accompany brain degeneration, as well as interference with normal functioning. There are more than a dozen types and causes of dementia.

Dementia is more prevalent among the elderly. However, it can occur at any point in life. In dementia, cognitive abilities are gradually lost, accompanied by brain degeneration. In people with dementia, there is an occurrence of abnormal progressive degeneration of brain tissue as a result of disease or injury.

Dementia is most common in late adulthood. The term Senile Dementia refers to dementia that begins after the age of 65. Alzheimer's Disease is the most common cause of senile dementia, but Parkinson’s Disease, Huntington Disease and Creutzfeldt-Jakob Disease are other common causes. Complications from high blood pressure and strokes may also cause it.

Scientific Studies

A large Canadian study has found an overall rate of senile dementia of around 8 percent, as well as a female-to-male ratio of about 2:1. Whereas 2 percent of 65- to 74-year-olds are estimated to have dementia, there is an increase in rate to 11 for 75- to 84-year-olds, as well as 34 percent for people who are 85 and above.

Impaired memory, in particular, for very recent events, is typically one of the first symptoms of dementia. Poor judgement, language problems and disorientation may appear gradually or sporadically, and people who develop dementia typically have distress episodes due to confusion. Their behaviour may become uninhibited, they may lose the ability to perform familiar tasks, and they may experience a significant physical decline in addition to cognitive impairments.

Comparing with adults aged 65 and older, those who are more frequently engaged in activities that stimulate cognitive functioning show a lower risk of subsequently developing Alzheimer's disease; but whether this truly reflects a causal relationship remains to be seen. However, one thing is certain: as people live longer lives, the need to find a cure for Alzheimer’s disease and other forms of senile dementia becomes a matter of urgency. Until then, many of us can expect our family members to become Alzheimer’s patients.

Caregiving

Being a caregiver for a spouse or elderly parent with dementia can, unfortunately, be a stressful and psychologically painful experience. Over half of the patients diagnosed with senile dementia show a combination of depression, anxiety, agitation, paranoid reactions, as well as disordered thinking, which may resemble schizophrenia. Ultimately, it could result in the inability to walk, talk, or recognise family members or close friends.

In-depth studies done in Finland, the United States, and Germany, have found that among adults above the age of 65 not suffering from dementia, 20 to 25 percent do have mild cognitive impairment. Combining cases of mild impairment and dementia, some experts have estimated that 79 percent of 65- to 74-year-olds; and 45 percent of people aged 85 and older, remain cognitively normal.

Though these are not pleasant statistics, they make it clear that even well into old age, cognitive impairment isn’t inevitable; and that even with the decrease of some mental abilities with age, more knowledge and wisdom could still be accumulated.        

Alzheimer's Disease (AD)

Alzheimer's disease is a progressive brain disorder which is the most common cause of dementia among adults over the age of 65, according to around 50 to 60 percent of such cases. An overall of 2 to 4 percent of the elderly is estimated to have AD.

The early symptoms AD, which worsen gradually over a period of years, include forgetfulness, poor judgement, confusion, and disorientation. Often, memory of recent events and new information is especially impaired. Forgetfulness by itself is not necessarily a sign of a person developing AD; however, memory happens to be the first psychological function that is affected, as AD initially attacks the subcortical temporal lobe regions—areas near the hippocampus, as well as the hippocampus itself—that help in the conversion of short-term memory into long-term memory.

Alzheimer's disease spreads across a person’s temporal lobes and then to the frontal lobes, as well as to other cortical regions. According to a German physician Alois Alzheimer, who first noticed the disease a century ago, patients afflicted with this disease have an abnormal amount of plaques and tangles in their brains. Plaques happen to be clumps of protein fragments which happen to build up on the outside of the neurons, whereas tangles are fibres that get twisted and wound up together within the neurons.

Neurotransmitter Systems

Neurons tend to become damaged and die, brain tissues shrink, and communication between the neurons is impaired as AD disrupts several neurotransmitter systems, especially the acetylcholine system. Acetylcholine plays a key role in synaptic transmission in several brain areas involved in memory, and drugs that help maintain acetylcholine functioning have had some temporary success in improving cognitive functioning in AD patients.

As AD progresses, working memory and long-term memory worsen. For example, if you read a list of just three words to a healthy 80-year-old and test his recall after a brief time delay, they tend to typically remember at least 2 words if not all three. On the other hand, a patient with AD will recall 1 or none.

Anterograde and retrograde amnesia become more severe and procedural, semantic, episodic, and prospective memory can all be affected. Patients may lose the ability to learn new tasks or remembering new information or experiences, as well as forget how to perform familiar tasks and have trouble recognising even close family members.

Genetic Causes

What causes AD and its characteristic plaques and tangles? According to scientific identification, several genes contribute to early-onset AD; an inherited form of the disease which develops before the age of 65 and as early as 30, but only accounts to about 5 to 10 percent of AD cases.

However, the precise cause of the more typical, late-onset AD remains elusive; but researchers have identified one genetic risk factor. This gene helps direct the production of proteins which carry cholesterol in the blood plasma, and high cholesterol and other risk factors for cardiovascular disease may likewise increase the risk of developing AD. A recent study found that even healthy elderly adults who carried this particular gene, as compared to peers that did not, performed more poorly on prospective memory tasks.

If you know anyone with AD, you are aware that it involves much more than memory loss. These patients experience language issues, disorganised thinking, and changes in mood as well as personality. Ultimately, they may lose the ability to speak and walk, and may also lose control over bladder and bowel functioning.

The Decay of Memory

Decay Theory

Information in sensory memory and short-term memory decays quickly with time, but does long term memory decay as well? An early explanation for forgetting was Decay Theory, which proposed that as time passed and being disused, long-term physical memory traces in the nervous system can fade away. But Decay Theory soon fell into disfavour as scientists were unable to locate neither physical memory traces nor measure physical decay.

However, of recent decades, scientists have begun unravelling the manner in which neural circuits change with the formation of a long-term memory formation, sparking new interests in examining the way these changes might decay over time.

Unfortunately, Decay Theory’s prediction of; the longer the time interval of disuse between learning and recall, the less should be recalled; is problematic. For example, some professional actors tend to display perfect memory for words last used by them on stage two years ago despite having moved on to new acting roles and scripts.

Moreover, when research participants learn a list of words or a set of visual patterns and are retested at two different times, they, at times, recall material during the second resting that they were unable to remember during the first. This phenomenon, called Reminiscence, seems inconsistent with the concept that a memory trace decays over time. To sum up, scientists still debate the validity of Decay Theory.

Motivted Forgetting

Psychologists propose that people, at times, are consciously or unconsciously motivated to forget. According to Sigmund Freud, it was often observed that during therapy sessions, his patients remembered long-forgotten traumatic or anxiety-arousing events. For example, one of his patients suddenly remembered with great shame such an event in which she, while standing beside her sister's coffin, thought: "Now my brother-in-law is free to marry me."

Freud's conclusion was that the thought was so shocking and anxiety-arousing that the woman had repressed it and pushed it down into her unconscious mind, and left it there to remain until it was later uncovered during a therapy session. Repression is a motivational process which protects us by blocking the conscious recall of anxiety-arousing memories.

The concept of repression is controversial, with some evidence supporting it while others disreputing it. People do tend to forget unpleasant events—even traumatic events—yet they can forget very pleasant ones as well. If a person can't recall a negative experience, is it due to repression or to normal information processing failures? Overall, it has been difficult to demonstrate experimentally that a special process akin to repression is the cause of memory loss in the case of anxiety-arousing events.

Prospective Memory

Have you ever forgotten things like mailing a letter, turning off your oven, purchasing a thing you need from the market, or keeping an appointment? In contrast to Retrospective Memory, which is a reference to events of the past, Prospective Memory concerns remembering to perform an activity in the future. That individuals forget to do things as often as they do is interesting, because prospective memory typically involves little content.

Often we need only to recall that we must perform an event-based task ("Remember to mail the letter on your way home" or "Remember to buy milk when you are at the supermarket") or a time-based tasks ("Remember to take your medication at 5:00 pm" or "Remember to keep your doctors appointment at 2:00 pm").

Successful prospective memory, however, draws on cognitive abilities such as planning and allocation of attention while performing other tasks.

During adulthood, do we become increasingly absentminded about remembering to do things, as suggested by a common stereotype? Numerous laboratory experiments support this view. Typically, participants are asked to perform a task requiring their ongoing attention while trying to remember to signal the experimenter at certain time intervals or whenever specific events take place.

Older adults, in general, tend to display poorer prospective memory, especially when the signalling is time-based. However, when prospective memory is tested outside the laboratory using tasks such as simulated pill-taking, healthy adults in their 60s to 80s often perform as well as—or even better than—adults in their 20s. Perhaps older adults feel more motivated to remember in such situations, or maybe they rely more on habit and on setting up of a standard routine.

Amnesia

As  H.M.'s case illustrates, the most dramatic instances of forgetting occur in amnesia. The term Amnesia is commonly referred to as memory loss due to special circumstances such as brain injury, illness, or psychological trauma. However, as we'll see shortly, there is one type of amnesia experienced by everyone.

Amnesia takes several forms: Retrograde Amnesia represents memory loss for events that took place sometime before the onset of amnesia. For example, H.M.'s brain operation, which took place at age 27, caused him to experience mild memory loss for events in life that had occurred during the preceding year or two. For example, when he was 25 to 26 years old.

Football players experience retrograde amnesia when they are knocked out by a concussion; they regain consciousness and cannot remember the events that had occurred just before being hit.

Anteretrogade Amnesia refers to memory loss for events that occur after the initial onset of amnesia. H.M.'s brain operation and, pratricularly the removal of much of his hippocampus, produced severe anterograde amnesia, robbing him of the ability to consciously remember new experiences and facts.

Similarly, the woman whose hand was pinpricked by Swiss psychologist Edouard Claparède during a handshake also suffered from anterograde amnesia; moments later, she could not consciously remember the episode. But, unlike HM's anterograde amnesia, hers was caused by Korsakoff's Syndrome, which can result from chronic alcoholism. It may also cause retrograde amnesia.

The Psychology of Hunger

Eating and digestion supply the body with the necessary fuel needed for function and survival. Metabolism is the body's rate of energy (or calorie) utilization and several psychological mechanisms that keep our body in energy homeostasis by regulating the food consumption rate. For example, some psychological signals induce hunger and prompt the need to eat, while others stop the intake of food by producing satiety (the state in which we don't feel hunger anymore).

However, this is not the case as many people believe that hunger and eating simply occur when energy levels in our bodies run low and that we feel full when our immediate energy levels are restored. Our body monitors its energy supplies, but this information interacts with other factors; for example, the amount and variety of food to regulate the food intake—making hunger and satiety not necessarily linked to immediate energy requirements. Moreover, homeostatic mechanisms are designed to prevent us from running low on energy in the first place. In evolutionary terms, an organism that did not eat until its energy supply started to become low (in any absolute sense) would be at a serious survival disadvantage.

Finally, many researchers believe that there is a set point; or, as said biologically, a determined standard; around which body weight (or more accurately, fat mass) is regulated. This view holds that if we tend to overeat or undereat, homeostatic mechanisms alter our energy utilization and hunger to make us return to close to our original weight. But some researchers argue that the set point theory has limitations. They propose that as we overeat or undereat, homeostatic mechanisms make it harder to keep gaining or losing weight, but do not return us to our original weight. This makes us possibly settle in a new weight over time. Stated in a different point of view, "Biology does not determine a fixed body weight but rather, a range or zone of body weight."

Genes and Environment

Some individuals gain weight more easily than others even with less consumption of foods as well as  less fatty food consumption, while there are others who eat in excess with more fatty food and still stay slim for example: South Esat Asians who eat an excessive amount of fat still stay slim while others can gain weight with less amount of fat consumption. The reason for this can be in the genes, making some individuals more susceptible to gaining weight due to low metabolism, while others stay slim due to high metabolism. But there can be hormonal factors which contribute to weight gain and loss as well; such as thyroid conditions, thyroid dominance and menopause in some people. Heredity influences one's basal metabolic rate, causing a tendency to store energy as fat or lean tissue. Identical twins that are raised apart are about as similar body mass as identical twins who are raised together. This makes the genetic factors account for about 40% to 70% of the variation in BMI among both genders.

According to studies, over 200 genes have said to be have been identified as possible contributors to human obesity. However, although heredity affects our susceptibility to obesity, the environment does play a part in causing obesity too. There haven't been much changes in genes in recent decades, but the rate of obesity has had a significant increase. Experts believe the reasons to be the abundance of inexpensive foods that taste good but contain a high percentage of fats and carbs; a cultural emphasis on getting the best value, which contributes to the supersizing of menu items; and the advances in technology, which decrease the need for daily physical activity.

The Pima Indians of Arizona have provided a striking example of the way genes and environment interact in producing obesity. The Pimas have a genetic predisposition to obesity and diabetes, but before the 20th century, both these conditions were rare among the members of the tribe. Their native diet and the physically-active lifestyle prevented their genetic predisposition from expressing itself. But Pimas born after World War II, in particular, have had a dramatic increase rate in obesity with the adoption of a westernized diet and sedentary lifestyle. Today, the Pimas living in Arizona have one of the highest rates of obesity and diabetes in the world. In contrast to this, however, the Pimas living in northwest Mexico have a much lower obesity rate than their Arizona counterparts due to their sticking to a more traditional diet with more performance of physical labour.

Dieting and Weight Loss

However, for millions of overweight people, being fat primes them to stay fat, in part by altering their body chemistry and energy expenditure levels. This is an example of why obese people generally have high levels of insulin (a hormone that is secreted by the pancreas helping convert glucose into fat) than people with normal weight do. Substantial weight gain can also make it hard to exercise vigorously, and dieting slows the basal metabolism as the body responds to food deprivation with a decrease in energy expenditure.

Does this mean that diets are doomed to fail? The common adage of "Ninety-five percent of individuals who lose weight, regain the lost weight within a few years" evolved from a single study that was done decades ago. According to Albert Stunkard, one of the researchers, 100 obesity patients were given a diet and sent off, which was 'state-of-the-art' in 1959. There are no good longterm estimates of weight loss success rates in part because we rarely hear from people who succeed (or fail) on their own without the help from clinics or treatment programmes.

There are reports of around one-third of Americans trying to lose weight, although not all of them are the ones who necessarily need to lose weight. There are significant sex and ethnic differences in dieting emerging from adolescence. Some dieters are motivated by health consequences, while the primary motivators to be slim are psychological concerns and social pressures—especially among women. Which may begin as a diet may, unfortunately, evolve into a life-threatening eating disorder.

Eating Disorders: Anorexia and Bulimia

According to researchers, the motivation of abnormal behaviour (like seen in anorexia and bulimia) could be caused by the contribution of psychological, environmental, and biological factors. Researchers are unable to experiment on individuals affected by these disorders in order to manipulate possible causes to check if individuals become anorexic or bulimic, but they are able to examine the factors associated with the disorders, as well as the changes that occur in the individuals when they are treated successfully.

Risk Factors

Two college freshmen named Sara and Lisa suffered from eating disorders. Sara was a victim of anorexia nervosa, which was an intense fear of being fat, causing her to severely restrict her food intake to the point of self-starvation. Despite looking emaciated and weighing 85 percent less than a person would be expected to be according to the said person's age and height, anorexic patients continue to view themselves as being fat. Anorexia causes a cease in menstruation, produces bone loss, stresses the heart, and increases risk of death.

Individuals like Lisa, who suffers from bulimia nervosa, are also in fear of getting fat. They tend to binge-eat, after which they purge the food by inducing vomiting or using laxatives. Often individuals suffering from bulimia consume between 2,000 to 4,000 calories during their binges. In some cases, they tend to consume around 20,000 calories per day. Although most bulimics are of normal body weight, repeated purging can cause severe physical consequences; which include gastric problems and badly-eroded teeth. Whereas most anorexics do not see their food restriction as problematic, bulimics typically do. However, they find it extremely difficult to alter their binge-purge pattern.

According to Becker, in 1999, around 90 percent of anorexic and bulimic individuals were women. According to some surveys, up to 10 percent of college women exhibited symptoms of bulimia although the general prevalence among North American women was 1 to 3 percent compared with 0.5 percent for anorexia. The latest statistics will be higher.

Sociocultural Factors

Anorexia and bulimia are more common in industrialized cultures, where being thin is equated to beauty. However, cultural norms alone cannot be held accountable for eating disorders as only a small percentage of women within a particular culture tend to be anorexic or bulimic; personality factors can be part of the issue. Anorexic individuals are often perfectionists. For example; Sara, who was a high-achiever (a highschool valedictorian), strove to live up to lofty self-standards which included strict ideals of an acceptably thin body. For Sara and Lisa, losing weight became a battle for success and control.

Their upbringing too may have played a role in their need for perfectionism and control. According to their description of their parents; they are disapproving, with expectations of abnormally-high achievement standards. For some anorexic children and teens, food refusal may be reinforced by the distress they cause their parents to feel; making self-starvation a way to punish their parents while gaining some control over their lives. As one anorexic patient said in a therapy session: it was like a power thing; I was showing my mother that  I don't need to eat and I can make her mad. The last thing a  parent wants is for you to die. You can get back at anyone, but if I  need to find a way, I had to forgive her as I am killing myself.

For individuals with bulimia, a different pattern from anorexia emerges; tending to be depressed and anxious, with an exhibition of low-impulse control, as well as lacking a stable sense of personal identity. Their food cravings are often caused by stress and negative mood, causing them to binge-eat to temporarily reduce their negative emotional state; followed by feelings of guilt, self-contempt, and anxiety—which is followed by the purging, maybe as a means of reducing these negative feelings.

Genetic Factors

On the biological side, genetic factors appear to predispose some individuals towards eating disorders. The concordance rate of eating disorders is higher among identical twins than among fraternal twins. The concordance rate between first-degree relatives, such as parents and siblings, are also higher than third and fourth-degree relatives. Researchers are searching for specific genes and combination genes that could be contributors to eating disorders.

Anorexia and bulimia exhibit abnormal activity in serotonin, leptin, and other body chemicals. According to the belief of some researchers, neurotransmitter and hormonal imbalances help in the causing of eating disorders; but others propose that the abnormal eating patterns are the initial cause of the chemical changes as a response that, once started, perpetuate eating and digestive irregularities. Other bodily changes also help in the perpetuating of eating disorders. An example of this is the stomach acid which is expelled into the mouth during vomiting, which causes those suffering from bulimia to lose taste sensitivity and also makes the usually unpleasant taste of vomit more tolerable.

Treating eating disorders can be difficult, taking years; but with professional help, around half of all anorexic and bulimic patients are able to make a full recovery while others are able to eat more normally while still maintaining their preoccupation with food and weight.