Overview to Understanding Abnormal Behavior

By WHITBOURNE, S.K., Halgin, R.P

Edited by Paul Ducham


It’s possible that you know someone very much like Rebecca, who is suffering from more than the average degree of adjustment difficulties in college. Would you consider that person psychologically disturbed? Would you consider giving this person a diagnosis? What if a person you knew was not only depressed, but also showed up on your floor seemingly ready to harm herself? At what point do you draw the line between someone who has a psychological disorder and someone who, like Rebecca, has an adjustment disorder? Is it even necessary to give Rebecca any diagnosis at all? Questions about normality and abnormality such as these are basic to our understanding of psychological disorders.  
Conditions like Rebecca’s are likely to affect you in a very personal way. Perhaps you have been unusually depressed, fearful, or anxious, or maybe the emotional distress has been a step removed from you: Your father struggles with alcoholism, your mother has been hospitalized for severe depression, a sister has an eating disorder, or your brother has an irrational fear. If you have not encountered a psychological disorder within your immediate family, you have very likely encountered one in your extended family and circle of friends. You may not have known the formal psychiatric diagnosis for the problem, and you may not have understood its nature or cause, but you knew that something was wrong and recognized the need for professional help.
Until they are forced to face such problems, most people believe that “bad things” happen only to other people. Other people have car accidents, succumb to cancer, or become severely depressed. We hope that reading this article will help you go beyond this “other people” syndrome. Psychological disorders are part of the human experience, touching the life—either directly or indirectly—of every person. As you read about these disorders and the people who suffer with them, you will find that most of these problems are treatable, and many are preventable.


Put yourself in the following situation. An urgent message awaits you from Jeremy’s mother. Your best friend in high school, Jeremy has just been admitted to a psychiatric hospital and begs to see you, because only you can understand what he is going through. You are puzzled and distressed by this news. You had no idea that he had any psychological problems. What will you say to him? Can you ask him what’s wrong? Can you ask him how he feels? Do you dare inquire about what his doctors have told him about his chances of getting better? What will it be like to see him in a psychiatric hospital? Do you think you could be friends with someone who has spent time in such a place?
Now imagine the same scenario, but instead you receive news that Jeremy was just admitted to the emergency room of a general hospital with an acute appendicitis. You know exactly how to respond when you go to see him. You will ask him how he feels, what exactly is wrong with him, and when he will be well again. Even though you might not like hospitals very much, at least you have a pretty good idea about what hospital patients are like. It does not seem peculiar to imagine Jeremy as a patient in this kind of hospital. It would probably be much easier for you to understand and accept your friend’s physical illness than his psychological disorder, and you would probably not even consider whether you could be friends with him again after he is discharged.
People with psychological disorders often face situations like Jeremy’s in which the people close to them aren’t sure how to respond to their symptoms. Even worse, they experience profound and long-lasting emotional and social effects even after their symptoms are brought under control and they can resume their former lives. They also must cope with the personal pain associated with the disorder itself. Think about Rebecca and her unhappiness. Rather than enjoying her newly found independence while at college like her classmates, she is experiencing extreme amounts of sadness and loneliness. She is unable to focus on her studies, make new friends, or even sleep.
Social attitudes toward people with psychological disorders range from discomfort to outright prejudice. Language, humor, and stereotypes all portray psychological disorders in a negative light and people often fear that people suffering from these disorders are violent and dangerous. There seems to be something about a psychological disorder that makes people want to distance themselves from it as much as possible. The result of these stereotypes is social discrimination, which only serves to complicate the lives of the afflicted even more.
You will read about a wide range of disorders involving mood, anxiety, substance abuse, sexuality, and thought disturbance. The case descriptions will give you a glimpse into the feelings and experiences of people who have these disorders, and you may find that some of these individuals seem similar to you or to people you know. As you read about the disorders, put yourself in the place of the people who have these conditions. Consider how they feel and how they would like people to treat them. We hope that you will realize that our discussion is not about disorders, but about the people with these disorders.


How would you define abnormal behavior? Read the following examples. Which of these behaviors do you regard as abnormal?
• Finding a “lucky” seat in an exam • Inability to sleep, eat, study, or talk to anyone else for days after a lover says, “It’s over between us”
• Breaking into a cold sweat at the thought of being trapped in an elevator
• Swearing, throwing pillows, and pounding fists on the wall in the middle of an argument with a roommate
• Refusing to eat solid food for days at a time in order to stay thin
• Engaging in a thorough hand-washing after coming home from a bus ride
• Believing that the government has agents who are eavesdropping on telephone conversations
• Drinking a six-pack of beer a day in order to be “sociable” with friends aft er work. If you’re like most people, you probably found it diffi cult to decide between normal and abnormal. It is surprisingly diffi cult to make this distinction, but it is important to establish some criteria for abnormality.
The mental health community currently uses diagnostic procedures to decide on whether a given individual fits the criteria for abnormality. There are currently five criteria for a psychological disorder. The first is that of “clinical significance,” meaning that the behavior involves a measurable degree of impairment. Second, the individual must be experiencing distress or must be engaging in behaviors that present the risk of death, hospitalization, or incarceration. Third, the individual’s behavior cannot be a socially expectable response to a particular event such as the death of a close friend or relative. Fourth, the behavior must be linked to some underlying disturbance within the individual, whether psychological or biological. Fifth, the individual’s behavior cannot be defined solely in terms of social rebellion or deviance. Thus, in some oppressive political symptoms, people were “diagnosed” as having a psychological disorder when in reality, the government sought to find a way to silence protestors.


However defined, we can best conceptualize abnormal behavior from multiple perspectives that incorporate biological, psychological, and sociocultural factors.

Biological Causes
The biological domain includes genetic and environmental influences on physical functioning. People with psychological disorders may inherit a predisposition to developing behavioral disturbances. Of particular interest are inherited factors that alter the functioning of the nervous system. There are also physiological changes that affect behavior, which other conditions in the body cause, such as brain damage or exposure to harmful environmental stimuli. For example, a thyroid abnormality can cause a person’s moods to fluctuate widely. Brain damage resulting from a head trauma can result in aberrant thought patterns. Toxic substances or allergens in the environment can also cause a person to experience disturbing emotional changes and behavior.
Psychological Causes
Psychological causes of abnormal behavior involve disturbances in thoughts and feelings. There are a variety of alternative explanations of abnormal behavior that focus on factors such as past learning experiences, maladaptive thought patterns, and difficulties coping with stress. The varying theoretical perspectives within abnormal psychology reflect differences in assumptions about the underlying causes of human behavior. Treatment models based on these theoretical perspectives reflect these varying assumptions.
Sociocultural Causes
The term sociocultural refers to the various circles of influence on the individual ranging from close friends and family to the institutions and policies of a country or the world as a whole. Discrimination, whether based on social class, income, race and ethnicity, or gender, can influence the development of abnormal behavior. For people who are diagnosed with a psychological disorder, social stigmas associated with being “mental patients” can further affect their symptoms. A stigma is a label that causes us to regard certain people as different, defective, and set apart from mainstream members of society. In addition to increasing the burden for them and for their loved ones, a stigma deters people from obtaining badly needed help, and thereby perpetuates a cycle in which many people in need become much worse. The stigma of psychological disorders affects people from ethnic and racial minorities more severely than those from mainstream society. For example, European-American adolescents and their caregivers are twice as likely as members of minority groups to defi ne problems in mental health terms or to seek help for such problems (Roberts, Alegría, Roberts, & Chen, 2005).
The Biopsychosocial Perspective

Table 1.1 summarizes the three categories of the causes of abnormality. Disturbances in any of these areas of human functioning can contribute to the development of a psychological disorder. However, we cannot so neatly divide the causes of abnormality. There is often considerable interaction among the three sets of influences. Social scientists use the term biopsychosocial to refer to the interaction in which biological, psychological, and sociocultural factors play a role in the development of an individual’s symptoms. The biopsychosocial perspective incorporates a developmental viewpoint. This means that individuals must be seen as changing over time. Biopsychosocial factors interact to alter the individual’s expression of behavioral patterns over time. Thus, it is important to examine early risk factors that make an individual vulnerable to developing a disorder. Similarly, risk factors may vary according to the individual’s position in the life span (Whitbourne & Meeks, 2011). The degree of influence of each of these variables differs from disorder to disorder. For some disorders, such as schizophrenia, biology plays a dominant role. For other disorders, such as stress reactions, psychological factors predominate. For other conditions, such as posttraumatic stress disorder, that result, for example, from experiences under a terrorist regime, the cause is primarily sociocultural. However, certain life experiences can protect people from developing conditions to which they are vulnerable. Protective factors, such as loving caregivers, adequate health care, and early life successes, reduce vulnerability considerably. In contrast, low vulnerability can heighten when people receive inadequate health care, engage in risky behaviors (such as using drugs), and get involved in dysfunctional relationships. The bottom line is that we can best conceptualize abnormal behavior as a complex interaction among multiple factors.

Table 1.1


The earliest approach to understanding abnormal behavior is spiritual; the belief that people showing signs of behavioral disturbance were possessed by evil spirits. Archeological evidence dating back to 8000 b.c. suggests that the spiritual explanation was prevalent in prehistoric times. Skulls of the living had holes cut out of them, a process called “trephining,” apparently in an eff ort to release the evil spirits from the person’s head (Maher & Maher, 1985). Archeologists have found evidence of trephining from many countries and cultures, including the Far and Middle East, the Celtic tribes in Britain, ancient and recent China, India, and various peoples of North and South America, including the Mayans, Aztecs, Incas, and Brazilian Indians (Gross, 1999).

Another ancient practice was to drive away evil spirits through the ritual of exorcism, a physically and mentally painful form of torture carried out by a shaman, priest, or medicine man. Variants of shamanism have appeared throughout history. The Greeks sought advice from oracles who they believed were in contact with the gods. The Chinese practiced magic as a protection against demons. In India, shamanism flourished for centuries, and it still persists in Central Asia.
       During the Middle Ages, people widely practiced magical rituals and exorcism, and administered folk medicines. Society considered people with psychological difficulties sinners, witches, or embodiments of the devil, and they were punished severely. Malleus Malificarum, an indictment of witches written by two Dominican monks in Germany in 1486, became the Church’s justification for denouncing witches as heretics and devils whom it had to destroy in the interest of preserving Christianity. The Church recommended “treatments” such as deportation, torture, and burning at the stake. Women were the main targets of persecution. Even in the late 1600s in colonial America, the Puritans sentenced people to burning at the stake, as evidenced by the famous Salem Witchcraft trials.


The humanitarian approach developed throughout history, in part as a reaction against the spiritual approach and its associated punishment of people with psychological disorders. Poorhouses and monasteries became shelters, and although they could not offer treatment, they provided some protective measures. Unfortunately, these often became overcrowded, and rather than provide protection themselves, they became places where abuses occurred. For example, society widely believed that psychologically disturbed people were insensitive to extremes of heat and cold, or to the cleanliness of their surroundings. Their “treatment” involved bleeding, forced vomiting, and purging. It took a few courageous people, who recognized the inhumanity of the existing practices, to bring about sweeping reforms. By the end of the eighteenth century, hospitals in France, Scotland, and England attempted to reverse these harsh practices. The idea of “moral treatment” took hold—the notion that people could develop self-control over their behaviors if they had a quiet and restful environment. Institutions used restraints only if absolutely necessary, and even in those cases the patient’s comfort came first.
Conditions in asylums again began to worsen in the early 1800s as facilities suffered from overcrowding and staff resorted to physical punishment to control the patients. In 1841, a Boston schoolteacher named Dorothea Dix (1802–1887) took up the cause of reform. Horrified by the inhumane conditions in the asylums, Dix appealed to the Massachusetts Legislature for more statefunded public hospitals to provide humane treatment for mental patients. From Massachusetts, Dix spread her message throughout North America and Europe.
            Over the next 100 years, governments built scores of state hospitals throughout the United States. Once again, however, it was only a matter of time before the hospitals became overcrowded and understaffed. It simply was not possible to cure people by providing them with the well-intentioned, but ineffective, interventions proposed by moral treatment. However, the humanitarian goals that Dix advocated had a lasting influence on the mental health system. Her work was carried forward into the twentieth century by advocates of what became known as the mental hygiene movement.
           Until the 1970s, despite the growing body of knowledge about the causes of abnormal behavior, the actual practices in the day-to-day care of psychologically disturbed people were sometimes as barbaric as those in the Middle Ages. Even people suffering from the least severe psychological disorders were often housed in the “backwards” of large and impersonal state institutions, without adequate or appropriate care. Institutions restrained patients with powerful tranquilizing drugs and straitjackets, coats with sleeves long enough to wrap around the patient’s torso. Even more radical was the indiscriminate use of behavior-altering brain surgery or the application of electrical shocks—so-called treatments that were punishments intended to control unruly patients.
          Public outrage over these abuses in mental hospitals finally led to a more widespread realization that mental health services required dramatic changes. The federal government took emphatic action in 1963 with the passage of groundbreaking legislation. The Mental Retardation Facilities and Community Mental Health Center Construction Act of that year initiated a series of changes that would affect mental health services for decades to come. Legislators began to promote policies designed to move people out of institutions and into less restrictive programs in the community, such as vocational rehabilitation facilities, day hospitals, and psychiatric clinics. After their discharge from the hospital, people entered halfway houses, which provided a supportive environment in which they could learn the necessary social skills to re-enter the community. By the mid-1970s, the state mental hospitals, once overflowing with patients, were practically deserted. These hospitals freed hundreds of thousands of institutionally confined people to begin living with greater dignity and autonomy. This process, known as the deinstitutionalization movement, promoted the release of psychiatric patients into community treatment sites.
          Unfortunately, the deinstitutionalization movement did not completely fulfill the dreams of its originators. Rather than abolishing inhumane treatment, deinstitutionalization created another set of woes. Many of the promises and programs hailed as alternatives to institutionalization ultimately failed to come through because of inadequate planning and insufficient funds. Patients shuttled back and forth between hospitals, halfway houses, and shabby boarding homes, never having a sense of stability or respect. Although the intention of releasing patients from psychiatric hospitals was to free people who had been deprived of basic human rights, the result may not have been as liberating as many had hoped. In contemporary American society, people who would have been in psychiatric hospitals four decades ago are moving through a circuit of shelters, rehabilitation programs, jails, and prisons, with a disturbing number of these individuals spending long periods of time as homeless and marginalized members of society.
          Contemporary advocates of the humanitarian approach suggest new forms of compassionate treatment for people who suffer from psychological disorders. These advocates encourage mental health consumers to take an active role in choosing their treatment. Various advocacy groups have worked tirelessly to change the way the public views mentally ill people and how society deals with them in all settings. These groups include the National Alliance on Mental Illness (NAMI), as well as the Mental Health Association, the Center to Address Discrimination and Stigma, and the Eliminate the Barriers Initiative. The U.S. federal government has also become involved in antistigma programs as part of efforts to improve the delivery of mental health services through the President’s New Freedom Commission (Hogan, 2003). Looking forward into the next decade, the U.S. government has set the 2020 Healthy People initiative goals as focused on improving significantly the quality of treatment services (see Table 1.2).

Table 1.2 Healthy People 2020 Goals

In late 2010, the U.S. government’s Healthy People project released goals for the coming decade. These goals are intended both to improve the psychological functioning of individuals in the U.S. and to expand treatment services.

• Reduce the suicide rate.
• Reduce suicide attempts by adolescents.
• Reduce the proportion of adolescents who engage in disordered eating behaviors in an attempt to control their weight.
• Reduce the proportion of persons who experience major depressive episodes.
• Increase the proportion of primary care facilities that provide mental health treatment onsite or by paid referral.
• Increase the proportion of children with mental health problems who receive treatment.
• Increase the proportion of juvenile residential facilities that screen admissions for mental health problems.
• Increase the proportion of persons with serious mental illness (SMI) who are employed.
• Increase the proportion of adults with mental disorders who receive treatment.
• Increase the proportion of persons with co-occurring substance abuse and mental disorders who receive treatment for both disorders.
• Increase depression screening by primary care providers.
• Increase the proportion of homeless adults with mental health problems who receive mental health services.


Early Greek philosophers were the first to attempt a scientific approach to understanding psychological disorders. Hippocrates (ca. 460–377 b.c.), considered the founder of modern medicine, believed that there were four important bodily fluids that influenced physical and mental health, leading to four personality dispositions. To treat a psychological disorder would require ridding the body of the excess fluid. Several hundred years later, the Roman physician Claudius Galen (a.d. 130–200) developed a system of medical knowledge based on anatomical studies.

         Scientists made very few significant advances in the understanding of abnormality until the eighteenth century. Benjamin Rush (1745–1813), the founder of American psychiatry, rekindled interest in the scientific approach to psychological disorders. In 1783, Rush joined the medical staff of Pennsylvania Hospital. Appalled by the poor hospital conditions, he advocated for improvements such as placing psychologically disturbed patients in their own wards, giving them occupational therapy, and prohibiting visits from curiosity seekers who would visit the hospital for entertainment.
        Reflecting the prevailing methods of the times, Rush also supported the use of bloodletting and purging in the treatment of psychological disorders as well as the “tranquilizer” chair, intended to reduce blood flow to the brain by binding the patient’s head and limbs. Rush also recommended submerging patients in cold shower baths and frightening them with death threats. He thought that fright inducement would counteract the overexcitement that he believed was responsible for the patients’ violent behavior (Deutsch, 1949).
         In 1844, a group of 13 mental hospital administrators formed the Association of Medical Superintendents of American Institutions for the Insane. The organization eventually changed its name to the American Psychiatric Association. German psychiatrist Wilhelm Greisinger published The Pathology and Therapy of Mental Disorders in 1845, which proposed that “neuropathologies” were the cause of psychological disorders. Another German psychiatrist, Emil Kraepelin, promoted a classification system much like that applied to medical diagnoses. He proposed that disorders could be identified by their patterns of symptoms. Ultimately, this work provided the scientific basis for current diagnostic systems.
        The scientific approach to psychological disorders also gained momentum as psychiatrists and psychologists proposed behavior models that included explanations of abnormality. In the early 1800s, European physicians experimented with hypnosis for therapeutic purposes. Eventually, these efforts led to the groundbreaking work of Viennese neurologist Sigmund Freud (1856–1939), who in the early 1900s developed psychoanalysis, a theory and system of practice that relied heavily on the concepts of the unconscious mind, inhibited sexual impulses, and early development.

        Throughout the twentieth century, psychologists developed models of normal behavior, which eventually became incorporated into systems of therapy. The work of Russian physiologist Ivan Pavlov (1849–1936), known for his discovery of classical conditioning, became the basis for the behaviorist movement begun in the United States by John B. Watson (1878–1958). B. F. Skinner (1904–1990) formulated a systematic approach to operant conditioning, specifying the types and nature of reinforcement as a way to modify behavior. In the twentieth century, these models continued to evolve into the social learning theory of Albert Bandura (1925–), the cognitive model of Aaron Beck (1921–), and the rational-emotive therapy approach of Albert Ellis (1913–2007).
         In the 1950s, scientists experimenting with pharmacological treatments invented medications that for the first time in history could successfully control the symptoms of psychological disorders. Now, patients could receive treatments that would allow them to live for extended periods of time on their own outside psychiatric hospitals. In 1963, the Mental Retardation Facilities and Community Mental Health Center Construction Act proposed patient treatment in clinics and treatment centers outside of mental hospitals. This legislation paved the way for the deinstitutionalization movement and subsequent efforts to continue to improve community treatment.

         Most recently, the field of abnormal psychology is benefiting from the positive psychology movement, which emphasizes the potential for growth and change throughout life. The movement views psychological disorders as difficulties that inhibit the individual’s ability to achieve highly subjective well-being and feelings of fulfillment. In addition, the positive psychology movement emphasizes prevention rather than intervention. Instead of fixing problems after they occur, it would benefit people more if they could avoid developing symptoms in the first place. Although its goals are similar to those of the humanitarian approach, the positive psychology movement has a strong base in empirical research and as a result is gaining wide support in the field.


As you’ve just learned, the scientific approach led to significant advances in the understanding and treatment of abnormal behavior. The essence of the scientific method is objectivity, the process of testing ideas about the nature of psychological phenomena without bias before accepting these ideas as adequate explanations.
      The scientific method involves a progression of steps from posing questions of interest to sharing the results with the scientific community. Throughout the scientific method, researchers maintain the objectivity that is the hallmark of the scientific approach. This means that they do not let their personal biases interfere with the data collection or interpretation of findings. In addition, researchers must always be open to alternative explanations that could account for their findings.
      Although the scientific method is based on objectivity, this does not mean that scientists have no personal interest in what they are studying. In fact, it is often quite the opposite. Many researchers become involved in the pursuit of knowledge in areas that relate to experiences in their own lives, particularly in the field of abnormal psychology. They may have relatives affl icted with certain disorders or they may have become puzzled by a client’s symptoms. In conducting their research, however, they cannot let these personal biases get in the way.

      Thus, in posing questions of interest, psychological researchers may wonder whether a particular kind of experience led to an individual’s symptoms, or they may speculate about the role of particular biological factors. Clinical psychologists are also interested in finding out whether a certain treatment will effectively treat the symptoms of a disorder. In either case, the ideal approach to answering these questions involves a progression through a set of steps in which the psychologist proposes a hypothesis, conducts a study, and collects and analyzes the data. Eventually, they communicate results through publication in scientific journals.


When using experimental design in research, an investigator sets up a test of a hypothesis by constructing a manipulation of a key variable of interest. The variable that the investigator manipulates is called the independent variable, meaning that the investigator controls it. The investigator sets up at least two conditions that reflect different levels of the independent variable. In most cases, these conditions are the “experimental” or treatment group (the group that receives the treatment) and the “control” group (the group that receives no treatment or a different treatment). The researchers then compare the groups on the dependent variable, which is the variable that they observe. Key to the objectivity of experimental research is the requirement that the researchers always randomly assign participants to the different groups. A study would be flawed if all the men were in the experimental group, for example, and all the women were in the control group.

        In research on the causes of abnormal behavior, it may be difficult to set up a true experimental study. Many of the variables that are of most interest to psychologists are ones that the investigator cannot control; hence, they are not truly “independent.” For example, depression can never be an independent variable because the investigator cannot manipulate it. Similarly, investigators cannot randomly assign people to groups based on their biological sex. Studies that investigate differences among groups not determined by random assignment are known as “quasi-experimental.”
        The majority of true experimental studies in abnormal psychology, at least those on humans, test not the causes of abnormal behavior, but the effectiveness of particular treatments where it is possible to design randomly assigned control and experimental groups. Investigators evaluate a treatment’s effectiveness by comparing the groups on dependent variables such as symptom alleviation. There may be more than one experimental group, depending on the nature of the particular study.
        It is common practice in studies evaluating therapy effectiveness to have a placebo condition in which participants receive a treatment similar to the experimental treatment, but lacking the key feature of the treatment of interest. If the study is evaluating effectiveness of medication, the placebo has inert ingredients. In studies evaluating effectiveness of therapy, scientists must design the placebo in a way that mimics, but is not the same as the actual therapy. Ideally, the researchers would want the placebo participants to receive treatments of the same frequency and duration as the experimental group participants who are receiving psychotherapy.
        Expectations about the experiment’s outcome can affect both the investigator and the participant. These so-called “demand characteristics” can compromise the conclusions about the intervention’s true effectiveness. Obviously, the investigator should be as unbiased as possible, but there still may be subtle ways that he or she communicates cues that affect the participant’s response. The participant may also have a personal agenda in trying to prove or disprove the study’s supposed true intent. The best way to eliminate demand characteristics is to use a double-blind method, which shields both investigator and participant from knowing either the study’s purpose or the nature of the patient’s treatment.

            In studies involving medication, a completely inert placebo may not be sufficient to establish true experimental control. In an “active placebo” condition, researchers build the experimental medication’s side effects into the placebo. If they know that a medication produces dry mouth, difficulty swallowing, or upset stomach, then the placebo must also mimic these side effects or participants will know they are receiving placebos.

Toward the DSM-5

Definition of a Mental Disorder

There are five criteria for a mental disorder in the DSM-5, the same number as was included in DSM-IV. There will be slight wording changes, but the criteria still refer to “clinically significant” to establish the fact that the behaviors under consideration are not passing symptoms or minor difficulties. DSM-5 refers to the behaviors as having a “psychobiological function,” a term that DSM-IV does not use. Both the DSM-IV and DSM-5 state that disorders must occur outside the norm of what is socially accepted and expected for people experiencing particular life stresses. DSM-5 also specifies that the disorder must have “diagnostic validity,” meaning that, for example, the diagnoses predict future behavior or responses to treatment. The diagnosis of abnormality also must be clinically useful, meaning that it provides either a better understanding of the disorder or leads to better assessment and treatment than would otherwise be the case. Finally, the authors of DSM-5 provide a caution against changing the lists of disorders (either adding to or subtracting) without taking into account potential benefits and risks. For example, adding a new diagnosis might lead to labeling as “abnormal” a behavior previously considered “normal.” The advantage of having the new diagnosis must outweigh the harm of categorizing a “normal” person as having a “disorder.” Similarly, deleting a diagnosis for a disorder that requires treatment (and hence insurance coverage) might leave individuals who still require that treatment vulnerable to withholding of care or excess payments for treatment.


Studies based on a correlational design involve tests of relationships between variables that researchers cannot experimentally manipulate. We express the correlation statistic in terms of a number between + 1 and - 1. Positive numbers represent positive correlations, meaning that, as scores on one variable increase, scores on the second variable increase. For example, because one aspect of depression is that it causes a disturbance in normal sleep patterns, you would expect then that scores on a measure of depression would be positively correlated with scores on a measure of sleep disturbances. Conversely, negative correlations indicate that, as scores on one variable increase, scores on the second variable decrease. An example of a negative correlation is the relationship between depression and self-esteem. Th e more depressed people are, the lower their scores are on a measure of self-esteem. In many cases, there is no correlation between two variables. In other words, two variables show no systematic relationship with each other. For example, depression is unrelated to height.
        Just knowing that there is a correlation between two variables does not tell you whether one variable causes the other. Th e correlation simply tells you that the two variables are associated with each other in a particular way. Sleep disturbance might cause a higher score on a measure of depression, just as a high degree of depression might cause more disturbed sleep patterns. Or, a third variable that you have not measured could account for the correlation between the two variables that you have studied. Both depression and sleep disturbance could be due to an underlying physiological dysfunction.
     Investigators who use correlational methods in their research must always be on guard for the potential existence of unmeasured variables infl uencing the observed results. However, beyond simply linking two variables to see if they are correlated, researchers can use advanced methods that take more complex relationships into account. For example, we can assess the relative contributions of sleep disturbances, self-esteem, gender, and social class with correlational methods that evaluate several related variables at the same time.


Investigators use a survey to gather information from a sample of people representative of a particular population. They use surveys primarily in studies involving a correlational design when investigators seek to find out whether potentially related variables actually do relate to each other as hypothesized. In a survey, investigators design sets of questions to tap into these variables. They may conduct a survey to determine whether age is correlated with subjective well-being, controlling for the influence of health. In this case, the researcher may hypothesize that subjective well-being is higher in older adults, but only after taking into account the role of health.

      Researchers also use surveys to gather statistics about the frequency of psychological symptoms. For example, the Substance Abuse and Mental Health Services Administration of the United States government (SAMHSA) conducts yearly surveys to establish the frequency of use of illegal substances within the population. The World Health Organization (WHO) conducts surveys comparing the frequency by country of psychological disorders. These surveys provide valuable epidemiological data that can assess the health of the population.

      Researchers report epidemiological data about the occurrence of psychological symptoms and disorders in terms of the time frame over which it occurs. The incidence of a disorder is the frequency of new cases of a disorder within a given time period. Respondents providing incidence data state whether they now have a disorder that they have never had before but now are experiencing. Incidence information can cover any time interval; people tend to report it in terms of one month, six months, and one year. Investigators use incidence data when they are interested in determining how quickly a disorder is spreading. For example, during an epidemic, health researchers need to know how to plan for controlling the disease, and so incidence data is most pertinent to this question.

     The prevalence of a disorder refers to the number of people who have ever had the disorder over a specified period of time. To collect prevalence data, investigators ask respondents to state whether, during this period of time, they experienced the symptoms of the disorder. The time period of reference can be the day of the survey, in which case we call it point prevalence. There is also one-month prevalence, which refers to the 30 days preceding the study, and lifetime prevalence, which refers to the entire life of the respondent. For example, researchers may ask respondents whether they smoked cigarettes at any time during the past month (one-month prevalence) or whether they ever, in their lifetimes, used cigarettes (lifetime prevalence). Typically, lifetime prevalence is higher than one-month or point prevalence because the question captures all past experience of a disorder or a symptom.


Researchers carry out most experiments in psychological laboratories in which participants provide data under controlled conditions. Participants are exposed to conditions based upon the nature of the experimental manipulation. For example, investigators may show participants stimuli on computer screens and ask them to respond. The collected data might include speed of reaction time or memory for different types of stimuli. Laboratory studies may also involve comparison of brain scan responses taken under differing conditions. Another type of laboratory study may involve observing people in small group settings in which the investigators study their interactions.

       Although laboratories are ideal for conducting such experiments, they may also be appropriate settings for self-report data such as responses to questionnaires. Researchers can ask participants to complete their responses in a fixed period of time and under conditions involving a minimum of distractions. They may also provide them with self-report instruments to complete on a computer, allowing for the investigator to collect data in a systematic and uniform fashion across respondents.


Many of the researchers, from what the profession regards as classic studies in early abnormal psychology, based their findings on the case study, which is an intensive investigation of an individual or small group of individuals. For example, Freud based much of his theory on reports of his own patients—the development of their symptoms and their progress in therapy. In current research, investigators carry out case studies for a number of reasons. They afford the opportunity to report on rare cases, or the development of a disorder over time may be the focus of the study. For example, a clinical psychologist may write a report in a published journal about how she provided treatment to a client with a rare type of fear.

The advantage of an in-depth case study is also a potential disadvantage in that it does not involve enough experimental control to make a useful addition to the literature. Investigators using case studies, therefore, must be extremely precise in their methods and, as much as possible, take an objective and unbiased approach. There are standards for use in qualitative research that can ensure that researchers present case study data in a way that will be valuable to other investigators.


In a single case experimental design (SCED), the same person serves as the subject in both the experimental and control conditions. Particularly useful for studies of treatment effectiveness, a single-subject design typically involves alternating off-on phases of the baseline condition (“A”) and the intervention (“B”). The profession also refers to SCEDs as “ABAB” designs, reflecting the alternation between conditions A and B. Figure 1.1 shows an example of an SCED involving self-injurious behavior.
     In cases where withholding the treatment in the “B” phase would present an ethical problem (because of an elimination of an effective treatment), researchers use a variation called the multiple baseline method. In a multiple baseline design, the researcher applies the treatment in an AB fashion so that it is never removed. The observation occurs across different subjects, for different behaviors, or in different settings. The researcher takes repeated measures of behavior in relation to introduction of the treatment. For example, in treating a suicidal client, an investigator may first target suicidal thoughts, and second, target suicidal behaviors. The power of the design is in showing that the behaviors change only when the researcher introduces specific treatments (Rizvi & Nock, 2008).


Researchers in the field of behavioral genetics and psychopathology attempt to determine the extent to which people inherit psychological disorders. Behavioral geneticists typically begin an investigation into a disorder’s genetic inheritance after observing that the disorder shows a distinct pattern of family inheritance. This process requires obtaining complete family histories from people whom they can identify as having symptoms of the disorder. The investigators then calculate the concordance rate, or agreement ratios, between people diagnosed as having the disorder and their relatives. For example, a researcher may observe that 6 out of a sample of 10 twin pairs have the same diagnosed psychological disorder. This would mean that, among this sample, there is a concordance rate of .60 (6 out of 10). We would expect an inherited disorder to have the highest concordance between monozygotic or identical twins (whose genes are the same), with somewhat lower rates between siblings and dizygotic or fraternal twins (who are no more alike genetically than siblings of different ages), and even lower rates among more distant relatives.

         A second approach in behavioral genetics is to study families who have adopted. The most extensive evidence available from these studies comes from the Scandinavian countries, where the governments maintain complete birth and adoption records. The research studies two types of adoptions. The first is an adoption study in which researchers establish the rates of the disorder in children whose biological parents have diagnosed psychological disorders, but whose adoptive parents do not. If the children have the disorder, this suggests that genetic factors play a stronger role than the environment. In the second adoption study, referred to as “cross-fostering,” researchers examine the frequency of the disorder in children whose biological parents had no disorder, but whose adoptive parents do.

       Twin studies are a third method of behavioral genetics. In these studies, researchers compare monozygotic twins reared together to those reared apart. Theoretically, if twins reared apart share a particular disorder, this suggests that the environment played a relatively minor role in causing that behavior.
       These kinds of studies enable researchers to draw inferences about the relative contributions of biology and family environment to the development of psychological disorders. However, they are imprecise and have several potential serious flaws. Adoption studies can be suggestive, but are hardly definitive. There may be unmeasured characteristics of the adoptive parents that influence the development of the disorder in the children. The most significant threat to the usefulness of twin studies is the fact that the majority of monozygotic twins do not share the same amniotic sac during prenatal development (Mukherjee et al., 2009). They may not even share 100 percent of the same DNA (Ollikainen et al., 2010).
      In gene mapping researchers examine and connect variations in chromosomes to performance on psychological tests or diagnosis of specific disorders. Molecular genetics studies how genes translate hereditary information. We use these methods in the study of abnormal psychology to determine how hereditary information translates into behavior disorders. They have led to widespread advances in the understanding of such disorders as autism, schizophrenia, and various anxiety disorders (Hoff man & State, 2010).