12.5: Case Studies

Learning Objectives

1. Describe some typical research questions that could be answered best with case studies.
2. Describe the strengths and weakness of case studies as a research method.

What are Case Studies?

A case study is an in-depth examination of an individual. Sometimes case studies are also completed on social units (e.g., a cult) and events (e.g., a natural disaster). Most commonly in psychology, case studies provide a detailed description and analysis of an individual. Often the individual has a rare or unusual condition or disorder or has damage to a specific region of the brain.

Like many nonexperimental research methods, case studies tend to be more qualitative in nature. Case study methods involve an in-depth, and often a longitudinal examination of an individual. Individuals may be observed in their natural setting, or the individual may be brought into a therapist’s office or a researcher’s lab for study. Archival data may also be a rich source of information. Basically, because of the in-depth nature of case studies and the time commitment, almost any measurement described in the chapter on measurement can be used to gather information on the case; interviews, naturalistic observation, structured observation, psychological testing (e.g., IQ test), and/or psychobiological measurements (e.g., brain scans), and surveys could all be used to collect information on the individual. Because of this variety in the information gathered, reporting about case studies will often focus on detailed descriptions of the case rather than on statistical analyses. With that said, some quantitative data may also be included in the write-up of a case study. For instance, an individual’s depression score may be compared to normative scores or their score before and after treatment may be compared.

HM is one of the most notorious case studies in psychology. HM suffered from intractable and very severe epilepsy. A surgeon localized HM’s epilepsy to his medial temporal lobe and in 1953 he removed large sections of his hippocampus in an attempt to stop the seizures. The treatment was a success, in that it resolved his epilepsy and his IQ and personality were unaffected. However, the doctors soon realized that HM exhibited a strange form of amnesia, called anterograde amnesia. HM was able to carry out a conversation and he could remember short strings of letters, digits, and words. Basically, his short term memory was preserved. However, HM could not commit new events to memory. He lost the ability to transfer information from his short-term memory to his long term memory, something memory researchers call consolidation. So while he could carry on a conversation with someone, he would completely forget the conversation after it ended. This was an extremely important case study for memory researchers because it suggested that there’s a dissociation between short-term memory and long-term memory, it suggested that these were two different abilities sub-served by different areas of the brain. It also suggested that the temporal lobes are particularly important for consolidating new information (i.e., for transferring information from short-term memory to long-term memory),

What happens when you remove the hippocampus? - Sam Kean. https://youtu.be/KkaXNvzE4pk

The history of psychology is filled with influential cases studies, such as Sigmund Freud’s description of “Anna O.” (see Note 6.1 “The Case of “Anna O.””) and John Watson and Rosalie Rayner’s description of Little Albert (Watson & Rayner, 1920), who allegedly learned to fear a white rat—along with other furry objects—when the researchers repeatedly made a loud noise every time the rat approached him.

The Case of “Anna O.”

Sigmund Freud used the case of a young woman he called “Anna O.” to illustrate many principles of his theory of psychoanalysis (Freud, 1961). (Her real name was Bertha Pappenheim, and she was an early feminist who went on to make important contributions to the field of social work.) Anna had come to Freud’s colleague Josef Breuer around 1880 with a variety of odd physical and psychological symptoms. One of them was that for several weeks she was unable to drink any fluids. According to Freud,

She would take up the glass of water that she longed for, but as soon as it touched her lips she would push it away like someone suffering from hydrophobia.…She lived only on fruit, such as melons, etc., so as to lessen her tormenting thirst. (p. 9)

But according to Freud, a breakthrough came one day while Anna was under hypnosis.

[S]he grumbled about her English “lady-companion,” whom she did not care for, and went on to describe, with every sign of disgust, how she had once gone into this lady’s room and how her little dog—horrid creature!—had drunk out of a glass there. The patient had said nothing, as she had wanted to be polite. After giving further energetic expression to the anger she had held back, she asked for something to drink, drank a large quantity of water without any difficulty, and awoke from her hypnosis with the glass at her lips; and thereupon the disturbance vanished, never to return. (p.9)

Freud’s interpretation was that Anna had repressed the memory of this incident along with the emotion that it triggered and that this was what had caused her inability to drink. Furthermore, he believed that her recollection of the incident, along with her expression of the emotion she had repressed, caused the symptom to go away.

As an illustration of Freud’s theory, the case study of Anna O. is quite effective. As evidence for the theory, however, it is essentially worthless. The description provides no way of knowing whether Anna had really repressed the memory of the dog drinking from the glass, whether this repression had caused her inability to drink, or whether recalling this “trauma” relieved the symptom. Like other nonexperimental research methods, case studies cannot show cause-and-effect relationships. It is also unclear from this case study how typical or atypical Anna’s experience was.

Figure \(\PageIndex{1}\): Anna O. “Anna O.” was the subject of a famous case study used by Freud to illustrate the principles of psychoanalysis. Source: http://en.Wikipedia.org/wiki/File:Pappenheim_1882.jpg

What Case Studies are Not

As described above, case studies are different from experimental designs in several ways, including:

• Focus is on a single “case”, rather than a large sample from a population.
• Focus includes more variables collected over a longer time period. (These can be considered DVs.)
• In traditional case studies, there’s no intervention (no IV in the traditional sense).
• Case studies tend to be exploratory. The goal of case studies is in-depth understanding of an ongoing behavior. There’s no research hypothesis. There’s little control over the situation or the case’s experiences.

Exercise \(\PageIndex{1}\)

Based on this summary, do case studies have high or low internal validty? In other words, how good are case studies at determining cause-and-effect?

Answer

Case studies tend to have low internal validity, meaning that the information gained does not determine cause-and-effect relationships.

A quick review of case studies make them seem like small-N designs, but that's not the case. Why not? First, small-N designs tend to have only one, specific outcome (DV) that is being observed, or maybe a few. But case studies can have as many outcomes as the researcher can access. Second, small-N designs tend to have a treament, or IV, while case studies tend to gather data on what has been happening but does not intervene. Because of these differences, small-N designs are structured to attempt to provide evidence of cause-and-effect relationships, while case studies are squarely nonexperimental.

Advantages and Disadvantages of Case Studies

Case studies are useful because they provide a level of detailed analysis not found in many other research methods and greater insights may be gained from this more detailed analysis. As a result of the case study, the researcher may gain a sharpened understanding of what might become important to look at more extensively in future more controlled research. Case studies are also often the only way to study rare conditions because it may be impossible to find a large enough sample of individuals with the condition to use quantitative methods. Although at first glance a case study of a rare individual might seem to tell us little about ourselves, they often do provide insights into normal behavior. The case of HM provided important insights into the role of the hippocampus in memory consolidation.

However, it is important to note that while case studies can provide insights into certain areas and variables to study, and can be useful in helping develop theories, they should never be used as evidence for theories. In other words, case studies can be used as inspiration to formulate theories and hypotheses, but those hypotheses and theories then need to be formally tested using more quantitative methods. The reason case studies shouldn’t be used to provide support for theories is that they are not experiments so they cannot show cause-and-effect. Case studies lack the proper controls that true experiments contain. As such, they suffer from problems with internal validity, so they cannot be used to determine causation. For instance, during HM’s surgery, the surgeon may have accidentally lesioned another area of HM’s brain (a possibility suggested by the dissection of HM’s brain following his death) and that lesion may have contributed to his inability to consolidate new information. The fact is, with case studies we cannot rule out these sorts of alternative explanations. As with all nonexperimental methods, case studies do not permit determination of causation.

Case studies suffer from problems with internal validity, but also with external validity. Because case studies are often of a single individual, and typically an individual chosen specifically because they are rare or unique in some way, researchers cannot generalize their conclusions to other individuals. With most research designs, there is a trade-off between internal and external validity. With case studies, however, there are problems with both internal validity and external validity. So there are limits both to the ability to determine causation and to generalize the results.

A final limitation of case studies is that ample opportunity exists for the theoretical biases of the researcher to bias the case description. Indeed, there have been accusations that the woman who studied HM destroyed a lot of her data that were not published and she has been called into question for destroying contradictory data that didn’t support her theory about how memories are consolidated. There is a fascinating New York Times article that describes some of the controversies that ensued after HM’s death and analysis of his brain that can be found at: https://www.nytimes.com/2016/08/07/magazine/the-brain-that-couldnt-remember.html?_r=0

All research designs have situations, samples, and research questions that they may be most appropriate as the design to answer the question. It is up to you as the researcher (and you as the reader of research) to decide, for each research study, what the most appropriate research design, the most appropriate operational definition of the independent variable (or not have an independent variable), and the most appropriate operational definition of the dependent variable for this research topic on the target population.

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References

Freud, S. (1961). Five lectures on psycho-analysis. New York, NY: Norton.

Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology, 3, 1–14.