Considering Case Studies
Most research in Psychology involves studying a group of "typical" people - that is, a sample of people meant to represent the target population.  But every so often, a person attracts the attention of Psychologists precisely because they are so unique - and studying their behavior might reveal important clues about the human mind.  
Try it Out

Read this article on the case of a woman code-named S.M., and consider the following:

1.  What is unusual about S.M.?

2.  What biological factors might offer an explanation for S.M.'s condition?

3.  What can we learn from this case study?

S.M. is special because she has no experience of fear.  Whether handling spiders and snakes, watching horror movies, or even spending time alone in a haunted house, S.M. isn't the slightest bit afraid.  Even when her life was genuinely at risk - like when she was being robbed at gunpoint - S.M. felt nothing.

S.M. also has damage to both sides of her amygdala, the result of a rare disease which causes lesions to form on parts of her brain.  This case study suggests that the amygdala - an almond shaped structure in the brain - may be the biological source of fear.  The amygdala is what makes people afraid, this study seems to suggest, and without a functioning amygdala, people would have no sense of fear.

In general, a case study is an in-depth investigation of a single person (or small group of people), often over long periods of time.  When carrying out a case study, researchers study a person in great detail, collecting data through a variety of methods.  These could include:

  • observations (watching how the person behaves in different situations)

  • interviews 

  • psychological testing, for instance IQ tests, questionnaires, and so forth

  • brain scans

  • and others methods

For instance, the psychologists studying S.M. used lots of different ways to explore her condition:  they observed her in scary situations, like holding spiders and snakes; they gave her questionnaires to report her emotions; they interviewed her about life-threatening events she'd experienced; and they even used a technique called experience sampling, in which the person is asked (at several random times each day) to describe their feelings.  In the case of S.M., all of the data - from observations to interviews to experience sampling - supported the conclusion that S.M. is truly a woman who does not experience fear.
Case Studies: What can they tell us?

Case studies can be fascinating in their own right, but most of the time Psychologists are so interested in case studies because they can provide new knowledge that applies beyond a single person.  For instance, we aren't just interested in S.M. for the sake her experiences alone, but because we want to learn something about the biological origins of fear in all people.

Case studies are usually carried out when there is an extraordinary or unusual situation that would be hard to study otherwise.  Psychologists have long suspected that the amygdala plays a role in fear, but how do you find out for sure?  You can't ethically do an experiment, which would involve intentionally causing amygdala damage to some people in order to study the consequences.  You could do this to animals, but the brains of animals and humans might not work the same way.  So when a person like S.M. comes along, it provides Psychologists with a rare opportunity to study the role of the amygdala in behavior.

Case studies can provide important evidence in support of an existing theory, such as the case with S.M.  The theory that the amygdala plays a role in fear is not new, but the case of S.M. helps provide important evidence to back this up.  In other instances, however, a case study might completely contradict what Psychologists expect to see, and can therefore lead to completely new theories about human behavior.   

On the other hand, it is important not to overstate the importance of a single case study.  There are some important limitations with case studies, which should always be kept in mind.

  • Case studies can't be replicated.  Unlike an experiment, which could be repeated many times to confirm the results, a case study is impossible to repeat.  No other person in the world will have exactly the same pattern of brain damage as S.M., and even people with a similar condition may be very rare.

  • Findings from one case might not apply to everyone.  Its mistaken to assume that the results from one case can be generalized to all people.  There is a chance that a different person might have a damaged amygdala and still experience fear, or have little experience of fear even with a healthy amygdala.  The human mind is very complex, and there could be lots of factors that contribute towards the experience of fear, with the amygdala perhaps being just one of them.

Although case studies are fascinating, a single case study is not enough reason to make any definite conclusions. More research needs to be carried out, or other similar cases investigated.  If evidence from a variety of sources - animals experiments, brain imaging studies, and multiple case studies similar to H.M.'s - all support the role of the amygdala as the biological source of fear, than Psychologists will be much closer to making a firm conclusion.
Exam Tip

When discussing a case study in an exam essay, be sure to give a balanced account.  In other words, explain why the case study is useful, describing the clues it tells us about the mind and behavior.  But also be sure to point out the limitations of cast studies, and why a single case study alone can't be used to draw definite conclusions.
Think Critically

Watch the video below on Dr. Money's case study of David Reinmar (50 min duration) and make notes on the following:

1.  What theory was Dr. Money trying to support through this case study?

2.  Why was Dr. Money so interested in the case of David?

3.  What data collection methods did Dr. Money use?

4.  Did the results support Dr. Money's theory?  Explain why or why not

  • I can define what a case study is, and explain how one is carried out

  • I can explain why cases studies can be useful

  • I can discuss some of the limitations of case studies, such as limited replicability and generalizability
Quiz Yourself!

1. What is NOT a feature of a case study?

a) In-depth investigation

b) Uses a variety of data collection methods

c) Large sample size

d) May take place over a long period of time

2.  Which is NOT a data collection method used in case studies?

a) Random sampling

b) Brain scans

c) Observations

d) Interviews

3.  Case studies are useful in Psychology because...

a) Variables are carefully controlled

b) Investigate situations that would be difficult to study otherwise

c) Demonstrate a cause-and-effect relationship

d) Can be generalized to the target population

4.  Generalizability of a case study refers to...

a) Applying the results from a case to other people

b) Using a variety of data collection methods

c) Selecting a participant from the general population

d) Repeating a case study with different participants

5.  Generalizability of a case study increases when...

a) Variabels are carefully controlled

b) A variety of data collection methods are used

c) The case is studied over a period of several years

d) Related case studies show consistent results


Quiz Yourself

1-C, 2-A, 3-B, 4-A, 5-D

Think Critically

1.  Dr. Money was trying to support the theory of gender neutrality.  This theory holds that boys and girls are not inherently different in their behavior.  The reason why boys and girls develop differently, according to the theory, is because they are treated differently by their parents and other adults - and not because of any fundamental biological difference between the genders.

2.  Dr. Money was interested in David because he was born a boy, but lost his male anatomy.  If Dr. Money could succeed in raising David as a girl, this would support the theory that sex differences in behavior are socially learned, rather than biologically determined.

3.  Dr. Money carried out observations of David, and conducted interviews with David, his brother, and their parents.

4.  The results failed to support Dr. Money's theory.  David never felt comfortable as a girl, and behaved in a more aggressive, stereotypically male fashion.  After learning the truth, David decided to transition back to being a boy.  This case suggests that biological differences between boys and girls do play a significant role in thier behavior.