You need to know most of what's on this page. The case study method features in Unit 1 (Biological) and Unit 2 (Clinical) and can be examined in Unit 3 (Review of Methods). You also need examples of case studies to back up your points.

WHY CASE STUDIES?

A case study is an in-depth study of one person, group or event. Case studies are used to study people or situations that cannot be studied through normal methods like experiments, surveys or interviews.

Freud's theories were developed through case studies; in particular the study of the 5-year-old "Little Hans". As part of the biology of aggression, you will learn about the case study of Phineas Gage.

CASE STUDIES

A case study is an in-depth study of a single person or a small group that all share a single characteristic (like a family).

Case studies focus on abnormal cases: people with deviant behaviour, mental disorders or unusual gifts.

Case studies are usually longitudinal studies - they take place over a period of time, typically months. They record changes in the behaviour and mental state of the participant(s) over that period.

Case studies usually use a mixture of methods. Older case studies (like those by Freud) used to focus on interviews and observations and collect qualitative data. More recent case studies mix this qualitative approach with questionnaires and biological measures (like brain scans or genetic profiling) to collect quantitative data too.

Case studies involve simply recording what happens to - or reconstructing what has already happened to - single participant or group of individuals. This is called the ideographic approach in science - it doesn't test hypotheses, look for causes or try to uncover laws. Case studies allow a researcher to investigate a topic in far more detail than might be possible if they were trying to deal with a large number of research participants.

If a case study shows interesting or unexpected results, it may be followed up with a wider-scale survey or experiment to draw conclusions about people in general - this is the nomothetic approach which tries to uncover scientific laws by "averaging out" the data on lots of individuals.

APPLYING CASE STUDIES

In Unit 1, the Biological Approach involves case studies. These fall into two groups:
The Cognitive Contemporary Study by Schmolck et al. also involves looking at a small group of individuals with brain damage - including H.M. It's not really a case study though: it's an experiment that compares the brain-damaged patients' test scores with each other and with a control group. However, Schmolck does single out H.M. to look at individually, so this part of the study could be seen as a case study!
The main application of case studies is in Unit 2 where you study Clinical Psychology. Clinical psychologists use case studies to understand mental disorders better. In particular, case studies can shed light on the difference between normal and abnormal behaviour as well as revealing how effective certain therapies are.

There are different types of case study in clinical psychology:
  • Prospective case studies observe an individual or group of people in order to determine what happens to them. For example, a patient might be watched over time to observe the progression of a mental disorder. Bradshaw (1998) follows a young woman called Carol receiving therapy for schizophrenia.
  • Retrospective case studies look at historical information. For example, psychologists might start with an outcome, such as a mental disorder, and then uncover information about the individual's life to determine risk factors that may have contributed to the illness. A good example is Freud's case study of Little Hans which revealed the boy's Oedipus Complex.
  • Instrumental case studies occur when the individual allows psychologists to understand more than what is initially obvious. A good example is Dr Milner's case study of H.M., which revealed much more about his memory problems than was obvious at first.

EVALUATING CASE STUDIES

This table sums up the strengths and weaknesses of case studies:
Generalisability

Case studies have tiny sample groups - often just a single person.
Remember - a sample isn't unrepresentative just because it's small. A sample of one person could be generalisable if that one person was the most statistically representative person in the world (average height, average IQ, etc.).
The problem with case studies is that they make a point of looking at unrepresentative people - people with deviant behaviour, mental disorders or unusual thought processes (like savants who have incredible memories). These people might not be representative of normal people - they might not even be representative of other unusual people.

On the other hand, the ideographic approach in psychology doesn't try to be generalisable. The point of a case study is to describe in detail. If this description is interesting or unexpected, then psychologists can move on to another nomothetic approach (like an experiment or a correlation) to produce more generalisable findings.
Reliability

Case studies that are rich in qualitative data may be unreliable. This is because they can be highly subjective: the researcher's own, highly personal, impression of the participant. This is a criticism often leveled at Freud's case studies.

To correct this, researchers often use standardised procedures to gather quantitative data as part of a case study. This often comes from:
  • Biometric data: this might include brain scans, genetic profiles, fingerprints or blood samples
  • Psychometric data: this often comes from filling in questionnaires or solving cognitive tests, like memory tests

Even with standardised procedures, case studies can be unreliable. This is because the participants being studied are often so unusual, it's hard to find anyone similar to replicate the study on. For example, H.M.'s brain damage was similar to, but not the same as, the other brain-damaged participants in the Schmolck et al. study. H.M. was a unique case.

Other participants in case studies are rare but not unique. Bradshaw's case study was of a middle-class young woman with schizophrenia: this is unusual, but not a one-off.
Application

Case studies are particularly useful in clinical psychology because they shed light on unusual conditions that don't fit the patterns of 'normal' behaviour.

A retrospective case study might suggest factors that could have caused a mental disorder. For example, case studies might explore childhood abuse or neglect in a patient's past as well as genetic differences or brain damage that make a patient unusual.

Prospective case studies help with the evaluation of therapies, by showing whether someone with an unusual disorder benefits from a particular type of therapy. For example, Bradshaw's case study of a young woman with schizophrenia suggests that cognitive therapy can be helpful for this disorder.

Instrumental case studies help us understand a disorder better by showing exactly how it affects a sufferer. Milner's case study of H.M. is a good example of this.

However, since these studies are ideographic, psychologists can't derive theories, laws or causal conclusions from them. Further study is needed to test hypotheses and produce generalised conclusions needed to help other sufferers.
Validity

The main advantage of case studies is the rich, in-depth data they gather. Case studies "get under the skin" of the participants and help the researchers understand the participants much more thoroughly than any one-off interview or stand-alone experiment would.

Because a case study normally takes a long time to carry out, the participant will get quite used to the researchers and act naturally around them. This reduces the problem of demand characteristics and social desirability bias (but doesn't entirely remove it, especially if the participant only meets with the researcher for a short period at intervals).

For the same reason, researchers get used to the participant and learn to understand and interpret this person's behaviour. This reduces the problem of ethnocentrism and cultural bias (but again, doesn't entirely remove it).

However, this can produce a new problem. In a case study, researcher and participant tend to develop a bond and a relationship forms between them. In particular, the researcher can get to know the participant pretty intimately. This can lead to loss of objectivity.
If you think about it, the whole point of a case study is to see the research participant "as a person" - but once you view someone as a person, it's hard to study them objectively. This is particularly a problem when studying people who have been through difficult experiences.
Ethics

The intimacy that case studies create between researcher and research participant can lead to ethical problems.

The ethical principle of Integrity demands that researchers conduct themselves professionally - this involves keeping a professional distance between yourself and your research participant. The researcher isn't supposed to befriend the participant or get romantically involved, but this also includes not promising favours or help that you can't deliver. This is particularly a problem when studying participants who are in custody, suffer drug addiction or have deviant fantasies.

A related problem comes from the principle of Minimising Harm, which states that a researcher should not "normalise" unhealthy behaviours. Participants who have delusions or deviant fantasies might feel encouraged if a psychologist appears to sympathise with them.

Social responsibility is important in ethical research. Studying rare or unusual cases is important, but researchers need to bear in mind the effect that this can have on public opinion. This particularly applies to case studies of serial sex offenders, terrorists or murderers because of the danger of "copycat" crimes or of creating stereotypes of minority groups.
My favourite FICTIONAL case study is in the 1991 film "Silence of the Lambs", when trainee FBI agent Clarice Starling (Jodie Foster) is sent to carry out a case study of imprisoned serial killer Hannibal Lecter (Anthony Hopkins). This is an instrumental case study: Starling's boss hopes Lecter's psychology will shed light on another serial killer case. The relationship between Starling and Lecter illustrates all the issues in case studies, especially objectivity and detachment. Watch it: it won all of the "Big Five" Oscars (Film, Directer, Screenplay, Actress, Actor).

STUDYING CASE STUDIES
IN COGNITIVE PSYCHOLOGY & CLINICAL PSYCHOLOGY

In Unit 1, you need to know about case studies as part of the Cognitive Approach; in particular, the celebrated patient H.M. whose brain damage affected his memory.

In Unit 2, you need to know about case studies as part of the Clinical Approach. The case study of Carol's treatment for schizophrenia is a good example.
Start with an evaluation point and back it up with evidence.
Evaluation + evidence = "logical chain of reasoning"
Issues & Debates (like ethics) make great conclusions

EXEMPLAR ESSAY
How to write a 8-mark answer

Evaluate the use of case studies as they are used in psychology. (8 marks)
  • A 8-mark “evaluate” question awards 4 marks for describing the case study method (AO1) and 4 marks for evaluating it (AO3). You need a conclusion to get a mark in the top band (7-8 marks). "Case studies" turn up in the Specification for the Biological Approach but could be the basis of a 20 mark question in Unit 2.

Case studies tend to be high in validity because they collect in-depth descriptive data, often over a long period of time. This produces great understanding of the participant. For example, Scoville & Milner's case study of H.M. revealed his memory problems.

Because of this intimacy, participants in case studies often show less demand characteristics and social desirability bias because they act naturally around the researcher. For example, Little Hans acted naturally around his father in Freud's case study.

This intimacy can lead to problems if the researcher loses his or her objectivity and starts to regard the research participant as a friend. This is particularly likely in a prospective case study where the researcher observes the subject growing up.

It can also lead to ethical problems if the researcher loses their professional detachment. Researchers should not form relationships with vulnerable clients or make promises they cannot carry out. This would break ethical guidelines from the BPS and the HCPC.

In conclusion, case studies are a great way to get "under the skin" of unusual or difficult individuals but they have to be monitored carefully to remain objective and professionally detached. An ethics panel is one way of doing this.

  • Notice that for a 8-mark answer you don’t have to include everything about case studies. I haven’t explored generalisability problems or instrumental case studies. But it is a balanced answer - half description, half evaluation.