Idiographic and nomothetic approaches to psychological investigation
Issues and debates
The idiographic versus nomothetic approaches debate concerns whether it is best to study and understand a person as being unique or as sharing the similarities of others. Idiographic refers to when an explanation centres on a person as an individual, seeking to find what uniqueness that person has that makes them who they are. Nomothetic, meanwhile, concerns the idea that people have similarities that allow them to be grouped together. Nomothetic explanations can therefore be generalised to all members of a group, while idiographic explanations are non-generalisable. Research based on the idiographic approach is unlikely to be performed on large numbers of people, as in experiments, as it would not be trying to establish universal laws generalisable to all members of a population. Case studies are an example of an idiographic study method, as they seek to assess only one person. The idiographic approach tends not to favour quantitative methods, where numerical data are generated, but instead qualitative methods, where non-numerical data are generated concerning attitudes, beliefs and self-reflections, often from self-report measures, such as interviews, questionnaires and diaries. The nomothetic approach seeks to classify people into groups, establish universal laws and create continuums upon which people can be placed.
Thigpen & Cleckley (1954) reported on the psychotherapeutic treatment of 25-year-old Eve White, who was referred to the clinicians due to her ’blinding headaches’. A case study was conducted that consisted of interviews with Eve and her family members, hypnosis sessions, observations, EEG readings and psychological tests, such as memory, IQ and personality tests. Emotional difficulties were revealed, mainly concerning Eve’s marital difficulties and personal frustrations. During hypnosis (and sometimes spontaneously) an alternative personality called ’Eve Black’ appeared, a totally different person characterised by irresponsibility, violence and a selfish desire for pleasure. Eve White had an IQ of 110 to Eve Black’s 104. Eve White also had superior memory ability to Eve Black. A third personality, called Jane, then appeared, with all three personalities showing different EEG readings. It was concluded that Eve had multiple personality disorder. This was an example of an idiographic approach, as it related to Eve as a unique example.
• Scoville (1957) reported on HM, an epileptic, who after surgery developed anterograde amnesia where he could not encode new long-term memories, though his short-term memory was intact. His brain was dissected on his death aged 82 to reveal damage to his hippocampus. As this related to a fairly unique case, it can be considered an idiographic approach.
• Herlitz et al. (1997) assessed LTM abilities in 1,000 Swedish participants, finding that females outscored males on tasks requiring episodic LTM. This suggested a gender difference in episodic LTM ability and, as it was an experiment performed on many participants, used a nomothetic approach, with the findings generalisable to the general population.
• Wagenaar (1986) found he had excellent LTM recall when testing himself on his diary entries of 2,400 events over 6 years. This self-report method of diary usage involves the idiographic approach, as it relates only to Wagenaar as an individual, with the findings not necessarily generalisable.
An idiographic stance, such as a case study, is often the seed prompting ideas for further research. It looks at behaviour and phenomena in detail from an idiographic, in-depth perspective that leads to research ideas. Inevitably, though, a nomothetic stance will be adopted at some point.
Those in the field who perceive psychology as, or wish it to be, a science use the nomothetic approach, as it fits the empirical research methods used in the established natural sciences, such as physics and chemistry, where the search is for general rules applicable to all. Those who prefer a less scientific approach, such as those who favour the psychodynamic and humanistic approaches, adopt a more idiographic approach.
Idiographic viewpoints seek to find behavioural patterns applicable to all. Conversely, a nomothetic stance means that theories often do not fit everyone and therefore we cannot adopt a one-size-fits-all approach. This inevitably makes them inappropriate for some people. This argument can also be applied to interventions and means that people are forced to use interventions not really applicable to them, which may have only a moderate effect on them, or no effect at all.
Most psychological research is nomothetic, which has a practical application in the therapies, treatments and interventions that are created, which can be successfully administered to great amounts of people. Interventions and treatments incurred from idiographic research are generally only applicable to that one individual.