aqa  Idiographic and nomothetic approaches to psychological investigation.


A key debate, is the one between the two research methods: nomothetic and idiographic. The debate concerns which method of enquiry is more important and which would allow greater and more valid investigation into the field of psychology.

The Nomothetic Approach

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Nomothetic research is about attempting to establish general laws and generalisations.  The focus of the nomothetic approach is to obtain objective knowledge through scientific methods. Hence quantitive methods of investigation are used, to try and produce statistically significant results. The subsequent laws that are created can be categorised into three kinds: classifying people into groups, establishing principles and establishing dimensions. An example of this from the world of psychology is the ‘Diagnostic and statistical Manuals of Mental Disorders’ (DSM), which provides the classifications for mental disorders, hence classifying people into groups.

The methods of investigation used by the nomothetic approach collects scientific and quantitive data. To do this, experiments and observations are used, and group averages are statistically analysed to create predictions about people in general. An example of this is Milgrim’s experiments on obedience. From his scientific experiments he found that 65% of his participants would harm another person, (via a 450v electric shock) potentially killing them, within the presence of an authority figure. Although there were many ethical issues with his experiment including the deception involved and potential harm to the participant, this is an example of nomothetic research. Milgrim repeated his experiments many times and as a result created his laws of obedience.

The nomothetic approach is considered scientific due to its’ precise measurement, prediction and control of behaviour, investigations of large groups, objective and controlled methods allowing for replication and generalisation. Due to this, it has helped psychology become more scientific by developing theories that can be empirically tested. Which is one of the key criteria of a science.

However the nomothetic approach does have its limitations. It has been accused of losing sight of the ‘whole person’, due to its extensive use of group averages. It also may give a superficial understanding, as people may display the same behaviour, but for different reasons. For example in the Milgrim study, can we be sure that all the behaviour displayed was for the same reasons?

Another limitation of this approach is that predictions can be made about groups, but not the individual. Telling someone that that they have a 3 in 100 chance of schizophrenia probably isn’t of much use to that individual.

There is also a potential underlying confounding variable with some of the research done following the nomothetic approach. Due to the extensive us of laboratory studies, the experiments often lack ecological validity, which means we cannot generalise the results to everyday life.

The Idiographic Approach

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The idiographic approach, unlike the nomothetic approach, focuses on the individual.  It suggests that everyone is unique and therefore everyone should be studied in an individual way. Due to this, no general laws are possible. The methods of investigation, by this approach tend to collect quantitive data, investigating the individual. Case studies are the most common method, but other research methods include: unstructured interviews, self-reports, autobiographies and personal documents.

Unlike the nomothetic approach, this provides a more complete understanding of the individual. As a result of this focus the individual is more likely to feel valued and unique. Also despite claims, that this approach is unscientific, it does satisfy some of the key aims of a science i.e. description and understanding.  However as subjective experience cannot be empirically tested, it remains unscientific. Despite this it is difficult to generalise from subjective knowledge of one person, no matter how detailed it is.

As it stands both the nomothetic and idiographic approach, both make valid contributions to research. However the relative value of each approach depends upon the purpose of the research. The idiographic approach is better suited to description, while idiographic is suited to predictions. The two approaches can be seen as complementary, idiographic research can further develop a nomothetic law. It may also serve as a source of ideas and hypotheses for later study. An example of where the two approaches have shown themselves to be complimentary is with Atkinson and Shirffons’ Multi-store model of memory. One of the key ideas of this theory is that for information to be transferred from the Short-term memory (STM) to the Long Term Memory (LTM), the information has to go through a rehearsal loop. The primary evidence for this theory comes from laboratory experiments, which display the primary and recencey effects. However the case study of Clive Wearing has also provided further support for this theory. Clive Wearing suffered extensive brain damage, and so only has a ‘7 second memory’. As a result he is unable to form new LTMs, as he cannot retain the information long enough for it to enter the LTM. This is an example where the two approaches have both contributed to a theory, and thus demonstrated that perhaps it is best that the two approaches are considered complimentary, rather than competing.


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