Definition of a psychological instrument
The following definition of a psychological instrument was developed by the APS Test and Testing Expert Group and endorsed by the APS Test Publishers and Suppliers Consultative Group (consisting of representatives of test publishers and suppliers in Australia). With regard to the definition, the term “psychological instrument” is used to refer to what may traditionally have been regarded as psychological tests but also includes other forms of psychological assessment such as personality inventories that are not appropriately regarded as “tests” but do provide important psychological information about individuals.
A further point that the Test and Testing Expert Group addressed is the important distinction between psychological instruments and psychometric instruments. The position adopted is that most psychological instruments have sound psychometric properties and hence can be regarded as psychometric instruments. There are other tests that also have these properties but are not regarded as psychological tests. These include tests that tap into other domains (e.g., instruments measuring language development that are used by speech pathologists) and tests that may be regarded as tapping into behavioural domains but not at a level that requires a full training in psychology to interpret the results meaningfully.
The characteristics of a psychological instrument
From consideration of the literature it is evident that there is no brief definition of “a psychological instrument”, and certainly not one that would adequately capture the essence of what constitutes a psychological instrument. Thus the definition is provided with reference to the characteristics of a psychological instrument. These are set out below.
A psychological instrument:
- is based on a test theory (e.g., classical; item response theory)
- draws upon psychological theory or theories and hence requires in depth knowledge of psychological theory to interpret the results meaningfully in context
- has sound psychometric properties including reliability and validity
- has an explicit empirical mechanism for interpreting an individual's scores, such as: population norms; criteria for determining clinical significance; and criteria for categorising individuals
- requires standardised administration and scoring procedures to be followed
- provides a basis to draw inferences about broader underlying behaviours and attributes from a sample of behaviour.
Test and testing resources
Psychological testing is undertaken by psychologists for a range of reasons to obtain information from individuals, groups and organisations. Testing is generally undertaken in the wider context of assessment that includes interviews and observations, as well as formal testing.
You will find a range of psychological testing guidelines, standards and resources for psychologists on the APS Resource Finder.