Testing and the whole notion of individual difference is something that psychology has embraced, investigated and developed throughout its history.

Broadly speaking psychological testing can be defined as the use of one or more standardized measurement instruments, devices, or procedures including the use of computerized psychological tests, to observe or record human behaviour.

This is a useful definition insofar as it highlights the main purpose of psychological testing i.e. to observe or record human behaviour, but what it does not do is differentiate between the two main types of testing, namely projective testing and psychometric testing. Two very different types of testing that you need to be aware of.

Projective testing

The best-known projective psychological test is the Rorschach inkblot test and it dates back to 1921. Its named after the Swiss psychiatrist Hermann Rorschach. Hermann Rorschach had a great interest in psychoanalysis and in 1918 he began experimenting with inkblots with his own patients. Encouraged by what he found, he published his findings in 1921.

Rorschach always cautioned that his findings were preliminary and stressed the importance of much more experimentation; sadly he could not do much of this himself as he died the following year in 1922. Initially Rorschachs work received little attention but in time his inkblot test became a popular method of psychological evaluation.

During the assessment patients are shown a series of inkblots and are asked to to say the first thing that comes to mind. Because the stimulus is ambiguous, it is claimed that the patient must impose his or her own structure and in doing so they reveal their thoughts, feelings, and themes, some of which are unconscious and have been projected into the inkblot image. (hence the term projective testing)

Psychometric testing

The important thing to note about psychometric testing is that its governed by 3 key principles:

1. INDIVIDUAL DIFFERENCE

To what extent does the individual being tested differ from other individuals in relation to the ability, trait or construct in question?

2. TEMPORAL DIFFERENCE

To what extent does the same individual differ in relation to the ability, trait or construct in question when measured on different occasions?

3. STATISTICAL ADHERENCE

In order to make an informed judgement about an individual you must have a normative frame of reference in place in order to analyse the test result.

Put simply you need a benchmark so that you can compare the test score youre interested in with the scores obtained from a representative sample.

If youre serious about pursuing a career as a psychologist, there is a very good chance that you will have learn about and become comfortable with the statistical procedures associated with psychometric testing.

This statement alone is enough to make most people consider an alternative career path but dont be phased by the thought of statistics because the principles you need to come to terms (although extending beyond the confines of this discussion) are actually very straight forward. Honest!

If you'd like to find out more about psychological testing, you can do so by visiting http://www.all-about-forensic-psychology.com/psychological-testing.html