What is Psychometric Testing?
Psychometric testing falls into three main categories:
- Ability testing
- Aptitude testing
- Personality questionnaires
Ability tests measure a person's potential, for instance to learn the skills needed for a new job or to cope with the demands of a training course. Ability tests are not the same thing as Tests of Attainment.
Tests of attainment assess specifically what people have learnt e.g. mathematical knowledge or typing skills. Of course what people have learned does depend on their ability in that domain in the first place, so the scores on the two types of test are conceptually linked.
The major difference between tests of ability and tests of attainment is in the way the scores from both types of test are used. Many ability test items look identical to those on attainment tests but attainment tests are different in one crucial respect - they are retrospective: they focus on what has been learnt and on what a person knows and can do now. Ability tests are prospective: they focus on what the person is capable of achieving in the future or their potential to learn. Bear in mind that some attainment is required before certain abilities can be measured, for instance, we need a certain knowledge of mathematics before our numerical ability can be measured. In addition a test of attainment cannot be used to directly infer ability. School examinations are one example of measures of achievement or attainment, and while we might draw some conclusions about an individual's ability on the basis of GCSE results we would not use them as a direct measure of ability since a less able student may work harder than a more able student to produce a better score.
General ability is usually divided up into specific abilities, reflecting the hierarchical structure of intelligence that is generally accepted by most workers in the field. So a general ability test might be composed of specific numerical, verbal and spatial ability scales brought together as a test battery. They can then be scored and interpreted individually as a specific ability or aptitude measure, or together as part of a general ability measure.
There is no widely accepted definition of the difference between ability and aptitude. Most people would agree that to some extent the two terms refer to the same thing: aptitude referring to specific ability, and ability referring to general aptitude. We could probably view ability as underlying aptitude, and aptitude as being more job related then ability. For instance a computer programmer might score highly on a verbal ability test and highly on a programmer aptitude test but not the other way around.
Aptitude tests tend to be job related and have names that include job titles such as the Programmers Aptitude Series (SHL). Ability tests on the other hand are designed to measure the abilities or mental processes that underlie aptitude and are named after them e.g. Spatial Ability - GAT (ASE). We have also mentioned that ability tests can be either general or specific in focus. An ability test such as the General Ability Test (GAT) is made up of four tests of specific ability - numerical ability; verbal ability; non-verbal ability and spatial ability. They can be used separately to assess specific abilities or together to assess general ability. There are tests which measure only general ability such as the Standard Progressive Matrices (which is one of the purest measures of general ability available) and there are tests which only measure specific abilities such as the ACER Mechanical Reasoning Test. You will find with experience that some tests fall into more than one category and that the distinction between the various categories is not always an easy one to define.
Personality is a term which is commonly used in everyday language but which has been given a particular technical meaning by psychologists. When we discuss personality we must remember that it is not a single independent mechanism but closely related to other human cognitive and emotional systems.
Before we go onto discuss what exactly personality is it might be useful to just consider what personality is not.
Personality is not the same thing as motivation which is goal directed behaviour designed to satisfy needs, interests and aspirations. Motivation is related to personality in that while personality may represent the way we behave motivation represents the why. Exactly how the underlying motives of behaviour are conceptualised depends very much on the school of thought to which one belongs, for instance a humanist might see the motivation behind behaviour as coming from a desire to achieve ones full potential whereas a psychoanalyst might look for unconscious motivations to do with unfulfilled sexual needs.
Personality is not the same thing as culture which is the values, attitudes and beliefs we share with others about the nature of the world.
Personality is not the
same thing as ability (usually held to be synonymous with
intelligence) which is the ability to identify, understand and
absorb the different components of a problem. Then to identify
the way they are related to each other and the logical
consequence of these relationships to work out the next step.
A Definition of Personality
We can define personality as -
those relatively stable and enduring aspects of an individual which distinguishes them from other people, making them unique, but which at the same time permit a comparison between individuals.
It is more useful to view personality not as something we have but rather as being to do with how we relate to the world, this is something which is rendered explicit in Goodstein and Lanyon's (1975) definition of personality as being -
the enduring characteristics of the person that are significant for interpersonal behaviour.
Within this general definition a number of different theoretical approaches exist:
- The Psychometric approach (Eysenck and Cattell).
- The Psychodynamic approach (Freud, Jung, Adler).
- The Social Learning approach (Mischel, Bandura).
- The Humanistic approach (Maslow, Rogers).
These approaches to personality are theoretically very different and such a diversity of different theories exist because personality is a hypothetical construct which can never be directly observed but only inferred from behaviour.
A History of Test Development
Attempts to measure differences between the psychological characteristics of individuals can be traced back to 400 BC when Hippocrates attempted to define four basic temperament types each of which could be accounted for by a predominant body fluid or humour; blood - sanguine (optimistic), black bile - melancholic (depressed), yellow bile - choleric (irritable) and phlegm - phlegmatic (listless and sluggish). Hippocrates' methods and the numerous other attempts that have been made since then were hardly scientific. The first attempt to scientifically measure the differences between individual mental abilities was made by Sir Francis Galton in the 19th Century who tried to show that the human mind could be systematically mapped into different dimensions. He studied, among other things, how people differed in terms of their ability to discriminate between stimuli and by collating the results he obtained he devised a system which would allow an individual's abilities to be compared to those of others - an idea on which we rely heavily today.
From the work of people like Galton and his French contemporary, Binet, a picture of the human mental domain emerged which saw general human ability as being composed of a number of specific abilities - a view which is still held today. The basic tenet of testing nowadays is based upon the principle of measuring human mental performance under different conditions and then making comparisons between people. Of course, the statistical rigour with which this is done today is much greater than was generally applied in Galton's day. There is a bewildering array of tests available to us measuring anything form hand-eye co-ordination to high level cognitive operations such as spatial reasoning.
How Are Psychometric Tests Constructed?
In it's simplest form a test will have a set of questions or tasks for the subject to complete, these are known as test items. Unfortunately, the layman associates the everyday use of the word 'test' with an examination which you either pass or fail. In the context of psychological testing the tools used are not generally viewed in this way, usually they are more concerned with describing rather than judging a person's abilities or aptitudes. It is the case however that most lay-people will view the word 'test' with some trepidation and it is difficult to convince them that their abilities or aptitudes are not 'on trial'. For this reason it is important that you avoid the use of the word test wherever possible; use the term assessment instead and describe the tests themselves as instruments. This becomes especially important in the case of personality assessment which is purely descriptive and where any implication of a good or bad personality, or a pass/fail mark on a test can prove seriously damaging to the individual. When we use the word test in this training manual it is in the technical sense and not the everyday sense.
All tests should come with a test manual which will contain information on how to carry out a standardised administration of the instrument as well as its technical specifications. The manual should always be carefully and thoroughly scrutinised before a decision is made on whether or not to use a particular test. The manual should include information about the test's reliability i.e. how stable or consistent a measure the test is, and the strength of its validity i.e. how well it actually measures what it claims to measure. (Note that validity depends on reliability and that a test cannot be more valid than it is reliable). The manual should also say something about the nature of the group of people on whom the test was standardised which will allow us to see how a person's performance on a particular test compares with that of other people. Sometimes information is presented on the performance of more than one type of group - this is because while it would be unfair to compare the performance of a school leaver on a particular test with that of a group of graduates it would not be unfair to compare his performance with that of a group of similar school leavers. Information about the groups with whom the test has been standardised is known as normative information.
The reason we need all of this information is that what psychological tests measure, such as numerical ability, cannot be directly observed and therefore cannot be directly measured. Something like numerical ability can only be inferred from the behaviour of the individual and as such is a hypothetical construct. For the same reason, exactly how much ability we can infer an individual has in a particular ability domain on the basis of a test score is seldom clear. What is important is that you go beyond the simple appearance of the test items into the technical details of the test construction and rationale. It is unacceptable to simply make a superficial inspection of an instrument's surface characteristics - many of the questionnaires we see in newspapers and magazines with titles such as 'test your word power' or 'how attractive are you to women' seem plausible enough and if presented in an attractively packaged set complete with manual might seem to be highly sophisticated and well designed instruments when in fact they are not and only look as though they are.