Psychological testing

Psychological testing is a field characterized by the use of samples of behavior in order to assess psychological construct(s), such as cognitive and emotional functioning, about a given individual. The technical term for the science behind psychological testing is psychometrics. By samples of behavior, one means observations of an individual performing tasks that have usually been prescribed beforehand, which often means scores on a test. These responses are often compiled into statistical tables that allow the evaluator to compare the behavior of the individual being tested to the responses of a norm group.

Psychological tests
A psychological test is an instrument designed to measure unobserved constructs, also known as latent variables. Psychological tests are typically, but not necessarily, a series of tasks or problems that the respondent has to solve. Psychological tests can strongly resemble questionnaires, which are also designed to measure unobserved constructs, but differ in that psychological tests ask for a respondent's maximum performance whereas a questionnaire asks for the respondent's typical performance. A useful psychological test must be both valid (i.e., there is evidence to support the specified interpretation of the test results ) and reliable (i.e., internally consistent or give consistent results over time, across raters, etc.).

It is important that people that are equal on the measured construct also have an equal probability of answering the test items correctly. For example, an item on a mathematics test could be "In a soccer match two players get a red card, how much players are left in the end?", however this item also requires knowledge on soccer to be answered correctly, not just mathematical ability. Group membership can also influence the chance on having items correct (differential item functioning). Often tests are constructed for a specific population, and this should be taken into account when administering tests. If a test is invariant to some group difference (e.g. gender) in one population (e.g. England) it does not automatically mean that it is also invariant in another population (e.g. Japan).

Psychological assessment
Psychological assessment is similar to psychological testing but usually involves a more comprehensive assessment of the individual. Psychological assessment is a process that involves the integration of information from multiple sources, such as tests of normal and abnormal personality, tests of ability or intelligence, tests of interests or attitudes, as well as information from personal interviews. Collateral information is also collected about personal, occupational, or medical history, such as from records or from interviews with parents, spouses, teachers, or previous therapists or physicians. A psychological test is one of the sources of data used within the process of assessment; usually more than one test is used. Many psychologists do some level of assessment when providing services to clients or patients, and may use for example, simple checklists to assess some traits or symptoms, but psychological assessment is a more complex, detailed, in-depth process. Typical types of focus for psychological assessment are to provide a diagnosis for treatment settings; to assess a particular area of functioning or disability often for school settings; to help select type of treatment or to assess treatment outcomes; to help courts decide issues such as child custody or competency to stand trial; or to help assess job applicants or employees and provide career development counseling or training.

Interpreting scores
Psychological tests, like many measurements of human characteristics, can be interpreted in a norm-referenced or criterion-referenced manner. Norms are statistical representations of a population. A norm-referenced score interpretation compares an individual's results on the test with the statistical representation of the population. In practice, rather than testing a population, a representative sample or group is tested. This provides a group norm or set of norms. One representation of norms is the Bell curve (also called "normal curve"). Norms are available for standardized psychological tests, allowing for an understanding of how an individual's scores compare with the group norms. Norm referenced scores are typically reported on the standard score (z) scale or a rescaling of it.

A criterion-referenced interpretation of a test score compares an individual's performance to some criterion other than performance of other individuals. For example, the generic school test typically provides a score in reference to a subject domain; a student might score 80% on a geography test. Criterion-referenced score interpretations are generally more applicable to achievement tests rather than psychological tests.

Often, test scores can be interpreted in both ways; a score of 80% on a geography test could place a student at the 84th percentile, or a standard score of 1.0 or even 2.0.

Types of psychological tests
There are several broad categories of psychological tests:

IQ/achievement tests
IQ tests purport to be measures of intelligence, while achievement tests are measures of the use and level of development of use of the ability. IQ (or cognitive) tests and achievement tests are common norm-referenced tests. In these types of tests, a series of tasks is presented to the person being evaluated, and the person's responses are graded according to carefully prescribed guidelines. After the test is completed, the results can be compiled and compared to the responses of a norm group, usually composed of people at the same age or grade level as the person being evaluated. IQ tests which contain a series of tasks typically divide the tasks into verbal (relying on the use of language) and performance, or non-verbal (relying on eye–hand types of tasks, or use of symbols or objects). Examples of verbal IQ test tasks are vocabulary and information (answering general knowledge questions). Non-verbal examples are timed completion of puzzles (object assembly) and identifying images which fit a pattern (matrix reasoning).

IQ tests (e.g., WAIS-IV, WISC-IV, Cattell Culture Fair III, Woodcock-Johnson Tests of Cognitive Abilities-III, Stanford-Binet Intelligence Scales V) and academic achievement tests (e.g. WIAT, WRAT, Woodcock-Johnson Tests of Achievement-III) are designed to be administered to either an individual (by a trained evaluator) or to a group of people (paper and pencil tests). The individually-administered tests tend to be more comprehensive, more reliable, more valid and generally to have better psychometric characteristics than group-administered tests. However, individually administered tests are more expensive to administer because of the need for a trained administrator (psychologist, school psychologist, or psychometrician).

Attitude tests
Attitude test assess an individual's feelings about an event, person, or object. Attitude scales are used in marketing to determine individual (and group) preferences for brands, or items. Typically attitude tests use either a Thurston Scale, or Likert Scale to measure specific items.

Neuropsychological tests
These tests consist of specifically designed tasks used to measure a psychological function known to be linked to a particular brain structure or pathway. They are typically used to assess impairment after an injury or illness known to affect neurocognitive functioning, or when used in research, to contrast neuropsychological abilities across experimental groups.

Personality tests
Psychological measures of personality are often described as either objective tests or projective tests. The terms "objective test" and "projective test" have recently come under criticism in the Journal of Personality Assessment. The more descriptive "rating scale or self-report measures" and "free response measures" are suggested, rather than the terms "objective tests" and "projective tests," respectively.

Objective tests (Rating scale or self-report measure)
Objective tests have a restricted response format, such as allowing for true or false answers or rating using an ordinal scale. Prominent examples of objective personality tests include the Minnesota Multiphasic Personality Inventory, Millon Clinical Multiaxial Inventory-III, Child Behavior Checklist, Symptom Checklist 90 and the Beck Depression Inventory. Objective personality tests can be designed for use in business for potential employees, such as the NEO-PI, the 16PF, and the OPQ (Occupational Personality Questionnaire), all of which are based on the Big Five taxonomy. The Big Five, or Five Factor Model of normal personality, has gained acceptance since the early 1990s when some influential meta-analyses (e.g., Barrick & Mount 1991) found consistent relationships between the Big Five personality factors and important criterion variables.

Another personality test based upon the Five Factor Model is the Five Factor Personality Inventory – Children (FFPI-C.).

Projective tests (Free response measures)
Projective tests allow for a freer type of response. An example of this would be the Rorschach test, in which a person states what each of ten ink blots might be.

Projective testing became a growth industry in the first half of the 1900s, with doubts about the theoretical assumptions behind projective testing arising in the second half of the 1900s. Some projective tests are used less often today because they are more time consuming to administer and because the reliability and validity are controversial.

As improved sampling and statistical methods developed, much controversy regarding the utility and validity of projective testing has occurred. The use of clinical judgement rather than norms and statistics to evaluate people's characteristics has convinced many that projectives are deficient and unreliable (results are too dissimilar each time a test is given to the same person). However, many practitioners continue to rely on projective testing, and some testing experts (e.g., Cohen, Anastasi) suggest that these measures can be useful in developing therapeutic rapport. They may also be useful in creating inferences to follow-up with other methods. The most widely used scoring system for the Rorschach is the Exner system of scoring. Another common projective test is the Thematic Apperception Test (TAT), which is often scored with Westen's Social Cognition and Object Relations Scales and Phebe Cramer's Defense Mechanisms Manual. Both "rating scale" and "free response" measures are used in contemporary clinical practice, with a trend toward the former.

Other projective tests include the House-Tree-Person Test, Robert's Apperception Test, and the Attachment Projective.

Sexological tests
The number of tests specifically meant for the field of sexology is quite limited. The field of sexology provides different psychological evaluation devices in order to examine the various aspects of the discomfort, problem or dysfunction, regardless of whether they are individual or relational ones.

Direct observation tests
Although most psychological tests are "rating scale" or "free response" measures, psychological assessment may also involve the observation of people as they complete activities. This type of assessment is usually conducted with families in a laboratory, home or with children in a classroom. The purpose may be clinical, such as to establish a pre-intervention baseline of a child's hyperactive or aggressive classroom behaviors or to observe the nature of a parent-child interaction in order to understand a relational disorder. Direct observation procedures are also used in research, for example to study the relationship between intrapsychic variables and specific target behaviors, or to explore sequences of behavioral interaction.

The Parent-Child Interaction Assessment-II (PCIA) is an example of a direct observation procedure that is used with school-age children and parents. The parents and children are video recorded playing at a make-believe zoo. The Parent-Child Early Relational Assessment (Clark, 1999) is used to study parents and young children and involves a feeding and a puzzle task. The MacArthur Story Stem Battery (MSSB) is used to elicit narratives from children. The Dyadic Parent-Child Interaction Coding System-II (Eyberg, 1981) tracks the extent to which children follow the commands of parents and vice versa and is well suited to the study of children with Oppositional Defiant Disorders and their parents.

Test security
Many psychological tests are generally not available to the public, but rather, have restrictions both from publishers of the tests and from psychology licensing boards that prevent the disclosure of the tests themselves and information about the interpretation of the results. Test publishers consider both copyright and matters of professional ethics to be involved in protecting the secrecy of their tests, and they sell tests only to people who have proved their educational and professional qualifications to the test maker's satisfaction. Purchasers are legally bound from giving test answers or the tests themselves out to the public unless permitted under the test maker's standard conditions for administration of the tests.