Many definitions have been offered for the construct of intelligence. The ability to solve problems and to learn and retain new information is probably as good a definition as any.

***** WAIS-III *****

***** WAIS-R *****

The WAIS-R reports Verbal, Performance and Full Scale IQ scores. These IQ scores are ratio IQs, meaning that for each age group the mean is set at 100 and standard deviation 15. Subjects are always compared with others in their age group, and IQ scores accordingly reflect relative performance within one's age group.

The manual reports standard error of measurements for each of the three IQ scores by age group. The average SEM for Verbal IQ is 2.74, for Performance IQ 4.14, and for Full-Scale IQ 2.53. This author, rather arbitrarily, recommends using five as an SEM for all three IQ scores. There is probably more error/noise in IQ scores reported from the field, and this extends the likely range of a true IQ for any score observed on testing.

There are 11 subtests on the WAIS-R, and each has a mean of 10 and standard deviation of 3. The subtests can be interpreted in addition to the three IQ scores, but in doing so be sure to use the age normed scaled scores. These are reported in a separate column, and always in parentheses. They are different from the scaled scores used to calculate IQs. Scores on the subtests are less reliable than IQ scores because they are based on fewer items, and interpreting them should take this into account.

***** Other IQ Tests *****

Any other test claiming to measure intelligence must establish concurrent validity with the WAIS-R This is because the WAIS-R is the instrument most widely recognized as having validity for the construct of intelligence. Some other tests of intelligence are the Slosson Intelligence Test-R, Revised Beta Examination (Beta-2), and Haptic Intelligence Scale for the Adult Blind. The G aptitude on the he GATB is also a general measure of intellectual ability.

Intelligence may be thought of as a global aptitude. Tests of aptitude are designed to measure more specific or focused areas that predict the likelihood to learn and master knowledge or skills needed for success in some vocation. Their purpose is to predict how successful an individual will likely be at learning different aspects of what a formal training program, or some other method, will try to teach them. They differ from achievement test which measure how much was actually learned -- after the training was received.

An aptitude test that many rehabilitation counselors take is the Graduate Record Examination (GRE). This test is designed to predict how much students will learn and how easily they will master materials presented to them in a graduate program. Higher scorers should learn more easily and with less effort, and for the same effort as invested by lower scorers, come away with more knowledge and skills. The examinations taken in their courses are achievement tests, as is the examination many readers are reviewing for -- the CRC Examination.

The aptitude test battery that is probably the most widely used by rehabilitation counselors is the General Aptitude Test Battery (GATB). GATB scores have a mean of 100 and standard deviation of 20. This instrument was developed by the U. S. Department of Labor, and it is used by state employment offices and in many rehabilitation sites.

The achievement testing most relevant in rehabilitation counseling is measuring the general educational development (GED) rather than acquired vocational skills of a client. One of the most widely used measures of GED is the Wide Range Achievement Test-Revised (WRAT-R). This test measures reading, spelling and basic arithmetic achievement which may be critically important in a training program. If a training program, for example, is using a text written at an 8th grade level, the rehabilitation counselor needs to know if his client has achieved that level of reading mastery.

Personality tests differ from intelligence, aptitude and achievement tests in that there are no right or wrong answers. They are generally untimed, and what is most important is an honest self-report. Most personality tests, such as the MMPI-2, are psychometric instruments with standardized administration, scoring and norms. Some instruments, such as the Rorschach and Thematic Apperception Test, are impressionistic measures of personality. While there are systems for scoring responses given on these instruments, they are frequently used in an impressionistic rather than psychometric way.

The most widely used test for diagnosing psychopathology is the Minnesota Multiphasic Personality Inventory-2. This instrument has four validity scales (?, L, F & K) and ten basic clinical scales. All scores are reported as T-scores where the mean is 50 and standard deviation 10. Many additional scales have been developed using the 567 true-false items on the MMPI-2, and these are commercially available as well. The test can be hand scored or scored and interpreted by computer.

The basic use of the MMPI-2 is to diagnose psychopathology. Reports describe likely personality characteristics and interpersonal/relational difficulties that may result. The test identifies psychopathology by comparing subject responses on the true-false items with responses of subjects with known types of psychopathology. Scales are constructed on a statistical basis without regard to specific item content.

There are many personality tests on the market such as the Sixteen Personality Factors Questionnaire, California Psychological Inventory, Myers-Briggs Type Indicator, Personality Assessment Inventory, etc. Each has a somewhat different focus and administering a battery of tests usually produces the best picture of an individual's personality dynamics. Tests of personality are normally administered and interpreted by a clinical psychologist, and the rehabilitation counselor uses the information in rehabilitation planning.

Rehabilitation counselors normally distinguish three types of vocational interests:

(1) Expressed Interests -- What a client verbally states he or she would like to do.
(2) Manifest Interests -- Activities the client actually engages in and enjoys.
(3) Tested Interests -- Results obtained from interest inventories.

As with personality tests, there are no right or wrong answers to interest inventories. They generally ask subjects what they like and dislike, and relate these preferences to the world of work. Some interest inventories are more oriented toward college level occupations, others to trade and technical occupations, and accordingly the inventory selected needs to be appropriate for the client.

Interest inventories vary in complexity from very sophisticated instruments such as the Strong Vocational Interest Blank for Men and Women (SCII) that is only scorable by computer, and usually interpreted by the computer as well, to instruments that can be self-administered, scored and interpreted such as the Self-Directed Search (SDS).

Both of the above instruments are designed around John Holland's well known work environment/personality model. The six occupational environments identified by Holland and used on these instruments are: Social, Enterprising, Conventional, Realistic, Investigative, and Artistic. Holland believed that each work environment reflected a somewhat different orientation toward life in values, interests, preferred activities, and interpersonal relational styles. Individuals working in environments compatible with their personality style were more likely to be satisfied with their work. This model will be discussed further in the Review of Vocational Development Theories section.

There are many other interest inventories on the market, and some are designed for specific populations such as poor readers. Other widely used interest inventories include the Gordon Occupational Checklist, Wide Range Interest-Opinion Test (WRIOT), Kuder Occupational Interest Inventory, and Geist Picture Interest Inventory.