Originally prepared by: Greg Machek (fall 2003)

Revised: Summer 2006

Outline (back to top)

Brief History of the Measurement of Intelligence

Characteristics of Individually Administered IQ Tests

The Testing Process

Final Thought

Brief History of the Measurement of Intelligence (back to outline)

The pursuit of an efficient and accurate way to compare cognitive abilities in humans is not new. As long ago as 2200 B.C., Chinese emperors used large-scale “aptitude” testing for the selection of civil servants, and stories such as that of the Wild Boy of Averyon, in the 18th century, have captured our imagination regarding the relative difference between “normal” and “abnormal” intellectual growth. By the end of the 19th century, the foundation was laid for how we assess intelligence today. For example, Sir Francis Galton sought to predict individuals’ intellectual capacity through tests of sensory discrimination and motor coordination. Although his belief that such capacities were necessarily correlated with intelligence was eventually determined to be unfounded, he ushered in an age of individual psychology and the pursuit of measuring intelligence by quantifying traits assumed to be correlated.

Shortly thereafter, Alfred Binet and Theodore Simon published what could be considered the precursor of most modern-day intelligence measures. Although their main purpose at the time was to diagnose mental retardation, the basic characteristics of their assessment are still used in today’s intelligence tests. For example, the Binet-Simon Intelligence Scales (1905) presented items in order of difficulty, and took into consideration the typical developmental abilities of children at various ages. The test also had fairly standardized instructions for how it was to be administered.

Characteristics of Individually Administered IQ Tests (back to outline)

Intelligence tests are also sometimes called “potential-based assessments” because they provide an educated guess as to how well an individual may be expected to perform in school.  In fact, there is much statistical data evidencing the power of such tests to predict future scholastic achievement. Discussions about this data can often be confusing due to the technical wording and procedures that these tests use. It may help to briefly explain some basic characteristics common to most, if not all, potential-based assessments.
Most potential-based assessments are standardized. Standardized tests have a straightforward set of criteria that the examiner must follow. These criteria dictate the way that the test is administered as well as scored; the wording of questions, what responses are acceptable, etc. The goal of standardization is to control all of the elements involved in the testing process with the exception of the child’s responses. The standardization can even extend to instructions about the testing environment, such as where the test should take place and who can be present.
Many potential-based tests are also norm-referenced. When a standardized test is normed, it means that it was initially administered to a large number of children, usually in the thousands. Ideally, this norm group is characteristic of the children who ultimately will be taking the standardized instrument. When looking at results from such a test, there exists a degree of confidence in comparing an individual’s scores to the scores of other people of  the same age. In this way it is possible to say how well a person performed relative to his peers.
It is also useful to understand the way in which scores from common standardized measures are represented. On a norm-referenced test, scores show where an individual’s results fall in relation to all other results obtained. Standardized measures are designed so that the scores of the norm group, which is selected so that it has people of all types of abilities, are distributed like a bell or normal curve.  The curve is largest in the middle because most people perform somewhere near the average. The distribution is much smaller to the left and the right, signifying that fewer students have exceptionally low or high scores. Standardized tests use standard scores to report results.  IQ tests use the number 100 to designate average scores and tend to use a smaller range of numbers to represent the total range of possible scores on the measure.
Fortunately, almost all scores are also given with their corresponding percentile ranks. This simplifies matters. For example, if you are told that a student obtains a score that falls at the 50th percentile, it means that his score is the same as the average score for all of the same-aged peers that also took that test. Hypothetically, percentiles tell you where an individual’s score ranks relative to other people who took the test. If a person’s score falls at the 99th percentile, it can be said that she would score as well or better than 99 out of 100 of her same-aged peers on that particular measure. Percentiles are unevenly distributed in the normal curve owing to the larger number of scores that are closer to the mean (average). Standard scores, however, are evenly spaced.

The Testing Process (back to outline)

The latest versions of the two most widely used tests are the Stanford-Binet-5 (SB5) and the Wechsler Intelligence Scale for Children—Fourth Edition® (WISC-IV®). Table 1 shows a list of some of the more commonly used intelligence measures. Note that some of these are “nonverbal” instruments. These tests rely on little or no verbal expression and are useful for a number of populations, such as non-native speakers, children with poor expressive abilities, or students with loss.

Table 1:

Test Age Range Description
Stanford-Binet Intelligence Scale, Fifth Edition (SBIS-V) 2 – 90+ An update of the SB-IV. In addition to providing a Full Scale score, it assesses Fluid Reasoning, Knowledge, Quantitative Reasoning, Visual-Spatial Processing, and Working Memory as well as the ability to compare verbal and nonverbal performance.
Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) 6 – 16-11 An update of the WISC-III, this test yields a Full Scale score and scores for Verbal Comprehension, Working Memory, Perceptual Reasoning, and Processing speed.
Woodcock-Johnson III Tests of Cognitive Abilities 2 – 90+ This test gives a measure of general intellectual ability, as well as looking at working memory and executive function skills.
Cognitive Assessment System (CAS) 5 – 17 Based on the “PASS” theory, this test measures ‘Planning, ‘Attention, ‘Simultaneous, and ‘Successive cognitive processes.
Wechsler Adult Intelligence Scale (WAIS) 16 – 89 An IQ test for older children and adults, the WAIS provides a Verbal, Performance, and Full Scale score, as well as scores for verbal comprehension, perceptual organization, working memory, and processing speed.
Comprehensive Test of Nonverbal Intelligence (CTONI) 6 – 18-11 Designed to assess children who may be disadvantaged by traditional tests that put a premium on language skills, the CTONI is made up of six subtests that measure different nonverbal intellectual abilities.
Universal Nonverbal Intelligence Test (UNIT) 5 – 17 Designed to assess children who may be disadvantaged by traditional tests that put a premium on language skills, this test is entirely nonverbal in administration and response style.
Kaufman Assessment Battery for Children (KABC) 2-6 to 12-5 This test measures simultaneous and sequential processing skills, and has subscales that measure academic achievement as well.

Following is information that will help parents understand the process children go through when taking such tests.

Not an Ordinary “Test”
Since IQ tests do not directly assess the same things that are taught in the classroom, it is difficult to “study” for them. Instead, preparation should probably consist of a good night’s rest. In addition, it is sometimes necessary to put a child at ease as to the expectations of the session. Since children usually think of tests as something that they can do “well” or “poorly” on, it may be appropriate to explain that the test they will be taking is different. IQ tests can be described as ones that aren’t concerned with “passing” and “failing.” It should be explained that the test aims to get a better understanding of a child’s unique abilities in a wide variety of areas.

Tasks Involved
In order to get a fuller understanding a child’s abilities, intelligence tests require him to perform a number of tasks that vary widely in what they are asking. For example, one task, often referred to as a subtest, may ask the child to answer questions about everyday knowledge. Another subtest may ask him or her to construct specific patterns of colored beads or blocks. Other subtests may tap into the child’s ability to recognize similarities between concepts or written symbols. The main idea is to measure many different abilities that may contribute to overall intelligence.

As Pleasant an Experience as Possible
Ideally, the actual testing session takes place in a room that is comfortable in environment and atmosphere.. The test administrator for most major intelligence tests is required to be a trained professional. This person is often a licensed school psychologist. The psychologist and the child are usually the only people in the room during testing. One of the most important aspects of the testing session is for a comfortable rapport to be established before testing takes place. If the student is rushed right into a novel, and possibly intimidating, task, her performance may suffer. The examiner must also be adept at dealing with a variety of different personalities and student characteristics, and be responsive to their needs during testing (e.g. allowing bathroom breaks, recognizing when fatigue has set in, etc.).

Probable Length of Testing
The time it takes to complete an individually administered intelligence test can vary depending on a child’s age, response style, and the amount of questions he answers acceptably. The questions on most subtests are designed to increase in complexity. For this reason, younger children will tend to “max” out more quickly than older students. In addition, more reticent or reflective students will tend to take longer. Whereas some subtests are timed, others allow ample time for the respondent to think through his answer before responding. On average, one should expect a single administration of such an instrument to take an hour and twenty minutes, give or take twenty minutes.

Reporting Irregularities
Since these tests are standardized, the examiner is obligated to adhere to the strict training that accompanies them. Any time that there are circumstances or variables that may impinge on the results of a test, the examiner is required to report this in her report on the testing session. For example, if a student appears overly guarded and shy, and this behavior may have kept him from answering correctly or with confidence, this should be noted. Likewise, if for some reason the climate in the room is not acceptable (overly hot, cold, dark, etc.), there is an obligation to report these situations. The examiner may decide that the irregularities were such that the assessment results are invalid.

Final Thought (back to outline)

Standardized intelligence tests have incurred some criticism (see our related Hot Topic: The Role of Standardized Intelligence Measures in Testing for Giftedness for a partial list). However, due to their long history, and the amount of work that has gone into them, they are a fairly reliable measure of expected school achievement. It is important to have some idea of their basic characteristics, as well as components of the testing process if you, or your children, will be coming in contact with such procedures.

For further reading:

Sattler, J. M. (1992). Assessment of children: Behavioral and clinical applications, Third Edition. Jerome M. Sattler, Publisher, Inc.: San Diego.
Sattler, J. M. (2002). Assessment of children: Behavioral and clinical applications, Fourth Edition. Jerome M. Sattler, Publisher, Inc.: San Diego.

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