Psychological tests are tools. Like all tools, their effectiveness depends on the knowledge, skill, and integrity of the user. Like a hammer, which can be used as a tool to build or as a weapon to assault, psychological tests can be used for positive purposes or they can be abused. Even though they have limitations, tests of intelligence are among psychology's most widely used tools.

To be effective, intelligence tests should be used in conjunction with other information about an individual. For example, an intelligence test alone should not determine whether a child is placed in a special education or gifted class. The child's developmental history, medical background, performance in school, social competencies, and family experiences should also be taken into account.

The single number provided by many IQ tests can easily lead to stereotypes and false expectations (Rosenthal Jacobsen, 1968; Rosnow Rosenthal, 1996). Many people do not know how to interpret the results of intelligence tests, and sweeping generalizations are too often made on the basis of an IQ score.

For example, imagine that you are a teacher in the teacher's lounge the day after school has started in the fall. You mention a student-Johnny Jones-and a fellow teacher remarks that she had Johnny in class last year; she comments that he was a real dunce and points out that his IQ is 78. You cannot help but remember this information, and it might lead to thoughts that Johnny Jones is not very bright so it is useless to spend much time teaching him.

Ability tests can help a teacher group together children who function at roughly the same level in math or reading so they can be taught the same concepts together. However, extreme caution is necessary when test scores are used to place children in such tracks. Periodic assessment of group members, especially children in the "low" group, is required. Ability tests measure only current performance. Maturational changes or enriched environmental experiences may boost a child's intelligence score, indicating that she should be moved to a higher-level group.

Despite their limitations, when used judiciously by a competent examiner, intelligence tests provide valuable information about individuals. There are not many alternatives to these tests. Subjective judgments about individuals simply reintroduce the bias the tests were designed to eliminate.