This is the age at which a child is described according to his or her intelligence. Mental age (MA) can be higher or lower than a child’s biological age, but generally, intelligence is thought to increase as a child’s biological age increases. In other words, mental age is the level of a person’s mental ability. It is based on the age required for an average person to reach the same level of intelligence. Often, standardized intelligence tests are used to measure mental age.
In 1905, French psychologist Alfred Binet first defined mental age and introduced intelligence tests. Along with his student Theodore Simon, he developed the Binet Scale, which is the basis of the Stanford-Binet test. This test measures intelligence using five factors of cognitive ability. These factors are knowledge, fluid reasoning, working memory, visuospatial processing, and quantitative reasoning. This test measures nonverbal and verbal responses. Each of these five factors is given a weight and these composite scores are usually condensed into a ratio known as IQ or intelligence quotient.
If a child’s actual age is the same as his mental age, he has an IQ of 100, which refers to average intelligence. However, if a 10-year-old scores 130 on an IQ test, his mental age is 13 (the average age-appropriate score is 100; thus, MA = (130/100) × 10 = 13). Since the average mental age of adults does not increase after the age of 18, the actual age of the adult taking the IQ test is 18.
Early versions of the Stanford-Binet test calculated a child’s mental age based on his performance on the test. But the concept of mental age is quite controversial. Proponents of the mental age theory argue that although children develop intellectually at different rates, their intellectual developmental paths are essentially the same. They also believe that mental age is of little significance to adults, whose intelligence changes slightly from year to year.
Opponents of mental age disagree with this concept, arguing that intellectual development does not follow a straight line. They say that some people may develop specific intellectual abilities more quickly than other intellectual skills. For example, a 15-year-old may be able to comprehend advanced college-level math, but read well below his grade level. Even intelligence tests have sparked much controversy about what types of mental abilities make up intelligence and whether IQ adequately represents those abilities.
Some also argue that the process of constructing and standardizing such tests is culturally biased. Many critics argue that intelligence tests favor students from affluent backgrounds and discriminate against those who are less socially, ethnically, or racially privileged. As a result, psychologists have attempted to design culturally irrelevant tests that truly reflect the innate abilities of students. One such test is the Johns Hopkins Perceptual test, devised by Leon Rosenberg in the early 1960s, which assesses the intelligence of preschoolers by having them try to match random forms. It avoids ordinary geometric shapes such as squares, circles, and triangles because some children may be more familiar with them than others.