Stanford-Binet Intelligence Scales

The Stanford-Binet Intelligence Scales is one of the most popularly used measures of intelligence. Around 1905, Parisian Theophilus Simon, in his work with developmental psychologist Jean Piaget, speculated about the successes and failures of elementary school children. As Piaget was becoming increasingly intrigued by the nature of some normal children's failures to read, Simon was working with Alfred Binet to develop a test (for the school children of Paris) to predict and distinguish between those who would do well in school and those who would not.

The result of Simon and Binet's efforts was the first intelligence scale (1905) used to identify children who were mentally retarded (or those who were thought not to be able to succeed in school). The items were arranged by difficulty at first and later on by age level, so by 1916, the test results yielded a mental age (MA) for test takers, and a ratio of chronological age (CA) and mental age provided a measure of whether a child was behind, even with, or ahead of his or her chronological age. For example, someone who is chronologically 120 months (10 years) old may have a mental age of 126 months and therefore be advanced in mental age, compared with chronological age.

The Simon-Binet scale became the Stanford-Binet scale in the early 20th century, when Lewis Terman [Page 951](then at Stanford University) authored the authoritative book on the administration and scoring of the test. Also, the IQ score, a ratio of mental age to chronological age, was first used. For the 120-month-old with a mental age of 126 months,

If one's mental and chronological ages are equal, then one's IQ score is 100, just about what we expect if someone is average.

It was convenient to have one number, a simple ratio of MA to CA, to express one's theoretical intelligence quotient. But this approach was never really embraced because the upper limit depends on the upper age limit for the test. For example, if the items go up only to an age level of 21 years, anyone with a CA greater than 21 years has to have an IQ less than 100. This is in part why we no longer think of intelligence as IQ but use more descriptive and informative terms for describing someone's level of intelligence.

The fourth edition of the Stanford-Binet is now the standard, and it is the result of many revisions over the past 100 years. The test, based on the g theory of intelligence, assesses three different general areas or types of intelligence: crystallized intelligence, fluid intelligence, and short-term memory. In theory, these types are independent of one another.

Crystallized intelligence reflects knowledge that is acquired or learned, such as the number of elements on the periodical table or the author of Moby Dick. Fluid intelligence is that general ability that Charles Spearman talked about, including such activities as problem solving, remembering, and learning. A test item that evaluates fluid intelligence might ask the test taker to copy a pattern created by the test administrator.

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