Lewis M. Terman provides a complete manual and theoretical explanation for the Stanford revision and extension of the Binet-Simon intelligence scale. The author addresses the significant problem of educational and vocational misplacement, demonstrating how traditional methods of judging intelligence through offhand observation or academic success are fraught with error. He argues that mental tests are indispensable for identifying retarded children, high-grade defectives, delinquents, and exceptionally gifted individuals.
The volume details the historical development of the Binet method and its core innovations, particularly the use of age norms to establish mental age and the intelligence quotient. Terman explains that general intelligence is not a single faculty but a combination of adaptive thought processes, involving the capacity to maintain a direction, make adaptations, and exercise auto-criticism. He presents extensive empirical data gathered from thousands of unselected children and adults to prove the reliability and validity of the standardized scale.
The text thoroughly covers the distribution of intelligence across the population, showing that mental ability follows a symmetrical curve without sharp dividing lines between normality and deficiency. Terman analyzes the relationship between intelligence quotients and school progress, revealing that bright children are frequently held back by an educational lockstep while dull children are promoted beyond their actual capabilities. He also examines sex differences, social class variations, and the vocational significance of mental measurement.
The second half of the book serves as a meticulous manual for examiners. It outlines general instructions for securing attention and rapport, avoiding fatigue, and administering the tests uniformly. Detailed instructions are provided for every year group from three years to superior adult, specifying the exact procedure and scoring standards for dozens of individual tests ranging from sensory discrimination and memory to abstract definitions and the interpretation of fables.
Ultimately, the work establishes psychological testing as an objective and hygienic necessity for public education, penal institutions, and vocational guidance. Terman concludes that recognizing an individual's true level of intelligence allows society to replace punishment and guesswork with rational treatment, ensuring that all intellects can be guided toward tasks commensurate with their native ability.
