Terms used in this section. All links are to external websites to help you find additional information on each.
There are a variety of measures for directly assessing cognition in children and adults.
For infants and toddlers, the Mullen Scales (Mullen Scales of Early Learning), the Bayley-III (Bayley Scales of Infant Development, Third Edition), or the M-P-R (Merrill-Palmer-Revised Scales of Development) all provide normative information. Each instrument has pros and cons, with the Mullen Scales and M-P-R having the advantage of providing cognitive scores based entirely on nonverbal abilities.
The Mullen Scales and the M-P-R can also be used with preschool children, although the SB-5 (Stanford-Binet Intelligence Scales, Fifth Edition) and the DAS-II (Differential Ability Scales, Second Edition) are often preferred, as they cover a much wider age range from preschool to adults: Ages 2–85 for SB-5 and ages 2 ½–18 for DAS-II (Differential Ability Scales, Second Edition). Both provide separate scores for verbal and nonverbal reasoning, and the wide age range of the SB-5 makes it particularly useful with older individuals who function within the lower levels of ability.
The Leiter-R (Leiter International Performance Scale, Revised) is an entirely nonverbal measure of cognition for individuals from preschool to adults, making no demands on either receptive or expressive language. For more able individuals, there are different versions of the Wechsler scales, with separate versions for young children 2 ½–7 years (Wechsler Preschool and Primary Scale of Intelligence, Third Edition), children through early adolescence 6–16 (Wechsler Intelligence Scale for Children, Fourth Edition) and adults (Wechsler Adult Intelligence Scale, Fourth Edition), as well as the KABC-II NU (Kaufman Assessment Battery for Children, Second Edition) for ages 3–18. The Wechsler scales provide separate scores for verbal and nonverbal reasoning while the KABC-II NU yields a nonverbal composite and is designed to minimize verbal instructions and responses.