Child Development

participate in their social, intellectual, and cultural
worlds. However, the term ‘‘development’’ is properly
applied across the entire lifespan and can also refer
to changes that are regressive rather than progres-
sive. For example, the reduction in visual acuity that
results from aging of the structures of the eye can also
be considered a developmental change.

Development can occur gradually and incremen-
tally (quantitative change) or involve stagelike transi-
tions (qualitative change). The term itself is neutral in
reference to whether the root cause is environmental
or genetic, although different theories of develop-
ment ascribe different roles to these interacting
forces.

See also: MILESTONES OF DEVELOPMENT; THEORIES
OF DEVELOPMENT

Bibliography
Bronfenbrenner, Urie. The Ecology of Human Development: Experi-
ments by Nature and Design. Cambridge, MA: Harvard Univer-
sity Press, 1979.
Reber, Arthur S. The Penguin Dictionary of Psychology. New York:
Penguin Books, 1985.
Liesette Brunson

DEVELOPMENTAL DISABILITIES

The term ‘‘developmental disabilities’’ includes all
mental and physical impairments or combination of
mental and physical impairments that (1) occur be-
fore a person is twenty-two years old; (2) are expected
to continue indefinitely; (3) result in limitations in
one or more areas of development such as physical,
cognitive, behavioral, emotional, or social develop-
ment; and (4) reflect a child’s need for individualized
services or treatment in school or community-based
settings. Developmental disabilities is a generic term
that includes medical or diagnosed conditions such as
Down syndrome and cerebral palsy that have a known
biological, genetic, or neurological cause. In addition,
children with developmental disabilities may be de-
layed in attaining developmental milestones such as
walking and talking for reasons that are unknown or
thought to be related to environmental conditions
such as poverty. Examples of common broad catego-
ries of developmental disabilities include mental re-
tardation, autism, and learning disabilities.

See also: DEVELOPMENTAL NORMS; MILESTONES OF
DEVELOPMENT

Bibliography
Batshaw, Mark, and Yvonne Perret. Children with Disabilities: A Med-
ical Primer, 3rd edition. Baltimore: Brookes, 1992.
Gallimore, Ronald, Lucinda Bernheimer, Donald MacMillan, Deb-
orah Speece, and Sharon Vaughn, eds. Developmental Perspec-
tives on Children with High-incidence Disabilities. Mahwah, NJ:
Erlbaum, 1999.

Levine, Melvin, William Carey, and Allen Crocker, eds. Develop-

mental-Behavioral Pediatrics, 3rd edition. Philadelphia: Saun-

ders, 1999.

Thurman, S. Kenneth, and Anne Widerstrom. Infants and Young

Children with Special Needs: A Developmental and Ecological Ap-

proach, 2nd edition. Baltimore: Brookes, 1990.

Marjorie Erickson Warfield

DEVELOPMENTAL NORMS

Developmental norms are defined as standards by

which the progress of a child’s development can be

measured. For example, the average age at which a

child walks, learns to talk, or reaches puberty would

be such a standard and would be used to judge wheth-

er the child is progressing normally. Norms have also

been used as a basis for the ‘‘ages and stages’’ ap-

proach to understanding child development, made

famous most notably by Yale University pediatrician

and educator Arnold Gessell and University of Chica-

go educator Robert Havighurst. In using the idea of

norms, Havighurst presented a set of developmental

tasks tied closely to what behavior one might observe

at what age. These sets of developmental tasks be-

came a tool for teachers to use to help judge the ap-

propriateness of certain types of curriculum for

children of certain ages or developmental levels.

While norms are usually thought of as being age-

related, norms can also be tied to other developmen-

tal variables such as race, ethnicity, and sex.

See also: MILESTONES OF DEVELOPMENT; STAGES OF

DEVELOPMENT

Bibliography

Leach, Penelope. Your Baby and Child: From Birth to Age Five. New

York: Knopf, 1997.

Schaefer, Charles E., and Theresa Foy Digeronimo. Ages and Stages:

A Parent’s Guide to Normal Childhood Development. New York:

Wiley, 2000.

Neil J. Salkind

DEWEY, JOHN (1859–1952)

John Dewey was born in Burlington, Vermont, to Ar-

chibald Sprague and Lucina Rich Dewey. He graduat-

ed from the University of Vermont in 1879 and then

worked for three years as a high school teacher, focus-

ing primarily in the areas of the classics, the sciences,

and algebra. Dewey was also an assistant principal

and principal before becoming a graduate student in

philosophy at Johns Hopkins University in 1882. He

earned his Ph.D. in 1884.

Dewey taught philosophy at the University of

Michigan for ten years (1884–1894) before moving to

the University of Chicago, where he was chairman of

120 DEVELOPMENTAL DISABILITIES