See also: APNEA; MILESTONES OF DEVELOPMENT
Bibliography
Anders, Thomas F., and Lisa A. Eiben. ‘‘Pediatric Sleep Disorders:
A Review of the Past Ten Years.’’ Journal of the American Acade-
my of Child and Adolescent Psychiatry 36, no. 1 (1997):9–20.
Carskadon, Mary A. ‘‘Patterns of Sleep and Sleepiness in Adoles-
cents.’’ Pediatrician 17 (1990):5–12.
Carskadon, Mary A., ed. Encyclopedia of Sleep and Dreaming. New
York: Macmillan, 1993.
Foulkes, David. Children’s Dreams: Longitudinal Studies. New York:
Wiley, 1982.
Kahn, André, Bernard Dan, José Groswasser, Patricia Franco, and
Martine Sottiaux. ‘‘Normal Sleep Architecture in Infants and
Children.’’ Journal of Clinical Neurophysiology 13, no. 3
(1996):184–197.
Mindell, Jodi A., Judith A. Owens, and Mary A. Carskadon. ‘‘Devel-
opmental Features of Sleep.’’ Child and Adolescent Psychiatric
Clinics of North America 8 (1999):695–725.
Sadeh, Avi, Amiram Raviv, and Reut Gruber. ‘‘Sleep Patterns and
Sleep Disruptions in School-Age Children.’’ Developmental
Psychology 36 (2000):291–301.
Wolfson, Amy R., and Mary A. Carskadon. ‘‘Sleep Schedules and
Daytime Functioning in Adolescents.’’ Child Development 69
(1998):875–887.
Mabel L. Sgan
Beverly J. Roder
SMILING
While people often think of smiling as only an indica-
tion that a child might find something funny, it is ac-
tually one of the most important forms of social
communication. Smiling appears within the first few
weeks of life as a response to a human voice and be-
comes a full-fledged social smile at about three
months of age. As a social behavior it encourages par-
ents to interact with developing infants and thereby
helps ensure the infant will be cared for as well as so-
cialized into the culture, which the parents represent.
In other words, it promotes bonding. Child develop-
ment specialists have studied smiling and have found
it to be a complex behavior that is integral to a child’s
healthy development. For example, the more infants
smile, the more time their mothers spend with them.
Children who do not smile early and often are not just
unhappy. Rather, there is some other issue at hand
that needs professional attention.
See also: PERSONALITY DEVELOPMENT; SOCIAL
DEVELOPMENT
Bibliography
Bailey, Kimberly. ‘‘What’s in a Smile?’’ [web site]. Available from
http://bipolar.about.com/health/bipolar/library/weekly/
aa000802a.htm?rnk=r8&terms=smiling; INTERNET.
Farris, Marinelam R. ‘‘Smiling of Male and Female Infants to
Mother vs. Stranger at Two and Three Months of Age.’’ Psy-
chological Reports 87 (2000):723–728.
Neil J. Salkind
SOCIAL CLASS
Social class is a concept that has been discussed and
argued about throughout the ages. Many different
theories exist concerning a workable definition. The
basis often used for describing social class comes from
nineteenth-century German theorist Karl Marx. He
believed in a three-class system consisting of capital-
ists, workers, and petty bourgeoisie. Since then, soci-
ologists have provided new conceptualizations of
social class. These conceptualizations include social
class as more than just an economic measure. Many
define social class as more of a social status, meaning
people in a specific class share similar experiences,
background, and position in society. Other factors
that influence social class rankings are occupational
prestige and general opinion of others in the commu-
nity. The concept of social status from German sociol-
ogist Max Weber (1864–1920) is used by a number of
American sociologists when explaining social class.
Weber saw property, skills, and education all contrib-
uting to the concept of social class. His view is similar
to and sometimes used interchangeably with socio-
economic status.
Classes are apparent in every large, complex soci-
ety, such as the United States. In this type of society,
roles are divided so that the group may function effi-
ciently. Social classes continue to exist within society
because people have learned how to live within them
and have passed this knowledge on to the next gener-
ation. People, or families, often associate with those
who are similar. They may have similar careers, in-
comes, and goals in life. By sticking together, people
reinforce the presence of social classes. These classes
extend across generations because social class is
somewhat inherited. A middle-class family cannot
give birth to an upper-class baby. The child is born
into the social class of the parents. As the child grows,
he will most likely form friendships with others simi-
lar to him, once again reinforcing the social class sys-
tem.Categories
Social classes may be described differently for
each region of the country, but most observers would
agree upon three general classes: upper, middle, and
lower. Because of the broad nature of these catego-
ries, the three main classes are often split into six,
more descriptive categories: upper-upper, lower-
upper, upper-middle, lower-middle, upper-lower,
and lower-lower. The additional classes help to dis-
criminate who falls into which class, but there is still
some ambiguity. The way in which each class is de-
fined depends on the perspective one takes. Someone
in upper-upper class may label upper-middle class372 SMILING