link with improved psychological adjustment of par-
ents and their children. Mediation has an important
place in helping families through the initial stress of
divorce, but it should not be viewed as a solution for
coping with the long-term issues that arise after the
dissolution of a marriage.
See also: CHILD CUSTODY AND SUPPORT; DIVORCE
Bibliography
Beck, Connie J. A., and Bruce D. Sales. Family Mediation: Facts,
Myths and Future Prospects. Washington, DC: American Psycho-
logical Association, 2001.
Dillon, Peter A., and Robert E. Emery. ‘‘Divorce Mediation and
Resolution of Child Custody Disputes: Long-Term Effects.’’
American Journal of Orthopsychiatry 66 (1996):131–140.
Emery, Robert E. Renegotiating Family Relationships: Divorce, Child
Custody, and Mediation. New York: Guilford Press, 1994.
Emery, Robert E. Sage Developmental Clinical Psychology and Psychia-
try Series, Vol. 14: Marriage, Divorce, and Children’s Adjustment.
Thousand Oaks, CA: Sage, 1999.
Emery, Robert E., and Melissa M. Wyer. ‘‘Divorce Mediation.’’
American Psychologist 42 (1987):472–480.
Emery, Robert E., Sheila G. Matthews, and Melissa M. Wyer.
‘‘Child Custody Mediation and Litigation: Further Evidence
on the Differing Views of Mothers and Fathers.’’ Journal of
Consulting and Clinical Psychology 59 (1991):410–418.
Hahn, Robert A., and David M. Kleist. ‘‘Divorce Mediation: Re-
search and Implications for Family and Couples Counseling.’’
Family Journal: Counseling and Therapy for Couples and Families
8 (2000):165–171.
Johnston, Janet R., and Linda E. G. Campbell. Impasses of Divorce:
The Dynamics and Resolution of Family Conflict. New York: Free
Press, 1988.
Kelly, Joan B. ‘‘The Determination of Child Custody.’’ Future of
Children: Children and Divorce 4 (Spring 1994):121–142.
Gary Resnick
MEIOSIS
Two types of nuclear division, mitosis and meiosis,
occur in cell biology. Most human cells (called diploid
cells) are formed through mitosis and contain forty-
six chromosomes in twenty-three matched pairs. By
contrast, meiosis produces haploid cells, each con-
taining a single set of twenty-three unpaired chromo-
somes. Sex cells (sperm and ovum) are haploid.
Prior to meiosis, DNA is replicated within a dip-
loid cell, resulting in four copies of each chromosome
(now numbering ninety-two). Two successive divisions
of the nuclear material occur during meiosis. As part
of the process, homologous chromosomes—paired
maternal and paternal chromosomes—exchange seg-
ments, thus recombining their genes. Four daughter
haploid cells are formed, each with one-quarter of the
genetic material (twenty-three chromosomes) of the
original diploid cell. When haploid cells unite in sex-
ual reproduction, each contributes half of the genetic
material that creates the offspring. Meiosis, therefore,
contributes to the genetic diversity within species.See also: MITOSISBibliography
Alberts, Bruce, Dennis Bray, Alexander Johnson, Julian Lewis,
Peter Walter, Keith Roberts, and Martin Raff. Essential Cell Bi-
ology: An Introduction to the Molecular Biology of the Cell. New
York: Garland, 1998.
Maryann Wzorek RossiMEMORY
Memory is involved in almost every aspect of chil-
dren’s behavior, from everyday occurrences such as
finding a misplaced toy, through the routine de-
mands of learning formulas for a math test, to emo-
tionally charged experiences such as explaining why
a particular punishment was unfair. In this overview
of memory development, the structure of the memory
system will be examined, different types of memory
processes will be defined, and age-related changes in
memory capabilities from infancy through middle
childhood will be described.Overview of the Memory System
The multi-store model of memory developed by
Richard Atkinson and Richard Shiffrin has guided re-
search in memory and its development. The model is
supported by extensive experimental evidence and is
applied productively in work with individuals who
have suffered brain injuries and students with typical
learning characteristics as well as learning difficulties.
In this information-processing model, illustrated in
Figure 1, human memory is seen as operating in a
manner analogous to that of a computer. The model
depicts three separate memory stores that function as
the hardware of the memory system: long-term mem-
ory, the sensory register, and working memory. Long-
term memory, which is what people typically mean
when they refer to memory, is a relatively permanent
memory store with an apparently limitless capacity. It
includes both semantic memory, a mental reference
book that contains facts about the world, and episodic
memory, a repository of stored traces of experienced
events. It should be noted, however, that representa-
tions of learned material or personal experiences do
not enter long-term memory directly. Information is
moved through earlier stores to long-term memory.
Sights and sounds from the world enter the mem-
ory system through the sensory register. This store
holds the icon of a visual display or the echo of a
sound for a very brief period of time. Within only one
second, information that an individual has not ex-MEMORY 255