the level of reflectivity-impulsivity and its expression
in student behavior.
It is important to note that correlational studies
have been conducted on any relationship between in-
telligence and each of the three cognitive styles.
There is consistent data indicating no direct relation-
ship exists between cognitive styles and intelligence.
Nevertheless, an individual’s ability to acquire knowl-
edge on an equal plane with peers, or to demonstrate
his or her knowledge in specific social or academic
settings, may be affected by cognitive styles. Through
early childhood development, continued success or
frequent difficulties in these abilities could affect per-
sonality and social interactions.
Because of the potential influence of cognitive
styles, additional educational research is necessary to
assess the full effect that cognitive style has on a
child’s perception, analysis, and application of infor-
mation presented in the classroom setting. There is
also an implication that some assessment techniques
used by educators may, by the nature of presentation,
solicit different responses from students with differ-
ing cognitive styles. These testing methods should
also be studied in terms of their interactions with indi-
vidual cognitive styles.
See also: COGNITIVE DEVELOPMENT
Bibliography
Bransford, John, Ann Brown, and Rodney Cocking, eds. How Peo-
ple Learn: Brain, Mind, Experience, and School. Washington, DC:
National Academy Press, 2000.
Brumby, Margaret N. ‘‘Consistent Differences in Cognitive Styles
for Qualitative Biological Problem-Solving.’’ British Journal of
Educational Psychology 52 (1982):244–257.
Greene, L. R. ‘‘Psychological Differentiation and Social Structure.’’
Journal of Social Psychology 109 (1972):79–85.
Morgan, Harry. Cognitive Styles and Classroom Learning. Westport,
CT: Praeger, 1997.
Nummendal, S. G., and F. P. Collea. ‘‘Field Independence, Task
Ambiguity, and Performance on a Proportional Reasoning
Task.’’ Journal of Research in Science Teaching 18, no. 3
(1981):255–260.
Salkind, Neil J., and John P. Poggio. ‘‘Sex Differences in Impulsivi-
ty and Intellectual Ability.’’ Sex Roles 4, no. 1 (1978):91–96.
Salkind, Neil J., and John Wright. ‘‘The Development of Reflec-
tion-Impulsivity and Cognitive Efficiency.’’ Human Develop-
ment 20 (1977):377–387.
Witkin, Herman A. ‘‘Individual Differences in Ease of Perception
of Embedded Figures.’’ Journal of Personality 19 (1950):1–15.
Witkin, Herman A., C. A. Moore, Donald R. Goodenough, and P.
W. Cox. ‘‘Field-Dependent and Field-Independent Cognitive
Styles and Their Educational Implications.’’ Review of Educa-
tional Research 47 (1977):1–64.
Witkin, Herman A., and Donald Goodenough. Cognitive Styles: Es-
sence and Origins. New York: International Universities Press,
1981.
L. R. S. Martens
COHORT
A cohort refers to a group of people that were born
at the same period of time. They are likely to share
some common experiences such as social, cultural,
and historical influences that are unique to them.
Examples of well-known cohorts include ‘‘baby
boomers’’ and ‘‘Generation Xers.’’ Cohort effects
arise when changes in performance are due circum-
stances specific to a particular time and place, rather
than age. Thus, if looking at physical development,
children born during times of conflict or war may
have retarded physical growth due to stress and food
deprivation. Therefore, growth pattern norms might
be inaccurate if based on this cohort. Another exam-
ple would be gender differences in vocational aspira-
tions for adolescents. Career choices by males and
females could depend on whether fifteen-year-olds
born in 1985 participated in the study versus fifteen-
year-olds born in 1935. Both cross-sectional and lon-
gitudinal research designs are susceptible to cohort
effects. A cross-sequential design may be used when
cohort effects are suspected.See also: DEVELOPMENTAL NORMS; STAGES OF
DEVELOPMENTBibliography
Miller, Scott. Developmental Research Methods, 2nd edition. Engle-
wood Cliffs, NJ: Prentice-Hall, 1998.
Katherine M. RobinsonCOMORBIDITY
Comorbidity is a medical term derived from the root
word ‘‘morbidity.’’ According to the Oxford English
Dictionary, morbidity refers to ‘‘the quality or condi-
tion of being diseased or ill; a pathological state or
symptom; a morbid characteristic or idea’’ as well as
‘‘prevalence of disease; the extent or degree of preva-
lence of disease in a district.’’ In reference to child de-
velopment, comorbidity is a term used when a child
is identified to have two or more simultaneous mental
health or physical disorders or diseases. The study of
comorbidity is the study of conditions that tend to
occur together. For example, there is a high comor-
bidity of attention deficit disorder and learning dis-
abilities in children, meaning that the prevalence of
learning disabilities is significantly higher than ex-
pected by chance among those with attention deficit
disorder, and vice versa.See also: LEARNING DISABILITIES; MENTAL
DISORDERS94 COHORT