PSYC 2020 Lecture 8: PSYC 2020 Lecture 8 Notes
PSYC 2020 Lecture 8 Notes
Introduction
Data on Individual Development
• The older adults in the cross-sectional studies had less schooling and, therefore, scored
lower on intelligence tests than the middle-aged and young adult samples.
• Their test scores had not declined but, rather, had always been lower than those of the
younger adults with whom they were compared.
• So the earlier cross-sectional research had discovered a cohort effect, not a true
developmental change.
• Despite this important limitation, the cross-sectional comparison is still the design that
developmentalists use most often.
• Why?
• Because it has the advantage of being quick and easy
• We can go out this year, sample individuals of different ages, and be done with it.
• Moreover, this design is likely to yield valid conclusions when there is little reason to
believe that the cohorts being studied have had widely different experiences while
growing up.
• So if we compared 4- to 5-year-olds with 7- to 8-year-olds, as Coates and Hartup did, we
might feel reasonably confident that history or the prevailing culture had not changed in
any major way in the three years that separate these two cohorts.
• It is mainly in studies that attempt to make inferences about development over a span
of many years that cohort effects present a serious problem.
• There is a second noteworthy limitation of the cross-sectional design
• It tells us nothing about the development of individuals because each person is
observed at only one point in time.
• So cross-setioal opaisos aot poide ases to uestios suh as Whe ill
this patiula hild eoe oe idepedet? o Will this aggessie 2-year-old
become an aggressive 5-year-old?
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