Understanding Psychology (10th Ed)

longitudinal research
A research 
method that investigates behavior as 
participants age.
sequential research
A research 
method that combines cross-sectional 
and longitudinal research by consider-
ing a number of different age groups 
and examining them at several points 
in time.
Study Alert
Be sure to be able to distin-
guish the three diff erent 
types of developmental 
research—cross-sectional 
(comparing people of 
diff erent ages at the same time); 
longitudinal (studying participants 
as they age); and sequential 
(a combination of cross-sectional 
and longitudinal).
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K E Y T E R M S 
developmental psychology p. 381
nature–nurture issue p. 381
identical twins p. 383
cross-sectional research p. 383
longitudinal research p. 384
sequential research p. 384
1. her
edity (or nature), envir
onment (or nurture); 
2.
true; 
3.
tr
ue;
4.
longitudinal, cr
oss-sectional
 Module 
35 
Nature and Nurture: The Enduring Developmental Issue 
385
R E T H I N K
1. When researchers fi nd similarities in development 
between very different cultures, what implications might 
such fi ndings have for the nature–nurture issue?
2. From the perspective of a child-care provider: Consider what 
factors might determine why a child is not learning to 
walk at the same pace as his peers. What kinds of envi-
ronmental infl uences might be involved? What kinds of 
genetic infl uences might be involved? What recommen-
dations might you make to the child’s parents about the 
situation?