Understanding Psychology (10th Ed)

principle of conservation
The 
knowledge that quantity is unrelated 
to the arrangement and physical 
appearance of objects.
concrete operational stage
According 
to Piaget, the period from 7 to 12 years 
of age that is characterized by logical 
thought and a loss of egocentrism.
formal operational stage
According 
to Piaget, the period from age 12 to 
adulthood that is characterized by 
abstract thought.
Children who have not mastered the 
principle of conservation assume that 
the volume of a liquid increases when it 
is poured from a short, wide container 
to a tall, thin one. What other tasks 
might a child under age 7 have diffi
culty 
comprehending?
feL82795_ch12_378-435.indd Page 406 7/31/10 12:52 AM user-f465
feL82795_ch12_378-435.indd Page 406 7/31/10 12:52 AM user-f465
/Users/user-f465/Desktop
/Users/user-f465/Desktop

---

 
Module 37 
Infancy and Childhood 
407
an experiment, they examine the effects of changes in one variable at a time. This 
ability to rule out competing possibilities characterizes formal operational thought. 
Although formal operational thought emerges during the teenage years, some 
individuals use this type of thinking only infrequently. Moreover, it appears that 
many individuals never reach this stage at all; most studies show that only 40–60% 
of college students and adults fully reach it, with some estimates running as low as 
25% of the general population. In addition, in certain cultures—particularly those 
that are less technically oriented than Western societies—almost no one reaches the 
formal operational stage (Keating & Clark, 1980; Super, 1980; Genovese, 2006). 
Stages Versus Continuous Development: Is Piaget Right? No other theorist has given 
us as comprehensive of a theory of cognitive development as Piaget. Still, many 
contemporary theorists suggest that a better explanation of how children develop 
cognitively can be provided by theories that do not involve a stage approach. For 
instance, children are not always consistent in their performance of tasks that—if 
Piaget’s theory is accurate—ought to be performed equally well at a particular stage 
(Feldman, 2003, 2004). 
Furthermore, some developmental psychologists suggest that cognitive develop-
ment proceeds in a more continuous fashion than Piaget’s stage theory implies. They