Understanding Psychology (10th Ed)

COGNITIVE DEVELOPMENT: CHILDREN’S 
THINKING ABOUT THE WORLD 
Suppose you had two drinking glasses of different shapes—one short and broad and 
one tall and thin. Now imagine that you fi lled the short, broad one with soda about 
halfway and then poured the liquid from that glass into the tall one. The soda would 
appear to fi ll about three-quarters of the second glass. If someone asked you whether 
there was more soda in the second glass than there had been in the fi rst, what would 
you say? 
You might think that such a simple question hardly deserves an answer; of 
course, there is no difference in the amount of soda in the two glasses. However, 
most 4-year-olds would be likely to say that there is more soda in the second glass. 
If you then poured the soda back into the short glass, they would say there is now 
less soda than there was in the taller glass. 
Why are young children confused by this problem? The reason is not immedi-
ately obvious. Anyone who has observed preschoolers must be impressed by how 
far they have progressed from the early stages of development. They speak with ease, 
know the alphabet, count, play complex games, use computers, tell stories, and com-
municate ably. Yet despite this seeming sophistication, there are deep gaps in chil-
dren’s understanding of the world. Some theorists have suggested that children 
cannot understand certain ideas and concepts until they reach a particular stage of 
 cognitive development 
—the process by which a child’s understanding of the world 
changes as a function of age and experience. In contrast to the theories of physical 
trust-versus-mistrust stage
According 
to Erikson, the fi rst stage of psycho-
social development, occurring from 
birth to age 1½ years, during which 
time infants develop feelings of trust 
or lack of trust.