Understanding Psychology (10th Ed)

Height
Weight
Boys (50th percentile)
Girls (50th percentile)
FIGURE 5 
As development progresses, 
the size of the head relative to the rest of 
the body decreases until the individual 
reaches adulthood. Why do you think the 
head starts out so large?
 
(Source: Adapted 
from Figure 5 from W. J. Robbins, 
Growth
. 
Copyright © 1928 Yale University Press. Used 
by permission of Yale University Press.)
Newborn 
3 years 
6 years
12 years
25 years
attachment 
The positive emotional 
bond that develops between a child 
and a particular individual.
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Module 37 
Infancy and Childhood 
399
after birth. Lorenz found that goslings whose eggs were raised in an incubator and 
which viewed him immediately after hatching would follow his every movement as 
if he were their mother. He labeled this process imprinting, behavior that takes place 
during a critical period and involves attachment to the fi rst moving object that is 
observed.
Our understanding of attachment progressed when psychologist Harry Harlow, 
in a classic study, gave infant monkeys the choice of cuddling a wire “monkey” 
that provided milk or a soft, terry-cloth “monkey” that was warm but did not 
provide milk. Their choice was clear: They spent most of their time clinging to the 
warm cloth “monkey,” although they made occasional forays to the wire monkey 
to nurse. Obviously, the cloth monkey provided greater comfort to the infants; milk 
alone was insuffi cient to create attachment (Harlow & Zimmerman, 1959; Blum, 
2002; see Figure 6). 
Building on this pioneering work with nonhumans, developmental psychologists 
have suggested that human attachment grows through the responsiveness of infants’ 
caregivers to the signals the babies provide, such as crying, smiling, reaching, and 
clinging. The greater the caregiver’s responsiveness to the child’s signals, the more 
likely it is that the child will become securely attached. Full attachment eventually 
develops as a result of the complex series of interactions between caregiver and child. 
In the course of these interactions, the infant plays as critical and active of a role as 
the caregiver in the formation of the bond. Infants who respond positively to a 
caregiver produce more positive behavior on the caregiver’s part, which, in turn, 
produces an even stronger degree of attachment in the child.