children again at ages 9, 14, and 21 months to see how the toddlers would re-
act to unfamiliar events, such as seeing a puppet speaking in an angry tone orbeing shown a large metal robot they could play with. Forty percent of the
infants classified as inhibited showed signs of fear, such as crying or hiding, at
14 and 21 months, but none of the uninhibited children did.
These temperamental differences can also be seen when the children reach
school age (Rimm-Kaufman & Kagan, 2005). One team of investigators mea-
sured children ’s fear of unfamiliar situations at 21 months of age (Reznick
et al., 1986). When the children reached age 5 1/2, they were brought back
into the laboratory and examined in a number of situations. Experimenters
coded how much the children played with unfamiliar children in the labora-tory playroom, how spontaneously they allowed themselves to fall onto a
mattress when playing a falling game, and how risky they were in a ball-
tossing game. As shown in Table 9.1, the children who had shown an inhib-ited behavior pattern as infants exhibited similar behaviors at age 5 1/2. In
other words, the toddler who clung to mother or father in a new situation
showed a similar style of behavior when examined 4 years later.
Some children appear to inherit a tendency to respond to unfamiliar situations with
increased arousal. When entering a new situation with new people, many of thesechildren display what we typically call “shy”behavior.234 CHAPTER 9 The Biological Approach