Understanding Psychology (10th Ed)

habituation
The decrease in the 
response to a stimulus that occurs after 
repeated presentations of the same 
stimulus.
FIGURE 2 
This newborn infant is clearly 
imitating the expressions of the adult 
model in these amazing photos. How 
does this ability contribute to social 
development? 
(Source: Courtesy of 
Dr. Tiff any Field.)
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396 Chapter 
12 
Development
near or far objects. By the age of 4 or 5 months, they are able to recognize two- and 
three-dimensional objects, and they can perceive the gestalt organizing principles 
discovered by psychologists who study perception. By the age of 7 months, neural 
systems related to the processing of information about facial expressions are highly 
sophisticated and cause babies to respond differently to specifi c facial expressions 
(see Figure 3). Overall, their perceptual abilities rapidly improve: Sensitivity to visual 
stimuli, for instance, becomes three to four times greater at 1 year of age than it was 
at birth (Johnson, 2004; Striano & Vaish, 2006; Leppanen et al., 2007). 
In addition to vision, infants display other impressive sensory capabilities. 
Newborns can distinguish different sounds to the point of being able to recognize 
their own mothers’ voices at the age of 3 days. They can also make the subtle 
perceptual distinctions that underlie language abilities. For example, at 2 days of 
Neuroscience in Your Life: 
Young Infants 
Recognize Emotions Early in Life
FIGURE 3
Using a method that measures electrophysiological responses in the brain 
(event-related potentials), researchers have found that by 7 months of age infants show 
distinct responses to happy, fearful, and neutral facial expressions using diff erent regions 
of their brain (specifi cally, the medial, semimedial, and lateral regions). For example, 
approximately 400 milliseconds after seeing a fearful face (see arrow), infants show greater 
brain activity than when seeing either a neutral or happy face. This demonstrates that infants 
recognize diff erences between these facial expressions. 
(Source: Leppanen et al., 2007, Figure 2.)
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