Lifespan Development. Tara L. Kuther

out an innate program thought to be controlled by the mirror neuron system, located in the premotor cortex (Binder et al., 2017). The mirror neuron system, an inborn capacity to make associations and respond to the actions of others by mirroring their actions in our own neural circuits, is apparent in both newborn humans and monkeys (Cook, Bird, Catmur, Press, & Heyes, 2014; Olsen, 2006; Shaw & Czekóová, 2013). The ability to copy others’ actions likely serves an evolutionarily adaptive purpose in humans, perhaps to aid the development of social communication (Tramacere, Pievani, & Ferrari, 2017). Newborns do not understand imitation; rather, the action of mirror neurons naturally syncs their body movements with the model. The regulatory mechanisms to inhibit imitative responding develop during infancy (Rizzolatti et al., 2008).

      Figure 4.7 Newborn Imitating Facial Expression

      In this classic experiment Meltzoff and Moore demonstrated that neonates imitated the adults’ facial expression more often than chance, suggesting that they are capable of facial imitation—a groundbreaking finding.

      Source: Meltzoff and Moore (1977). Reprinted with permission of AAAS.

      In summary, infants enter the world equipped with several basic learning capacities that permit them to learn even before birth. Newborns display classical and operant conditioning, imitation, and habituation, illustrating that they are wired to attend to their environment. Not only do infants display early competencies that permit them to learn quickly but they are also surprisingly adept at sensing and perceiving stimuli around them.

      Thinking in Context 4.3

      1 What do early learning capacities mean for parenting? What information about habituation, conditioning, or imitation should parents be aware of, if any? Why?

      2 How might these learning principles be applied to address childrearing issues, such as how to get infants to sleep through the night or how to introduce new foods?

      Sensation and Perception During Infancy and Toddlerhood

      Visiting the doctor’s office for the first time in her young life, Kerry followed the doctor’s finger with her eyes as he passed it over her face. “I think she sees it!” said her surprised mother. “She most certainly does,” said the doctor. “Even as a newborn, your Kerry can sense the world. She can see, hear, and smell better than you know.” Newborns can see, hear, smell, taste, and respond to touch, but it is unclear how infants perceive sensory stimuli. Developmental researchers draw a distinction between sensation and perception. Sensation occurs when our senses detect a stimulus. Perception refers to the sense our brain makes of the stimulus and our awareness of it. The newborn is equipped with a full range of senses, ready to experience the world.

      Vision

      It is impossible to know whether the fetus has a sense of vision, but the fetus responds to bright light directed at the mother’s abdomen as early as 28 weeks’ gestation (Johnson & Hannon, 2015). At birth, vision is the least developed sense, but it improves rapidly. Newborn visual acuity, or sharpness of vision, is approximately 20/400 (Farroni & Menon, 2008). Researchers study visual acuity, sharpness of vision or the ability to see, in infants with the use of preferential looking tasks designed to determine whether infants prefer to look at one stimulus or another. For example, consider an array of black and white stripes. As shown in Figure 4.8, an array with more stripes (and, therefore, many more narrow stripes) tends to appear gray rather than black and white because the pattern becomes more difficult to see as the stripes become narrower. Researchers determine infants’ visual acuity by comparing infants’ responses to stimuli with different frequencies of stripes because infants who are unable to detect the stripes lose interest in the stimulus and look away from it. Preferential looking studies show that infants reach adult levels of visual acuity between 6 months and 1 year of age (Mercuri, Baranello, Romeo, Cesarini, & Ricci, 2007). Improvement in vision is due to the increasing maturation of the structures of the eye and the visual cortex, the part of the brain that processes visual stimuli.

      Figure 4.8 Visual Acuity

      Researchers and pediatricians use stimuli such as the Teller Acuity Cards illustrated here to determine what infants can see. Young infants attend to stimuli with wider lines and stop attending as the lines become smaller.

      Source: Leat, Yadev, and Irving (2009).

      Description

      Figure 4.9 Externality Effect and Face Perception

      The externality effect refers to a particular pattern of infant visual processing. When presented with a complex stimulus, such as a face, infants under two months of age tend to scan along the outer contours, such as along the hairline. Older infants scan the internal features of complex images and faces, thereby processing the entire stimulus.

      Source: Shaffer (2002, p. 190); adapted from Salapatek (1975).

      Newborns are born with preferences for particular visual stimuli. Newborns prefer to look at patterns, such as a few large squares, rather than a plain stimulus such as a black or white oval shape (Fantz, 1961). Newborns also prefer to look at faces, and the preference for faces increases with age (Frank, Vul, & Johnson, 2009; Gliga, Elsabbagh, Andravizou, & Johnson, 2009). How infants explore visual stimuli changes with age (Colombo, Brez, & Curtindale, 2015). Until about 1 month of age, infants tend to scan along the outer perimeter of stimuli. For example, when presented with a face, the infant’s gaze will scan along the hairline and not move to the eyes and mouth. By 6 to 7 weeks of age, infants study the eyes and mouth, which hold more information than the hairline, as shown in Figure 4.9 (Hunnius & Geuze, 2004). Similarly, the ability to follow an object’s movement with the eyes, known as visual tracking, is very limited at birth but improves quickly. By 2 months of age, infants can follow a slow-moving object smoothly, and by 3 to 5 months, their eyes can dart ahead to keep pace with a fast-moving object (Agyei, van der Weel, & van der Meer, 2016; Richards & Holley, 1999). The parts of the brain that process motion in adults are operative in infants by 7 months of age (Weaver, Crespi, Tosetti, & Morrone, 2015).

      Newborns see color but they have trouble distinguishing among colors.

      Phanie / Alamy Stock Photo

      Like other aspects of vision, color vision improves with age. Newborns see color, but they have trouble distinguishing among colors. That is, although they can see both red and green, they do not perceive red as different from green. Early visual experience with color is necessary for normal color perception to develop (Colombo et al., 2015; Sugita, 2004). Habituation studies show that by 1 month of age, infants can distinguish among red, green, and white (Teller, 1997). By 2 to 3 months of age, infants are as accurate as adults in discriminating the basic colors of red, yellow, and blue (Matlin & Foley, 1997; Teller, 1998). By 3 to 4 months of age, infants can distinguish many more colors as well as distinctions among closely related colors (Bornstein & Lamb, 1992; Haith, 1993). Seven-month-old infants detect color categories similar to those of adults; they can group slightly different shades (e.g., various shades of blue) into the same basic color categories as adults do (Clifford, Franklin,