Lifespan Development. Tara L. Kuther

infants need to traverse their environment. Through their exploration, infants perceive affordances—the nature, opportunities, and limits of objects (E. J. Gibson & Pick, 2000). The features of objects tell infants about their affordances, including their possibilities for action, such as whether an object is squeezable, mouthable, catchable, or reachable. Infants explore their environment, not randomly but rather systematically searching to discover the properties of the things around them (Savelsbergh, van der Kamp, & van Wermeskerken, 2013). From this perspective, perception arises from action, just as it influences action (J. Gibson, 1979). Exploration and discovery of affordances depends on infants’ capacities for action, which is influenced by their development, genetics, and motivation. For example, a large pot might offer a 10-year-old the possibility of cooking because the child has developed this capacity and can perceive this affordance of the pot. An 18-month-old infant may perceive very different affordances from the pot based on her capacities, such as a drum to bang or a bucket to fill. We naturally perceive affordances, such as knowing when a surface is safe for walking, by sensing information from the environment and coordinating it with our body sensations, such as our sense of balance (Kretch, Franchak, & Adolph, 2014). In this way, our perception of affordances, the opportunities for exploration, influences how we move and interact within our environments (Adolph & Kretch, 2015).

      Newborns have remarkable capacities for sensing and perceiving stimuli. Their senses, although well developed at birth, improve rapidly over the first year of life. Moreover, capacities for intermodal perception mean that infants can combine information from various sensory modalities to construct a sophisticated and accurate picture of the world around them.

      Thinking in Context 4.4

      1 How might infants’ powerful sensory capacities prime them to learn how to think about their world? Learn language?

      2 How might parents and caregivers design caregiving environments that are tailored to infants’ early learning and sensory capacities and stimulate development? What advice would you give on how to design such an environment for a newborn? For a 6-month-old infant?

      Motor Development During Infancy and Toddlerhood

      Newborns are equipped to respond to the stimulation they encounter in the world. The earliest ways in which infants adapt are through the use of their reflexes, involuntary and automatic responses to stimuli such as touch, light, and sound. Each reflex has its own developmental course (Payne & Isaacs, 2016). Some disappear early in life and others persist throughout life, as shown in Table 4.1. Infants show individual differences in how reflexes are displayed, specifically the intensity of the response. Preterm newborns, for example, show reflexes suggesting a more immature neurological system than full-term newborns (Barros, Mitsuhiro, Chalem, Laranjeira, & Guinsburg, 2011). The absence of reflexes, however, may signal neurological deficits.

Table 4.1

      Gross Motor Development

      Gross motor development refers to the ability to control the large movements of the body, actions that help us move around in our environment. Like physical development, motor skills evolve in a predictable sequence. By the end of the first month of life, most infants can reach the first milestone, or achievement, in motor development: lifting their heads while lying on their stomachs. After lifting the head, infants progress through an orderly series of motor milestones: lifting the chest, reaching for objects, rolling over, and sitting up with support (see Table 4.2). Notice that these motor achievements reflect a cephalocaudal progression of motor control, proceeding from the head downward (Payne & Isaacs, 2016). Researchers have long believed that all motor control proceeds from the head downward, but we now know that motor development is more variable. Instead, some infants may sit up before they roll over or not crawl at all before they walk (Adolph & Robinson, 2015). Similarly, infants reach for toys with their feet weeks before they use their hands, suggesting that early leg movements can be precisely controlled, the development of skilled reaching need not involve lengthy practice, and early motor behavior does not necessarily follow a strict cephalocaudal pattern (Galloway & Thelen, 2004).

Table 4.2

      Success at initiating forward motion, or crawling (6–10 months), is particularly significant for both infants and parents. Infants vary in how they crawl (Adolph & Robinson, 2015). Some use their arms to pull and legs to push, some use only their arms or only their legs, and others scoot on their bottoms. Once infants can pull themselves upright while holding on to a chair or table, they begin “cruising,” moving by holding on to furniture to maintain their balance while stepping sideways. In many Western industrialized countries, most infants walk alone by about 1 year of age.

      By the end of the first month of life, most infants can lift their head while lying on their stomach.

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      Once babies can walk, their entire visual field changes. Whereas crawling babies are more likely to look at the floor as they move, walking babies gaze straight ahead at caregivers, walls, and toys (Kretch et al., 2014). Most beginning walkers, even through 19 months of age, tend to walk in shorts spurts, a few steps at a time, often ending in the middle of the floor (W. G. Cole, Robinson, & Adolph, 2016). Independent walking holds implications for cognitive, social, and emotional development, as it is associated not only with more attention and manipulation of objects but also with more sophisticated social interactions with caregivers, such as directing mothers’ attention to particular objects and sharing. These behaviors, in turn, are associated with advanced language development relative to nonwalkers in both U.S. and Chinese infants (Ghassabian et al., 2016; He, Walle, & Campos, 2015).

      Fine Motor Development

      Fine motor development refers to the ability to control small movements of the fingers such as reaching and grasping. Voluntary reaching plays an important role in cognitive development because it provides new opportunities for interacting with the world. Like other motor skills, reaching and grasping begin as gross activity and are refined with time. Newborns begin by engaging in prereaching, swinging their arms and extending them toward nearby objects (Ennouri & Bloch, 1996; von Hofsten & Rönnqvist, 1993). Newborns use both arms equally and cannot control their arms and hands, so they rarely succeed in making contact with objects of interest (Lynch, Lee, Bhat, & Galloway, 2008). Prereaching stops at about 7 weeks of age.

      Voluntary reaching appears at about 3 months of age and slowly improves in accuracy. At 5 months, infants can successfully reach for moving objects. By 7 months, the arms can reach independently, and infants are able to reach for an object with one arm rather than both (J. P. Spencer, Vereijken, Diedrich, & Thelen, 2000). By 10 months, infants can reach for moving objects that change direction (Fagard, Spelke, & von Hofsten, 2009). As they gain experience with reaching and acquiring objects, infants develop cognitively because they learn by exploring and playing with objects—and object preferences change with experience. In one study, 4- to 6-month-old infants with less reaching experience spent more time looking at and exploring larger objects, whereas 5- to 6-month-old infants with more reaching experience spent more time looking at and touching smaller objects. The older infants did this despite first looking at and touching the largest object (Libertus et al., 2013). With experience, infants’ attention moves away from the motor skill (like the ability to coordinate their movement to hit a mobile), to the object (the mobile), as well as to the events that occur before and after acquiring the object (how the mobile swings and how grabbing it stops the swinging or how batting at it makes it swing faster). In this way, infants learn about cause and how to solve simple problems.