Читать книгу Lifespan Development - Tara L. Kuther - Страница 55

Do children slowly grow into adults, steadily gaining more knowledge and experience and becoming better at reasoning? Or do they grow in spurts, showing sudden, large gains in knowledge and reasoning capacities? In other words, is developmental change continuous, characterized by slow and gradual change, or discontinuous, characterized by abrupt change? As shown in Figure 1.2, a discontinuous view of development emphasizes sudden transformation, whereas a continuous view emphasizes gradual and steady changes.

Scientists who argue that development is continuous point to slow and cumulative changes, such as a child slowly gaining experience, expanding his or her vocabulary, and learning strategies to become quicker at problem solving (Siegler, 2016). Similarly, they point out that middle-aged adults experience gradual losses of muscle and strength (Keller & Engelhardt, 2013).

The discontinuous view of development describes the changes we experience as large and abrupt, with individuals of various ages dramatically different from one another. For example, puberty transforms children’s bodies into more adult-like adolescent bodies (Wolf & Long, 2016), infants’ understanding and capacity for language is fundamentally different from that of school-aged children (Hoff, 2014), and children make leaps in their reasoning abilities over the course of childhood, such as from believing that robotic dogs and other inanimate objects are alive to understanding that life is a biological process (Beran, Ramirez-Serrano, Kuzyk, Fior, & Nugent, 2011; Zaitchik, Iqbal, & Carey, 2014).

It was once believed that development was either continuous or discontinuous—but not both. Today, developmental scientists agree that development includes both continuity and discontinuity (Lerner, Agans, DeSouza, & Hershberg, 2014). Whether a particular developmental change appears continuous or discontinuous depends in part on our point of view. For example, consider human growth. We often think of increases in height as involving a slow and steady process; each month, an infant is taller than the prior month, illustrating continuous change. However, as shown in Figure 1.3, when researchers measured infants’ height every day, they discovered that infants have growth days and nongrowth days, days in which they show rapid change in height interspersed with days in which there is no change in height, illustrating discontinuous change (Lampl, Johnson, Frongillo, & Frongillo, 2001). In this example, monthly measurements of infant height suggest gradual increases, but daily measurements show spurts of growth, each lasting 24 hours or less. Thus, whether a given phenomenon, such as height, is described as continuous or discontinuous can vary. Most developmental scientists agree that some aspects of lifespan development are best described as continuous and others as discontinuous (Miller, 2016).