Lifespan Development. Tara L. Kuther

the ability to use symbols such as words and mental pictures to represent objects and actions in memory. In developing this ability, infants are freed from immediate experience: They can think about objects that they no longer see directly in front of them and can engage in deferred imitation, imitating actions of an absent model. Now, external physical exploration of the world gives way to internal mental exploration. Children can think through potential solutions and create new solutions without engaging in physical trial and error but simply by considering the potential solutions and their consequences. Table 5.1 summarizes the substages of sensorimotor reasoning.

      Evaluating Sensorimotor Reasoning

      Piaget’s contributions to our understanding of cognitive development are vast and invaluable. He was the first to ask what develops during childhood and how it occurs. Piaget recognized that motor action and cognition are inextricably linked, a view still accepted by today’s developmental scientists (Libertus, Joh, & Needham, 2016).

      Description

      Figure 5.2 Primary, Secondary, and Tertiary Circular Reactions

      Source: Adapted from Papalia et al., 2001.

      Piaget’s work has stimulated a great deal of research as developmental scientists have tested his theory. However, measuring the cognitive capabilities of infants and toddlers is very challenging because, unlike older children and adults, babies cannot fill out questionnaires or answer questions orally. Researchers have had to devise methods of measuring observable behavior that can provide clues to what an infant is thinking. For example, researchers measure infants’ looking behavior by determining what infants look at and for how long. Using such methods, they have found support for some of Piaget’s claims and evidence that challenges others. One of the most contested aspects of Piaget’s theory concerns his assumption that infants are not capable of mental representation until late in the sensorimotor period (Carey, Zaitchik, & Bascandziev, 2015). A growing body of research conducted with object permanence and imitation tasks suggests otherwise, as described in the following sections.

      Violation-of-Expectation Tasks

      Piaget’s method of determining an infant’s understanding of object permanence relied on the infant’s ability to demonstrate it by uncovering a hidden object. Critics argue that many infants may understand that the object is hidden but lack the motor ability to coordinate their hands to physically demonstrate their understanding. Studying infants’ looking behavior enables researchers to study object permanence in younger infants with undeveloped motor skills because it eliminates the need for infants to use motor activity to demonstrate their cognitive competence.

      One such research design uses a violation-of-expectation task, a task in which a stimulus appears to violate physical laws (Hespos & Baillargeon, 2008). Specifically, in a violation-of-expectation task, an infant is shown two events: one that is labeled expected because it follows physical laws and a second that is called unexpected because it violates physical laws. If the infant looks longer at the unexpected event, it suggests that he or she is surprised by it, is aware of physical properties of objects, and can mentally represent them.

      In a classic study, developmental researcher Renée Baillargeon (1987) used the violation-of-expectation method to study the mental representation capacities of very young infants. Infants were shown a drawbridge that rotated 180 degrees. Then the infants watched as a box was placed behind the drawbridge to impede its movement. Infants watched as either the drawbridge rotated and stopped upon hitting the box or did not stop and appeared to move through the box (an “impossible” event). As shown in Figure 5.3, 4½-month-old infants looked longer when the drawbridge appeared to move through the box (the “impossible” unexpected event) than when it stopped upon hitting the box. Baillargeon and colleagues interpreted infants’ behavior as suggesting that the infants maintained a mental representation of the box, even though they could not see it, and therefore understood that the drawbridge could not move through the entire box.

      Other researchers counter that these results do not demonstrate object permanence but rather illustrate infants’ preference for novelty or for greater movement (Bogartz, Shinskey, & Schilling, 2000; Heyes, 2014). For example, when the study was replicated without the box, 5-month-old infants looked longer at the full rotation, suggesting that infants looked at the unexpected event not because it violated physical laws but because it represented greater movement (Rivera, Wakely, & Langer, 1999). Nevertheless, studies that use simpler tasks have shown support for young infants’ competence. Four- and 5-month-old infants will watch a ball roll behind a barrier, gazing to where they expect it to reappear (von Hofsten, Kochukhova, & Rosander, 2007). When 6-month-old infants are shown an object and the lights are then turned off, they will reach in the dark for the object (Shinskey, 2012), suggesting that they maintain a mental representation of the object and therefore have object permanence earlier than Piaget believed.

Table 5.1

      A-Not-B Tasks

      Other critics of Piaget’s views of infants’ capacity for object permanence focus on an error that 8- to 12-month-old infants make, known as the A-not-B error. The A-not-B error involves the following scenario: An infant is able to uncover a toy hidden behind a barrier. He then sees the toy moved from behind one barrier (Place A) to another (Place B), but he continues to look for the toy in Place A, even after watching it be moved to Place B (see Figure 5.4). Piaget believed that the infant incorrectly, but persistently, searches for the object in Place A because he lacks object permanence.

      Some researchers, however, point out that infants look at Place B, the correct location, at the same time as they mistakenly reach for Place A, suggesting that they understand the correct location of the object (Place B) but cannot keep themselves from reaching for Place A because of neural and motor immaturity (Diamond, 1991). Other researchers propose that infants cannot restrain the impulse to repeat a behavior that was previously rewarded (Zelazo, Reznick, & Spinazzola, 1998). When looking-time procedures are used to study the A-not-B error (Ahmed & Ruffman, 1998), infants look longer when the impossible event occurs (when the toy is moved from Place A to Place B but is then found at Place A) than when the expected event occurs (when the toy is moved from Place A to Place B and is found at Place B). This suggests that infants have object permanence, but their motor skills prohibit them from demonstrating it in A-not-B tasks. One longitudinal study followed infants from 5 to 10 months of age and found that between 5 and 8 months, infants showed better performance on an A-not-B looking task than on a reaching task. Nine- and 10-month-old infants performed equally well on A-not-B looking and reaching tasks (Cuevas & Bell, 2010). Age-related changes in performance on A-not-B and other object permanence tasks may be due to maturation of brain circuitry controlling motor skills and inhibition as well as advances in the ability to control attention (Cuevas & Bell, 2010; Marcovitch, Clearfield, Swingler, Calkins, & Bell, 2016).

      Description

      Figure 5.3 Object Permanence in Young Infants: Baillargeon’s Drawbridge Study

      (A) Side view of habituation and test displays. Infants were habituated to a 180-degree drawbridge-like motion. (B) In the Experimental Condition, infants completed two types of test trials with a new object, a box. The Impossible Test involved the same full 180° rotation from habituation, but now the screen surprisingly passed through the box as it completed its rotation (with the box disappearing as it became obscured). The Possible Test involved a novel shorter rotation of screen up to the point where it would contact the box, where it stopped; this motion was “possible” in terms of solidity