Lifespan Development. Tara L. Kuther

and long-term memory. The structure of the information processing system remains the same throughout the lifespan. With development, we get better at moving information through our cognitive system in ways that allow us to adapt to our world. We can process more information, retain more information, and do so more quickly and efficiently.

      Attention

      Attention refers to our ability to direct our awareness. The ability to focus and switch attention is critical for selecting information to process it in working memory and is influenced by neurological development, including advances in myelination (Qiu, Mori, & Miller, 2015). Important developments in attention occur over the course of infancy and continue throughout childhood.

      Infant attention is often studied using the same methods used to learn about their visual perception. Preferential-looking procedures (measuring and comparing the length of time infants look at two stimuli) and habituation procedures (measuring the length of time it takes infants to show a reduction in how long they look at a nonchanging stimulus) are used to study infants’ attention to visual stimuli, such as geometric patterns (Ristic & Enns, 2015). Infants show more attentiveness to dynamic stimuli—stimuli that change over tim—than to static, unchanging stimuli (Reynolds, Zhang, & Guy, 2013).

      The toy keys have captured this infant’s attention. Infants are more attentive to dynamic stimuli—stimuli that change over tim—than to static, unchanging stimuli.

      iStock/kamsta

      Description

      Figure 5.5 Information Processing System

      By around 10 weeks of age, infants show gains in attention. As infants’ capacities for attention increase, so do their preferences for complex stimuli. For example, in one experiment, 3- to 13-month-old infants were shown displays that included a range of static and moving stimuli (Courage, Reynolds, & Richards, 2006). From about 6½ months of age, infants’ looking time varied with stimulus complexity, decreasing for simple stimuli such as dot patterns, increasing slightly for complex stimuli such as faces, and increasing more for very complex stimuli such as video clips (Courage et al., 2006). Overall, looking time peaked at 14 weeks of age and dropped steadily, demonstrating infants’ growing cognitive efficiency. As infants become more efficient at scanning and processing visual information, they require less exposure to stimuli to habituate.

      Recently, researchers have begun using brain imaging techniques to measure infants’ brain activity because the development of infant attention is thought to be closely related to neurological development in the areas underlying attentional control (Reynolds, 2015). In response to tasks that challenge attention, infants show activity in the frontal cortex (used for thinking and planning) that is diffuse (widely spread) at 5.5 months of age but more specific or localized by 7.5 months of age (Richards, 2010).

      Memory

      Habituation studies measuring looking time and brain activity demonstrate that neonates can recall visual and auditory stimuli (Muenssinger et al., 2013; Streri, Hevia, Izard, & Coubart, 2013). With age, infants require fewer trials or presentations to recall a stimulus and are able to retain material for progressively longer periods of time (Howe, 2015). Infants can also remember motor activities. In one study, 2- to 3-month-old infants were taught to kick their foot, which was tied to a mobile with a ribbon, to make the mobile move (as shown in Figure 5.6). One week later, when the infants were reattached to the mobile, they kicked vigorously, indicating their memory of the first occasion. The infants would kick even 4 weeks later if the experimenter gave the mobile a shake to remind them of its movement (Rovee-Collier & Bhatt, 1993).

      Although infants have basic memory capacities common to children and adults, they are most likely to remember events that take place in familiar contexts and in which they are actively engaged (Rose, Feldman, Jankowski, & Van Rossem, 2011). Emotional engagement also enhances infants’ memory. One method for testing the effect of emotional engagement on memory is the still-face interaction paradigm. In this experimental task, an infant interacts with an adult who first engages in normal social interaction and then suddenly lets his or her face become still and expressionless, not responsive to the infant’s actions (Tronick, Als, Adamson, Wise, & Brazelton, 1978). Infants usually respond to the adult’s still face with brief smiles followed by negative facial expressions, crying, looking away, thumb sucking, and other indications of emotional distress (Shapiro, Fagen, Prigot, Carroll, & Shalan, 1998; Weinberg & Tronick, 1994). In one study, 5-month-old infants who were exposed to the still face demonstrated recall over a year later, at 20 months of age, by looking less at the woman who had appeared in the earlier still-face paradigm than at two other women whom the infants had never previously seen (Bornstein, Arterberry, & Mash, 2004). In sum, memory improves over the course of infancy, but even young infants are likely to recall events that take place in familiar surroundings in which they are actively engaged and that are emotionally salient (Courage & Cowan, 2009; Learmonth et al., 2004).

      Infants’ Thinking

      In infants’ eyes, all of the world is new—“one great blooming, buzzing confusion,” in the famous words of 19th-century psychologist William James (1890). How do infants think about and make sense of the world? As infants are bombarded with a multitude of stimuli, encountering countless new objects, people, and events, they form concepts by naturally grouping stimuli into classes or categories. Categorization, grouping different stimuli into a common class, is an adaptive mental process that allows for organized storage of information in memory, efficient retrieval of that information, and the capacity to respond with familiarity to new stimuli from a common class (Quinn, 2016). Infants naturally categorize information, just as older children and adults do (Rosenberg & Feigenson, 2013). Without the ability to categorize, we would have to respond anew to each novel stimulus we experience.

      Just as in studying perception and attention, developmental researchers must rely on basic learning capacities, such as habituation, to study how infants categorize objects (Rigney & Wang, 2015). For example, infants are shown a series of stimuli belonging to one category (e.g., fruit: apples and oranges) and then are presented with a new stimulus of the same category (e.g., a pear or a lemon) and a stimulus of a different category (e.g., a cat or a horse). If an infant dishabituates or shows renewed interest by looking longer at the new stimulus (e.g., cat), it suggests that he or she perceives it as belonging to a different category from that of the previously encountered stimuli (Cohen & Cashon, 2006). Using this method, researchers have learned that 3-month-old infants categorize pictures of dogs and cats differently based on perceived differences in facial features (Quinn, Eimas, & Rosenkrantz, 1993).

      Figure 5.6 Rovee-Collier Ribbon Study

      Young infants were taught to kick their foot to make an attached mobile move. When tested one week later the infants remembered and kicked their legs vigorously to make the mobile move.

      Source: Nick Alexander; Levine and Munsch (2010).

      Infants’ earliest categories are based on the perceived similarity of objects (Rakison & Butterworth, 1998). By 4 months, infants can form categories based on perceptual properties, grouping objects that are similar in appearance, including shape, size, and color (Quinn, 2016). As early as 7 months of age, infants use conceptual categories based on perceived function and behavior (Mandler, 2004). Moreover, patterns in 6- to 7-month-old infants’ brain waves correspond to their identification of novel and familiar categories (Quinn, Doran, Reiss, & Hoffman, 2010). Seven- to 12-month-old infants use many categories to organize objects, such as food, furniture, birds, animals, vehicles, kitchen utensils, and