Children under 2 years of age currently have unprecedented access to electronic media. A series of reports from large-scale surveys of parents indicate that from about 3 months of age most infants have been exposed to some television or video and that by age 2 years about 90% are regular viewers and spend about 1ā2 h a day watching (Barr, Danziger, Hilliard, Andolina, & Ruskis, 2010; Linebarger & Vaala, 2010; Rideout & Hamel, 2006; Radesky, Silverstein, Zuckerman, & Christakis, 2014; Schmidt, Rich, Rifas-Shiman, Oken, & Taveras, 2009; Valkenburg et al., 2007; Zimmerman, Christakis, & Meltzoff, 2007b). More recent reports from Common Sense Media indicate that children under 2 years currently watch slightly less traditional TV and DVD material (about 56 min per day) but are beginning to spend more time viewing with other mobile devices (Rideout, 2013). Although parents report that most of the viewing is of child-appropriate material, infants and toddlers are also exposed to an additional 5.5 h daily of ābackgroundā TV that is not intended for them specifically but is usually viewed by older children and adults (Lapierre, Piotrowski, & Linebarger, 2012).
This amount of screen media exposure has raised a number of concerns among parents, developmental scientists, and other professionals, prompting both scientific inquiry and a public debate about the positive and negative potential of these media to affect young children's cognitive and social development. Among the most serious concerns are that the excitement of television with its formal features and rapid pace of scene change might hinder children's developing attention processes (Christakis, Zimmerman, DiGiuseppe, & McCarthy, 2004), and that television and DVDs are passive media and a poor substitute for the more interactive and brain-enriching activities implicit in social exchanges, language, storybook reading, and play that are interrupted or displaced by video viewing (Christakis et al., 2009). Collectively, these concerns prompted the American Academy of Pediatrics (AAP, 1999) to recommend that children under 2 years of age be discouraged from watching any screen media at all. Although a recent policy statement of the AAP (2011) reaffirmed its original recommendation, parents' ownership of baby media continues (Linebarger & Vaala, 2010; Mol, Neuman, & Strouse, 2014; Rideout, 2013).
On the opposite side of the debate are those who support age-appropriate screen media for infants and toddlers as an opportunity to foster learning and brain development, and many videos either explicitly or implicitly endorse this expectation in their promotional materials (Fenstermacher et al., 2010; Garrison & Christakis, 2005; Vaala & Lapierre, 2014). Although claims about the enrichment value of these media are largely unsubstantiated (Garrison & Christakis, 2005; Hirsh-Pasek et al., 2015; Linebarger & Vaala, 2010), 30% of parents surveyed indicated that learning and brain development were among their primary reasons for providing age-appropriate videos to their infants (Zimmerman, Christakis, & Meltzoff, 2007a; Zimmerman et al., 2007b). Advocates of videos for babies who look to science for guidance point to research showing the: (1) greater readiness for school among preschoolers who watched Sesame Street and other educational programs (Anderson, 1998; Mares & Han, 2013; Wright et al., 2001) and (2) positive association between viewing certain types of television content (e.g., Blue's Clues; Dora the Explorer) and better language development (Anderson & Hanson, 2010; Linebarger & Walker, 2005) and prosocial behavior (Friedrich & Stein, 1973). These findings, along with research that documents infants' and toddlers' remarkable ability to learn and remember (Oakes & Bauer, 2007; Bauer, 2007), make the idea of optimizing early learning using high-quality video material both plausible and appealing to parents.
Over the past decade, research has provided a great deal of information about the potential effects of television and video material on very young children's development, and many of these concerns about attention and learning are now fairly well understood. Predictably, the questions and answers have become more complex as the research focus has shifted from the amount of time children spent viewing video to a number of other variables that are arguably even more important. These include the child's age and cognitive maturity, the content of the program being viewed, and the social context in which viewing occurs (Anderson & Hanson, 2010; Barr, 2013; Linebarger & Vaala, 2010). This literature will be reviewed along with more recent work on the impact of newer interactive mobile technologies such as tablets, smartphones, and e-storybooks on attention and learning in the youngest viewers.
Television and the Development of Attention
Although the construct of attention defies simple definition, there is agreement that it is not a unitary process but comprises several different āvarieties of attentionā (James, 1890) such as alerting, detection, orienting, selectivity, focusing, shifting, and resisting distraction. Although a number of models of attention have been proposed over the years (see Raz & Buhle, 2006), the Posner and Rothbart (2007) framework is particularly well suited to consider its development. In that view, attention is made up of three independent through interactive networks: alerting, orienting, and executive control, each with its own neural foundation and characteristic behavior. Convergent evidence from behavioral and neuroimaging research indicates that these networks are immature at birth and emerge slowly from endogenous neurobiological processes in interaction with typical sensory, cognitive, and caregiving environments (Posner, 2012; Rothbart & Posner, 2015). The alerting and orienting networks that guide the direction of attention and the selection of targets are the earliest to develop and mature rapidly over the first 6 months. The higher-order executive network provides the basis for the voluntary control of attention that is needed to adapt to the demands of particular situations. This network undergoes a protracted period of development into adolescence, with significant advances between 2 and 7 years of age, although precursor signs of self-regulation appear earlier in infancy (Colombo, 2001; Rothbart & Posner, 2015). The executive attention network is foundational to the emergence of executive functions, those higher-order cognitive processes (i.e., working memory, inhibition, attention flexibility) that underlie children's capacity for self-regulation, planning, problem solving, and monitoring (Diamond, 2013; Garon, Bryson, & Smith, 2008).
Television and Attention Deficits
Concerns about the impact of television on the development of the attention networks were first raised in the 1970s following the appearance of fast-paced children's television programming such as Sesame Street and a correlated increase in reported attention problems (e.g., distractibility, hyperactivity) in school (Geist & Gibson, 2000; Singer, 1980). Although this complex question was not resolved at the time (Acevedo-Polakovich, Lorch, & Milich, 2007; Anderson & Hanson, 2010), it received renewed interest in the infant and toddler literature a decade ago with the marketing of television and video programming that specifically targeted that age group. Christakis et al. (2004) analyzed parent-report data from two large-scale surveys and found a significant correlation between the amount of television children viewed at 1 and 3 years of age and subsequent attention problems that were consistent with attention deficit hyperactivity disorder (ADHD). However, their data did not establish a causal link between television viewing and later attention and their criteria for identifying a deficit was very broad. Subsequently, Zimmerman and Christakis (2007) reported that the correlation between the amount of television viewed by children younger than 3 years and later attention was significant only when the content of the programs was categorized as violent entertainment. When the program content was educational or nonviolent entertainment, the correlation was not significant. Moreover, the amount and type of television viewed by 4- to 5-year-olds were unrelated to later attention. The authors concluded that the first 3 years were a sensitive period for potential harm from viewing fast-paced (violent) television, although the absence of an effect among older children implied that the problem may be transitory.
Christakis and Zimmerman suggested that exposure to the unnaturally fast pace of sound and image change in video material during this sensitive period might alter synaptic connections in the neural networks underlying attention and shorten the infant's attention span. Further, they contended that fast pace repeatedly elicited the orienting response at the expense of sustained attention and information processing, compelling infants to stare fixedly at the screen. However, this contention is not consistent with research showing that from as early as 6 months of age, infants regulate their attention during periods of extended viewing. They sustain their attention across changes in the formal features (e.g., pace, sound) of the material and c...