the fact that objects cannot pass through other objects or disappear into thin air). A fourth risk, which may not rise to the level of a public health concern, is that products purporting to educate infants may not only waste parents’ time and money, but also the existence and advertising of such products may generate unrealistic concerns and goals with respect to their infants’ development.

These analyses of media effects on very young children involve both studies of longitudinal data as well as experimental observations. Christakis described research studies in which he and his colleagues used data from the National Longitudinal Survey of Youth 1979 to investigate the effects of frequent television viewing on cognitive development. Measures of cognitive development in children at ages 6 and 7 were regressed on television viewing at younger ages. The conclusion was that modest adverse effects can result from viewing at young ages, when potential confounding variables, such as parental characteristics, were controlled. In contrast, other participants observed that certain educational programs for young children are associated with improvements in their cognitive developments. These differences suggest that media influences may differ by developmental stage as well as across social and cultural groups.

DeLoache described experimental research that has explored the effects of symbolic representations and media exposure on the development of very young children, noting that the potential for both beneficial learning and harm needs to be further investigated (DeLoache, Pirroutsakos, and Uttal, 2003; DeLoache, 2005). The experimental research she described was mainly based on the premise that the best way to determine what infants and toddlers can learn or be taught is to try to teach them, for example, to imitate a series of actions or problem-solving exercises. In addition, simple observations of the length of time that infants look at particular displays can be used to assess what kinds of visual stimuli they prefer. Such research can help identify what kinds of media might have beneficial effects on infant learning and development.

Participants were intrigued with the research on young children, but many commented on how much remains to be understood. Socioeconomic differences and many other contextual factors, for example, have not been thoroughly investigated. At the same time, the mechanisms by which many influences—from early literacy experiences, to family placement, to the nature of their media exposure—affect children are also not yet fully understood. Such mechanisms may include the content or exposure of certain forms of media, the social context and relationships surrounding the child’s experience with different types of media, and the displacement effects of media on other behaviors and exposures.