The development of digital and communication technologies in recent decades has significantly changed the lifestyles of adults, but also of children.
This has been highlighted in a study carried out in the UK between 1975 and 2015, which examined the schedules of schoolchildren aged eight to 16 year old. The results of this study showed an increase in time spent at home, as well as an increase in the use of screens in children’s activities (Mullan, 2019). In response to these changes, different organisations have raised the issue of screen exposure and its impact on children’s development.
The World Health Organisation published in April 2019 a press release in which the health agency set targets for physical activity, screen time and sleep for children under five years old. One of its recommendations is to limit or even eliminate screen time for children under four (World Health Organization, 2019). Recent figures show that in France, 87% of two-year-olds watch television, 68% of them daily. They spend an average of 6 hours and 50 minutes per week on this activity (Berthomier & Octobre, 2019).
In the United States, the American Academy of Pediatrics published a set of recommendations in 2016 to accompany screen use with children (AAP Council on Communications and Media et al., 2016). The authors recommend removing screens before the age of two and limiting screen exposure to one hour per day for children under five.
In this publication, the AAP cites several studies investigating the link between screen time and overweight and obesity (Bellissimo et al., 2007; Paes et al., 2015; Wen et al., 2014). According to these studies, screen time is correlated with an increase in Body Mass Index (BMI), which could be explained by being exposed to advertisements for food and eating while watching television, which would decrease attention to the sensation of satiety. It is interesting to note that the obesity factor in these studies is mainly television, which is a non-interactive medium, very different in its use from new multimedia practices. In its conclusion, the AAP proposes not only to control screen time, but also to encourage more social and creative uses of new technologies.
With regard to sleep, an association between the presence of a screen in the child’s room and a reduction in sleep time has been observed in several studies conducted in the United States. The time of exposure to screens before bedtime has a significant impact on sleep time, which could be explained by cognitive stimulation but also by the inhibition of melatonin secretion caused by blue light (Garrison et al., 2011; Salti et al., 2006; Vijakkhana et al., 2015).
From a cognitive development perspective, two studies were conducted in the United States in 2005 and 2007 on the possible effects of screens on cognitive and language development. The 2005 study was based on national data (National Longitudinal Survey of Youth) and focused on children who were seven years old at the time of the last surveys conducted (1994, 1996, 1998 and 2000). By observing the scores of these children on the Peabody Individual Achievement Test (PIAT), the authors showed a negative impact of television on cognitive skills for children under the age of three, then a reversal of the trend and a positive impact on reading recognition and short-term memory for children aged three to five. The authors suggest several ways to interpret these results. Time spent watching television takes the place of time spent playing, imagining and interacting with others, all of which are beneficial to the development of young children. The content of what is watched can also be detrimental to cognitive development, and there is little content suitable for children under three. Finally, the screen itself can be a hindrance to cognitive development by the very fact of looking for a long time in the same direction (Zimmerman & Christakis, 2005).
The 2007 study focuses on children under two years of age and is specifically concerned with language development (Zimmerman et al., 2007). A cohort of 1008 parents of children aged 2 to 24 months answered a series of questions regarding interactions with their child, the child’s use of screens, the types of content viewed and completed a short version of the MacArthur-Bates Communicative Development Inventory (CDI). A significant effect of screen time on the CDI score was found, with one hour of exposure per day being associated with a decrease in score of about 17 points compared to no exposure for children aged 8-16 months. This effect is, for example, larger than the positive effect of daily reading, which is associated with an increase of about 7 points in the CDI score compared to less frequent reading. The deleterious effect of screen time on language acquisition disappears after 16 months, which corroborates the observations of the previous study.
More recently, a study conducted in Taiwan (Lin et al., 2015) found a correlation between television viewing time and cognitive, language and motor delays in children aged 15 to 35 months. Two groups of 75 children each were compared, one including children with more television exposure than the 2009 AAP recommendations (screen exposure before age two, more than two hours per day from age two), and a control group whose screen exposure met the AAP recommendations (no screen time before age two, less than two hours per day after age two). The level of development was measured on the one hand with the Chinese version of the Bayley Scales of Infant Development (BSID-II) for cognitive and language skills, and on the other hand with the Chinese version of the Peabody Developmental Motor Scales (PDMS-2) for motor skills. The results show a strong correlation between early exposure to screens and developmental delays, which is consistent with previous findings. This latest study suggests the need to measure the longer-term effects of television exposure on young children’s development.
Finally, the issue of emotional and behavioural development is raised in several studies. A link between screen exposure time and behavioural and social problems has been found in studies conducted both in the United States (Christakis et al., 2004) and in Japan (Cheng et al., 2010). The focus is on early exposure to screens: children are between one and three years old in the former study and 18 and 30 months old in the latter. The researchers measured attention problems (Behavioral Problems Index, hyperactivity subscale BPI) and emotional and behavioural symptoms (Strengths and Difficulties Questionnaire SDQ). Here again, the deleterious effect of screens seems to diminish or even disappear as the children get older.
The issue of attention deficit disorder with or without hyperactivity (ADHD) has been the subject of specific research. This is the case, for example, of a study in which results from observations on humans were combined with experiments conducted on mice (Christakis et al., 2018). This experiment is based on the hypothesis that exposure to screens represents excessive sensory stimulation (ESS) for babies. Young mice were therefore subjected to excessive sensory stimulation and their behaviour was compared to that of a control group not subjected to ESS. The observations showed a negative effect of excessive sensory stimulation on the anxiety level, memory and learning of the young mice. The mice also tended to exhibit more risky behaviour and increased motor activity. The underlying hypothesis proposed by the authors concerns the very nature of the media which, independently of its content, and therefore of the viewer’s cognitive engagement, excessively stimulates too many senses, over durations that are too long for the cognitive development of toddlers.
The trend towards increased use of screens in everyday life seems to be accompanied by a diversification of the uses made of these screens. It would therefore be interesting to study more specifically the impact of each of these uses on children’s development. Beyond the potential harmful effects, digital technology has proved its usefulness in many areas of everyday life, a usefulness that has been largely confirmed with the coronavirus pandemic (teleworking, educational continuity, maintenance of social links at a distance, etc.). As this digital revolution is clearly unstoppable, it seems wise to be aware of the risks it entails for individuals in general, and children in particular, in order to make the most of this technological opportunity.
References
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