These days, young children are exposed to a wide range of smart devices (e.g., smartphones and tablet computers) and their usage of smart devices is rapidly increasing worldwide [1-3]. Recent results showing that 70-80% of under-fives in the UK use smart devices [4]. According to Common Sense Media results, 72% of children aged 0-8 used digital tools in 2013, compared with 38% in 2011. The use of children under two years of age increased significantly from 10% in 2011 to 38% in 2013 [5]. In Korea, the rate of use of smart devices is increasing rapidly and the proportion of children and adolescents using such devices is increasing. According to the ‘Actual Situation of Infant & Toddler Smartphone Exposure and Protection Measures’ of the Child-Raising Policy Institute, infants and children’s smartphone usage rate reached 53.1% by 2013. The average age of first use of smartphones is 2.27, which means that toddlers are already exposed to smartphones before he or she reaches the age of three [6]. The average amount of time spent on smartphones per day for infants and toddlers was 31.65 minutes [7]. The increasing amount of time children are spending on smart devices has raisen concerns on the impact of these behaviors on their psychological development. However, most of the recent research on children’s use of technology focus mainly on school children and adolescents [8]. According to Holloway et al., the use of smart devices by young children has not been studied comprehensively, because the introduction of smart devices is relatively recent and their usage are difficult to evaluate [9,10]. Recognizing the rapidly changing use patterns of digital media use is important in determining how digital media is affecting children’s lives. It is the most rudiment stage in understanding the impact of smart devices. The purpose of this study was to investigate the exposure status of smart devices (exposure time, content, initiation of first exposure) among 2-5 years old children.

There has been a lack of empirical research on the exposure of smart devices for infants and toddlers. This is the first study to investigate the full range of media use of young children in Korea. In Korea, which has seen remarkable technological advances over the last few decades, electronic media devices have become more accessible and personalized. This study examined the use patterns of smart devices among children aged 2-5 years of age in community. As a result of the study, the majority of children lived in home environments using different digital devices and media.

Research has shown that TV and smartphones are the most popular digital devices used by children. TV viewing is considered as a passive activity that negatively affects cognition, physical and social development [11]. In this study, 39% of the toddlers used TV almost every day. On weekend, many children watched TV for more than an hour. In case of smartphones, on weekends, 23.4% of toddlers used their smartphones for over an hour. 31.3% of the children were using smartphones before 24 months of age.

The results are similar to other studies conducted in Korea [12]. According to Hong’s research, the average daily TV watching time of 2-year-old toddlers was 1.21 hours, and 32.6% of toddlers watched TV for more than 2 hours. This result is also similar to those of other countries. A study conducted in the Czech reported that children watched TV for an average of 1.2 to 1.5 hours per day. All participants spent more time on the media during weekends than on weekdays. On weekdays, children averaged less than 1 hour on average, and spent more than 78 minutes on weekends [13]. In the UK, screening time for 5-6 year-old children was also found to use media for much more time on weekends than on weekdays [14].

Compared to the previous study, the viewing time of the television is decreasing and the use time of the smart device is increasing gradually, the initiating age of the smart devices use is getting younger [6]. According to a study conducted in Korea (2013), the time to start using smartphones was 2.27 years. 56.9% of toddlers were watching TV every day and 14.8% of toddlers were using smart devices every day [6]. Although both studies differ in methodology and overexposure questions, the use of TV in toddlers is gradually decreasing, and the use of smart devices including smart phones is gradually increasing.

This tendency appears in the US and Europe, but it is showing up at high speed in Korea, where 98% of the population owns smartphones. As new media is integrated into children’s lives, the time spent watching TV has slowed down over the last 20 years. Using data from the National Health and Nutrition Examination Survey (NHANES) between 2001 and 2012, the average time spent watching TV among preschool children was significantly reduced [15]. On the other hand, the use of mobile devices (smartphones and tablet computers) by young children has increased dramatically since the Kaiser Family Foundation began research into the use of technology for parents of 0- to 8-year-olds [3]. In 2011, 52% of children aged 0-8 were able to access mobile devices, but by 2013 they increased to 75% [5].

Smart devices are becoming increasingly popular in the homes of young children [16]. Touch-based multi-modal interface smart device provides an easy-to-use platform for young children, especially when compared to a mouse that require fine motor and keyboard techniques. The impact of smart devices on the physical, cognitive, and social development of young children is limited for a number of reasons [17].

Many studies have shown that excessive screen time for young children is associated with language delay, attention problems, obesity, aggressive behavior, sleep problems [4,10,18,19]. In addition, screen time habits formed at young childhood can later predict negative psychological and health outcomes in life [20-22]. Thus, building appropriate screen time habits in young children can have a significant impact on their health and well-being throughout their lifetime. Factors affecting screen time for school-aged children and adolescents may not be relevant to young children’s group because early developmental stages are distinct periods. Early use of media, increased cumulative time of media usage, and media content are all important independent predictors of poor executive functioning [23]. Because directional reactions to new stimuli are very strong for young children, they pay attention to the attractive and fast-changing features of smart devices such as animation, sound, and highlighting [13]. However, these features can decrease the comprehension of young children [24]. There is little research on media use for preschool children. However, when young children play video games or use the computer, they use these media for just under an hour, which is not a trivial amount of time in a young child’s day. The results of this survey clearly show that young children are growing in environments exposed to media. According to one study in the United States [25], 90% of children have already started watching television by age 2, and a Canadian survey shows that 25% of 2-5 year olds watch TV for more than 2 hours each day. In this study, too many children are exposed to TV and smart device before 24 months.

The findings of this study cannot be generalized to overall population because of the relatively small sample size and largely homogenous SES backgrounds. Also, current survey data is based on a questionnaire written by parents, which may be vulnerable to socially undesirable biases. Future research will provide more reliable data by directly observing the use of electronic and measuring screen time in the homes.

In order to provide a stronger rationale for the screen time guidelines, we must consider the broader factors that affect use of smart devices, such as parent factors, environment, and child’s factors.

In recent years, over-exposure to smart devices has become an important area in the public mental health field. The majority of children spend more time watching screen media than ever before. Despite concerns about overuse of smart devices by children, research on Asian countries is very limited. Most smart device overexposure studies are being conducted in the US and Europe. The findings do not examine the impact of smart devices on children and families. They simply describe the characteristics and usage patterns of smart device exposure. Although TV is still the most common type of screen device that exposes children, this research shows that smartphones are the second most commonly used screen media in addition to TVs. Research shows that over the weekend, TV viewing and smartphone usage are particularly high, so weekend can be an important goal in mediation to reduce screen time. To encourage healthy screen habits from childhood, doctors and mental health professionals should educate parents about the impact that media exposure can have on their children and be aware of their importance.