This longitudinal birth cohort study presented data on: (a) the amount of time spent on television viewing in infants and toddlers, (b) the association between time spent on television viewing and language development, and (c) parental perceptions on television viewing toward their children's development.
The definition of "watching television" in this (and other) study has to be carefully evaluated. Watching television in the very young child (especially in the child who is younger than 1 year old) is difficult to evaluate. In this study, we assume that children, who were left to expose to television would be able to learn and understand words and pictures on television; thus, would regard as watching television. In addition, with our limited resources, we were able to record broad frequencies of television viewing for 6 months old children. Although, recording television viewing time with viewing diaries is more reliable than parents' report, it requires high parent's effort and cooperation. The amount of viewing time recorded by parents' self report may tend to be underestimated, and is a more-to-common practice.
According to the AAP, exposure to television should be restricted in children who are younger than 2 years old [7
]. However, 98.0% of 6-month-old, 95.3% of 1-year-old and 96.5% of 2-year-old children in Thailand watched television. These are comparable with other studies from different countries where more than 90% of children younger than 2 years old were reported to watch television [10
]. Findings from our and other studies reflect that the AAP guidelines have not been heeded.
The increased time spent on television viewing was found when the children were older. Time spent on television viewing increased from 1.23 ± 1.42 hours per day at the age of 1 year to 1.69 ± 1.56 hours per day when the children were 2 years old. A study from the USA also documented the increased time spent on television viewing in children during their first 3 years [11
]. However, time spent on television is cultural and socioeconomically dependent, varies amongst families, and is likely to be influenced by habit of parents and other members in the family [20
One of the intentions of this study was to assess the association between delayed language development and the maximum time spent on television recommended by the AAP [7
]. However, only seven two-year-old children followed the AAP guidelines (not watching television). Thus, we have analysed the association between delayed language development and time spent on television viewing at ≥ 2 or < 2 hours per day. No association between delayed language development at the age of 2 years and time spent on television viewing (≥ 2 hours per day) was found. However, the only 16 children with delayed language development detected in the study may not have been adequately powered to identify any association. In contrast, other study proposed that exposure to television before the age of 3 years could deteriorate children's cognitive development, thus, resulted in lower reading performance in early elementary school [21
]. Longer follow-up (e.g. at the age of 3 or 4 years) should illustrate clearer direction.
Factors responsible for impaired language development are complex and have not been clearly identified. However, evidence has suggested that gender and genetics may involve in these intricate mechanisms. Delayed language development was observed amongst siblings who had family history of language impairment [22
]. Furthermore, other studies proposed that boys are more likely to have impaired language development than girls, possibly due to genetics and neurobiological factors [23
]. Our study, on the multivariate analysis, has confirmed this observation (OR = 6.9, 95% CI = 1.5–31.3). The study found no association between maternal education and monthly family income and delayed language development, which inconsistent with other studies [25
]. This is probably due to our sample population was ascertained through two institutions from certain geographical areas of the country (Bangkok). Therefore, this population may not be representative of the Thai population and might affect the association between delayed language development and socioeconomic status.
Findings from this study showed that 64% of 2-year-old children in Thailand had television set in their bedrooms. According to the AAP recommendations, this was not a good practice, as television sets should be removed from children's bedrooms [7
]. Again, this recommendation may not be simply applied to the environment and the culture in Thailand (and, probably, other Asian countries), where parents would prefer their child staying in the same room with them until the school age. Furthermore, in many low socioeconomic status families in Thailand, only 1–2 rooms are available in their houses; and that all family members would be forced to stay in the same room.
Regarding types of programmes, although evidence has suggested that educational television programmes may increase school readiness in children [5
], the benefits of these programmes are questionable in infants [14
]. A recent study has suggested that only the infant-directed educational programme with parental co-viewing, not the general educational programme for children, could enhance infant-mother interactions [17
]. This type of program with parent co-viewing may improve children's long-term developmental outcome [29
]. Meanwhile, adult programmes could provide negative effects to cognitive and language development [30
]. Our study did not record types of television programmes watched by the children.
The positive parental perceptions on television viewing toward children's development were demonstrated for the first time in Thailand. Other study in the USA has previously documented similar findings [19
]. Parents believed that screening media (e.g. television, DVD, video), if appropriately used, are educational and useful to their child's brain development [19
]. Those positive parental attitudes on television viewing may be influenced by television programmes, which have claimed to have educational value for children. However, positive parental perceptions may be deleterious to children, if parents do not carefully concern about the types of programme. A number of research demonstrated detrimental impact of the television viewing to cognitive and social development, if the content in the programmes was not appropriated to children [2
]. Therefore, parents should closely monitor contents of the programmes and should decide appropriately which television programmes are useful for their child.
In this study, modified CLAMS was used to identify children with delayed language development. Different cultures may also limit the use of original CLAMS in identifying children with delayed language development. We have also concerned that administering only the items at 21 months of age may affect a number of children with delayed language development reported in this study.