This story was first published in The Straits Times on Dec 29, 2013
Website designer Shirley Sim used to get her four-year-old son to watch television whenever she needed to work from home.
On some days, the 38-year-old's son would watch up to eight hours of educational DVDs or children's programmes.
That was until his kindergarten teachers complained of his hyperactivity in class. The child psychologist she consulted said TV could be a key factor contributing to his condition.
Extensive research has been conducted on the effects of television on children and it shows that TV often does more harm than good.
Research shows that watching TV programmes or DVDs designed for infants actually delays language development.
For example, a 2008 Thai study published in the journal Acta Paediatrica found that if children under 12 months watched TV for more than two hours a day, they were six times more likely to have delayed language skills.
Too many hours spent watching TV can also be a factor in attention deficit hyperactivity disorder (ADHD). Studies have shown that the amount of TV a child is exposed to between ages one and three has a direct effect upon later attention problems.
Watching TV, in other words, can shorten attention spans.
A study by Professor Dimitri Christakis from Seattle Children's Research Institute and the University of Washington in 2004 found that a child who watched two hours of TV a day before the age of three would be 20 per cent more likely to have attention problems by age seven.
Why does TV have such a negative effect on children?
Prof Christakis explains that it exposes children to flashing lights, scene changes, quick edits and auditory cuts which may overstimulate developing brains.
Things happen fast on the TV screen, so children's brains may come to expect this pace, making it harder to concentrate if there is less stimulation.
A New Zealand study discovered that those who watched the most TV were the least likely to go to university and get a degree.
It monitored the TV habits of 1,037 children aged between five and 15 in 1972 and 1973.
When it was finally published in 2005, it tracked the educational achievements of the same children.
The study found that the 7 per cent of children who watched TV for under one hour a day were the most qualified by the time they were 26.
But shockingly, the over 20 per cent who sat in front of the TV for more than three hours each school day ended up doing the worst at all academic levels.
The researchers also discovered that although excessive teenage TV viewing was strongly linked to leaving school without any qualifications, earlier childhood viewing had the greatest impact on getting a degree.
At this stage, even bright children and those from well-off families who watch a lot of TV are less likely to go on and get a degree.
The researchers concluded that excessive TV viewing leads to poor educational achievement. It displaces homework and revision and takes up time which would be better spent in more educational pursuits, such as reading.
What parents can do
If your child is under two, do not let him or her watch any TV at all, recommends the American Academy of Paediatrics.
For older children, some TV is beneficial but parents should select the programmes and limit viewing time to no more than two hours a day.
Parents should check the age-appropriate level to see if a show contains violence and sexual themes. Research has shown that watching violent programmes may desensitise children when it comes to real violence.
Glamorised body images in the media create expectations about attractiveness, and some depictions of sex or substance abuse run the risk of normalising risky behaviour or illegal activities.