Teachers are held accountable for failings in the educational performance of their pupils. But the real culprit remains at large.
A formidable body of medical evidence indicates television as a primary factor affecting school performance and educational outcome. For all age groups, a direct relationship is emerging between the amount of time spent watching television and children's ability to learn and perform in school later, irrespective of the quality of the programmes watched.
The Journal of the American Medical Association reported in 2005 that television viewing among children under the age of three is found to have "deleterious effects" on mathematic ability, reading recognition and comprehension in later childhood. Another study two years later at Columbia University College of Physicians and Surgeons on 14 to 22-year- olds concluded: "Frequent television viewing during adolescence may be associated with risk for development of attention problems, learning difficulties, and adverse long-term educational outcomes."
Those watching one or more hours per day at age 14 "were at elevated risk for poor homework completion, negative attitudes toward school, poor grades and long-term academic failure."
Those watching three or more hours per day were most affected and "were at elevated risk for subsequent attention problems and were the least likely to receive post-secondary education."
A longitudinal study reported by Hancox et al in 2005 in the American Archives of Pediatrics and Adolescent Medicine, concluded that "television viewing in childhood and adolescence is associated with poor educational achievement by 26 years of age. Early exposure to television may have long-lasting adverse consequences for educational achievement and later socioeconomic status and wellbeing."
The authors describe a "dose-response" relationship between the amount of television watched and declining educational performance, which has biological plausibility. Significant long-term effects occurred even at so-called modest levels of television viewing of between one and two hours per day. They also wrote "the overall educational value of television viewing was low . These findings offer little support for the hypothesis that a small amount of television is beneficial."
The media prominence of Harry Potter has caused many to labour under the misapprehension that children are reading more. The opposite is true - and the National Foundation for Educational Research has found that nine to 11-year-olds now prefer comics to story books.
Early exposure to and increasing time spent watching screen technology is linked to a significant continuing decline in time spent reading books. This and frequent use of computer games were recently cited in an international study of reading and literacy as significant causes of England's rapid descent from third to 19th place in the Progress in International Reading and Literacy Study between 2001 and 2006.
Even background television greatly disrupts younger children's ability to play, concentrate and learn, with, according to a study by Evans Schmidt et al this year, serious implications for subsequent cognitive development.
It seems that irrespective of the educational quality of the programme, the medium of the TV screen affects, among other things, the development of sustained attention, which is vital for learning. While younger children may be more vulnerable to these effects, screen-related attentional damage is now being found to occur in all age groups.
The American Academy of Pediatrics journal reported in 2004 that children who watched television at ages one and three had a significantly increased risk of developing ADHD-type attentional problems by the time they were seven.
For every hour of television a child watched per day, there was a 9 per cent increase in attentional problems. The authors suggest that their findings may be an understatement of the effects on children. Now, TV viewing between ages five and 11 is linked with short attention span, poor concentration and being easily distracted later in adolescence.
Researchers in New Zealand, in another study that appeared in the same journal last year, believe "the effects may be long-lasting". But why? Today there are far more zooms, pans and edits than ever before. Along with TV displacing key educational and play activities, this increased audio-visual stimulation may harm the child's rapidly developing brain.
Rapidly changing images, scenery and events, colours, and high-fidelity sounds are highly stimulating and extremely interesting. TV is the flavour enhancer of the audiovisual world. Little in real life is comparable. TV may overpay the child to pay attention to it, and in so doing it may physically corrupt the reward system underpinning their ability to pay attention (to a teacher or book) when the screen is off.
This overpayment appears to come in the form of the neurotransmitter, dopamine, seen as rewarding us for paying attention, especially to things that are novel and stimulating. Screen entertainment causes our brain to release dopamine and, for example, ADHD is linked to a change in dopamine functioning.
The effects of screen viewing occur at viewing levels below that of the average child. And British children are watching more TV and at younger ages. The average six-year-old will have already watched TV for more than one full year of their lives. When other screen time is included, the figure is far higher. British children aged 11 to 15 now spend 55 per cent of their waking lives - seven and a half hours a day - watching TV and computers according to the British Market Research Bureau in 2004. A study by Zimmerman in 2007 showed that over the course of childhood, children spend more time watching TV than they do in school.
Now, a study of 17-year-olds by Barr-Anderson et al, in the journal Pediatrics finds that even adolescents with a TV in their bedroom exhibit "poorer school performance". Teachers, schools and Government should make it clear to parents and pupils that the amount of time spent watching a TV screen may have a long-term impact on school performance, educational outcome and attentional functioning.
Screens in the bedrooms of children of primary school age should be considered an abdication of parental responsibility.
Dr Aric Sigman is a fellow of the Royal Society of Medicine and associate fellow of the British Psychological Society.
Johnson, J.G., et al (2007)Extensive Television Viewing and the Development of Attention and Learning Difficulties During Adolescence, Archives of Pediatrics amp; Adolescent Medicine, 161:5, 480-486
Twist, L., Schagen, I., et al (2007)Readers and Reading: The national report for England 2006 (PIRLS: Progress in International Reading Literacy Study), Slough: National Foundation for Educational Research www.nfer.ac.uk
Sigman, A. (2007) Visual Voodoo: The biological impact of watching television, Biologist, 54:1, 14-19
Barr-Anderson, D.J., et al (2008)Characteristics Associated With Older Adolescents Who Have a Television in Their Bedrooms, Pediatrics, 121:4, 718-724
Evans Schmidt, M. (2008)The Effects of Background Television on the Toy Play Behavior of Very Young Children, Child Development, 79:4, 1137- 1151
Landhuis, C.E., et al (2007)Does Childhood Television Viewing Lead to Attention Problems in Adolescence? Results from a prospective longitudinal study, Pediatrics, 120:3, 532-537
Zimmerman, F.J. (2007) News release from the University of Washington, August 7 2007
"Baby DVDs, videos may hinder, not help, infants' language development," by Joel Schwarz
Full references for other studies mentioned in the column can be found in Aric Sigman'sRemotely Controlled: How television is damaging our lives (Vermilion, 2007).