SYDNEY, Sept. 3 (Xinhua) -- An Australian study has found that young children who spend excessive time in front of a TV or computer screen will on average experience a decline in academic performance.

Published on Thursday, the study showed that 8 and 9 years olds who watch more than two hours of TV per day were impacted in their reading ability by the time they reached 10 to 11 -- while just one hour or more on the computer predicted a similar decline in numeracy skills.

However, the study found no such links between video games and academic performance.

Conducted by the Murdoch Children's Research Institute (MCRI), the research assessed 1239 young people, utilising the results of Australia's National Assessment Program - Literacy and Numeracy (NAPLAN).

It correlated watching more than two hours of TV a day at the age of 8 or 9 with 12-point lower numeracy and reading score, and using a computer for more than one hour a day with a 14-point lower numeracy result.

Lisa Mundy from the MCRI said electronic media had become the most popular leisure-time activity for children, despite impacting academic performance through reducing physical activity, sleep or time spent on homework, as well as having the potential to diminish concentration.

"The mid-primary school years are a time when academic difficulties are often first evident and predictive of lower academic performance and school dropout later," Mundy said.

"These middle years are also a time when children's electronic media use dramatically rises and children have more say over the media they consume."

The researchers said they hope the findings will assist parents, teachers and clinicians to consider the type and timing of TV and computer exposure in developing media plans for children.