So many young people in the Australian study used cellphones that the researchers had trouble finding enough for a control group.

Young people who regularly send text messages seem to perform certain brain tasks more quickly but with less accuracy, say Australian experts.

In one of the first studies of its kind, epidemiology professor Michael Abramson of Monash University and his colleagues analyzed the cognitive capacities and mobile phone use of 317 children aged between 11 and 14 around Melbourne. The team considered cellphone use in terms of making calls as well as sending text messages, known as SMS or short message service.

The findings were reported online ahead of print publication in the journal Bioelectromagnetics.

"We suspect that using mobile phones a lot, particularly things like predictive texts for SMS, is training kids to be fast but inaccurate," said Abramson. (When someone enters the first few letters of a word, predictive texting software offers to fill in the rest.)

In the Mobile Radiofrequency Phone Exposed Users' Study (MoRPhEUS) children were asked how many times they used the phone to speak or send SMS text messages each week.

Learning differences

A quarter of the children made more than 15 voice calls a week and a quarter of them made more than 20 text messages a week, said Abramson.

The researchers then tested the young people's response times and accuracy in carrying out certain tasks using a battery of computer tests, ranging from memory tasks like those used to play the card game concentration — the ability to flexibly hold information in short-term memory and learning associations between images — as well as the ability to track and predict the motion of an object such as a football. 

For example, associative learning declined by a factor of 0.016 and accuracy was reduced by a factor of 0.049 between those reporting the most text messages per week and those with the least messages.

After adjusting for factors such as age, gender, ethnicity, socio-economic status and handedness, the researchers were able to detect a consistent relationship between mobile phone use and cognition, or thinking and learning.

"We regard the findings as reassuring," Abramson said in an email. "This study provides evidence that using mobile phones is changing children's behaviour. However, we have not found any serious or long-lasting effect on the way that they think or learn."

'We don't think that the mobile phones are frying their brains'

Abramson said the findings were the same regardless of whether the children were making phone calls or texting.

He said given the amount of radiation transmitted when texting is 0.03 per cent of that transmitted during voice calls, which suggests radiation is not to blame for the brain effects.

"We don't think that the mobile phones are frying their brains," he said.

Repeated predictive texting is likely to be training the young people to act fast without thinking, not caring about accuracy.

The researchers were surprised to find that 94 per cent of kids studied were using a mobile phone and 77 per cent had their own phone — too many to form a sizable control group.

They now plan to re-do the study with primary school students.

With files from the Australian Broadcasting Corporation