Children who own a mobile phone by the age of nine perform less well in school tests by the age of 13, new Irish research has found.

According to researchers from the Economic and Social Research Institute (ESRI), children are ‘increasingly getting access to mobile phones, and mobile phone ownership is now occurring at a time in children's lives where their literacy and numeracy skills are developing'.

They set out to determine if there was any link between phone ownership and academic outcomes, and whether delaying ownership benefitted children.

"The mobility of mobile phone technology allows it to have a potentially unprecedented impact on children's development. It can seamlessly cross into school and home settings and it is difficult for parents and teachers to supervise and monitor usage, as it accompanies the child throughout the day.

"Consequently, the frequency of engagement with mobile phone technology is likely to be far higher for than other forms of technology," they noted.

The researchers used data from 8,500 children taking part in the Growing Up In Ireland study - an ongoing study which has been monitoring the development of nearly 20,000 children since 2007.

They found that 40% of children in Ireland own a mobile phone by the age of nine. Furthermore, in both reading and maths, these children ‘fare less well in terms of their academic development as they move into adolescence'.

Those who had a phone from the age of nine scored an average of 4% less in standardised reading and maths tests at the age of 13.

The researchers noted that children attending more socially disadvantaged schools were more likely to own a mobile phone by the age of nine, while children with parents who have a higher income and a higher level of education were less likely to have their own phone by the same age.

However, the observed link between mobile phone ownership and test scores remained even when factors which usually influence tests scores, such as socioeconomic class, were taken into account.

The researchers suggested that the findings may help schools to make decisions about access to such devices during school hours, particularly primary schools.

"The findings suggest that there may be significant educational costs arising from early mobile phone use by children. Parents and policymakers should consider whether the benefits of phone availability for children are sufficiently large to justify such costs," they said.

According to ESRI associate research professor, Selina McCoy, this is the first time the ESRI has looked at the impact of mobile phone ownership on children's academic development.

"It is important to keep monitoring this going forward in order to provide evidence for the growing debate about the potential effects of screen time and mobile phone use on young people in Ireland," she said.