A parents' group is calling for official guidelines on the amount of time children spend on screens in New Zealand schools.
The group has set up a new website, sensiblescreenuse.org, which argues that "moderate" use of computers is good for children, but too much is bad for them.
"Moderate" use has been defined as up to about 25 minutes a day or one to three times a week for young primary-aged children, rising gradually to up to half the school day in high school.
The group's founder, Auckland children's physiotherapist and mother of four Julie Cullen, says some schools are exceeding these limits.
"Some schools have one-on-one devices even for 5-year-olds," she said.
"Our local school has higher screen use than I would like to see. Ninety per cent of the children's learning is on screens in the last few primary school years, and they are looking at Bring-Your-Own-Device down to young ages."
The website expresses most concern about game-based learning apps, such as Reading Eggs, which give children musical and visual rewards when they get the right answers. Some reward them with tokens which the children can use for virtual online shopping.
"Even digital bursts of sparkles and cheering can create a dopamine hit that encourages children to seek out the response again and again," it says.
"Literature does exist that specifically suggests using the physiology of video game addiction to benefit learning via gamification."
Cullen said children might make short-term gains through such games, but the long-term evidence was that NZ children's literacy was declining.
The website links to numerous studies, but Cullen conceded that the evidence was still mixed.
"I think we need to be having a conversation about this," she said. "I think guidelines are needed because there are health risks."
A summary report published last month by the Organisation for Economic Cooperation and Development (OECD) said current scientific research:
• "Is not conclusive enough to support evidence-based guidelines on optimal amounts of screen use or online activities; and
• "Does not provide evidence of a causal relationship between screen-based activities and mental health problems, although some associations between screen-based activities and anxiety or depression have been found."
It quoted a recent British study of 15-year-olds which found that mental wellbeing peaked at one hour a day of computer use and declined with every extra hour, although the decline on a 70-point scale was only from 48 points at one hour to 44 points at seven hours a day.
"However, it is still wise to take a precautionary approach including turning off devices when not in use, switching off screens an hour before bed, and designating times (e.g. while having dinner or driving) and locations (e.g. the bedroom) as media-free," the report said.
A guide issued in January by Britain's Royal College of Paediatrics and Child Health also found there was not enough evidence to prescribe fixed screen limits, but recommended that "families should negotiate screen time limits with their children based upon the needs of each individual child, the ways in which screens are used and the degree to which use of screens appears to displace (or not) physical and social activities and sleep".
NZ Paediatric Society president Dr Tim Jelleyman said no similar guide had been developed here, but a computer screen could not replace human interaction in child development.
"There's nothing that can beat interacting with a person and, what's more, interacting with a person who cares dearly for you," he said.
Ministry of Education deputy secretary Ellen MacGregor–Reid said the ministry "keeps a watching brief on emerging evidence".
She noted that a recent British study concluded: "The association we find between digital technology use and adolescent well-being is negative but small, explaining at most 0.4 per cent of the variation in wellbeing."
• For a high school student, no more than half the learning school day should be spent on computers (up to 2.5 hours).
• Minimal computer use in educational settings for under-5s.
• Between starting school and high school, computer time should increase gradually.
• Classrooms should reflect a balance of learning modalities.
• Homework to be given in digital and print form, to suit all learners and families.