New Canadian research has found that parents who reward their children with screen time for good behaviour could be encouraging children to spend more time in front of a screen, especially on weekends.

Carried out by researchers at the University of Guelph, the new study involved 62 children between 18 months and five years of age and 68 parents, who were questioned about how they monitor their children's screen time, when children are allowed screen time and whether the parents spend time in front of a screen when around their children.

"We wanted to investigate the impact of parenting practices on toddler and preschooler screen time because this is the age when habits and routines become established and they tend to continue throughout life," said Tang. "Also the use of mobile devices, such as tablets and smartphones, has soared in popularity among this age group in recent years."

The findings, published in the journal BMC Obesity, showed that the majority of parents use screen time to control behaviour, especially on weekends.

The results also showed that children of parents who use screen time as a reward or revoke it as punishment actually spend more time on a smartphone, tablet, computer or in front of the television than children whose parents don't, around 20 minutes more a day on weekends.

The researchers suggested that such an approach leads to more screen time because using it as a reward or punishment increases a child's attraction to the activity.

"It's similar to how we shouldn't use sugary treats as rewards because by doing so we can heighten the attraction to them," explained study author Jess Haines. "When you give food as a reward it makes children like the carrot less and the cake more. Same thing with screen time."

Children also spent more time in front of a screen if their parents used their phone, tablets and other screens in front of them, with the effect even stronger when the mother was the one spending time in front of a screen.

"It's possible the parent is allowing the child to be in front of a screen while they are," said Haines. "For parents of younger children, this isn't as common because parents can have their screen time while a child is napping or in bed. But as children get older, out-grow their naps and have later bedtimes, spending time in front of a screen without children around becomes more difficult."

Children who were allowed to use screens during meals also experienced more time in front of a screen, something which the researchers discourage, explaining the mealtime is a good opportunity for families to connect with each other.

Children under two years of age should not have any time in front of a screen at all, they added.