"Our study shows that preschool kids who get too much screen time, on video games, internet-connected devices, television screens, and other digital mediums are among those showing delays and deficits in learning by the time they enter school at the age of five".
Approximately 2,400 mothers from Calgary, Alberta reported on the amount of screen time their children consumed.
Dr Max Davie, from the Royal College of Paediatrics and Child Health (RCPCH), said: "We would, in the light of this paper, reiterate our advice that families spend time interacting as a family, that screens are not allowed to interfere with sleep, and that screen based interaction is no substitute for in person contact".
Researchers tested children involved in the study, and found they were failing to meet developmental milestones in language and communication, problem-solving, and fine and gross motor skills.
Children in the study had an average of 17 hours of screen time a week when they were two years old, and 25 hours a week by the time they were three. This involves controlling the number of hours spent in front of screens but it can also include establishing device-free zones (such as the dinner table) and baskets where everybody puts their devices at certain points of the day, to make room for family connection. But rather than banning devices completely, the study recommends simply limiting hours and setting "no screen" zones and times, which, in the long run, could even help develop healthier habits and attitudes towards devices.
"We were particularly interested in the long-term impact of screens, which is why we followed children over time, from ages 2 to 5, and repeatedly assessed both screen time and children's developmental outcomes", Madigan said.
"What the study shows is that when kids are watching screen time they're not actually getting opportunities to practice those really important developmental skills that can set them on a path to success", explained Madigan. These amounts all exceed the Canadian Pediatric Society's recommended guidelines of no more than one hour a day (of preferably educational programming) for kids between two and five years old.
Higher levels of screen time at the ages of two and three years turned out to be "significantly associated" with poorer test results at three and five years.
The team explains that there are possibly two ways in which the screen time could affect the children.
Madigan was supported by the Alberta Children's Hospital Foundation and the Canada Research Chairs program. Statistical analysis was used to predict and find an association between more screen time and the test results on the developmental skills.
The lead author of the study says it shows that "positive stimulation for physical and cognitive development comes from interaction with caregivers". "What these findings tell us is that one reason there may be disparities in learning and behaviour at school entry is because some kids are in front of their screens far too often in early childhood".
Madigan encourages parents and guardians to set a good example and attempt to engage their children while they're watching the devices.