It was completed by 370 parents, with 97 per cent of them having TVs, 83 per cent tablets, 77 per cent smartphones and 59 per cent internet access.
Lead author Hilda Kabali said children younger than a year were exposed to the devices in surprisingly large numbers.
Fifty two per cent had watched TV, 36 per cent had touched or scrolled a screen, 24 per cent had called someone, 15 per cent used apps and 12 per cent played video games.
Most children were using mobile devices by the age of two.
"We didn't expect children were using the devices from the age of six months," Ms Kabali said.
"Some children were on the screen for as long as 30 minutes."
-AAP