The average age when children get their first phone is now 10.3 years old, according to Kids & Tech: The Evolution of Today's Digital Natives, a report from the Influence Central agency based on a survey of 500 women.
As well as acquiring mobile devices younger, children are opening their own social media accounts earlier: 11% had their first before the age of ten, while 39% got one between the ages of 10 and 12.
And this confluence of social and mobile will be key to reaching this group as it grows up, suggested Stacy DeBroff, founder and CEO of Influence Central.
"Kids carry their phones seemingly everywhere, and use them to access social media," she told Mobile Marketer. "Capturing kids' attention within this blurring of the lines between mobile and social will be the new frontier of marketing."
Some 38% of children accessed the internet via their phone, double the proportion the agency found doing so last time it undertook this research in 2012.
More were also going online via their own laptop or tablet: 64% compared to 42% four years ago. The use of a shared computer has fallen from 70% to 54% over the same period.
The spread of wifi has also enabled them to have more privacy when accessing the internet. In 2012, 85% did so in a shared room but that proportion has fallen to 76%; conversely, 24% now have private access in their bedrooms, up from 15%.
Consequently, parents have altered how they impose restrictions on device use: 41% placed strict limits on where and when their children can use them, down from 49%, but those who imposed "some" limits increased from 44% to 50%.
And there has also been a slight rise in the proportion of parents using online programs to control and filter sites or platforms, from 23% to 27%.
Data sourced from Mobile Marketer; additional content by Warc staff