There was certainly worry about this earlier, though I don't know if there was any research done. My parents limited screen time when I was growing up (born 1985).
I do think there's been a substantial change in child-targeted media over the years. In the days of broadcast only tv, you couldn't turn the tv on at any time of day and expect to find children's programming. The advent of cable and home video players changed that, but not everybody had cable and not everybody chose to buy kids show recordings. Parents could make those decisions occaisionally and then be stuck with them, rather than having to fight a continuous battle of self-control.
Other big changes occurred with the rise of children's programming on youtube and the invention of smartphones. Basically in less than 100 years we've gone from no childrens screen media exising at all to an unlimited quantity available for free in every adult's pocket 24 hours a day.
I do think there's been a substantial change in child-targeted media over the years. In the days of broadcast only tv, you couldn't turn the tv on at any time of day and expect to find children's programming. The advent of cable and home video players changed that, but not everybody had cable and not everybody chose to buy kids show recordings. Parents could make those decisions occaisionally and then be stuck with them, rather than having to fight a continuous battle of self-control.
Other big changes occurred with the rise of children's programming on youtube and the invention of smartphones. Basically in less than 100 years we've gone from no childrens screen media exising at all to an unlimited quantity available for free in every adult's pocket 24 hours a day.