Not saying that it wouldn't be an issue at older ages as well, since for millenia children learned by watching the other people around them and learning from them, not from screens. That's my essential point - that's utterly essential for infants, even more at that age than later. Not that suddenly it becomes ok!

But if we want to keep the discussion on topic, we should talk about the age group being studied. Beyond that, we want to have a different study.

(edit, grammar because it's really too early in the morning for writing)