Yes, I worry a lot, Janni. It seems clear that children's attention spans are being eroded by constant switches of information, soundbites etc. My attention span is worse than it ever was and I don't exactly blame FB, messageboards etc for this, but it certainly doesn't help. Short, sharp nuggets of info don't help develop concentration skills, and application skills (I mean as in "applying yourself" to a sustainted task; nothing to do with computer applications!).
As an adult I have the choice whether or not to wreck my head
but peer pressure and the normalisation of screens being on all day, with phones to fill in any quiet moments, signals ... well, maybe not the downfall of society, but it would need to be a clever child to be able to deal with all the constant info properly.
I have a 10-year-old FB friend and she uploads new "posing" pics of herself almost daily - serious face, or tongue out to the side, looking up ... worryingly narcissistic imo.
I know this probably sounds po-faced and scaremongering, but I just don't feel it's worth taking the risk with my DC, so I limit their TV as much as I possibly can ... they're 5, 3 and baby, and probably see about 30 mins-1 hr per week [sic].
Personal bugbear! But I think this really is the transition generation, and another 10 or 15 years will show quite clearly the detrimental effect of too much screen time.