So now a study recommends we don't yell at teenagers because the effect is as bad as hitting them? To be fair, I've not had the urge to yell at a kid, nor hit one for any reason, but then, I'm not a parent of one, either. Hence, it's not my prerogative.
What happens when kids get yelled at? Apparently, they "feel sad" and sometimes "angry". But isn't that the reason why we yelled at them in the first place? To make them feel sad and angry as a consequence of something stupid they did or said. If they're smart, they won't do it again. If they're not, they'll just have to repeatedly keep feeling sad and angry until they become smart. That's how some people learn, sorry.
Yeah, I get the rationale for positive reinforcement for positive action ("more carrot, less stick"), but kids also have to experience negative consequences for negative behaviour because... that's life! Consequences come swiftly and unexpectedly. Very seldom will they arrive after a calm deliberation in which various strategies are weighed and debated before being regretfully meted out. Put one foot out of line, get your head bitten off. When parents snap and lose it, that's the lesson to learn. Once the kids leave the comfort and security of their parents' home, the rest of the world isn't going to treat them much nicer. They'd better get used to that reality fast.
And, anyway, why can't kids feel sad and frustrated? Why would we want to deprive them the right to feel sad and frustrated? A childhood is good only if the kid grows up feeling positive and happy all the time? No wonder the pharmacies are doing so well these days.