Maybe, but that observation isn’t particularly relevant for this data, which examines what young people say about themselves. I completely agree that older folks’ observations are not a useful source of data about generational differences. That’s why the studies rely on the voices of the generation itself. This question also seems to assume that an argument which has been made before must be wrong. That seems nonsensical at best. Instead, it makes sense to listen to what young people have to say, and to find out how that’s different from what they said 10, 20, or 30 years ago.

Related to this is “people have always worried about the effects of new technology – they said the same thing about novels, TV, etc.” Again, just because it’s been said before doesn’t make it wrong. For example, people were probably right to worry about TV: It’s also correlated with depression, and political scientist Robert Putnam concluded in his book Bowling Alone that TV was the primary reason community groups and social capital declined after 1950.

As for novels, we don’t have data to determine if they had negative effects when they were introduced. But among today’s teens, those who read books, magazines, and newspapers are happier than those who don’t. Thus, this observation isn’t particularly relevant to today’s teens.