In my Scientific American column this month I noted that it’s typically older people who seem to disapprove of the younger ones' immersion in electronics. Of course that's a typical generational reaction; it used to be the radio that would rot young people’s brains…then TV…and now phones and tablets.

But what does science say about the effect of touch-screen devices on children?

Not much; the touch-screen era is still very young. But a handful of studies investigating intensive device use have emerged, including the ones summarized here. Most seem to suggest that moderation in screen time is a good idea, although some point out benefits. Here are more details about what they found—and how:

Study: Cognitive control in media multitaskers
Published: April 2009
Subjects: 262 college students
Conclusion: “These results suggest that heavy media multitaskers are distracted by the multiple streams of media they are consuming or, alternatively, that those who infrequently multitask are more effective at volitionally allocating their attention in the face of distractions.”

Study: Adolescents' use of instant messaging as a means of emotional relief
Published: January 2013
Subjects: 150 adolescents
Conclusion: “Findings revealed that IM [instant messaging] conversation significantly contributed to the well-being of distressed adolescents. In addition…introverted participants profited from IMing more than did extraverts.”

Study: Do television and electronic games predict children's psychosocial adjustment?
Published: March 2013
Subjects: 11,014 British five- and seven-year-olds
Conclusion: “TV but not electronic games predicted a small increase in conduct problems. Screen time did not predict other aspects of psychosocial adjustment.”

Study (pdf): Parents' perspectives: Children's use of technology in the early years
Published: March 2014
Subjects: 1,028 parents
Conclusion: “Of children who have a touch screen at home, children of lower socioeconomic status are twice more likely to look at stories daily than their more advantaged peers… All children are more likely to enjoy reading more if they use both books and a touch screen to look at stories, compared to books only.”

Study: Five days at outdoor education camp without screens improves preteen skills with nonverbal emotion cues
Published: October 2014
Subjects: 105 preteens
Conclusion: “Our study suggests that skills in reading human emotion may be diminished when children's face-to-face interaction is displaced by technologically mediated communication.”

Study: Sleep Duration, Restfulness and Screens in the Sleep Environment
Published: January 2015
Subjects: 2,048 fourth- and seventh-graders
Conclusion: “Sleeping near a small screen, sleeping with a TV in the room and more screen time were associated with shorter sleep durations. Presence of a small screen, but not a TV, in the sleep environment and screen time were associated with perceived insufficient rest or sleep. These findings caution against unrestricted screen access in children's bedrooms.”