Screens by age: what the research says.

Babies have difficulty learning from screens. Trials of particular baby-video and baby-reading products did not support their learning claims. More screen time at age 1 has also been associated with later developmental delays. #14, #76, #77, #78

Video calls are the exception because they can work like a conversation: a relative on screen can see, hear, and respond to your baby. The value is in the connection. #67, #96, #98

Background TV can interrupt focused play and reduce parent–child conversation. Competing speech can make words harder for babies to recognize, and a small study linked background TV during infant play with smaller later vocabularies. #73, #74, #116, #117

In experiments, when mothers turned to a phone during play or feeding, they responded less to their babies, and babies became more distressed. Studies of everyday phone use found smaller or no links with later development and bonding, so the concern is phone use that pulls attention away from a baby, not a phone in the room. #87, #109, #110, #111, #112, #113, #114

Young children generally learn more from face-to-face demonstrations than from video. Shared viewing can help, but evidence of benefits does not establish that video is better than available screen-free alternatives. #13, #78

Background TV reduces how much parents talk and the variety of words they use. Competing speech made new words harder for 22- to 24-month-olds to learn, while phone distractions can disrupt parent–toddler interaction. #118, #119, #88, #89

A small trial with 16- to 30-month-olds also found preliminary sleep benefits from replacing screens with other activities in the hour before bed. #100

More screen time at ages 2 and 3 has been linked to poorer developmental scores later in preschool. Experiments also show that some content can immediately interfere with skills such as self-control and working memory. These findings support limiting routine use, although they do not establish that every screen activity is harmful. #12, #86

Some educational programs and apps support learning, but a benefit does not necessarily mean they outperform available books, responsive teaching, or play. OSFP recommends screen-free days as the usual routine to protect time for these activities, with selected screen use when it offers a clear advantage. #81, #82, #83

These years establish reading and writing foundations. Handwriting instruction improves writing skills. In children’s digital books, unrelated interactive features can distract and reduce comprehension, while features that support the story can help. The design and teaching matter, not simply whether a resource is digital or print. #43, #46

Providing devices alone does not reliably improve learning. Some well-designed programs help, but benefits depend on the task, instruction, and comparison activity. These findings do not establish that routine device use improves core learning in K–2. #26, #27

Paper tends to have an advantage for understanding informational text, although results vary. Upper-elementary students do not always recognize when their comprehension is worse on screen. #1, #32, #33, #44

Screen use and emotional or behavioral difficulties predict each other over time, with small average associations. Earlier smartphone ownership has also been associated with poorer health outcomes in a large study. These findings support caution but do not identify a proven birthday for a first phone. #59, #94

Social-media findings vary with the young person and experience. Studies associate heavier use with later emotional difficulties, while research on broader digital use finds small average links with well-being. Population-level causation remains unsettled, and averages can hide individual harms and benefits. #25, #54, #72

School phone-policy evidence is mixed: one English study found better exam results after bans, while a later observational study found no association with better overall well-being. A phone policy alone should not be expected to solve every problem. #38, #47

Bedtime device access and use are associated with poorer sleep. Social-media experiences can include both support and harm, depending on content, contact, and the teen’s circumstances. Much of this evidence is observational. #71, #72, #91

College studies favor taking and reviewing handwritten notes on average. That finding supports teaching the option but does not establish that handwriting is best for every high-school student. #39