Is your smartphone making your kid dumber? What a new study found

A new study of nearly 750 Norwegian children found that higher smartphone use by a child’s primary parent was associated with slower growth in receptive vocabulary, while owning a digital device at ages 4 to 5 was associated with lower language scores at the start of the study.

The population-based cohort study followed 747 children from roughly age 5 to age 7, examining whether children’s screen habits and their parents’ screen use were associated with changes in receptive vocabulary and grammar. Researchers accounted for differences in parental education and household income.

The study, published in JAMA Pediatrics on August 17, used annual assessments of receptive vocabulary and grammar, including standardized measures of children’s ability to understand words and grammatical structures. Researchers also used latent growth modeling to distinguish children’s language levels at the beginning of the study from changes in those skills over time.

Parent smartphone use, child device ownership linked to language measures

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The findings were mixed. Most measures of screen use were not associated with children’s language growth. 

"It may be surprising to some that our study shows a weaker correlation between children's screen time and language skills than some previous studies have found," Øistein Anmarkrud, a professor and researcher of the study, told FOX Local. "We put our data through a very rigorous test and given that we also know children's language development is quite stable over time, we were actually a little surprised by the correlations we did find." 

However, two associations stood out: greater daily smartphone screen time by a child’s primary parent was linked to slower growth in children’s receptive vocabulary. Each additional hour of daily smartphone use by the primary parent was associated with 0.42 fewer points in children’s annual growth in receptive-vocabulary raw scores.

Also, children who owned a digital device had lower language and grammar scores at the starting point of the study. Children who owned a digital device at ages 4 to 5 scored an average of 5.13 points lower in receptive vocabulary and 4.56 points lower in receptive grammar at baseline than children who did not own a device.

"So one reflects a developmental trajectory association, the other reflects a baseline difference," Anmarkrud continued. "Children owning a device was associated with their language skills at the start of the study, not with how quickly their language grew over time. That is a meaningful difference: it tells us these 4- to 5-year-old children who own a digital device already scored a bit lower when we first measured them." 

He added, "It is also reasonable to assume that whether a child owns a digital device may to some degree reflect the child’s access to digital media and opportunities to use it without parental supervision." 

Findings did not link digital device use to language delays

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The researchers emphasized that these findings do not establish that smartphones or digital devices directly cause language delays. In particular, the association between device ownership and lower language scores was observed at the start of the study rather than as a difference in subsequent language growth.

"One should obviously be cautious about giving very strong or definitive advice based on a single study," Anmarkrud explained. "A more general recommendation might be that parents should make thoughtful decisions about when their child gets a digital device of their own, how much freedom the child has regarding what the device is used for and when it is used, and whether the child uses the device independently or together with an adult." 

Screen use was measured only at the study’s onset; parents reported most screen-use measures; researchers did not assess what children watched or did on screens, whether they used them with an adult, or why parents used their phones.

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But the findings add nuance to an ongoing debate about children and screens. Rather than suggesting that all screen use is harmful, the results indicate that the type and context of screen use may be important. Parental smartphone habits and children’s access to personal devices could provide useful information for parents and clinicians assessing factors associated with language development.

The researchers concluded that family-level screen use may be a meaningful consideration when evaluating children’s language development, while noting that further research is needed to better understand the relationships and determine why parental smartphone use may be associated with slower vocabulary growth.

"Screen use should be considered at the family level, not just in terms of how much time a child spends on a screen. Our findings suggest that parental smartphone use and children's device ownership may be meaningful indicators of risk for poorer language outcomes. So it is not only about the child's own screen habits, but also the broader digital environment in the home," Anmarkrud said.

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