"More time spent multitasking between different types of media is also associated with greater impulsivity and a poorer working memory in adolescents," said Amy S Finn from University of Toronto in Canada.
According to Finn, the term "media multitasking" describes the act of using multiple media simultaneously, such as having the television on in the background while texting on a smartphone.
While it has been on the rise over the past two decades, especially among adolescents, its influence on cognition, performance at school, and personality has not been assessed before.
It asked them how many hours per week they spent watching television or videos, listening to music, playing video games, for reading print or electronic media, talking on the phone, using instant or text messaging, creating crafts or writing.
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Participants rated how often they combined these with another such activity. Aspects of their working memory, their manual dexterity and vocabulary, and their levels of grit, conscientiousness and impulsiveness were also tested, researchers said.
Participants were also asked whether they believed that their ability was fixed or could be improved, they said.
Overall, participants reported consuming a great deal of media, and on average watched 12 hours of television per week.
They tended to multitask between mediums 25 per cent of the time, researchers said.
The results show how participants' media consumption patterns outside of school are related to their performance in school tests, they said.
Teenagers who spent more time media multitasking fared significantly worse academically than others. They scored lower in certain aspects of their working memory, tended to be more impulsive and were more likely to believe that intelligence is not malleable, researchers said.
"We found a link between greater media multitasking and worse academic outcomes in adolescents. This relationship may be due to decreased executive functions and increased impulsiveness - both previously associated with both greater media multitasking and worse academic outcomes," said Finn.
The findings were published in the journal Psychonomic Bulletin & Review.