The two countries were selected for the study due to the high rates of smartphone ownership among their young adults.

Eighty percent of Americans own smartphones, while the ownership rate in South Korea is about 90 percent.

"Mobile media is facilitating our communication needs more than traditional media such as television, radio or newspapers," said co-researcher Seok Kang from the University of Texas, San Antonio.

For nearly a year, the researchers conducted online surveys and analysed the data of more than 1,600 students from both countries.

Participants measured the amount of time they spent using their smartphones and for what purpose they used them. The study was published in the journal Computers in Human Behaviour.