Transcript for Study looks at the impact of screen time on children
Next tonight here, Diane sawyer reporting screen time. Think about this number tonight. Americans on average spend an average of 49 days a year, 49 days on their phones. Tonight's two-hour special takes a deep dive, the effect on our take a look at what Diane and her team discovered. Reporter: This is 2 1/2-year-old Jenson. I think he's about to suss out that she's on the device. Reporter: It takes just 15 seconds for Jensen to start his campaign to get mom Melissa to look up from that screen. We have some other things to do, mommy. We have some other things to do, mommy. And he just walks away. Reporter: This mom is helping researchers replicate a study she is doing something very difficult for her, asked to keep looking down. And remember, just for two minutes. Come on, mommy. Reporter: He repeats the plea seven times. We have another thing to do, mommy. Mommy! You are not listening to me, mommy. Listen to me, mommy. Reporter: And here is another fact about grownups and phones. On average, we unlock our phones 80 times a day. Cell phones, I think, are qualitatively different than other forms of distraction because they're with us all the time. They're ubiquitous. They have been engineered to grab our attention. Reporter: This is little hunter who seems to have learned that when she has to compete with the phone, she might as well just give up. She's sitting down and she's waiting. She knows her mother is not available right now. Reporter: When it was over -- Jensy, come here give hug. Reporter: Jenson's mom said it was a revelation. I was actually really surprised at his reaction. Reporter: So did this mom. I think you don't realize when you're at home in your own environment. I think I'll pay attention more now to not pick my phone up. It's really eye opening for so many of us. Tonight, so many questions answered in Diane's reporting. For example, how much information can they really find out about you, where you walked, trips you made years ago, images from your milestone moments saved. It's all great reporting. And apple CEO Tim cook and cha he wants to you do with your screen time Diane sawyer airing tonight, a short time from now after "World news tonight."
This transcript has been automatically generated and may not be 100% accurate.