Giving young children a two-minute warning that "screen time" is about to end makes transitions away from tablets, phones, televisions and other technological devices more painful, a new University of Washington study has found. Researchers expected that this ubiquitous parenting tool - which aims to make it easier for children to disengage from an activity they're absorbed in - would help smooth transitions away from screen time.

Some things did make that switch easier, like having routines, disengaging at a natural stopping point or simply having a battery die. But children aged 1 to 5 who were given a two-minute warning by their parents were more upset when the screen went away. Parents also reported that features like "autoplay" - which automatically starts another video when one ends - or suggested videos that pop up and tempt children to keep watching were a frustrating and driving force behind many of their battles.

The findings, which were based on interviews and a diary study of families who documented screen time transitions in detail, are outlined in a paper to be presented at the Association for Computing Machinery's 2016 CHI conference in San Jose, Calif.

"We were really shocked - to the point that we thought 'well, maybe parents only give the two-minute warning right before something unpleasant or when they know a child is likely to put up resistance,'" said lead author Alexis Hiniker, a UW doctoral candidate in human-centered design and engineering. "So we did a lot of things to control for that but every way we sliced it, the two-minute warning made it worse."

The researchers in the UW's Computing for Healthy Living and Learning Lab initially interviewed 27 families about how they manage media and screen time experiences for their toddlers and preschoolers. Those answers informed a diary study in which 28 different families documented screen time experiences over the course of two weeks - what children were watching, on what kind of device, what parents did during that time, what prompted screen time to end and how upset or amenable children were.

Surprisingly, 59 percent of the time parents reported that their child had a neutral reaction to ending screen time. Another 19 percent of the transitions evoked a positive reaction, and 22 percent evoked a negative reaction.

"Most of the time these transitions actually go pretty smoothly, which can be hard for parents to recognize," said senior author and associate professor of human-centered design and engineering Julie Kientz. "If one out of five experiences is unpleasant enough that parents are always bracing themselves and worried about it, that colors their perceptions."

The researchers also found that the most common parental activity during screen time was doing chores or caring for other children. Parents also used technological devices to distract toddlers while they had to endure something unpleasant, like medical treatments.

"We did not see parents using screens as electronic babysitters so they could work or do something fun," said Hiniker. "They usually pull out the iPad as a last line of defense or in a moment of desperation because the parent hasn't showered all day."

The most common trigger for putting devices away (39 percent of the time) was a situational change that made screen time impossible or incompatible with family activities - reaching your destination in a car or needing to leave for school or having a friend knock on the door to play.

The second most common trigger (25 percent) was that the toddler or preschooler lost interest - which was at odds with parents' perception that this is quite rare. Other reasons for ending screen time included parental discretion (15 percent), previously agreed-upon rules (9 percent) or the technology reaching a natural stopping point like the end of a game or video (11 percent).

Parents reported that screen time transitions were easier when they were part of a routine. The same child who might argue and negotiate for more screen time after a Friday night treat may be perfectly fine with turning off the TV when breakfast is ready if that is part of the daily household routine.

Natural stopping points in the content children were viewing or in the games they were interacting with made transitions easier - which represents an opportunity for content developers and technology designers to help families have more positive media experiences, the researchers say.

Screen time transitions also went more smoothly if the technology was to blame. Children were less likely to be upset, for instance, if they couldn't watch a video because WiFi was unavailable. One couple who regretted allowing their child to watch a particular show on vacation encountered tantrums when they wouldn't let him watch it at home. When they told him the show wasn't available in Seattle, the fights evaporated.

That raises the question of whether a two-minute warning issued by the technology itself - rather than a parent - might still prove helpful, researchers said. A family might set a specific amount of screen time in an app and let the child pick an activity to follow. At two minutes out, the app could remind the child that it's almost time to eat lunch or meet a friend or get out the play dough.

"The kids we looked at for this particular study are right in that power struggle age," Kientz said. "It's much easier to do that with a person than with technology. Once you take that parental withholding component out of it, kids are a lot more accepting."