Tristan Harris doesn't want you to stop using your phone altogether, but he does want you to feel like the time was well spent.

As a former design ethicist at Google and an expert on the ways tech companies design their products to keep users engaged, Harris has seen firsthand that many apps aren't designed with that kind of altruism in mind.

At best, Harris has found, the apps can lead people to feel mild dissatisfaction toward their lives; at worst, they can contribute to worsening mental health.

At this year's TED Conference in April, Harris gave several examples of how tech companies engineer their apps to be as irresistible as possible, seemingly without regard for consequence.

YouTube, for instance, will gradually learn what kinds of videos you prefer and begin tailoring its recommendations in an endless stream of suggestions. It also incorporates autoplay, a feature that will queue up the next video while the current video is ending.

This puts the onus on the viewer to stop binge-watching videos, which assumes people have total control over how much they watch. NYU psychologist Adam Alter has criticized this emphasis society puts on willpower, saying "there are very few examples of humans doing a good job exerting self-control for very long periods of time."

In his TED talk, Harris goes a step further, criticizing tech companies for feeding off one another's strategies.

"If you're Netflix, you look at [YouTube] and say, well, that's shrinking my market share, so I'm going to autoplay the next episode," he said. "But then if you're Facebook, you say, that's shrinking all of my market share, so now I have to autoplay all the videos in the newsfeed before waiting for you to click play."

The evolution of the user experience then becomes a "race to the bottom of the brain stem" in which people's basest desires are being exploited for web traffic, according to Harris.

He also offered criticism for Snapchat's Snapstreaks feature, which shows the number of consecutive days people send snaps to one another.

"What they just did is they gave two people something they don't want to lose," Harris said. "Because if you're a teenager, and you have 150 days in a row, you don't want that to go away. And so think of the little blocks of time that that schedules in kids' minds."

There are a raft of other strategies for hijacking attention that Harris has outlined in the past. In a 2016 Medium post, he took issue with the whole system of notifications and alerts that induce feelings of reward, isolation, and social cohesion.

"Imagine millions of people getting interrupted like this throughout their day, running around like chickens with their heads cut off, reciprocating each other — all designed by companies who profit from it," he wrote. "Welcome to social media."

Experts have credited these strategies as factors in the growing number of teen mental health issues, which are increasingly leading to suicide. Research has found teenagers who more frequently use social media face greater risks of depression and anxiety than kids who spend time outdoors or with members of their community.

To curb these trends, Harris and other experts have called on doctors to educate parents about the risks of too much screen time. They have also advocated for tech companies to regulate the designs that allow people to scroll or watch endlessly.

"There's nothing in your life or in our collective problems that does not require our ability to put our attention where we care about," Harris said in his talk. "At the end of our lives, all we have is our attention and our time. What will be time well spent for ours?"