There are apps to track your sleep, your steps, and your pets, but this may be the first that tracks your friends.
Pplkpr, pronounced "People Keeper," connects to a Bluetooth heartrate monitor and measures your response when certain people are around. One goal is to help you identify your most toxic companions.
A student who tested out the app explains in this video that pplkpr helped her realize that her friend Mark is "kind of a dick."
The app's creators, Carnegie Mellon artists-in-residence Lauren McCarthy and Kyle McDonald, call Pplkpr both a "real app" and an "art project." Anyone can download it for free from iTunes, but the creators also want people to think deeply about what they learn by tracking their emotional response to their friends.
"There were students that said, 'It told me to stop talking to this guy or stop posting on my so-called friend's wall,' " McCarthy told The Huffington Post in an interview conducted via video chat. "They said, 'I think it was good. It made me realize the truth.' "
Here's how it works: Pplkpr takes a list of your Facebook friends and allows you to track how they make you feel when you spend time with them in real life.
For example, if you're grabbing coffee with Todd and he's yammering on about his amazing new apartment, you might feel a bit stressed about your tiny, shabby studio. The heart monitor would pick this up and let you know that Todd makes you anxious. If this happens each time you hang with him, you may identify Todd as a toxic influence.
The app tracks positive feelings too, like excitement and arousal. Pplkpr was built to work with a Mio heart rate band, but others types work, too.
If you don't want to wear a heart monitor, the app still works. It won't automatically interpret your feelings, but you can tell pplkpr the moment someone scared you, made you bored or a variety of other emotions, all with a couple of taps. The app keeps track of all of this and susses out patterns, so you'll eventually know which of your so-called friends give you bad vibes.
McCarthy and McDonald understand that some may view their app as bizarre or even transgressive: In fact, that's sort of the entire point.
"We were trying to take it one step far enough to make it seem outrageous. It's critical of this quantified self, big data trend that we're seeing," McCarthy told HuffPost.
In the ideal sense, these trends are supposed to help people improve their lives. For example, Fitbit wristbands tell you how many steps you take throughout the day and track the quality of your sleep, all in an effort to make you healthier.
Critics might say all of this data could result in unnatural fixations -- as in this satirical piece by humorist David Sedaris. Experts say the numbers can oversimplify complex ideas, like what affects an individual's metabolism.
A promotional video for pplkpr bears this out, with a narrator cheerfully explaining how the app will "automatically manage your relationships so you don't have to" -- a notion that might remind you of the movie Her, with its greeting card company that expresses personal sentiments for customers so they don't have to. But pplkpr isn't totally critical of trendy tech.
"There's a part that's kind of earnest or optimistic about exploring these ideas," McCarthy said. She points out that pplkpr can be a sort of litmus test for your views on personal data tracking.
"You might realize it's terrifying, or you might realize there's something interesting in the reflection," McCarthy said.