According to the team, the device is 87 percent accurate with your measurements on file, but it's still up to 70 percent accurate without them. "Just by generally knowing what human heartbeats look like in different emotional states," team member and PhD student Mingmin Zhao said, "we can look at a random person's heartbeat and reliably detect their emotions."

It sounds like the perfect lie detector for people who tend to hide their feelings, but it has a number of other potential applications. Film companies can use it during test screenings to get a deeper look at how their movie affects people, while connected homes can adjust lighting, heating and other components based on their residents' moods. More importantly, doctors can use it as a non-invasive method to keep an eye on patients with depression, anxiety issues and other medical conditions.

"By recovering measurements of the heart valves actually opening and closing at a millisecond time-scale, this system can literally detect if someone's heart skips a beat," Fadel Adib, another team member explained. "This opens up the possibility of learning more about conditions like arrhythmia, and potentially exploring other medical applications that we haven't even thought of yet."