How do you react when you’re frustrated? Clench your fists? Pull out your hair? Smile? Oh — you don’t smile when you’re frustrated? According to a new study from MIT, you actually do; and they have computers programmed to prove it to you.

Participants were tasked with acting out expressions of delight or frustration, as webcams recorded their expressions. Then, they were either asked to fill out a tedious survey designed to evoke frustration or were invited to watch a video designed to cause delight — also while being recorded, according to a press release from MIT News. Experiments were conducted the MIT Media Lab, and were led by Eshan Hoque, a graduate student in the Affecitve Computing group.

When asked to fake frustration, Hoque told MIT News that 90 percent of subjects did not smile. When those same subjects were forced to fill out a detailed online form that lost all of their information once they hit “submit,” however, 90 percent of them did smile.

Although still images show little difference between the frustrated smiles and the delighted smiles of those looking at cute babies, the progression of the two were different. “Often, the happy smiles built up gradually, while frustrated smiles appeared quickly but faded fast,” according to MIT News.

Understanding what underlies emotions was a major goal of the research. “People with autism are taught that a smile means someone is happy,” Hoque said, but research now shows that isn’t necessarily the case. This research could then help train those who have difficulty interpreting expressions to more accurately gauge the expressions they’re seeing.

Hoque says this research could also be helpful to marketers, telling MIT News, “Just because a customer is smiling, that doesn’t necessarily mean they’re satisfied.”

Now, I’ll start thinking twice when anyone smiles at me. Which is frustrating. Which will also make me smile. Everything comes full circle, doesn’t it?

For more on the research, and some words from Hoque, you can watch the video below.