It’s not clear what it plans to do with it yet, but Apple has gobbled up a startup whose technology can read facial expressions.

The tech giant has reportedly acquired Emotient, a San Diego-based company that uses artificial technology to detect emotion from facial expressions, Apple confirmed to The Wall Street Journal. The company’s technology has primarily been used by advertisers, doctors, and retailers, though it’s not clear what Apple AAPL plans to do with it.

According to the Journal, Emotient had been seeking to raise new funding but was unable to do so. The company had previously raised a total of $8 million from investors such as Intel Capital and Seth Neiman.

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Apple’s purchase is not surprising. Artificial intelligence-based analysis of human faces has been a hot topic in Silicon Valley, especially in the last couple years. Heavyweights like Facebook FB and Google parent company Alphabet GOOGL have been investing heavily in artificial intelligence, machine learning, and image recognition. Facebook, for example, has been experimenting with its facial recognition capabilities. One feature scans a user’s photos and suggests friends they should tag, while another scans their smartphone’s camera roll for photos of their friends. It has also released Moments, an app that helps users organize their photos by grouping them by event and friends.

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And decrypting human emotions by analyzing facial expression is a growing area among tech companies. Along with Emotient, others like Affectiva are also working with brands and retailers to help them with a variety of tasks including preventing shoplifting and figuring out what a shopper thinks of a display of merchandise. Others, like IntraFace, are working on virtual and augmented reality applications. And as Fortune‘s Stacey Higginbotham has written, this type of emotion detection is coming to us soon, whether we want it or not.

This isn’t Apple’s first acquisition in the artificial-intelligence field as applied to humans. In October, Apple confirmed that it had acquired VocalIQ, a company whose technology helps computers understand natural speech.