In a promotional video, Inc. says its Cloud Cam home security camera provides “everything you need to monitor your home, day or night." In fact, the artificially intelligent device requires help from a squad of invisible employees.

Dozens of Amazon workers based in India and Romania review select clips captured by Cloud Cam, according to five people who have worked on the program or have direct knowledge of it. Those video snippets are then used to train the AI algorithms to do a better job distinguishing between a real threat (a home invader) and a false alarm (the cat jumping on the sofa).

An Amazon team also transcribes and annotates commands recorded in customers’ homes by the company’s Alexa digital assistant, Bloomberg reported in April.

AI has made it possible to talk to your phone. It’s helping investors predict shifts in market sentiment. But the technology is far from infallible. Cloud Cam sends out alerts when it’s just paper rustling in a breeze. Apple Inc.’s Siri and Amazon’s Alexa still occasionally mishear commands. One day, engineers may overcome these shortfalls, but for now AI needs human assistance. Lots of it.

At one point, on a typical day, some Amazon auditors were each annotating about 150 video recordings, which were typically 20 to 30 seconds long, according to the people, who requested anonymity to talk about an internal program.

The clips sent for review come from employee testers, an Amazon spokeswoman said, as well as Cloud Cam owners who submit clips to troubleshoot such issues as inaccurate notifications and video quality. “We take privacy seriously and put Cloud Cam customers in control of their video clips," she said, adding that unless the clips are submitted for troubleshooting purposes, “only customers can view their clips."

Nowhere in the Cloud Cam user terms and conditions does Amazon explicitly tell customers that human beings are training the algorithms behind their motion detection software.

And despite Amazon’s insistence that all the clips are provided voluntarily, according to two of the people, the teams have picked up activity homeowners are unlikely to want shared, including rare instances of people having sex.

Clips containing inappropriate content are flagged as such, then discarded so they aren’t accidentally used to train the AI, the people said. Amazon’s spokeswoman said such clips are scrapped to improve the experience of the company’s human reviewers, but she didn’t say why unsuitable activity would appear in voluntarily submitted video clips.

The workers said Amazon has imposed tight security on the Cloud Cam annotation operation. In India, dozens of reviewers work on a restricted floor, where employees aren’t allowed to use their mobile phones, according to two of the people. But that hasn’t stopped other employees from passing footage to non-team members, another person said.

The Cloud Cam debuted in 2017 and, along with the Alexa-powered line of Echo speakers, is one of several gadgets Amazon hopes will give it an edge in the emerging smart-home market.

The $120 device detects and alerts people to activity going on in their homes and offers them free access to the footage for 24 hours.

Users willing to pay about $7 to $20 for a monthly subscription can extend that access for as long as one month and receive tailored alerts—for a crying baby, say, or a smoke alarm.

Amazon doesn’t reveal how many Cloud Cams it sells, but the device is just one of many home security cams on the market, from Google’s Nest to Amazon-owned Ring.

This story has been published from a wire agency feed without modifications to the text. Only the headline has been changed.