Google Duplex calls are made by humans one-fourth of the time

When Google unveiled Duplex last year, it was touted as a booking system that uses eerily human-sounding artificial intelligence to make reservations.

Turns out that about 25% of the time, it actually is a human -- and not a robot -- placing the call to book an appointment, Google said Wednesday. And about 15% of the time, a call is started by the AI software and is handed off to a human in a call center to complete the booking. The New York Times earlier reported the numbers. 

When the service works correctly, a lifelike sounding bot makes restaurant and hair appointments for people who use the Google Assistant, the search giant's digital assistant software. Duplex uses verbal tics like "uh" and "um," elongates certain words, and moves its voice up and down to mimic human speech.

From the moment Google CEO Sundar Pichai demoed the product last May, it plunged Google into a debate over AI ethics because people freaked out over the software's ability to deceive people. Google said later it would build in disclosures to tell people they were talking to a robot.

But despite all the controversy, the actual success rate of the software suggests the service is still heavily reliant on humans. Google takes several signals into account when it decides to use a human caller instead of a robot, according to the Times. For example, Duplex might use a human when the service isn't sure if a restaurant takes reservations.

Meanwhile, Google is expanding its Duplex brand into other areas of booking. The company unveiled an update to the service last month that automates filling out forms on the mobile web, using information from your calendar, Gmail and Chrome autofill. It can be used for booking rental cars and movie tickets. 

Watch this: Google Duplex expands beyond phone calls and can book you a rental car

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