NEW YORK (AP) — Google Inc. will pay $3.2 billion to buy Nest Labs, which develops high-tech versions of devices like thermostats and smoke detectors.

The search engine operator was an early investor in Nest Labs. It says the company's Nest Learning Thermostat "has been a consistent best-seller."

The thermostat is designed to learn how inhabitants like their homes to be heated and cooled. Once it learns the consumers' preferences, it automatically adjusts the temperature on its own.

The Nest Protect alarm is intended to be less annoying than traditional alarms: when it detects rising smoke or carbon monoxide levels, it lights up yellow and speaks with human voice, giving consumers an option to turn the device off if there is no emergency. They can stop the alert by waving an arm.