New York, Apr 28 (IANS): Two US retailers are testing cameras that could guess people's age, sex or mood to determine their buying habits.

Grocery store chain Kroger is testing cameras embedded in a price sign above shelves in two stores on the outskirts of Cincinnati and Seattle. Video screens attached to the shelves can play real-time ads and show discounts to shoppers, Xinhua news agency reported.

The cameras guess a shopper's age and gender, but the information is anonymous and the data is not being stored, Kroger said. If the tests work out well, the company said it could expand it into other locations.

Drugstore chain Walgreens installed cooler doors with cameras and sensors at six locations including New York, San Francisco and Washington.

Instead of using usual clear glass doors that allow customers to see inside, the retailer put video screens that display ads along with the cooler's contents.

This new technology, which could help physical stores to better compete with online rivals like Amazon, has raised concerns over privacy as people may not realize that they are being watched while picking their groceries.