Google Inc. has added product reviews to its Product Listing Ads, the image-anchored paid marketing messages that shoppers see when searching for items on the search engine.

Google says that under the new program, shoppers in the United States will see star ratings—a Google example uses a five-star system—along with the number of reviews offered for a particular product. Clicking on the review section calls forth the consumer comments on the product.

The review data stem from the product information fed to Google by retailers for inclusion in their Product Listing Ads, along with other sources, including companies that help merchants sell on web marketplaces. “This 5-star rating system represents aggregated rating and review data for the product, compiled from multiple sources including merchants, third party aggregators, editorial sites and users,” says Mike Capsambelis, product manager, Google Shopping. “We believe these ratings will help differentiate products across Google.com and Google.com/shopping and will help merchants drive more qualified traffic through Product Listing Ads. In initial tests, product ratings also helped increase click-through-rates of Product Listing Ads.”

Google gave no immediate data to support that claim.

Until October, Google will “allow product ratings to be shown across all Product Listing Ads where we have product review data available. After the grace period, we’ll only show ratings for products from merchants who choose to share their reviews with us,” Capsambelis says.

Retailers interested in including review data with their Product Listing Ads need to fill out a product ratings form via Google. The coming months will bring an expansion of the program to countries other than the United States, Capsambelis says.

Google introduced paid Product Listing Ads in October 2012. Product Listing Ads feature product images and prices from merchants prominently in the central area of a Google search results page. They replaced free comparison shopping listings.