Google has extended personalised search to users who aren’t signed in to a Google account.

The extension will be based on 180 days worth of search activity, which will be stored on an anonymous cookie. This will have implications to search marketing agencies.

Andreas Pouros, CEO of New York SEO agency Greenlight, hit out against the extension saying:

This might restrict the breadth of sites that are delivered to the user, leading searchers to only see sources of information that they typically agree with, which deals with cognitive dissonance in a detrimental way for society at large… Consider how this might affect search results for Barack Obama if he searched for health care reform or Al Gore if he searched for climate change.

Google has created a video explaining the service and how to opt out if a user wishes.

The search giant has also announced the extension of search into images, called Google Goggles. Users can employ the feature to search for a range of categories (including brands, landmarks, stores, wine, artworks), taking a photo with a smartphone, laptop or, less likely, a PC and be led to information.