US Patent 9430779 Determining visual attributes of content items

Methods, systems, and apparatus for determining the visual attributes of content items are described. In one aspect, a method includes receiving a request to serve supplemental content to be presented with a page requested by a user of a client system; selecting one or more attributes randomly from a plurality of attributes for presenting the supplemental content to the user, wherein the selected one or more attributes are different than at least one previous attribute used to present one or more items of supplemental content to the user previously; and transmitting the supplemental content and the selected one or more attributes to the client system for presentation along with the requested page.