Abstract Researchers and practitioners devote substantial effort to targeting banner advertisements, but less effort on how to communicate with consumers once targeted. Morphing enables a website to learn (actively and near optimally) which banner advertisements to serve to each cognitive-style segment in order to maximize click-through, brand consideration, and purchase. Cognitive-style segments are identified automatically from consumers' clickstreams. This paper describes the first large-sample random-assignment field-test of banner morphing -over 100,000 consumers viewing over 450,000 banners on CNET.com. On relevant webpages, CNET's click-through rates almost doubled relative to control banners. We supplement the CNET field test with a focused experiment on an automotive information-andrecommendation website. The focused experiment replaces automated learning with a longitudinal design to test the premise of morph-to-segment matching. Banners matched to cognitive styles, as well as the stage of the consumer's buying process and body-type preference, significantly increase click-through rates, brand consideration, and purchase likelihood relative to a control. Together the field and the focused experiments demonstrate that matching cognitive styles provide significant benefits above and beyond more-traditional targeting. Such improved banner effectiveness has strategic implications for allocations among media
