Just because a user didn't click on a banner ad, doesn't mean the ad space was wasted. At least, that is the theory presented in the Journal of Consumer Research.

In a paper entitled "An Examination of Different Explanations for the Mere Exposure Effect," professors Xiang Fang, Surendra Singh and Rohini Ahluwalia suggest that banner ads not only register with users on a subliminal level, but that the effect is positive.

The study found that rate of exposure to ads for users who read a banner-ad-laced essay had no effect on negative feeling toward the brand. When students were asked about positive feelings toward the brand, the researchers found that an increase in the exposure rate lead to a corresponding increase positive feelings toward the brand.