A new study suggests that marketers shouldn’t fixate on the number of people who click on ads. According to the research, just seeing an ad on a Web page can impact memory. The findings could have a significant impact on the way online advertising is made and metered.

Typically, to be considered effective, an online advertisement has to elicit a response–usually a click of the mouse–from a potential customer. But Chan Yun Yoo, an assistant professor at the University of Kentucky’s School of Journalism and Telecommunications, found that when people view Web advertisements, they store information in two different types of memory: explicit and implicit.

Explicit memory involves facts learned through conscious interaction, while implicit memory involves unconscious retention. Explicitly remembered information includes ad slogans, product benefits, and website addresses. In contrast, implicit memory might only come into play when external stimuli trigger concepts. For instance, a consumer might only recall a brand of toothpaste from a television ad when he or she discovers it while browsing in a store. Or the consumer might develop an unconscious affinity for a certain brand despite not knowing specific facts about it.

Subjects who paid attention to a banner advertisement were more likely than those who didn’t to recall whole words and facts from the ad–facts stored in explicit memory. All ads had the same level of impact in the unconscious explicit memory, however, whether or not they’d been clicked. Yoo’s findings are relevant because they challenge the assumption that online advertising is only effective when it gets a direct response from the viewer. His study was published in the spring 2007 edition of Journalism and Mass Communication Quarterly.

Donna Hoffman, codirector of the Sloan Center for Internet Retailing at the University of California, Riverside, says that Yoo’s research applies traditional ideas about media impact to the Internet. In other mediums, such as television, advertisers do not typically assume that audience members will interact with the ad. Hoffman says the notion that banner ads may have some impact on perception begs the question, “What are the most effective ways to advertise in the new medium?”

Yoo says that the implications of his work are twofold: advertisers “need to reconsider the objectives of Web advertising” and use “impression-based metrics more than performance-based metrics when it comes to measuring the effectiveness of Web advertising.” Click-through rates, which represent the percentage of people who clicked on an ad after viewing it, might be useful to determine whether an ad elicited an immediate response. But ad impressions–that is, the number of times an ad is displayed–might be a better measure of the impact required to build a brand image.

Many advertisers offer companies and individuals both impression- and performance-based measurements. Google’s Adsense allows revenue to be collected in number of impressions or per click. Popular video-sharing website Revver relies mainly on click throughs, but it recently introduced impression-based advertising.

Heather Luttrell is president of online marketer IndieClick, based in Los Angeles, which charges according to impressions. The company’s goal is to connect retailers with viewers who are highly relevant to the advertiser, ensuring an attentive audience.

“Clicks are not the most important thing,” Luttrell says. How people find the site is not as important as tracking what they do once they go to the site. IndieClick found that click throughs accounted for only a fraction of the increased site activity created by an ad campaign. On a consistent basis, Luttrell says, site statistics “showed seven times more traffic at that destination site than we would have shown through click through alone.”

Yoo recommends focusing on targeting neither explicit nor implicit memory but, rather, both. A larger campaign might not be based exclusively on click-through behavior, he says, and many of the implicit effects of online advertising are not yet fully understood.