The purchase funnel that takes consumers from awareness to transaction and retention has been an article of faith among marketers for many years. TV advertising, for instance, is “upper funnel.” Yellow Pages, at the point of sales consideration, has been “lower funnel.”

Google has other ideas. Any purchase consideration must now consider the impact of search (of course). But the impact of ratings and reviews, check-ins and other proxies and extensions for word of mouth also play into it.

Speaking at San Diego Interactive Day, Google Director of Local & B2B Markets Sam Sebastian said that shopping drivers are now based on “stimulus,” “the first moment of truth” and “zero moment of truth.” The zero moment of truth — ZMOT — is based on passive information sought by consumers.

It is reflected well in an evaluation of Google data from January 2007 to December 2010 in the U.S., U.K., Brazil, France and Germany. During that period, searches for reviews were up 98 percent, searches for coupons were up 339 percent, local search was up 177 percent, and searches for weight loss were up 154 percent. Eighty-three percent generally rely on “trust places” like user ratings or product reviews, said Sebastian, citing data recently released by Booz Allen.

“New behavior drives a surge in search volume,” said Sebastian. “You have to sell, have to optimize and sell to repeat customers. [Especially when] they are making the emotional part of their decision.”