Yahoo! Search Marketing is planning tests of graphical banner ads to be displayed on its pay-per-click contextual ad network, a spokesperson said. Implementation of such a feature would allow advertisers to incorporate more visual, brand-oriented imagery into their contextual ads, and perhaps let them craft messages designed to reach people earlier in the purchase cycle. “A lot of details haven’t been determined, but we are testing,” said Gaude Paez, a spokesperson for Yahoo! Search Marketing, formerly known as Overture Services.