JOURNALISTS over the years have assumed they were writing their headlines and articles for two audiences -- fickle readers and nitpicking editors. Today, there is a third important arbiter of their work: the software programs that scour the Web, analyzing and ranking online news articles on behalf of Internet search engines like Google, Yahoo and MSN.

The search-engine "bots" that crawl the Web are increasingly influential, delivering 30 percent or more of the traffic on some newspaper, magazine or television news Web sites. And traffic means readers and advertisers, at a time when the mainstream media is desperately trying to make a living on the Web.

So news organizations large and small have begun experimenting with tweaking their Web sites for better search engine results. But software bots are not your ordinary readers: They are blazingly fast yet numbingly literal-minded. There are no algorithms for wit, irony, humor or stylish writing. The software is a logical, sequential, left-brain reader, while humans are often right brain.

In newspapers and magazines, for example, section titles and headlines are distilled nuggets of human brainwork, tapping context and culture. "Part of the craft of journalism for more than a century has been to think up clever titles and headlines, and Google comes along and says, 'The heck with that,' " observed Ed Canale, vice president for strategy and new media at The Sacramento Bee.