By John Zappe

Employees who are serious about changing jobs give off cues that, if you know what to look for, can give you time to act before it's too late.

These are not the kinds of tell-tale signals every manager recognizes.

"You might think that someone who starts showing up to work late, failing to return phone calls and emails, and taking lots of sick days might be about to leave, but those weren't unique behaviors that applied only to the quitters," says Tim Gardner, a Utah State University associate professor at the Jon M. Huntsman School of Business. Unlike a worker who starts taking days off in the middle of the week, or who prowls job boards, or inadvertently leaves a resume in the copier, the signs of a serious job seeker are more subtle.

He and his research partners, Huntsman professor Steve Hanks and Chad H. Van Iddekinge, of Florida State University, set out to identify the clues that soon-to-depart workers give weeks or months in advance of actually resigning.

Starting from a list of almost 1,000 cues compiled by surveying employers, the team eventually came up with 18 "disengagement" behaviors that start showing up a month or two before the employee gives notice.