Saul Hansell has an interesting NYT piece on Google’s use of unorthodox interview techniques, like challenging applicants with brainteasers and asking people, “Have you ever made a profit from a catering business or dog walking?”

There is a brief mention in the piece of an earlier recruitment campaign that Chip and I think was ingenious Here’s the challenge for a recruiter: How do you lure in the right people while deterring the wrong people? One way to do that is to talk: “Google is looking for the brightest, most motivated technology whizzes in the universe!”Â

A better way to do it is to tease.  Imagine a black equation on a white billboard (better seen than described). More precisely, an equation + a “.com” text string. No other markings. No clue as to why there’d be an equation on a billboard, or who was responsible for it.   The “.com” ending hinted that if you could crack the equation, and then add a “.com” to the end of your answer, you’d be rewarded somehow. This is a great example of making an idea stick via a “curiosity gap.”

 The answer led to another riddle. Eventually, having made the cut, you’d find out that Google was behind the mystery, and you’d arrive at a page where you could submit your resume to Google.Â

What a smart way of enticing the right people–people sufficiently analytical to solve a rather tough riddle–while remaining invisible to the wrong people.