"A nudge is any small feature of the environment that sneaks into our attention and steers our behavior," Reishus read aloud without his reading glasses. He was interpreting the blurry dust jacket text of a self-help volume that evidently suffered from vertigo (he had found it hugging the floor at the base of a tall, revolving book rack).

What Reishus meant was that auto-intelligized peripheral cues can shape our responses, like they do in Amsterdam – which, as anyone knows who has tried to enjoy munchies alongside its canals, is the urine capital of the world. At the Amsterdam airport, the local union of restroom hostesses conscripted an artist to paint a fly near the drain of each urinal. The idea was that the fly would provoke coffee-shop-city travelling dudes into pulling their zippers all the way down to take nasty aim instead of serendipitously coating the restroom walls, floor, ceiling, sinks, light fixtures, mirrors...

"[The result was that] urine mis-steerage was decreased by 18 percent," Reishus continued, "which meant that three hostesses were made redundant.

"Or take as example the famous orangutan at the Heidelberg zoo who can whistle, Ujan. No one nudged him, Ujan learned all on his own – in a sense, he invented whistling. Sure, for enough sweets he'll favor zoo visitors with a short, lopsided solo. Fini. But once everyone's gone, once even the zoo keepers have left, Ujan sits in the corner, rocking, whistling for only himself, sometimes for hours. Wild, crazy-cat orangutan riffs...

"Where does the nudge come in?  He's got two of the females snapping their fingers."