By labeling a tripwire, you can make it easier to recognize, just as it’s easier to spot the word “haberdashery” when you’ve just learned it. Pilots, for example, are taught to pay careful attention to what are called “leemers”: the vague feeling that something isn’t right, even if it’s not clear why. Having a label for those feelings legitimizes them and makes pilots less likely to dismiss them. The flash of recognition—Oh, this is a leemer—causes a quick shift from autopilot to manual control, from unconscious to conscious behavior.

That quick switch is what we need so often in life—a reminder that our current trajectory need not be permanent. Tripwires provide a sudden recognition that precedes our actions:
I have a choice.

Chip Heath & Dan Heath, Decisive: How to Make Better Choices in Life and Work, New York, 2013, pp. 236-237