Research findings confirm that people are more likely to comply with your request if you accompany it with a rationale.

In a series of experiments, a stranger tried to cut the waiting line to use a copier by simply asking “May I use the Xerox machine?” In the next round, a legitimate reason was added to the request (“because I’m in a rush”), and then a meaningless reason was added (“because I have to make copies”). While 60 percent agreed to let the stranger cut the line in the first case, when any reason – legitimate or meaningless – was provided, nearly everybody complied (94 and 93 percent).

In web design, it means that for any request that isn’t obvious, conversion rate might be increased by simply providing a rationale. Most of the times, simple microcopy is enough, for example putting a “Why do we ask?” link next to input fields like Social Security Number.

Read on: How a Single Word Can Control Your Prospects’ Actions

The discussion of the experiment can be found in Robert Cialdini’s books: Influence: The Psychology of Persuasion and Yes!: 50 Scientifically Proven Ways to Be Persuasive