Ask not what you can do for your client ...

This part is intuitive: In order to increase sales, reduce the number of decisions a potential customer has to make.

But Adam Ferrier, a psychologist-cum-adman who uses the principles of neuropsychology to help hotels fill beds, adds that the blueprint for doing this is counterintuitive.

Ask not what you can do for your customers, he preaches, but what your customers can do for you.

Request favors of them. Make them work to customize their experience.

Give them consistent experiences? Not necessarily. It's more powerful to reward them randomly, he contends.

Ferrier addressed attendees at the LE Miami conference earlier this month, and did a convincing job of explaining how asking your clients to do a bit of work will increase sales faster than an airtight, logical presentation of why you're the best choice.

The fact that logic doesn't win in advertising is not terribly surprising; it doesn't take a great deal of sophistication to understand the importance of emotions in decision-making.

But Ferrier says there is something more important than thoughts or feelings: Focus first on actions.

Once we act, thoughts and feelings will follow, he says. If you ask people to act in a manner they associate with how they behave toward friends, they will begin to think of you as a friend. To do otherwise is to invite feelings of cognitive dissonance.

To psychologists, this is known as the Ben Franklin Effect. Franklin wrote in his autobiography that he needed the support of a rival, and knew that the man had a "scarce and curious book." He wrote to ask the man to do him the great favor of lending it to him. The rival not only did so, but afterward spoke to Franklin "with great civility" and "ever after manifested a readiness to serve me on all occasions."

Attitude followed action, not the other way around.

These days, the theory could be updated as the "Ikea Effect." Once you've put together a piece of furniture (and saved Ikea the trouble of doing so), you feel much more attached to it than if you had simply bought it preassembled.

And people who attach through action feel invested (or endowed) with greater ownership and act in ways that reflect increased loyalty.

Is the hotel pillow menu in your room that gives you the choice of having your head supported by down feathers, hypoallergenic foam or wheat husks really a benefit to help you sleep? It might be, but it also gives you feelings about your stay that could only be described as proprietary.

Loyalty creates further supportive action. Ferrier discussed an experiment in which people were asked to tell others to take shorter showers in order to conserve water. Those who simply heard the message did take slightly shorter showers on average, but those who were recruited to preach the message took dramatically shorter showers.

That's why, after every service you experience these days, whether it's a hotel, flight, concert or even website purchase, you're asked to do the provider a favor and fill in a survey. Yes, your feedback will be analyzed, but it's also an opportunity for the provider not only to ask a favor but to get you to rate them positively. Having done that, customers' feelings and thoughts lead to supportive action next time they book.

It's also well established, Ferrier said, that adding randomness into benefits is a powerful way to keep people coming back. It's why people will sit at slot machines for hours with the full knowledge that the odds are against them.

Ferrier used this understanding to create an inventive and successful hotel campaign for Australia's Art Series Hotel brand.

The hotel group was searching for ways to increase occupancy during off-seasons. To this end, they launched "Overstay Checkout." The premise was simple: If the hotel didn't need your room the next day, not only did you not have to vacate by the official checkout time, you didn't have to leave at all until the room was needed, whether that was a matter of hours, days or even a week or more.

At the end of the campaign, guests had overstayed 343 nights and 1,286 hours, with some lucky guests booking one night and staying seven. The goal had been to see paid bookings increase in this period by 1,000 rooms; they went over goal, with 1,550 rooms. Their online conversion rate jumped 66% during the period.

Art Series Hotels also picked up an unanticipated $37,214 in room service, bar and restaurant revenue. More than 8.3 million tweets were associated with the campaign, and they valued the media coverage, which was extensive, at $1.5 million.

All for an investment of $80,000.

Ferrier has written a book, "The Advertising Effect: How to Change Behavior" (Oxford University Press, 2014), that documents these and other psychological insights his advertising group, Cummins & Partners, uses.

He's apparently quite convinced of the power of his arguments: "Please consume this book responsibly," he advises on the cover.

Email Arnie Weissmann at aweissmann@travelweekly.com and follow him on Twitter.