Reward schemes - what we can learn from Cafe Nero

I just read an interesting scientific paper article about reward schemes: basically the closer people are to earning a reward, the harder they try.

The example given is for coffee - buy 10 cups and get one free. As people get closer to their free cup of coffee, they speed up how often they buy coffee!

This is probably relevant to the WoW (Walk once a week scheme) too - the closer they are to earning the badge, the more likely they are to walk!

The really interesting bit was when they changed the system to make people think they were closer to the reward. Rather than "collect 10 stamps to earn a free coffee", they said "collect 12 stamps to collect a free coffee - but here are two stamps for free". Although the collectors were the same distance to their coffee (10 stamps), they acted as if they were closer to earning their reward!

SO, we could tweak WoW by giving free "WoW ticks" while simultaneously making the reward harder to earn.