研究人员Joseph nunes和Xavier Dreze在关于上述洗车实验的论文中做出了总结。他们发现比起一开始便被要求集满8个章并最终获得免费洗车机会的顾客（19%）来说，事先拥有2个免费的章并洗满8次车的顾客人数更多（34%）。尽管他们都只需要盖满8个章便可以获得免费洗车机会。Nunes和Xavier还发现，这些获得2个免费盖章的顾客总是能够更快地达到目标。
Endowed Progress Effect and Game Quests
by Jamie Madigan
Imagine that two people, Kim and Carlos, notice that their cars are filthy and both go to the same car wash to make things right. With their wash they each receive a special card that lets them earn a free car wash if they get the card stamped enough times during future visits. Kim’s card says it requires 10 purchases for a free wash, but the perky girl at the counter gave her a head start with two free stamps. The card Carlos got doesn’t have any free starter stamps, but it only requires 8 future purchases instead of 10. So both Kim and Carlos are looking at the same number of purchases to score their complimentary car cleaning.
Who do you think is more likely to come back enough times to fill up his or her card? Kim or Carlos?
It turns out that it’s Kim, who got saddled with a card that required 10 total stamps, but who received enough free stamps to get her 20% of the way towards her goal. This is thanks to a phenomenon called “the endowed progress effect.” Basically, the idea is that when you give people just a feeling of advancement towards a distant goal, they’re more likely to try harder and try longer to reach that goal, even relative to people who have an equally easy goal but who got no sense of momentum off the bat.
Researchers Joseph Nunes and Xavier Dreze coined the term in a paper where they did the car wash experiment described above. They found that 34% of people who got a 10-stamp card with 2 freebies ended up coming back enough to redeem the cards, compared to 19% of customers who started with an unstamped card requiring only 8 stamps. This despite the fact that both sets of customers only needed 8 stamps for a free wash. Nunes and Xavier also found that those endowed with the two free stamps tried to reach their goal faster by waiting less time between washes.
Why? The researchers argue that the reason for the results is that by giving out free stamps, the merchant was framing the task (i.e., buying enough car washes to get a freebie) as one that has already been undertaken. There’s a substantial body of research that shows people are naturally motivated to complete tasks that they feel they’ve started and will want to remain consistent with previous intentions. Other research has shown that the closer someone gets to completing a goal the more likely they are to increase their efforts towards closing that last little gap. Apparently, giving people a couple of free holes on a punch card is enough to trigger both of these effects.
This has a few interesting possibilities for game design. Imagine, for example, that I’m playing through Fallout: New Vegas 5 and I get a quest to save 10 slaves from a nearby encampment. One way to deliver that quest to me would be to meet a NPC and have her say “Hey, there’s 10 slaves. Go free all 10.” And so I’d go off, and the quest would tick up “0 out of 10 slaves rescued, 1 out of 10 slaves rescued,” et cetera. Alternatively, if the game designer wanted to invoke the endowed progress effect, I could first receive the request upon opening the cell door for a pair of slaves on the outskirts of the encampment. One of the slaves could say “There were 12 of us altogether! Free the others!” and my progress would start off as “2 out of 12 slaves rescued” as the first two sprint off over the horizon. According to everything discussed above, I’d be much more motivated to complete this quest if it were presented this way.
Other examples aren’t hard to imagine. What if some NPC wanting 12 Goretusk livers in World of Warcraft gave me two to start with and raised the request to 14? What if, upon learning a new crafting skill that requires combining 5 widgets into one superwidget, the game gets me started with 1 widget and makes the recipe call for 6? What if, when I’m waiting impatiently in a multiplayer matchmaking lobby for Halo: Reach to find me 10 opponents, the game populates the first two slots with “Player Found!” after a couple of seconds even though it’s still looking? Would I be more likely to wait for the rest even if the search takes a long time? Well, you get the idea. If you’ve got other examples, let’s hear them in the comment section.(source:psychologyofgames)