If a few actions (including espousing actions for other people) are enough to justify how we like to think of ourselves, then we do not need to perform any additional virtuous actions. It's as if we accumulate moral points for ethical actions, and having accumulated "enough" we are free to act amorally, or even immorally. That's why reminding people of what wonderful humanitarians they are causes them to give less to charity.

"Virtuous acts can license subsequent asocial and unethical behaviors," writes Nina Mazar and Chen-Bo Zhong of the University of Toronto in a paper scheduled for publication in the coming months in Psychological Science.

When the green buyers were then given a chance to cheat on a computer game, and lie about it to the scientists in order to win more money—basically, to steal—they did. Buyers of conventional products did not. And in an honor system in which they took money from an envelope to pay themselves their winnings, the green buyers stole six times more than the conventional buyers did.

Two new experiments suggest there is something to this. Mazar and Zhong had 156 volunteers (University of Toronto students) visit online stores that carried mostly green products, or only a few. After browsing for a while, some of the volunteers played the dictator game: they were given $6, and told they could propose to divide the money with a partner any way they liked.

The caveat: the partner could accept or reject the proposed division, and if he rejected it, then no one would get any money. Proposing a 5-to-1 split was therefore likely to send both parties home empty-handed, whereas a 3-3 split, or even a 4-2, was more likely to pay off.

Volunteers who saw lots of green products proposed more generous splits than those who saw conventional ones, by $2.12 to $1.59—one third more. That reflects the well-established priming effect, in which subtle cues shape our behavior (if we see pictures of upscale restaurants, we tend to improve our table manners; seeing Apple’s logo makes people more creative, at least in lab experiments). Simply seeing green products, which symbolize high ethical standards and selflessness, causes people to unconsciously adjust their behavior to be more ethical and generous, in this case by sharing more money.

Buying green products—some of the volunteers were given $25 to spend in the green store, while others were given $25 to spend in the conventional store—had an entirely different effect. Volunteers who bought up to $25 worth of ecofriendly stuff from the green store shared less money ($1.76) than those who purchased from the conventional store ($2.18). (Just to be clear, the volunteers were not given a choice about which online store to patronize.)

For the green buyers, altruism in the dictator game decreased.

(Source)