People with re-usable bags were not only more likely to buy organic food but also to stock up on junk food.
“Grocery store shoppers who bring their own bag are more likely to purchase organic produce and other healthy foods. But those same shoppers often feel virtuous because they are acting in an environmentally responsible way. That feeling can easily persuade them that they should treat themselves to cookies or potato chips” said the authors of the study.
They examined loyalty cardholder data from which they could see when the shoppers had used their own bags. They were more likely to buy junk food on those occasions.
This is not the only example of when people reward themselves for virtuous behaviour. A recent study of people exercising while on a diet showed that they rewarded themselves by binge eating. It seems as if we have a rewards balance sheet where we allow ourselves an unhealthy but enjoyable treat when we have done something good.
I look forward to further research in this field. Would helping an old lady to cross the road or giving to charity make you pop into the fast food shop next door?