While consumers are more likely to "go green" on the high street where they can be seen making altruistic choices, the privacy of online shopping brings out an entirely different behaviour.
When people are not being watched by their peers they are more willing to shun the ethical products in favour of comfort and convenience, the report says.
The habit has been studied by Vladas Griskevicius, of the University of Minnesota's Carlson School of Management, who found eco-friendly shopping decisions are not always motivated by a social conscious.
He discovered that people were more likely to buy energy efficient light bulbs from the shops, but tended to opt for the old-fashioned type online.
The same trend was also found when people purchased white goods, electronics and even domestic cleaning products over the internet.