LOS ANGELES — Scientists have come upon two magic words capable of making consumers believe a plain old cup of coffee tastes better and should be more expensive: “eco-friendly.”

In a series of experiments, researchers asked people to sample two identical cups of coffee brewed from the same batch of arabica beans using a “standard model coffee machine,” according to a report published this week by the journal PLOS ONE. The researchers told the study volunteers that one of the cups was made with “eco-friendly” coffee beans and the other was not. Over and over, people who said they cared about the environment gave the “eco-friendly” coffee higher marks.

“With the right convictions, an ‘eco-friendly’ label is sufficient for a product to taste better than a non-labeled objectively identical alternative,” they wrote.

The research team used a questionnaire to assess the value volunteers placed on recycling, sustainability and other environmentally themed activities. (Sample question: “Do you feel guilt when you buy non-eco-friendly alternatives?”) 

The responses were used to sort coffee-tasters into “high sustainability” and “low sustainability” groups.

In the first experiment, 74 percent of the high sustainability consumers said they preferred the “eco-friendly” coffee to the “not-eco-friendly” alternative and gave it higher ratings for taste. They also were willing to pay about 25 percent more for it. Meanwhile, the low sustainability volunteers were basically split between the two options and weren’t willing to pay extra for the goodie-goodie joe.

In the next experiment, volunteers were not told which cup of coffee was “eco-friendly” until after they had tasted both samples. In that case, the label didn’t influence their ratings for taste. However, high sustainability volunteers were still willing to pay more for the “eco-friendly” coffee even when they were told their preferred cup of coffee was of the “not-eco-friendly” variety.

“This finding indicates that their willingness to pay a premium for eco-friendly alternatives is – at least in part – based on altruistic (e.g., for the sake of the environment) rather than on more self-serving reasons (e.g., biased taste preferences),” according to Wednesday’s study.

But were they really being altruistic, or were they merely acting altruistic because they wanted to impress the researchers? To find out, the team conducted a third experiment.

This time, researchers told volunteers which coffee was “eco-friendly” and which one wasn’t before they took their first sip. Then, some volunteers reported their taste and price preferences directly to a researcher, while others were asked to write down their answers and leave them in a sealed box. If volunteers were motivated by peer pressure, those who gave their feedback in person would give the “eco-friendly” coffee higher ratings than those who gave their feedback anonymously.

But that’s not what happened. “Social desirability did not influence the eco-label effect on taste,” the researchers wrote.

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