A Toyota Motor Corp. Prius hybrid automobile is driven along a street in Tokyo, Japan, on Wednesday, Feb. 12, 2014. Photographer: Kiyoshi Ota/Bloomberg

These days, environmental consciousness is everywhere. For the most part, we all recycle, turn off lights when we leave the room -- and some of us go a lot farther. We take relatively costly actions -- buying a hybrid vehicle like a Prius, installing solar panels on the roofs of our homes -- that signal outwardly just how much being energy conscious matters to us on a personal level.

But there's a problem. According to recent psychological research, these outwardly symbolic displays of green values are, if anything, too powerful. They can fool outside observers into thinking that we're a lot more environmentally conscious than we are. Perhaps worse still, they may lead us to fool ourselves.

Such is the upshot of a new study by two Swiss researchers, Bernadette Sütterlin and Michael Siegrist, based at Institute for Environmental Decisions at the science and technology-focused Swiss university ETH Zurich. The researchers sought to examine the role of what they called the "symbolic significance fallacy" in our evaluation of energy-conserving behaviors. The idea, which grows out of a large body of research on cognitive biases and mental shortcuts, is that we tend to focus far too much on outward symbols (like Prius driving) in judging whether people are energy conscious. As a result, these powerful symbols bias us into overrating certain kinds of seemingly green behavior, and underrating other behaviors that may be quite green, but don't seem that way to us at first glance.

The researchers showed as much with a pretty unforgettable research design. In one of the experiments reported in their paper, they asked Swiss research subjects to evaluate the energy consciousness of two drivers, one of whom drives a Prius, and one of whom drives an SUV. But the Prius driver drives his more fuel efficient car 28,700 km per year, and the SUV driver only drives his less fuel-efficient car 11,400 km per year, as follows:

Bernadette Sutterlin and Michael Siegrist, "The reliance on symbolically significant behavioral attributes when judging energy consumption behaviors," Journal of Environmental Psychology, Volume 40, December 2014, Pages 259–272.

If you carefully do the math, you'll see that at least as the scenario is described here, there is only one possible conclusion: the Prius driver uses significantly more fuel per year. Yet overwhelmingly, when given this information, people rate the Prius driver as more energy conscious -- a phenomenon that recurred across several different experimental designs. "It is something on the order of 80 or 90 percent of people who are going for the wrong answer" in one of the designs, says study author Michael Siegrist. "So it is a very large effect."

The paper reports three separate studies with different variations on this theme. Sometimes, as in image above, people saw both vehicles and descriptions of both drivers at the same time. But other times, they only saw one scenario (the Prius, and the SUV) and were asked to rate just one driver. The question they were asked also varied: In some versions, they were merely asked how "energy conscious" the driver was; while in other versions they were asked a more pointed question (translated from German): "How do you judge the energy consumption of Mr. XY with regard to the mobility behavior described above?" In this latter case, it is particularly hard to see how the subjects could miss the fact that they were supposed to evaluate the distance driven and energy used.

So either people are really terrible at math, or something very different is going on. Siegrist thinks it's the latter. "Roughly 90 percent of the people were making the wrong decision, so it cannot be that they were unable to calculate the thing," he comments. Moreover, he points to the final study in the paper, where stripping out the pictures of the two vehicles, and saying nothing about the type of car being driven, led to a very different response. In this case, without any symbolic information to bias them, people were much better at figuring out which driver actually used more energy.

Sütterlin and Siegrist also found very similar results for other kinds of energy use. One study scenario considered a commuter who took the train a very long distance to work, as opposed a driver who drove only a short distance (people favored the commuter, even though the driver used less energy). Another considered a person with a very large home who kept the temperature in every room at 18 degrees Celsius, versus a person with a very small home who kept the temperature in every room at 22 degrees Celsius (people favored the person who opted for 18 degrees, even though the size of the home meant that that person used more energy).

What's the upshot of all this? First of all, Siegrist says the results should make us concerned about what he calls "moral licensing": The idea that doing something that is symbolically green, like driving a Prius, licenses you to do other things in your life that aren't (like driving it huge distances).

So does this mean that there are green phonies out there -- people who adopt surface-level energy conscious behaviors but really aren't? Siegrist says it's possible. "I definitely think that some people who are having friends who are green -- some of the behavior, like driving the right car, might be important for being accepted by colleagues. So I guess this exists." If for some strange reason you want to be a green poseur, this research unfortunately suggests that a lot of people may fall for it.

So in sum, as we move into a world full of hybrids, electric vehicles, rooftop solar installations, and much else, we should bear something in mind. Energy use calculations may not be very intuitive or easy to carry out, but the fact remains that there is only one way to evaluate whether someone is actually green: Substance.