New research finds paying people an hourly wage, or otherwise getting them to think in time-as-money terms, makes them less likely to act in environmentally friendly ways.

How can people be convinced to think about the environmental consequences of their behaviors? New research suggests one surprising piece of the answer may be: Pay them a salary, rather than an hourly wage.

“People are less likely to engage in environmentally friendly behavior if they are paid by the hour, a form of compensation that leads people to see their time as money,” write University of British Columbia psychologists Ashley Whillans and Elizabeth Dunn.

In five studies, described in the journal Organizational Behavior and Human Decision Processes, they consistently found that “thinking about the economic value of time decreases environmental behavior.”

“When time is perceived as valuable, individuals may become irrationally overprotective of their time,” they explain. “When facing even a trivial trade-off, people are less likely to engage in environmental behavior when they put a price tag on their time.”

The takeaway here is that “the payment structures used by organizations may enhance or undermine sustainable behavior.”

Whillans and Dunn's first study uses data from Wave 18 of the British Household Panel Survey, which featured 4,128 salaried respondents and 2,802 who were paid hourly wages. Even after taking into account such factors as gender, monthly income, and marital status, “hourly (vs. salaried) workers reported less frequent engagement in environmental behaviors,” they report.

Another study featured 184 university students, who began by anticipating what their lives would be like during their first year out of college. Specifically, they “reported how many hours they would work per week, how many weeks they would work per year, and their expected income.”

Afterwards, half of them “were informed that they had just calculated their future hourly wage,” which meant they were “explicitly asked to think about their own time as money.”

The others simply went on to the final part of the study, in which they “rated the likelihood they would engage in 14 environmentally friendly behaviors their first year after graduation, such as reusing ziplock backs and paying bills electronically.”

The result: Compared to those in the control group, participants who were in a time-is-money mindset “reported reduced intentions to engage in environmental behaviors," seeing them as "less worthwhile."

A third study, featuring 54 students, used that same manipulation. But instead of predicting their future intentions, this one measured present-day behavior.

After thinking about their first year out of college, participants were asked to complete a series of tasks, “one of which involved cutting out shapes from construction paper.” They were told they could “discard the paper in a trash bin inside the room, or a recycling bin just outside the room.”

Overall, 60 percent proved willing to walk those few extra steps. But the participants were "five times less likely to recycle if they had calculated their future hourly wage,” the researchers report.

The researchers concede that most of the effects they found were relatively small. What's more, one study found the impact of the hourly wage mindset was negated by getting people to think about the way they could personally benefit from pro-environment behaviors (such as getting premium parking spaces by carpooling).

That said, Whillans and Dunn note that “subtle changes in environmental behavior can translate into meaningful differences when multiplied by a large number of individuals.” If moving away from a time-is-money mentality changes behavior even a little, the cumulative effect could be quite substantial.

The takeaway here is that “the payment structures used by organizations may enhance or undermine sustainable behavior.” That’s certainly valuable information for civic-minded corporations and government entities alike to keep in mind.

An employee who is not asked to put a price tag on their time is also more likely to be an environmentally responsible citizen.