Envy. Socrates viewed it as “the ulcer of the soul.” Shakespeare's Iago, in Othello, gave us the term “green-eyed monster,” forever tingeing it an emerald hue. In Dante's Divine Comedy, once resentful individuals trudge through purgatory with their eyes wired shut, never to see the world through jaundiced lenses again.

Most of us are well acquainted with this powerful sentiment, often defined as the pain of occupying an inferior position relative to another and a desire for what that other person has. The yearning could be directed toward a gleaming red Ferrari, a fortuitous business deal or something as simple as a piece of Scharffen Berger chocolate. Among the seven deadlies, it occupies a unique position: it's the only sin that is never fun.

Yet envy has come under closer scrutiny recently, and psychologists have begun to adopt a more nuanced view. In its familiar sinister form, envy can lead us to harm others and even take pleasure in their suffering. But it need not always be laced with evil. Envy can also motivate us to try harder and perform better on challenging tasks. The trick is to learn to channel the more productive of its two forms.

Envy's Two Faces
The idea that envy need not always be destructive dates back to none other than Aristotle. He described its dark, destructive side and the pleasure a person can take in another's pain, today captured by the German term schadenfreude. He also suggested that envy could encourage people to strive harder to reach a desired state—a facet that was long overlooked in empirical investigations of envy.

Recent findings support Aristotle's early characterization. Social psychologist Niels van de Ven of Tilburg University in the Netherlands and his colleagues compared how people from their home country and those from the U.S. and Spain expressed intense feelings of envy in their respective languages. (In Dutch, as in German, Polish and Thai, two words can mean envy, whereas English and Spanish have a single word.) In 2009 the psychologists found that regardless of language, their subjects' experiences divided into two types: malicious envy, characterized by negative thoughts and ill will, and benign envy, in which hostility is less evident. Although dark feelings still factored in, the subjects mentioned more positive sentiments, such as admiration. They were more likely to believe that the envied person deserved good fortune and to express a desire to make up the difference through their own efforts.

The various brands of envy affect human behavior in distinct ways. In a follow-up experiment, they instructed some of their Dutch-speaking students to recall a situation in which they felt admiration, benign envy or malicious envy. (The other subjects recalled nothing.) All students then tackled a brainteaser. The participants who experienced benign envy were more persistent and successful in solving the puzzle than their peers in the other groups. The researchers concluded that Danish philosopher Søren Kierkegaard was correct when he surmised, “Admiration is happy self-surrender; envy is unhappy self-assertion.”

Other potential benefits of envy have emerged from the work of researchers interested in our history as a species. Evolutionary psychologists Sarah E. Hill of Texas Christian University and David M. Buss of the University of Texas at Austin suggest that repeatedly comparing ourselves with our neighbors could have helped us assess how we were faring in the competition for resources. Furthermore, the frustration and feelings of inferiority ignited by envy can act as a warning signal that alerts us to disadvantage. Those who are motivated by envy to make up for a deficiency might then outperform those who felt indifferent.

Of course, evolutionary explanations are notoriously difficult to test. So Hill and her colleagues examined a related hypothesis—that envy might enhance our performance even today. In one study, they asked students to recall situations in which they felt envious. Then in a seemingly unrelated activity, the participants read fictitious interviews about the career goals of students their own age. The people who had reflected on envious memories spent more time reading the interviews and remembered more details in a memory test than a control group. Envy appears to sharpen our attention to our social surroundings and heighten our interest in potential competitors.

Managing the Malaise
Although most of us covet the advantages of others more often than we care to admit, we generally do not respond with full-blown envy. To understand why not, our team at the University of Cologne in Germany set out to learn how we suppress envious impulses before they take hold. We are finding that we tamp down these reactions for a couple of reasons: not only is envy socially undesirable, it can also be extremely unpleasant and painful—hence, we go to great lengths to either conceal our discontent or transform the attendant emotions. In other words, we exert self-control to quell an upwelling of envy.

Self-control can be diminished, however, by any factor that limits our thinking—for example, dealing with complex interactions, time pressure or other stresses. So we hypothesized that by taxing a person's alertness and emotional well-being, we could stir up envy. As part of a 2012 study, we conducted a “sweets test” with passersby at a street carnival in Cologne. We guessed that most people would be inebriated and thus in a weakened state of self-control. One by one, the carnival-goers drew straws to see whether they or our assistant would eat an expensive chocolate versus a mediocre candy. But we rigged the drawing so that our revelers always settled for the so-so sweet. As it turned out, the people with higher alcohol levels admitted to feeling especially envious of our assistant. When we repeated the test with more passersby but without our assistant (we told participants that other subjects had already gotten a chocolate), the effect disappeared. It seems a person must be physically present to become an object of envy.

Envy can also exaggerate desires. If a neighbor buys a luxury car, for example, we may suddenly find ourselves toying with the same idea. To observe the interplay between envy and desire, we conducted another taste test, this time in our laboratory. We taxed some of our study participants' self-control by placing them under a heavy cognitive load. (The load consisted of holding a difficult eight-digit number in mind.) We also gave them simple butter cookies, whereas others in the room received high-quality ice cream. Here, too, we found that those with diminished self-control expressed more envy and a stronger desire for the fancy dessert.

So are we simply at the mercy of our impulses, or can they be voluntarily controlled? We looked into this question in a final taste test, in which our participants were told they had been randomly assigned to drink sauerkraut juice rather than a fruit smoothie. We measured their impulsiveness under different conditions: when they were alone, when a smoothie drinker was in the room, and when they were under either a heavy or a light cognitive load.

All our participants then viewed images of the two drinks and other random objects. They used a joystick to indicate as quickly as possible where the image appeared on the screen. Pulling the joystick caused the images to grow larger, as if they were approaching; pushing it caused the images to recede. We found that participants whose self-control had been compromised by a difficult task were much quicker to pull the joystick when the smoothie appeared than a random object or the sauerkraut juice—but only when our smoothie-sipping accomplice sat next to them. Yet we observed the exact opposite response for the participants with intact self-control. If our accomplice with the fruity beverage sat next to them, they more swiftly pushed away the smoothie. To reiterate, they expressed less desire for the smoothie than for the random objects and sauerkraut juice. Perhaps to mitigate their negative emotions, they rejected the envied beverage in a case of sour grapes. Much like Aesop's fabled fox, they may have first coveted and then disparaged a delicious treat that was out of reach.

Yet we need not denigrate our desires, because that which causes pain can also lead to gain. To defang malicious envy, it may help to concentrate on the aspects of the situation that are within your control. For example, if you find yourself fixated on a colleague's blockbuster success, focus on fleshing out a game plan for a goal of your own. If envy fails to fuel your motivation, try invoking a sense of gratitude instead. Dwelling not on what we lack but on all that we have can help us value our own numerous boons and lucky breaks.