Stress often drives us to pursue a reward (dessert, drink, new 'toy') more intensely, but new Swiss research has found that we're no more likely to enjoy the indulgence than an unstressed person with the same treat.

The findings are published in the Journal of Experimental Psychology: Animal Learning and Cognition.

"Most of us have experienced stress that increases our craving for rewarding experiences, such as eating a tasty bar of chocolate, and it can make us invest considerable effort in obtaining the object of our desire, such as running to a convenience store in the middle of the night," said lead author Eva Pool, M.S., a doctoral student at the University of Geneva.

"But while stress increases our desire to indulge in rewards, it does not necessarily increase the enjoyment we experience."

During the study, stress prompted chocolate lovers to exert three times as much effort to smell chocolate than unstressed chocolate lovers, and yet both groups reported similar levels of enjoyment when they got a whiff of the pleasing aroma.

Researchers recruited 36 male and female university students who said they love chocolate. To induce stress, the participants were asked to keep one hand in ice-cold water while being observed and videotaped. Another group immersed a hand in lukewarm water.

Ten minutes before and 30 minutes after the experiment, researchers collected samples of the students' saliva and tested them for levels of cortisol, a stress hormone.

Finally, all subjects had to press a handgrip for the chance to smell chocolate when they saw a certain symbol. The researchers measured their efforts at the chance to smell chocolate and asked then participants how pleasant they found the odor.

"Stress plays a critical role in many psychological disorders and is one of the most important factors determining relapses in addiction, gambling, and binge eating," said another author, Tobias Brosch, Ph.D., also of the University of Geneva.

"Stress seems to flip a switch in our functioning: If a stressed person encounters an image or a sound associated with a pleasant object, this may drive them to invest an inordinate amount of effort to obtain it."

Prior studies with laboratory rats support the idea that wanting and enjoying depend on two distinct networks of neurons that can be activated independently.

"Although the findings with rodents provide a novel explanation for the stress-induced increase of reward pursuits, to the best of our knowledge, they have never been demonstrated in humans," the study said.

More research on people is necessary to confirm the findings, according to the authors, who recommend future studies that would explore the effect of more intense everyday life stressors on human wanting and enjoying.

Source: American Psychological Association

Woman wanting a donut photo by shutterstock.

Stress Increases Desire for Reward, But Pleasure Remains the Same