Do you tend to sit hunched over, staring down at your laptop or phone? Most of us do--you may be doing it right now. But as an experiment at San Francisco State University shows, we should all make an effort to sit up straighter. Especially if we're tackling a difficult task.

The study, published in the journal NeuroRegulation, measured the performance of 125 students who were asked to subtract by 7, starting from 964, for 30 seconds. Half were asked to sit up straight while they worked and the other half were asked to slouch. Then the groups were told to switch postures and do the exercise again, this time starting at 834.

Interestingly, the students who found the exercise easy and weren't intimidated by it experienced little difference in their performance whether they sat up straight or slouched toward the floor. But those who dreaded doing the subtractions in their heads and thought the exercise was tough found it significantly easier and less intimidating when they were sitting up straight. 

This makes some sense, the study's authors write, because curling toward our middles is a classic defensive posture, as we instinctively protect our internal organs from a perceived threat. By slumping, we're telling out subconscious selves that we are not safe. And the more we feel unsafe, the more difficult it is to focus our minds and concentrate on solving a problem. In other words, our fear of a task in itself makes that task more difficult. Unless you're much more confident than most people, you've probably had this experience yourself. 

On top of that, there are physiological reasons why sitting up straight could in itself improve your performance. When you slouch, you compress the space for your lungs, reducing their capacity by up to 30 percent. That means less oxygen can get to your brain.

So sitting up straight may actually help your brain function better, as well as help you think more clearly because you feel calmer and more confident. SFSU professor Erik Peper, the study's lead author, said in a statement. "You have a choice. It's about using an empowered position to optimize your focus." Seems like sitting up straight really is worth the effort.