This Simple Psychological Trick Can Make You Feel More Productive Multi-tasking isn't the key to feeling more accomplished at the end of the day.

Imagine you had complete freedom to structure a single hour of your workday for maximum productivity and happiness.

Would you labor uninterrupted over a single project — or would you divide the hour into a few different slots, one for a client phone call, one for weeding through your inbox, and one for making headway on that project?

If you were like most people, you'd choose the latter option. But you wouldn't be doing yourself any favors.

According to research from professors at Duke University's Fuqua School of Business and the University of Pennsylvania's Wharton School, we generally assume that multitasking will make us happier than focusing on a single activity. And we're right — sort of.

"We are told over and over again that variety is the spice of life, the key to happiness," study coauthor Jordan Etkin tells Business Insider. "But we don't always experience variety as positive."

When we're engaged in different tasks over the course of a long period of time — say, a day or a week — we do in fact feel happier. But when we're constantly switching up our activity within the span of 10 minutes or an hour, we actually feel less happy.

In one telling experiment, researchers instructed some college students to spend an hour studying for a bunch of different classes and told others to study for a single class. When the hour was up, the first group said they felt less productive, and therefore less happy, than students in the second group.

The researchers suspect that it all boils down to how productive you feel, which in Western cultures is key to happiness. Switching back and forth between different tasks over a short time period is "costly in terms of our cognitive resources," Etkin says. That leaves us feeling stressed and limits our ability to perform well on any single task.

"Even if we accomplish what we set out to, we don't feel as productive," Etkin says.

Of course, the easy solution would be to divide the day into hour-long slots in which we focus on single tasks. But few of us actually have the liberty to do so, not when the boss needs a project update in the next 15 minutes and there are 12 urgent emails in our inbox.

Fortunately, the researchers suggest a simple psychological hack to overcome this problem. If you're obligated to perform multiple tasks at once, mentally bucket them under a single category.

So, for example, while you're responding to those emails and banging out that project update, tell yourself that everything you're doing is work-related. Or you could imagine that all those tasks are helping you get a promotion. Simply reducing the perception of task variety, without changing anything about the tasks themselves, is enough to make us feel happy and productive.

Then, when you've got a whole Sunday to spend as you please, you can bounce around between working out, cooking, and socializing with friends — a surefire recipe for feeling happy and energized when you're back at the office Monday morning.