When it comes to work clothes, we are in a new era — the era of Mark Zuckerberg's hoody, and Mary Barra's "jeans allowed" policy. Where 20 years ago, dark power suits with sculpted shoulders emanated prosperity and productivity, now people seem to think henleys do the trick.

Even in corporate environments that have not adopted the casual, start-up ethos, business casual is the new business formal; weekend wear is the new business casual; and pajamas are legitimate uniforms for the growing ranks of telecommuters and freelancers who work from the privacy of their bedrooms. Suits are gross.

Given the changing fads, you may not want to start showing up at work in a three-piece suit and a tight half-Windsor, especially if you work at a flip-flop office. But there's some evidence that for most of us, a return to slightly more formal work attire may be a good thing. Even if you work at home.

Clothes can make you smarter
Last year, the phrase "enclothed cognition" — an offshoot of "embodied cognition," the idea that aspects of your thoughts are shaped by your body — entered the b-school vocabulary. The term came from Adam D. Galinsky, a professor at Northwestern's Kellogg School of Management, who found that when people don a white lab coat they believe belongs to a doctor, they become more focused and careful — effectively a little smarter when performing cognitive tasks.

For the study, Galinsky assigned 58 under grads to either wear a white, doctor's lab coat, or simply the street clothes already on their backs. He then used incongruent trials that tested their focus and mental acuity. He found that those who wore the lab coat made about half as many errors as those who wore street clothes.

In his next test, he assigned 74 students three sartorial options. Some would wear a white coat, and were told it was a doctor's coat. Others wore an identical coat, but were told it was a painter's coat. And a third group merely looked at a white "doctor's" coat. The subject then took an attention test where they were asked to point out differences between two images and speedily write them down. Those who wore the "doctor's" coat performed significantly better than the other two groups.

Though the results were white, doctor's coat-specific, Galinsky's work implies that merely wearing an item associated with intelligence can improve your cognitive abilities. "Clothes invade the body and brain, putting the wearer into a different psychological state," said the New York Times about Galinky's findings.

It is up to you whether you want your PJs invading your mind while you work, or something a little more smart and attractive.

Clothes can also make others think you're smarter
Of course, we're not implying you should show up at the office tomorrow in a white coat with a name tag that says "doctor, not artist." But it's worth thinking about what symbolizes smart and effective in your own office.

Tracy Morris, a professor of psychology at West Virginia University, for years studied how attire impacts perception. For one test, Morris asked a group of professors to dress in three types of garb — formal professional (full dark suits), business casual (slacks or skirts and nice shirts), or casual (jeans, a plaid flannel, sneakers). I should mention here that she conducted her study in the mid-90s.

The professors then gave lectures. Controlling for content, as well as non-verbal behavior like eye contact and smiling, she then asked students to rate professors on several attributes involving competence, character, sociability, composure, and extroversion.

What she found: Perceptions of professional attributes, like competence, composure, and knowledge, "are effected most by dress, with formal dress resulting in the most positive perception." Perceptions of instructor competence were highest in the formal condition, with business casual a close second, and the lowest ratings for the casual wear.

Of course, the study took place in the 90s, and the definition of formal business attire in most industries has shifted toward the more casual (though thankfully away from flannels). Nevertheless, it's worth thinking about what is "formal" in your industry and dressing accordingly.

It also impacts how you see yourself on the job
This one is directed at those who are wearing jeans and sneakers in a mostly slacks and oxfords office — meaning, those who tend to dress more casually than others. Even if you're not violating a dress code, some evidence says dressing "properly" has an impact on how you see your own skill set.

In a 1994 study, Yoon-Hee Kwon, from North Illinois University studied how clothing impacts the way you rate yourself on ten occupational attributes: Responsibility, competence, knowledgeability, professionalism, honesty, reliability, intelligence, trustworthiness, willingness to work hard, and efficiency. Cross-referencing these attributes against broad guidelines like "properly dressed" or "not properly dressed," she found that when wearing appropriate clothes, a person's sense of these occupational traits were augmented.

Once again, the idea is not to show up at work dressed for a gala, or even to wear anything obtrusively businesslike if your office is casual. The idea is simply, if you're dressing like a schlub for work, maybe step it up a notch.