While appearance isn't everything, making a good initial impact is very important. There are a number of beneficial reasons for dressing up smart for your career and a number of mental changes that come with looking sharp, for both the observer and yourself .
Dressing smart makes us feel powerful. A phycology study at California State University suggests that looking more formal than is required broadens our perspective and encourages wearers to think in a more abstract way. By feeling more powerful, people in formal attire are less likely to get caught up on small details and tend to think about the larger picture. The wearer begins to distance themselves from social elements such as what others may be thinking about him or her and can focus more on the professional implications of the task at hand.
There is a well documented link between power and abstract thinking throughout history. What this means is that the thinker removes the facts and thinks more conceptually. This is effective for some areas of business, but not others. It is very helpful when problem solving as the person would tend to think of the whole process rather than just the obstacle. It's also effective when receiving criticism because the thinker can take a step back from the social implications rather than letting the negativity drag down their self esteem. The opposite of subtract thinking is concrete thinking, which is particularly effective when following a process and focussing on small details
As wearing formal attire makes you appear more professional, people will listen more to what you have to say and find you more trustworthy. Somebody wearing a suit emits a lot more confidence than somebody wearing a tracksuit, at least in a formal work atmosphere. If you consider somebody asking for change to catch the bus, are you more likely to part with 50 cents to a businessman or to somebody is casual attire?
There is a subconscious mindset that somebody wearing formal attire is successful and moving upwards in the world. We naturally see somebody who is working to make a difference, in one way or another.
Other research suggests that wearing formal attire in business environments where it is not essential or part of a dress code has even greater effects. By raising the bar a notch, you will be making the people in your immediate proximity uncomfortable and making a larger statement with your choice of formal attire. You will increase the margin between those who chose to down dress and, even if only on a subconscious level, you will place yourself at the top of the hierarchy.
Obviously it depends on your job and the environment that you work in as to which attire will help you settle into the right mindset for the task at hand, but when you have the chance to and you need to boost your abstract thinking, put away the polo top and trade it for something a little smarter. You might just feel the difference that you need.