You've no doubt heard that first impressions are both incredibly fast and incredibly hard to shake. But despite these facts being old news, recent science on the subject may still just shock you.

Studies of first impressions have determined that people don't just judge you quickly. They judge you, literally, in the blink of the eye -- in a tenth of a second to be exact.

That's the central revelation of a recent New Scientist article by Simon Makin (subscription required for the full piece) recapping research in the area. In it, he points to studies that compared people's opinions of election candidates formed from brief glimpses of their photographs to actual election results, and other work comparing lightning fast evaluations of teachers with student feedback after a whole semester of classes. Both were shockingly accurate.

The bottom line? Not only do we make split-second judgments of character traits like trustworthiness and competence, but these impressions are often freakishly correct. "We can accurately judge a person's honesty in only a tenth of a second," declares Makin, though he cautions that such quick assessments can be unfairly clouded by prejudice.

What, if anything, can you do about it?

That's fascinating, but also slightly frightening. With so little time to work with, is there anything you can consciously do to improve your chances of making a good impression? Unfortunately, the answer appears to be not much.

"No one has worked out what to do to pass yourself off as a winner," Makin writes. "It seems to be an overall body signal that is both given out and picked up unconsciously, and is greater than the sum of its parts. This makes it very difficult if not impossible to fake."

While there's next to nothing you can do to control how you come off in the initial milliseconds of a meeting, science does suggest that at least one (very slightly) longer-term strategy can pay off -- copy people's body language. Research out of the UK using computers avatars shows that appropriately timed mimicry (after a three-second rather than a one- second delay, so fine calibrations matter) caused study subjects to feel more warmly towards the avatars.

You're probably already doing this, however. "We do it effortlessly, without thinking all the time," claims Makin. Which depending on your viewpoint, could either comfort you ('Great, I'm already doing all I can do!') or depress you ('So there really are no scientifically validated hacks for better first impressions then.')

On to second impressions then

Recent research might not have a lot to say about making a good first impression, but coaches and body language experts certainly have a whole lot of tips to offer, from paying more attention to eye contact to watching the pace of your speaking.

Makin's article suggests these probably won't have much of an effect on the important but mysterious "first first impression" you make in milliseconds, but they still could help nudge others towards a different assessment over a longer time period -- a sort of slower, more conscious, more controllable (though perhaps less powerful) "second first impression." Here's a roundup of tips.