7 Tips to Make Sure Your LinkedIn Picture Is Helping, Not Hurting, Your Prospects Your photo on the professional network says a lot more about you than you think.

At first blush, it may have seemed like a good idea -- a great profile pic. What better way to convey one's importance than to pose with a former president? But the man gripping Bill Clinton's hand looks scared and nervous, seeming almost to shrink alongside the charismatic leader. Rather than projecting an air of success, he comes off as star-struck and immature.

Another person, a female executive assistant, offers up a relaxed grin, but the probable source of her good spirits can be seen lined up on the bar behind her, and an excess of exposed skin makes her smile the last thing you're likely to focus on.

If you were looking for a new employee or recruiting a leader for a company, how likely would it be that you'd hire either of these people? Do a gut-check. And yet, these are the representations that these individuals decided to attach to today's most popular professional networking site, LinkedIn.

Unlike eras past, it now only takes a few seconds and a handful of poorly chosen pixels to handicap your career ambitions. Whether we realize it or not, we make instantaneous judgments about every person and image we see -- and the same is true for recruiters and others getting their first impressions from what we put online.

Related: 8 Types of Photos You Should Never Use on Your LinkedIn Profile

"Face perception involves a specialized neuronal network and is one of the most developed visual perceptual skills in humans," notes a recent study out of the Karolinska Institute in Stockholm, Sweden. "Facial appearance can affect judgments of attributes such as trustworthiness, aggressiveness and competence."

Another study published this year in Proceedings of the National Academy of Science supports this, finding that facial characteristics factor strongly into people's perception of an individual's character, strengths, weaknesses and ability to lead in different situations.

These impressions are formed quickly and without our active participation, often driven by subtle differences in facial features and expression.

According to research, happy faces come off as more trustworthy -- political candidates with competent-looking faces are more likely to win and people are more likely to convict defendants who "look guilty."

For CEOs, looking healthy is more important than looking smart, according to the journal Frontiers in Human Neuroscience. Study participants chose more healthy-looking faces over less healthy-looking faces for leadership in 69 percent of trials, in which they were shown two photos of one man, digitally altered to appear more or less intelligent or more or less healthy. They used modifications to facial features and complexion that researchers had found correlated to people's judgments of these qualities in others.

And while we've all been advised (or chastised) to "never judge a book by its cover," some research supports the notion that our flash judgments are often correct. For example, a new study by researchers in the Department of Psychology at the University of York says that accurate first impressions can be attained from measurements of physical features in everyday images of faces, including those found on social media. The university sought to examine how different judgments can be boiled down to three distinct dimensions -- approachability, dominance and youthful-attractiveness -- by taking 1,000 faces, describing them in terms of 65 different features such as eye height and eyebrow width, and combining these measures to explain the variation in human raters' social judgments of the same faces.

On the other hand, researchers from Columbia and Princeton found that even slight variations in facial expressions by the same person can lead others to vastly different conclusions about that individual's personality.

"Our findings suggest that impressions from still photos of individuals could be deeply misleading," according to one author of the study, Princeton University's Alexander Todorov.

For most people, however, forming snap judgments from pictures is a hard impulse to fight. Clearly that would include recruiters, 91 percent of whom use social media to screen candidates, according to a recent survey by social-media monitor Reppler.

All this to say the obvious: choosing the right photo to convey leadership capability -- or even overall capability -- is paramount, especially in the professional universe that is LinkedIn.

A poor choice can be damaging to your professional brand and even hamstring your career opportunities. Glossing over the all-too-obvious no-nos, such as using party shots or vacation pics that reveal too much information, there are more subtle offenses.

Glancing across my own network and LinkedIn's "people you might know" feature, I come across one man on his mobile phone, wrinkled shirt and sweater, cluttered background, deeply in tele-conversation. He clearly didn't know he was being photographed, but he must have liked the end result: It's now his profile image.

Another fellow stares sternly into the camera while also being blinded by the sun, creating the unfortunate impression that he is scowling at the viewer.

A connection's profile picture was taken in the early 1980s. I know this because we had coffee in 2014.

Try it yourself: Go through the scores of profile images on display on LinkedIn (or any social-media site for that matter) and observe your gut's very first impulse for each. As the science confirms, we're all at the mercy of everyone else's snap judgments about our capabilities, intelligence, likability and vigor. If we're lucky, people go beyond their emotional impulse to decide whether to take a deeper look at us, but we shouldn't count on it.

Related: How to Find the Most Fascinating People on LinkedIn

Here are some pointers to consider when selecting an image intended to promote you to the professional world:

1. Appear approachable.

It's always smart to go with a professional headshot, but this doesn't mean it has to be bland. Show some spark, so anyone viewing your photo sees someone professional, but also someone with whom they'd want to work. You don't necessarily have to be attractive, either, to have an impact: recent research published in Psychological Science, a journal of the Association for Psychological Science, found average, typical faces to be the most trustworthy.

2. Remember, this is about YOU.

Make sure you are front and center, and the focus of the photo. If you opt for a more exciting shot in a specific locale, be wary of distracting backgrounds that may outshine you. Close-ups really are your best bet. The profile picture on LinkedIn is quite small. Having your head and shoulders fill the frame ensures those viewing your profile get a good look at your confident and approachable expression.

3. If your professional headshot is old enough to buy a drink in a bar, it's time for a new one.

You may look fantastic in that old mug, but you don't want a connection or a recruiter expecting someone entirely different, should you ever meet face to face.

4. Look the part.

Your clothes do matter. Consider whether your desired (future) job or position requires formal or informal attire. You know the old chestnut: dress for the job you want, not the one you have. This applies to pictures on a professional networking site as well. And since the appearance of health is so important for C-suite execs, you may also want to schedule a haircut or a spa treatment ahead of the shoot.

5. Skip the Facebook-eque photos.

It's advisable to maintain a level of professionalism in all social media if you have a high-level job or are seeking one, so especially resist the urge to post arty shots, memes or cartoons and pictures of partners, kids or pets on LinkedIn.

6. No selfies allowed.

Even if you're not in full-fledged duckface, it's obvious when a photo is self-taken, and three problems are inherent. One, the stigma of the selfie is such that it's not an acceptable method of photography for any professional endeavor. Two, self-taken shots tend to be of lower quality, since your ability to control for light, etc., is limited. And three, it's lazy. Hand someone else the camera.

7. What works for Brad Pitt …

Yes, a moderate amount of Photoshop is allowed. Slight adjustments to tone and lighting and removal of blemishes can give your countenance the appearance of health and vitality. A sharp contrast in facial features, which can easily be softened, is also one of the cues people unconsciously use to decipher how old someone looks, notes psychology professor Richard Russell, who has been collaborating with researchers from a department of Chanel Research and Technology. Subtle Photoshopping also gives finished photos a more polished appearance overall.

These days, having an optimized LinkedIn profile is as important in the professional world as an up-to-date resume or CV -- and it should be treated similarly. Just as you agonize over the design and details of that piece of paper and digital file that is the sum report of your professional qualifications, as much attention should be paid to the composition of your LinkedIn photo, that small square that, in an instant, seems to tell people so very much about you.

Related: 4 Simple, Effective Head Shot Photography Tips