If you're contemplating a change in your LinkedIn profile picture, you'd be well advised to read this article first. A recent study published in the Psychological Science Journal, found that different pictures of the same person produce markedly different first impressions. Does a smiling profile picture infer a positive attitude, or does it suggest that you don't take things too seriously? You can even go a step further and submit your next photo to Photofeeler, a photo-ranking website, to learn what your profile picture says about you. Do you appear competent, likable or influential? I'm not sure I'm brave enough to send mine across!