Close your eyes and conjure up an image of Donald Trump. What's the first mental picture you get? Is he grinning from ear to ear? Or maybe shouting, his brows furrowed in anger, both arms raised in the air? The many faces of Donald Trump have been on constant display over the last several months, plastered on newspaper covers and television screens across the world as he shouts, laughs, and fist pumps his way toward the GOP nomination. Trump's unbridled emotion is a key factor in his popularity among voters, according to body language expert and author Patti Wood. Wood says that Trump is better at expressing emotion — and specifically, a broad range of emotion — than any other candidate in the race. "Trump has what we callemotional contagion," Wood says, "meaning he has very strong, very clearly communicated emotions, and because of his charisma, those emotions transfer to the voter. So, we can't stop watching him. If he's on the screen, and we're looking at several other people too, his loudness, his gestures, and his expressions all draw our attention straight to him." According to Wood, it's a leader's ability to show and communicate a broad range of emotions that translates into perceived power and charisma. Whether he's on the national debate stage or at a small-town campaign appearance, Trump doesn't shy away from big reactions. "When we think of him, in our mind we have an image of him smiling, and then we have an image of him sneering," Woods says. "It's that vast scope of emotion, that broad band between those two extremes and his hold on it, that makes him look powerful." Emotional expression is key to public speaking, Wood says, because it makes a speaker appear more human, relatable, and trustworthy. And the more expressive the better. She says Trump's "electric smile" — corners of the mouth upturned, raised eyebrows, and wide eyes — provides "instant charisma." Because many people think effective leadership means being cool and collected, they try to repress their feelings. But experts say it's usually better to let your passion shine through. "We hide emotions in an attempt to stay in control, look strong, and keep things at arm's length, but in reality, doing so diminishes our control and weakens our capacity to lead," leadership consultant Doug Sundheim writes in the Harvard Business Review. "Genuine emotion stands in stark contrast. It's a real person sharing a real feeling." "When we hear it, we're riveted — for one because it's rare, but also because it's real," he adds. "Sometimes it's uncomfortable and a little messy. But that's what makes it powerful."