If you're a CEO, you're being watched. A little more than you usually are, anyway. Research led by two Harvard Business School professors is attempting to find keys to the CEO's success through close study not of the exec's decisions or of others' opinions but of what they say and how they look when they say it. Using video interviews with 130 leaders, the researchers applied machine-learning tools to scrutinize the words that CEOs chose, how much they tended to stray from topic to topic, the positivity or negativity of the words they used, and their facial expressions. The era of machine learning has provided a boost for that last task.