We often think that once we trust somebody we can become vulnerable. But it turns out that becoming vulnerable is one key ingredient for actually building trust. Now I'll start off with an example of somebody that wasn't trusted and whose trust was hard to build. Here, Elizabeth Petrakis, just days before her wedding, was asked to sign a prenuptial agreement. And her husband had a large real estate holding, and she was guaranteed in this prenuptial agreement $25,000 a year for every year they were married. Now in her words, this prenuptial agreement was a thorn in her side, and this is one of the things that led to her divorce. So here prenuptials demonstrate low trust, and that represents a lack of vulnerability. And that's an impediment to building trust. It turns out, we can actually make ourselves more vulnerable, and when we do that, we can actually end up building trust. And one way that we can do this is through pratfalls. By doing things like spilling coffee or spilling pens, we make mistakes that make us seem warmer, more approachable. Now, we have to balance that with competence. So here's a question, who do you trust more? Someone who spills coffee, or someone who doesn't spill coffee? Now, we might think, hey, why would I trust somebody who's demonstrated lower competence? But it turns out that by spilling coffee, we demonstrate a humanity, a humility, a vulnerability that can make us more likable. And, in fact, this is exactly the study that was done a couple of decades ago with students preparing for a quiz bowl competition. And here's the important twist. It turns out the person who's demonstrated high competence, who gets these questions right, and then spills coffee, is the most liked. If you're not very competent, then spilling coffee doesn't really help. Now, it turns out this exact problem is one that psychiatrists face. In a very short period of time, they need to walk into a room and gain the trust of someone to spill their inner most secrets. Now, to spill those innermost secrets, it turns out it helps if they spill coffee, or spill their pens, or tell a bad joke at the beginning. And this demonstration of warmth is exactly what people are trying to do where, whether it's Obama getting a dog, Ron Klein talking about his son, or the rest of us making some mistake or disclosure. Now, vulnerability is not just about sharing failures, but it can also be done doing things like off-key singing, as we might do in karaoke, or drinking with people, making ourselves more vulnerable to others. Now talk about drinking in a much more serious context, and here we're going to take us to the Bosnia War, where Milosevic was in the midst of a war and the US worked very hard to try and negotiate a peace. Now here they pulled the lead people out to Dayton, Ohio. And Milosevic faced off one of the great negotiators of all time, Richard Holbrooke. So Holbrooke negotiated, and they spent weeks negotiating. And it was late into the night, they were drinking scotch, and in fact they drank so much scotch as they were looking through maps, they ended up naming one of the corridors Scotch Road as they partitioned the former Yugoslavia. Now, they announced that here we found our road, Scotch Road, and at two in the morning, they announced a deal. It turns out this alcohol, this vulnerability, help them bridge that gap, gain trust to reach a deal. But there's a downside. Milosevic here wasn't thinking through the full range of consequences, and shortly after this, he ends up getting pulled to the Hague and prosecuted for war crimes. So when we think about building trust, vulnerability is actually really important. By making mistakes like spilling coffee or spilling pens, we demonstrate that vulnerability. But we can do it by self-disclosure, admitting failures. But there's a risk that when we demonstrate vulnerability we could, like Milosevic, not think through all the different consequences we should be thinking about. Or you want to think about making sure you don't demonstrate vulnerability or self-disclosure in a way that harms your credibility. So a psychiatrist can spill pens and say I've never been very good with my hands, but a surgeon can't.