We tend not to trust people if we can't see their hands. It is a cardinal rule of rapport building to always keep your hands visible. It is an indication that people don't want to communicate if their hands are (or become) "hidden" from view. Of course we all know where their hands really are, but this is a subconscious consequence of the emotional brain demonstrating anxiety, subtly retreating and perhaps trying to "hide" something. This is especially true when the stakes are high during negotiations, job interviews, business meetings, speeches, debates, in a court of law, etc. If you're interviewing a new employee and upon asking them a question, their hands disappear beneath the table - you would be well advised to delve deeper into the particular issue being discussed at that moment. In this setting, there would also be a strong tendency for this same nervous interviewee to sit back in their chair - another sign of disengagement and a desire to minimize conversation.
Which side of the table pictured above has increased anxiety? If I were a member of the other side, I'd want to ask myself "Why?". Don't be the Zebra who dismisses some intriguing spots - and ended up in the leopards stomach.