A handful of my friends have an odd trait where they say something and immediately laugh after it in an attempt to judge its success. The topic is usually a rant along the lines of, "These people have no idea what they are talking about." An example:
My teacher said to make my art darker but when I made it dark he complained that it was too dark. *Laugher*
The emotion is very much a nervous laughter but I want to describe it so that it is separate from the nervous laughter present when someone makes a mistake or is embarrassed. This is more of an "am I right?" action looking for positive feedback to confirm their suspicions. In the example above, my friend was frustrated by the perceived conflicting direction given by the teacher and was looking for support. The laughter is a constant participant in this behavior.