Media richness theory is a framework that describes a medium's ability to reproduce the information sent over it.  The more ambiguous and uncertain a task remains, the richer format of media is suitable to it.  Thus, more personal means of communication are more effective than a leaner, less rich media.  For example, a conversation on a cell-phone cannot reproduce the hand gestures, facial expressions, and other nonverbal cues communicated through interaction as could a video chat on the computer (Dennis and Kinney, 2000).