Media richness theory (MRT), sometimes referred to as information richness theory, is a framework used to describe a communication medium's ability to reproduce the information sent over it. It was introduced by Richard L. Daft and Robert H. Lengel in 1986 as an extension of information processing theory. MRT is used to rank and evaluate the richness of certain communication media, such as phone calls, video conferencing, and email. For example, a phone call cannot reproduce visual social cues such as gestures which makes it a less rich communication media than video conferencing, which affords the transmission of gestures and body language. Based on contingency theory and information processing theory, MRT theorizes that richer, personal communication media are generally more effective for communicating equivocal issues in contrast with leaner, less rich media.