This urban legend is told by a lot of trainers and consultants. Mehrabian is a professor who is best known for his research on verbal and non-verbal communication. One of his findings is that tone of voice and body language are also important next to his words. In certain situations (communication about feelings and attitude), the influence of the communication is based on 7% words; 38% tone of voice and 55% body language.
This “7%-38%-55% Rule” has been overly interpreted in such a way, that some people claim that in any communication situation, the meaning of a message was being transported mostly by non-verbal cues, not by the meaning of words. And that’s not true. This is a nice example of an urban legend that is still being spread because some principles are very strong: simple (voice and body language are very important); unexpected (words count only for 7%) and credible (because the source is a professor).
Some people have already started a campaign to stop the Mehrabian myth. This movie explains it very well.