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7-38-55 (Mehrabian's Rule)

last edited by: Joao Sarmento on Jan 12, 2020 7:11 AM login/register to edit this page

1 History
   1.1 The First Study
   1.2 The Second Study
2 The Truth about the Formula
3 Conclusion
4 References

You have probably read or heard of the magic formula “7% of communication is transmitted by words, 38% by tone of voice and 55% by body language!”, described as a universal rule of communication. Is this really so?

7-38-55 rule is based on two studies by Albert Mehrabian, from the University of California, in 1967 that clearly demonstrated that the impact and credibility of any communicative act mainly depends on:

  • 55% - Body language
  • 38% - Paralinguistic (eg. tone of voice)
  • 7% - Words/message
When these three factors reinforce each other, communication is congruent.


It is a fact that body language plays a key role in communication but it is important to understand that this idea has been completely decontextualized and removed from its original meaning. The formula was developed from two studies conducted in 1967 by Albert Mehrabian, Morton Wiener and Susan Ferris at the University of California at Los Angeles (UCLA). It should be borne in mind that the purpose of the authors was not the analysis of communication in general but only the communication of emotions and attitudes.

The First Study

In the first study 30 psychology students were asked to listen to 9 words recorded on an audio tape: 3 positive words, 3 negative words and 3 neutral words. These words were spoken with different voice tones and students had to guess which emotions were associated using a quantitative scale. Of course, tone of voice was a better predictor of emotions than the content of words. This result was obvious because listening to the pitch of the voice contains more emotional information than listening to isolated words without any associated context.

The Second Study

In the second study, 37 psychology students were asked to listen to an audio recording of the word “maybe”, spoken in three different voice tones (positive, negative and neutral). After listening to the recording, they were shown black and white photographs of a female face with positive, negative and neutral facial expressions. As in the previous study, they had to guess which emotions were associated with tone of voice and facial expressions. Once again, the results were evident. It was easier to identify positive, negative and neutral emotions by looking at the facial expressions in the photographs than by listening to the word “maybe” with different tones of voice.

The Truth about the Formula

Mehrabian combined the statistics from the two studies and created the formula 7-38-55. It is important to note that this researcher was one of the pioneers in the analysis of human communication and his studies were innovative. However, they must be contextualized. First, they were done in a controlled laboratory environment, something very different from an interaction in a real context. On the other hand, they were performed over 50 years ago, with a small and unrepresentative sample of the general population (UCLA Psychology students). But more importantly, these studies refer exclusively to the communication of emotions and attitudes and not to communication as a whole. The author himself has posted a post on his personal page to avoid misunderstandings:

Please note that this and other equations concerning the relative importance of verbal and nonverbal messages are derived from experiences that deal with the communication of emotions and attitudes (i.e., like and dislike). Unless a communicator is talking about their emotions or attitudes, these equations are not applicable.


If you take this formula to the letter, you may find that just having a powerful tone of voice and confident body language can communicate a message effectively. But it will be? Imagine you are visiting a country whose language you do not know. If words only corresponded to 7% of communication, it would be enough to be aware of the vocal tone and body language of your interlocutor to capture 93% of the message. Of course, this does not allow you to decode the whole message (unless it is the isolated expression of an emotion). Communication is a fluid process, and the weight given to the three elements varies according to the context and content of each interaction.


  1. Mehrabian, A. & Wiener, M. (1967). Decoding of inconsistent communications. Journal of Personality and Social Psychology 6 (1), p. 109-114.
  2. Mehrabian, A. & Ferris, S. (1967). Inference of attitudes from nonverbal communication in two channels. Journal of Consulting Psychology, 31 (3), p. 248-252.
  3. Mehrabian, A. (1971). Silent messages. Belmont, CA: Wadsworth.

last edited by: Joao Sarmento on Jan 12, 2020 7:11 AM login/register to edit this page


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