In the 70's, Albert Mehrabian studied the relative importance of verbal and nonverbal messages. The three elements of linking people together in a face-to-face situation are abbreviated as the "3 Vs": Verbal, Vocal and Visual. Mehrabian's findings on inconsistent messages of feelings and attitudes have become known as the 7%-38%-55% Rule: 7% of the message goes through words, 38% through tone of voice and 55% through body language.
Models for Call center activity where no visual contact is possible, propose 18% for words and 82% for voice quality (including tone, inflection, pitch, rate and volume). Note that these figures are consistent with Mehrabian's rule: when we remove its visual part (55%), words represents 7/(7+38) = 16% of the remaining communication channel.
While these figures have been discussed (mainly because of their dependency to the context), they clearly emphasis the importance of non verbal communication in human relationship. This is why it is so difficult to work closely with people you never met (or even hear if you're just interacting through email).
Let's compute how Mehrabian's law is distorted by networking:
- The average talking speed is 120 to 150 words per minute, while the average word length (in English) is of 5.1 characters, 6.1 if we add a separator. So a standard conversation takes approximately 150 words per seconds * 6 characters * 8 bits per characters (ASCII) = 7.2 Kbit/s.
- Voice transmission requires from 8 Kbit/s (low quality codec, like in mobile telephony) to 64 Kbit/s for good quality and even higher for hifi coding.
- Videoconferencing and tele-presence systems use from 250 Kbit/s (low quality) to 4 Mbit/s (High definition) and 15 Mbit/s for a multi-screen conference room.
For a "good enough" communication involving 7 Kbit/s for words, 64 Kbit/s for voice and 2 Mbit/s for a one-screen teleconference, we then find the 0.3%-3%-97% Rule that gives the % of the bandwidth allocated to verbal, vocal and visual purpose. It is interesting to see the efficiency of each channel:
- 7% of the information (words) is conveyed by 0.3% of the bandwidth --> Efficiency ratio of 7/0.3 = 23;
- 38% of the information (voice) is conveyed by 3% of the bandwidth --> Efficiency ratio of 38/3 = 13, approximately half of words' one;
- 55% of the information (image) is conveyed by 96% of the bandwidth --> Efficiency ratio of 55/96 = 0.57 (i.e. 40 time lower than words and 23 time lower than voice).
Would we accept the above figures, no wonder that historically people started with exchanging written messages which remain the most efficient communication channel. It took 1000s of years to come to phone calls that still have very impressive information to bandwidth ratio. 100 year later, imaging technology (codec, screens and camera) and networking (bandwidth, quality of service, application SLAs and Wan governance) make videoconferencing and telepresence possible.
Let's be ready for teleportation in a few 10s years…
(Illustration: see no evil, hear no evil, speak no evil at Toshogu, Nikko, Tochigi Prefecture, Japan)
PS: there is a notable exception to Mehrabian's rule: literature, music and painting/sculpture, when talented artists are able to bring us - just with words or sounds or colors or forms - in their own world and create into our brain images, impressions, feelings, souvenirs and thoughts. In the other hand, one can say that as this communication is not bi-directional, the rule just does not apply...
