Activity, or the fraction of time each person talks, is the simplest measurement. Not surprisingly, the more someone talks, the more interested in the conversation he or she is assumed to be. Engagement measures how the speakers influence one other. Are they talking in smooth succession, or are there long pauses between utterances? Does one speaker hesitate more often than another? Stress measures the variation in the pitch and volume of each speaker’s voice to determine whether his or her voice betrays any discomfort or anxiety. Mirroring, finally, is a measurement of the speaker’s empathy–how frequently he or she adopts the vocal intonations and inflections of the other, or repeats short phrases such as "uh huh" and "OK" if the other says them first.
Pentland then collaborated with other researchers in fields ranging from psychiatry to business in order to put his markers to the test. Could they be used to predict what would happen in various social situations, say, landing a date, or getting a job or a raise?
In most scenarios, the predictions that Pentland and his colleagues were able to make turned out to be shockingly accurate. Using nothing but these simple, nonlinguistic clues–and analyzing conversations that lasted between five minutes and just over an hour, depending on the experiment–the researchers were able to calculate the likelihood of a given outcome with an average accuracy rate of almost 90%.
If men engaged in mirroring, for example, women were more likely to be attracted to them. Men, by contrast, were more attracted to women who varied the tones of their voices. Pentland and several Media Lab graduate students used his markers to analyze more than 50 speed-dating sessions, where participants interacted with one another for five minutes before deciding if they wanted to contact the other person for an actual date. By the end of the analysis, the researchers could predict with 83% accuracy whether or not two people would exchange phone numbers.
What does Robin Hanson say?: "There must be some reason we are unconscious of these cues, even though our subconscious clearly notices and uses them. So some sort of hell will probably break loose when tech makes it easier for us to see and publicize these cues."