The Handshake: Two Seconds of Personality Data

William Chaplin and colleagues had a problem that most nonverbal research does not: they needed to measure a handshake objectively. Their solution was to train four coders to a criterion, then have each of them shake hands twice with each of 112 participants across two sessions, rating grip strength, completeness of grip, temperature, dryness, duration, vigor, texture, and eye contact.

The coders agreed with each other. Handshakes were consistent within individuals across sessions and across coders, which means handshake style is a stable personal characteristic rather than a mood.

And it correlated with personality. A firm handshake — strong grip, complete grip, vigorous, longer duration, with eye contact — was associated with higher extraversion and emotional expressiveness and with lower shyness and neuroticism on standard personality inventories. It also predicted the coders' first impressions: firm handshakers were rated more favorably. The relationship between handshake and impression was stronger for women in their data than for men.

So the handshake is not entirely superstition. It carries a real, if modest, signal.

The consequences are not modest. Later research at the University of Iowa on mock employment interviews found that independently rated handshake quality predicted interviewers' assessments of hiring suitability, and did so beyond the effects of other nonverbal behavior and self-reported personality. A ritual lasting under two seconds moved a hiring judgment.

This is where the chapter earns its place in a book about manipulation rather than a book about etiquette, because of a property the Chaplin study does not address and the Iowa result makes urgent.

The handshake is the single most rehearsable signal in the nonverbal repertoire.

Almost everything else in Part 2 is either autonomic and unfakeable — pupil dilation, blush, thermal response — or requires suppressing a response you cannot fully monitor. The handshake requires none of that. It is a two-second voluntary motor performance with a small number of parameters, all consciously controllable, all improvable with an afternoon of practice, and all coachable. Executive presence training teaches it. Sales onboarding teaches it. It appears in every guide to interviewing ever written.

Which means the correlation with personality that Chaplin measured is a correlation in a population that has mostly not trained. Among people who have trained, the signal carries no information about personality at all — it carries information about training, and training correlates with a completely different set of things.

The impostors in Part 5 of this guide understood this instinctively. Frank Abagnale, Ferdinand Demara and Christian Gerhartsreiter were all praised for their bearing and their manner, and bearing is a performance with a rehearsal cost of approximately nothing.

The general rule this yields is worth applying beyond handshakes: weight a nonverbal signal in inverse proportion to how easy it is to rehearse. Grip, posture, eye contact and vocal steadiness are cheap to fake and should carry almost no weight in a judgment that matters. Autonomic responses are expensive to fake and carry more. Verifiable facts are not nonverbal at all and carry more still.