(Bk Business) Carol Kinsey Goman Ph.D.-The Nonverbal Advantage_ Secrets and Science of Body Language at Work -Berrett-Koehler Publishers (2008)

Chapter 3: The Eyes Have It
53
Blinking Rates
During conversation a normal blink rate is six to eight blinks
per minute—and the eyelids are closed for about one-tenth
of a second. This rate speeds up when someone is under pressure.
For example, when most people are lying, their blinking
rate increases dramatically. Police interrogators and customs
inspectors look for a change in the blink rate that might
signify areas where the person is trying to cover something
up. Psychologists are also aware of the significance of the
blink rate when a patient is trying to conceal something. Of
course, rapid blinking can also indicate annoying lighting in
the room or a heightened level of anxiety for a variety of reasons.
It could even be exhibited if a person is telling the truth
but is worried or insecure about not being believed.
Elongated Blinking
Elongated blinking is an unconscious gesture other people
use to exclude you during a conversation. When someone’s
eyelids close for more than a second, it is an attempt to block
you from their sight. And when
combined with a backward
head tilt (a looking-down-thenose
gesture), it’s also a sign
that the person is bored with
you, is completely disinterested
in the topic, or feels superior.
He’s displaying a smug
sense of superiority.