Three Seconds

Research: Hugs Follow a 3-Second Rule

Ever wondered how long a hug lasts? The quick answer is about 3 seconds, according to a new study of the post-competition embraces of Olympic athletes. But the long answer is more profound. A hug lasts about as much time as many other human actions and neurological processes, which supports a hypothesis that we go through life perceiving the present in a series of 3-second windows.
Crosscultural studies dating back to 1911 have shown that people tend to operate in 3-second bursts. Goodbye waves, musical phrases, and infants' bouts of babbling and gesturing all last about 3 seconds. Many basic physiological events, such as relaxed breathing and certain nervous system functions do, too.

And not just humans:

A 1994 study of giraffes, okapis, roe deer, raccoons, pandas, and kangaroos living in zoos, for example, found that although the duration of the animals' every move, from chewing to defecating, varied considerably, the average was, you guessed it, 3 seconds.