[00:06.39]How do you Know when someone is lying?
[00:09.42]1 How the ancient Chinese did it
[00:13.88]The Chinese used rice.
[00:16.17]An examination for truthfulness
[00:18.09]might go something like this:
[00:20.24]"Is your surname Zhang?"
[00:21.96](They know the guy's surname is,in fact,Zhang.)
[00:25.04]"Yes."
[00:26.75]The interrogators hand Mr Zhang some rice.
[00:29.63]They have already counted the number
[00:31.32]of rice grains.
[00:33.25]"OK. Put this handful of rice in your mouth.
[00:36.41]Hold it for three seconds.Spit it out."
[00:39.51]Then they count how may rice grains come out.
[00:42.75]"Did you steal the chicken?" "No."
[00:46.01]"OK.Put this handful of rice in your mouth.
[00:49.34]Hold it for three seconds. Spit it out."
[00:52.54]"Again, they knew how many grains went in,
[00:55.26]and they count how many come out.
[00:57.81]If more grains come out after the question
[01:00.31]about the stolen chicken than came out
[01:02.96]after the "easy" question,
[01:04.96]where the suspect truthfully gave his name,
[01:07.25]they know he's lying.
[01:08.96]How? The stress of being caught
[01:11.29]lying makes the suspect's mouth drier.
[01:14.19]Fewer grains stick.
[01:16.63]More come out Mr Zhang stole the chicken.
[01:19.94]
