Detecting a lie: Cognition overload

Lie detection has found its way into many sciences and has led to development of complex procedures and technology to hint when a person is lying. But as usual, there are always ways of making things work much simpler.

You can catch a lie right in your conversation and on the spot by just knowing the situation a brain has to go through while lying. If some one is telling the truth, they just have to say what they know; that is, access the memory and relay the information to the other person (you). But when some one is lying, they have to do a lot of thinking; creative thinking, mostly because they have not rehearsed the responses to all kinds of questions.

This is not the topping - along with creative thinking a liar also has to multitask so that they don't appear to lie or think much about it. This is a difficult process for the individual. The liar has to process so much information at the same time that they often get to pause and think which appears to be giving away their dishonesty. To prevent this, an intelligent liar will make use of any information they can grab. This is, technically, like grabbing on to straws. The liar is looking for any information they that can support their stance or even more importantly take some load off their cognition and let them process more information and think out. They will find it very helpful to give 'yes' or 'no' answers or to simply pick out from given choices. The brain can only process a few chunks of information at the same time before the 'working memory' loss starts to occur. This is the reason things like phone numbers are only upto 7 digits and even then divided so as to be easily notable.

Now here goes the trick - the thing a liar is starving the most at is cognitive power, if you induce even more cognitive overload on the person, they will get slower (or even panic) and might gasp for any option to get out of the situation. Now you help them get out. Give them choices between two likely to be lies (which ofcourse would both still be lies). It will be much easier for you to think of such options than the liar having to think of anything in the process at all.

Here's an example:

Liar: I couldn't come to meet you today because I was busy.

You (after inducing more cognitive load): Did you miss it because you were busy with that assignment you were doing?

Liar: Yes.

The liar takes the bait for a Yes / No answer from the spoon feeding to the lying.

Under the cognitive overload, the liar having to answer a multiple choice question will find it as a blessing and go for an option as quick as possible instead of saying anything that is not among the choices. This is what gives a liar out. A liar always chooses from the given choices; some one telling the truth will rather not go for any of the options you gave.