Are your characters lying? Is that what you want them to do? You don’t want to break the Show, Don’t Tell writing rule. How do you show your reader when one of your characters is telling a lie?
At a time like this, it’s best to call in a professional. A policeman, a detective, an expert in body language would be helpful.
You might know that some cultures do affect body language. They’ve become clichés. The broad hand gestures of a Sicilian, for instance.
Did you know that men have more trouble lying than women do? Or that when you ask someone to imagine something, their eyes will move in a different direction than if you ask them to remember something?
But if your character has a head injury, these cues may not apply.
For instance, if the character you want to show is lying is right-handed and not recently concussed in your story, I suggest you do what good cops all over the world do.
First, show how this character normally behaves and speaks. Sometimes this is called lulling the suspect into a false sense of security. Have your good guy character ask innocuous questions and watch for body cues when the person is relaxed and yes, states that his address matches that shown on his driver’s license. What his date of birth is. What he did two weekends before the murder. Show the character’s normal pace of speech.
When the hard questions start [where were you yesterday between the hours of 10 pm and midnight?] have your good guy or gal look for changes in posture and speech patterns. And have your reader look at the motion of the right-handed suspect’s eyes.
If he’s lying, chances are his eyes have shifted to the left, rather than to the right, as they did when he remembered what he was doing two weekends ago. With this eye shift to the left, you can show your reader the suspect is making things up.
Naturally this kind of writing isn’t restricted to detective stories. Other genres also need good body language writing to show what’s going on with their characters.
Fortunately, you don’t need to call in the FBI when you have a question about body language. Here are some books and web sites that can help you out.
http://www.blifaloo.com/info/lies_eyes.php
Body Language for Dummies by Elizabeth Kunke
Body Language by Julius Fast
Changingminds.org