Niall
He talks really fast. Usually he talks at a normal pace, but if he's lying he talks really fast. You almost can't tell what he's saying. He thinks if you can't understand him you'll let it go.
Liam
His voice gets higher. Usually he talks in his normal deep voice, but if he's telling you a lie, then his voice gets an octive higher. He always thinks you won't know the difference.
Louis
It's harder to tell when he's lying 'cause he's always moving when he talks, but you've figured it out. His knees bounces. And really bad too. If he's sitting then his knee bounces. If he's standing then his entire leg bounces.
Harry
He stands or sits completely still. Usually he moves a little, but not when he's lying. He thinks that if he moves even the slightest then it'll give him away.
Zayn
He always looks down. He usually loves looking at you when talking, but he knows his eyes are very expressive and would give him away.