Their left.
This is what psychologists believed (Although it has since been disproved by various studies)
It's to do with accessing different parts of the brain.
Looking Left indicates - accessing memories
Looking Right indicates - drawing from your imagination
A better method of telling if someone is telling the truth is to look for 'ticks' ( hair moves, hand to head actions e.t.c )
Also look for 'erm's and other stalling phrases