Many types of body language may indicate when a person is lying. People may fidget, tense their shoulders or have a facial expression that does not match the emotional content of what they're saying. One way to judge whether a person may be lying is to look at his eye movements. Although not all eye movements indicate a particular person is lying, changes in the way a person uses his eyes may indicate that something's fishy about his story.
Establish a baseline. Watch how a person uses her eyes normally. Do they regularly make or avoid eye contact? Do they shut their eyes tightly when trying to remember something, or do they look to one side or the other? Knowing what a person's regular behaviors are like helps you know when they changed. Changes in how a person uses her eyes are one indication the person may be telling a lie.
Watch for eye contact. A person who maintains eye contact through an entire story may be trying to deceive you, according to Health Guidance. This is because people usually break eye contact and look toward a non-moving object while trying to access their memories of an event. If they don't break eye contact in this way, they may be making up a memory instead of recounting what really happened.
Note which direction the eyes move. As a general rule, people look to their left if they are accessing a memory and to their right if they are inventing a new story. Remember that these directions are reversed if you are directly facing the person: she will look to her left, which is your right, if telling the truth and to her right, which is your left, if lying. Also, these directions may be switched in left-handed people, who may store memories in different parts of their brains than right-handed people.
Examine the pupils of the eyes. According to Health Guidance, the pupils of the eyes may dilate if a person is telling a lie. Because pupil dilation is an involuntary movement, a person cannot control it to seem more believable. Remember, however, that a person's pupils may dilate for other reasons as well, such as a change in lighting from lighter to darker.