Liza explains that our brain processes information from our senses and makes conclusions (perceptions) about our environment. When these perceptions are wrong, this is an illusion. They show a few examples of an optical illusion.

Temple, an autistic student, watches a short film on optical illusions and is immediately intrigued by it. She sets out to achieve the effects in the movie and does so after much persistence.

Jerry Andress explains several optical illusions and suggests that the discrepancy between our perception and the reality is not a mistake of the brain; the brain tried its best to map out the reality with whatever information it had.

Beakman explains how vision works involving the brain and eyes. He then explains how this works to create optical illusions.

In this scene, Dr. House has a very frank conversation with a clinical psychopath.