By placing a hand on the target's head, the user will be able to enter the target's subconscious and extract any information needed, even if the target has forgotten it himself or has had it blocked. The Yamanaka clan has to use special machines and the assistance of other ninja to enter the person's mind, while Pain was able to do so by simply grabbing the top of their head. Memories that have mental blocks on them will require longer periods of time to probe through and obtain.
