For example, a person may see written "No Trespassing" on a board and may infer from this that intelligence agencies are spying on him. Aphemia is the alternate term for mutism. Mutism is absence of speech with apparently normal level of consciousness. Mutism can be dissociative (hysterical) in which an individual (commonly a child or adolescent) stops speaking at once without involvement of any neurological or physical contributing factor; or it can be elective (selective) in which a child does not speak at all in certain situations (such as in school) but speaks well in other conditions (like at home or at play). A rare cause of mutism is akinetic mutism which results due to a lesion around the 3rd ventricle of the brain. Apperception is a normal phenomenon and refers to the ability to understand sensory inputs in their context, to interpret them and to incorporate them into experience. Failure of apperception is seen in delirious states. Astasia-abasia is a form of psychogenic gait disturbance in which gait becomes impaired in the absence of any neurological or physical pathology. The person usually walks in a bizarre manner. They stagger and appear as if going to fall, but always manage to catch hold of something in time. Sometimes these people cannot even stand, but on the other hand they are well able to move their legs while lying down or sitting. Often associated with conversion disorder or somatization disorder. Alternate term for loosening of association. A milder form of derailment of thought, it is marked by the individual leaping from topic to topic which have only the most tenuous, if any, connection with each other. This is in contrast with flight of ideas, whereby the individual's successive ideas may be linked and "understandable" to the listener. See also Akataphasia and Entgleisen term introduced by (Cameron). From "aut" ="self" and -"ism" = "state or orientation". Originally, Eugen Bleuler used this term to describe schizophrenia. In general, it refers to any (pathological) tendency to be self-absorbed to such a degree that the feelings, thoughts and desires of a person are governed by his internal apprehension of the world and not by an external reality shared with others. Today the term is used most often to refer to a specific developmental syndrome (see autism spectrum). Autistic thinking is a term used to refer to thinking not in accordance with consensus reality that emphasizes preoccupation with inner experience.