There is an Unusual neurological disorder called Alien Hand Syndrome in which the sufferer's hand seems to take a mind of its own, They feel that they have no control over the movements of the 'alien' hand, but that, instead, the hand has the capability of acting autonomously independently of the sufferer's will. The hand effectively has 'a will of its own.' Alien hands can perform complex acts such as undoing buttons, removing clothing, and manipulating tools. Sometimes the sufferer will not be aware of what the alien hand is doing until it is brought to his or her attention, or until the hand does something that draws their attention to its behavior.
Sufferers of alien hand will often personify the rogue limb, for example believing it to be "possessed" by some intelligent or alien spirit or an entity that they may name or identify. There is a clear distinction between the behaviors of the two hands in which the affected hand is viewed as "wayward" and sometimes "disobedient" and generally out of the realm of their own voluntary control, while the unaffected hand is under normal volitional control ( In Psychology Volition or Will is the cognitive process by which an individual decides on and commits to a particular course of action.). At times, particularly in patients who have sustained damage to the Corpus Callosum ( that which connects the two Cerebral Hemispheres), the hands appear to be acting in opposition to each other. For example, one patient was observed putting a cigarette into her mouth with her intact, 'controlled' hand (her right, dominant hand), following which her alien, non-dominant, left hand came up to grasp the cigarette, pull the cigarette out of her mouth, and toss it away before it could be lit by the controlled, dominant, right hand. The patient then surmised that "I guess 'he' doesn't want me to smoke that cigarette." This type of problem has been termed "intermanual conflict" or "diagonistic Ideomotor Apraxia"
It is theorized that alien hand syndrome results when disconnection occurs between different parts of the brain that are engaged in different aspects of the control of bodily movement. As a result, different regions of the brain are able to command bodily movements, but cannot generate a conscious feeling of self-control over these movements. As a result, the "sense of agency" (It is the pre-reflective awareness or implicit sense that it is me who is presently executing bodily movements or thinking thoughts) that is normally associated with voluntary movement is impaired or lost. There is thus a dissociation between the process associated with the actual execution of the physical movements of the limb and the process that produces an internal sense of voluntary control over the movements, with this latter process thus normally creating the internal conscious sensation that the movements are being internally initiated, controlled and produced by an active self.
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