Deactivation switch

A deactivation switch, or off switch, was a component of Soong-type androids. Located in the small of the back, this switch could be activated by a press of the fingers. Paired with the switch were a number of small projections. These projections, as Data defined them, were "an android alarm clock". They measured the time this type of android remained unconscious. If the switch was repeatedly pressed, as happened to Data by Lore, the android could appear he suffered from seizures. 

During the reassembly of Lore in 2364, Data confided with Dr. Beverly Crusher on the location and use of the deactivation switch. 

In 2365, Commander William T. Riker used the switch in a demonstration to prove that Data was only a machine and nothing more.