Abstract: A mind-controlled switch is described, which comprises input circuitry for receiving mind state data from a first external device, an actuator, responsive to user actuation to set one or more threshold mind state values, and control circuitry for controlling a second external device in dependence on the mind state data and the mind state value(s). Notably, the mind-controlled switch is provided separately both from a first external device (which actually collects the mind state data from the user) and the second external device, which is the device being controlled by the switch. Accordingly, the second external device need not have its own mind-controllable functionality, but can instead be a conventional device which is imbued with this functionality by way of the separate mind-controlled switch.