The quality of `aboutness', or `world-directedness', that has been claimed to be a distinguishing feature of mental processes as opposed to physical ones. It has been proposed that `intelligent' computer performances possess only a secondary, or derivative, intentionality: this has been used as an attack on the pretensions of artificial intelligence to explain the human mind. See also Computationalism, Functionalism, Intentional System/Intentional Stance, Turing test.