 Armstrong (1968, 1981, 1999) is perhaps the leading defender of a simple, quasi-perceptual, self-detection account of introspection. He describes introspection as a “self-scanning process in the brain” (1968, 324), and he stresses what he sees as the important ontological distinction between the state of awareness produced by the self-scanning procedure and the target mental state of which one is aware by means of that scanning—the distinction, for example, between one’s pain and one’s introspective awareness of that pain.