The theory of enactionism, as explained by Foley (1997), proposes that humans create meaning and revisions to meaning through our biological response to the environment. External stimuli are received through the senses, our sense-carrying^{Endnote 9} neural receptors, and the way we respond to external stimuli reflects an internal neurochemical change in the brain’s configuration (see endnote 7), whether or not individuals can articulate those changes or the meaning of them. Furthermore, Foley argues, the brain and nervous system—and thereby the mind, exist as a self-modifying system that responds not only to external stimuli (changes in the environment) but also to changes within the body itself. Each organic response changes the way a person thinks—and the way a person thinks circumscribes future possible responses. Unlike the pre-given, external environment posited by the concept of mental representations,

the “environment” [for the enactionist and] for the purposes of the sensory receptor cells emerges from the world only through the present organization of the organism's nervous system, which … is partly a function of its history of previous organizations… The nervous system "affords" (see Gibson 1979) the world as "environment" its significance for present and possible subsequent states of organization, and, in turn, the world contributes to generating a history of the organism's states. (p. 10)