Having assumed the status of a principle in the ecological psychology of James J. Gibson (1904-1979), it holds that animal and environment, as well as perception and action, are yoked by the two fundamental reciprocities that function in distinct, but complementary ways a reciprocity between internal and external frames of references (i.e., between internal and external degrees of freedom) and a reciprocity between movement and the detection of the resultant information it generates (i.e., between the generation of force fields and the generation of flow fields). It has been questioned whether the affordance concept actually abides by the principle of mutualism. This is because affordances are supposed to exist independently of the observer who may or may not perceive them. The result is that the perceiver must be excluded from the determination of affordances, which is thus contrary to the principle.
See Affordance, Degrees of freedom (or Bernstein’s) problem, Direct realist account, Ecological psychology, Information, Organism, Perception, Perception-action coupling, Principle