James J. Gibson

Keijzer (2015) starts from the point that every living cell is sensitive to chemical and physical features, so any cell can act as a sensor. Against this, Keijzer sets the sensory device typical of animals with nervous systems: a spatially extended array of many sensitive cells working in parallel. The retinal and skin surfaces are the examples given, with Gibson (1966) cited¹. A single cell can signal the presence or intensity of a feature such as light. An array lets the organism become sensitive to patterns across a surface. Braitenberg (1984) is cited alongside Gibson for this².

Keijzer proposes a skin brain organization in small, soft-bodied organisms that crawl in contact with a substrate. If the substrate obstructs contraction or extension of the body, the animal would sense the obstruction as a disturbance in the patterning of its body surface, with no dedicated external sensor. Keijzer concludes that internal sensitivity suffices for a basic form of active touch and cites Gibson (1962) and O'Shaughnessy (1989) for the term³.

Bruineberg, Kiverstein and Rietveld contrast Helmholtzian accounts, in which perception is unconscious inference resembling scientific hypothesis-testing, with other views. They say the free-energy principle is consistent with several accounts of self-organizing living systems. Ecological psychology, cited as Gibson (1979), is named in that list alongside autopoiesis⁴.