nucleation

LIT-904: Preliminaries to a theory of action with reference to vision

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Properties5
StatusActive — read 2026-10-14 (NOTE-826) in full, in its 1975 Haskins report form; worth reading as the essay that made the coordinative structure the unit of action control and tuning its means of control: the executive cannot command muscles, so it specifies a ballpark and sets the parameters of relatively autonomous units, as one sets the stiffness and rest length of a spring. Read it knowing that Turvey borrows the term from Easton (1972), that its evidence is reviewed reflex-probe studies of simple single-joint movements, and that its account of vision setting the tuning is speculation.
Version2
Tagsembodied-cognition, behavioral-integration
Cited as “paper” byNOTE-826 — Turvey — Preliminaries to a theory of action
Cited as “source” byTHEORY-302 — Coordinated action is controlled by tuning relatively autonomous coordinative structures, not by commanding muscles: a higher level specifies an equivalence class of acceptable states and sets the parameters of self-regulating units, leaving the realized details to them

Graph View

M. T. Turvey (1977), “Preliminaries to a theory of action with reference to vision”, in R. Shaw and J. Bransford (eds.), Perceiving, Acting and Knowing: Toward an Ecological Psychology, Hillsdale, NJ: Erlbaum (reprinted Routledge 2017) — DOI-10.4324/9781315467931. Preprint: Haskins Laboratories Status Report on Speech Research SR-41 (1975), pp. 1–49 (ERIC ED109722).

Key takeaways

From the reading, NOTE-826.

  • No keyboard executive. The same impulses to a muscle give different movements in different states and loads, and the controller has far fewer degrees of freedom than the limbs, so muscles cannot be commanded one by one.
  • Coordinative structures. “Reflexes and functional combinations of reflexes”, relatively autonomous units; “a term borrowed from Easton (1972a) but used here with greater latitude” (p. 8).
  • Ballparks. After Greene, the executive specifies equivalence classes of states, not states, and is ignorant of how lower levels realize them.
  • Tuning. Higher levels set the gain, equilibrium and damping of self-regulating units. Reflex probes show the spinal segmental apparatus retuned, specifically and nonspecifically, in the 30–100 msec before a voluntary movement; Fel’dman’s joint goes to a preset equilibrium whatever its initial conditions.
  • Vision. Changing optical properties control locomotion and may set tunings directly; unchanging ones (affordances) select action plans. Argued, not measured.

Standing in the record

Filed on 2026-10-11 with the coordinative-structure readings, as the usual source credited with the term. Read on 2026-10-14 in NOTE-826, in the 1975 report version.

The reading corrects the credit: Turvey borrows the term from Easton and widens it from reflexes to functional combinations of reflexes. In his sense a coordinative structure lies within one body, so its use for the dancing couple (CLAIM-175, CASE-046) would be a further widening by the record. Reciprocal compensation, which CASE-046 calls the signature of a coordinative structure, is Kelso et al. (LIT-902), not this essay. Filed from the reading: THEORY-302, control by tuning of autonomous units.

No instruction for machine-learning practice; nothing for the anthology.

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