The Theory of Information Pickup and Its Consequences (Gibson, 1979, Chapter 14)

So far, all the traditional accounts of perception have been rejected. Perception is not based on sensations detected by the retina, enriched by memories or processed into experience. Meaning is not simply associations from the past, nor innately given. In this chapter, Gibson brings together things we have already reviewed to lay out the theory of specifying information, and then discusses the (very radical and far ranging) implications of this theory. This is the key to the ecological approach.

Analog Computation

A recent preprint (Friedrich, 2026) describes the notion of analog computing, and proposes that it be taken seriously as a form of computation that might show up in cognition (alongside, not necessarily replacing, digital computation). He lays out the basic idea, connects it to some empirical literature, and makes the case for it being one of the options in the toolkit. 

I read it after a good discussion on Bluesky, in which I asked how this is different from dynamical systems approaches. 

Real question: what’s the difference between analog computation and dynamical systems theory (eg the watts governor)?

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— Andrew D Wilson (@adw.bsky.social) November 7, 2026 at 1:20 PM

The answers were informative! There is a key difference, and one with implications for whether this approach is useful to the ecological approach. The short answer is no, it's not especially useful, because it's representational. The slightly longer answer seemed worth blogging though. 

Not Every Behaviour Entails an Affordance

There are two approaches to formalising Gibson's notion of affordances. The first is to treat them as dispositional properties of the environment; properties the environment offers the organism to support possible actions. The second is as relations in the organism-environment system; not localised to the environment but formed when the organism-environment system is formed as a perception-action loop. I am firmly Team Dispositional Properties, because I think this best aligns with Gibson's goals, it allows actual science on the coordination and control of action (Wilson, 2026) and because there is currently no working account of how you might perceive a relational affordance. 

Despite all this, the relational account remains alive, well, and probably the main way people think about affordances. One reason is the drive to make ecological psychology align with the commitments of radical enactivism, a drive I have no interest in (I think enactivism is ok but nothing we owe our allegiance). I think the other big reason is that only the relational account really allows you to talk about affordances for things other than the coordination and control of actions, and as the ecological approach expands the things it is trying to explain people want to apply the ecological tools we have, and that means affordances. 

Except actually, it doesn't. 

Locomotion and Manipulation (Gibson, 1979, Chapter 13)

Gibson turns his attention now to two major forms of behaviour, locomotion and manipulation, and discusses the optical basis for the control of these action. He considers the visual information available in these tasks, and how these can be used to control the behaviours, without appeal to a central controller (such as the brain). In this chapter Gibson proposes that these and other behaviour are all 'regular without being regulated' (pg. 215) and the question is, 'how can this be'? While he doesn't fully answer this question, he introduces the key optic flow features we will need for these two behaviours. 

Looking with the Head and Eyes (Gibson, 1979, Chapter 12)

In this chapter, Gibson places head and eye movements on an ecological footing, and makes them the activity of a distributed perceptual system (c.f. Gibson, 1966) who's job it is to look around. 

We have to look around because our heads get in the way of our eyes. Even animals with eyes on the side have this problem, but for animals with front-facing eyes over half the optic array that is ambient to a point of observation is occluded by the head (which of course also specifies the presence of the self). Looking around is about reversing that occlusion and revealing things as required. 

The Discovery of the Occluding Edge and Its Implications for Perception (Gibson, 1979, Chapter 11)

Gibson introduced us to the notion of occlusion in Chapter 5. Occlusion is when one surface is progressively covered up by another surface, and the details of how optical texture is deleted specifies the occluding edge and the fact that occlusion is happening. In this chapter, Gibson details the radical implications of this fact of the optic array for theories of perception. Most importantly, given occlusion, vision cannot be based on images, series of images, or perspective structure, and it is not limited to working when sensations fall on the retina. Vision is a process that extends back and forwards in time, and this is enabled by information. 

Experiments on the Perception of Motion in the World and Movement of the Self (Gibson, 1979, Chapter 10)

Chapter 9 was about perceiving persistence in the environment. Chapter 10 is about perceiving change, and the evidence that this also might be direct. 

In contrast to retinal image based theories, Gibson proposes that change is perceived because of 'disturbances of structure in the ambient array' (pg 162). A key point here is that 'Disturbances of structure can specify events without being similar to them' (pg 162); this is a key fact about information. It does not get its meaning because it is somehow a copy of the world; it gets its meaning because of the laws that govern it's creation.