Lecture 12: The Space Enigmas IV: On Learning Space Perception (Turvey, 2019, Lectures on Perception)

This Lecture is in roughly two parts. The first brief section walks through a Helmhotzian method for perceiving depth via unconscious inference. This inference process is learned (Helmholtz wanted to be an empiricist) but as usual entail loans of intelligence in the form of some givens not acquired via experience. This then raises a question: what exactly is experience, and what about it is used to be the basis for future inference? It turns out what counts as the relevant parts of experience can be very non-obvious, raising many problems that need more modern, less Cartesian solutions. 

Lecture 11: Doctrines of Sensations and Unconscious Inferences (Turvey, 2019, Lectures on Perception)

This Lecture is about Helmholtz, and his theory of sensations being integrated into perceptual experience via unconscious inference. Everything in here should look very familiar to anyone who has ever taken a Sensation and Perception class, because modern theories of indirect perception are literally versions of this account. (I'll note as well that, while there are embodied and ecological interpretations of the free energy principle (e.g. Bruineberg et al, 2018), one common interpretation is that it is an implementation of Helmholtz's unconscious inference; e.g. Friston and Kiebel 2009; Hohwy, 2013). 

Unconscious inference is a firmly Cartesian programme. It is about using the physiological measurements of things like light, and inferring their underlying causes (i.e. what is happening in the world to be perceived). Unsurprisingly, it is going to run into the same main problem, namely unrepayable loans of intelligence. 

Lecture 10: The Space Enigmas III: Local Signs and Geometrical Empiricism (Turvey, 2019, Lectures on Perception)

The previous two lectures have covered aspects of the problem of space perception. We perceive objects, and these inhabit space - they are at some distance from us and each other, etc. So what is space, and how do we come to know about it? We've tried using touch (a sense that lives in 3D) to provide the necessary clues (this was Berkeley, and the story of Flatland). This doesn't work because touch isn't a perfectly reliable source of space information, it's a perceptual system like vision and faces the same kinds of problems. We've also tried to just make space a necessary feature; not an object of perception, but a mode of perception (this was Kant, and the power of Euclidean geometry). This doesn't work, because there are perfectly coherent non-Euclidean geometries, that all provide different answers when measuring the same space. As soon as there is more than one geometry, choosing one becomes part of the problem and you cannot simply assume it. 

Given this, how might you go about selecting the right geometrical description to use as the basis for your experience of space? Turvey discusses one major attempt to show how this might happen, specifically Helmholtz's account of how to derive a geometry (a notion of space) from non-spatial local signs. 

This Lecture involves quite a bit of mathematical detail, which I am not going to get into here because it's slightly besides the point. The overall goal, however, is to take some sensory raw material that isn't intrinsically about space (because it can't be), and work to turn it into an experience that is about space. This is going to be the start of the move to talk about sensations and perception, the organising principle still at the heart of all non-ecological discussions of how we come to experience the world. More on this in the next lecture. 

Lecture 9: The Space Enigmas II: Kant, the Nature of Geometry, and the Geometry of Nature (Turvey, 2019, Lectures on Perception)

The first space enigma was the fact that vision lives in the two dimensions of Flatland, but produces an experience of three dimensional Spaceland. You can't logic or experience your way from Flatland to Spaceland (as described in the famous book). Berkeley tried to solve this problem by providing a guide, in the form of the Spaceland-dwelling body, but this fell apart and the only remaining suggestion was an unrepayable loan of intelligence from God. 

Another way to consider this problem that leads to another proposal is what Turvey calls 'the outness problem'. This is the annoying fact that sensations on the retina are experienced as things out there, in the world. This makes space a necessary precursor to perceptual experience: however the outness problem is solved, a notion of space is required to drive the search for a solution. Kant is the main person who worked to establish how space might be baked into perception; 'Space, therefore, is not an object of perception...but something very different, namely, a mode of perceiving objects' (Turvey, 2019, pg 124). Spoiler alert: it doesn't work, for interesting reasons that feed into the development of the ecological analysis. 

Lecture 8: The Space Enigmas I: Berkeley (Turvey, 2019, Lectures on Perception)

One of the big problems that emerges from all the proceeding discussions of perception is how we are able to perceive space. Space has been considered as a mathematical concept (in terms of Euclidean geometry), as a psychological concept (a construction of the mind) but never really as a biological, ecological concept. This first chapter about space perception is focused on one mathematical conception, some of it's implications, and one specific attempt to deal with those implications (Berkeley's New Theory of Vision). 

Turvey, Lectures on Perception: The Story So Far

I have now reviewed the first 7 Lectures on Perception from Turvey' textbook (posts indexed here). I feel like I've reached a natural pause point before carrying on with the rest of the lectures, and I wanted to summarise what I thought has been going on so far.

These are lectures on perception, quite generally. While Turvey will explain the ecological approach, that's not what is currently going on. Right now Turvey is laying out the scope of the question 'what kind of material system could be a perceiving system?' and reviewing the typical, non-ecological answers to that question.

The main takeaway at this point is that we have been trying to answer that question using 17th century notions of material systems, specifically Newtonian mechanics. This has placed what turn out to be unacceptable restrictions on the kinds of properties we are allowed to invoke, and theories of perception have had to fill the gaps with unpayable 'loans of intelligence'. 21st century physics, however, has more on offer; complexity science and quantum mechanics teach us many valuable lessons on how to expand our horizons so that perception becomes possible, rather than miraculous. 

Lecture 7: Empiricism and the Man in the Inner Room (Turvey, 2019, Lectures on Perception)

The last two Lectures have laid out the mechanical, Cartesian analysis of the problems of perception. Every flavour of this analysis, right up to an including modern representational accounts, rests on 'loans of intelligence', in which important work that's required to make the system work is simply given to the system. For example, Descartes proposes a set of cognitive axioms to ground the inferential processes required to implement knowledge, and makes these innate (specifically, given by God). This won't do - if we want to develop a naturalised theory of perception, we need an account of where every part of the system comes from. 

The Cartesian programme is a form of rationalism, roughly the claim that knowledge is based in reason rather than experience. This chapter reviews the opposing camp of empiricism, roughly the claim that knowledge is based in experience rather than reason. Turvey reviews the approaches of Locke, Berkeley, and Hume, with respect to how they assert a mind can come to know about the world via experience. They end up running into very similar problems as Descartes et al, because of their continued commitment to the mechanistic hypothesis. We are going to have to reject both of these as we progress.

Lecture 6: The Cartesian Program (Turvey, 2019, Lectures on Perception)

Turvey is arguing that modern psychology is still operating within a mechanistic framework, which assumes things like linear chains of causation and predicative properties. In the last lecture, he laid out the kinds of properties this framework allows, and connects his critique of them to the more interesting notions of causation and impredicativity he introduced in Lecture 4. 

In this Lecture, he spells out the way psychology implements the mechanistic framework and identifies that it is, specifically, a Cartesian implementation. Here, we will learn the form of the program, and note how it shows up in the familiar terms of cognitive psychology. 

Lecture 5: The Mechanistic Hypothesis (Turvey, 2019, Lectures on Perception)

In the previous lecture, Turvey spent a lot of time defending the idea that nonlocal causality is a legitimate option for a physical system. He did this by looking at quantum mechanics and the extraordinarily robust evidence it has provided for nonlocality. The reason he did this is because perception as a two-term relation (direct perception) seems to require at least some nonlocal causality in order to work without additional terms (epistemic mediators). 

This chapter is a discussion of properties and how to organise them - ontology. Part of Turvey's work is to lay bare the fact a lot of our science is still working within the 17th century, mechanistic framework - all psychologists have encountered the idea that there are primary and secondary properties of things, and that we are in the business of understanding how the secondary ones work. But, as Turvey is describing, science has moved on, and the possible types of legitimately physical (primary) properties has expanded far beyond what Galileo, etc thought possible. For example, in quantum mechanics, particles don't have properties such as 'position' or 'velocity' until they are placed into a relation with either a position or a velocity measuring device. The property 'position' is impredicative, both defined and actualised by the presence of the relation to a position measurer. Historically, properties that are both defined and actualised by the property holder is in the relation have been considered to be secondary properties; subjective, not objective properties. But quantum mechanics considers particle position to be perfectly real, and it has the extraordinary level of empirical success required to back that claim up. 

This chapter walks the reader through the development of the mechanistic framework that still drives how we classify properties, thus affecting how we study them. It ends by identifying that this taxonomy begins to creak as we use it at the scale of behaviour, and points to the success of quantum physics to suggest a more expansive and interesting taxonomy of real properties is both required and an option. 

Lecture 4: Simulative, Projective, and Locality Assumptions (Turvey, 2019, Lectures on Perception)

This lecture is a brief history of the common assumptions made in theories of perception about how things 'over there' can cause us to have a given perceptual experience. The simulative and projective elements can be quickly dealt with; the big claim in this lecture is that the right notion of causation for perception is non-local, as it is in quantum mechanics. (Note: Turvey is not saying perception is a quantum process. He's just going to use it as a framing to explain what non-local causation is, and he will rely on the rigorous empirical testing it has passed in physics to say it is a viable notion of causation for a physical system.)

Lecture 3: Direct Perceiving, Indirect Perceiving (Turvey, 2019, Lectures on Perception)

In this lecture, Turvey provides a formal definition of what it means to claim a theory of perception is direct vs indirect. A theory of direct perception invokes lawfully specifying information, while all indirect theories invoke at least one mediating physiological or psychological process. Direct theories are allowed to discuss internal states, etc (Gibsonian neuroscience isn't a contradiction in terms), but these states are not allowed to alter information so it is no longer lawfully related to the environment. The big Turvey word we will learn about in this chapter is impredicative entailment - exciting! I'll also briefly point to some implications this chapter has for my recent papers with Sabrina on neuroscience and mechanism.

Lecture 2: Organism-Environment Dualism (Turvey, 2019, Lectures on Perception)

In this Lecture, Turvey lays out the organism-environment dualism that lies at the heart of pretty much all attempts to answer the question, how can an organism come to know about it's environment via perception? He discusses Descartes' mechanistic (mechanical) approach, and then pivots back to the idea that Composition, Environment, Structures (CES) systems are the only approach that can possibly cope with the nature of the problem. 

Lecture 1: What Kind of Systems Do We Study? (Turvey, 2019, Lectures on Perception)

The first thing to do is to characterise what it is we are studying when we are studying perception. Turvey states we are studying epistemic, intentional systems and spends this chapter explaining each term. He does the most work on system; intentional and epistemic are primarily just defined and noted as being features of the system we are going to have to engage with. 

As usual, I will try to efficiently review the key points and then add some reflections on what the chapter made me think about. 

Reading Group: Turvey (2019), Lectures on Perception

Michael Turvey runs a famously intense graduate level class on perception and action at CESPA. He has recently, finally, published a book of his lectures, in which he basically develops the ecological approach to perception-action from first principles. I've been reading the lectures in small bites (each one is a good 20 minute read to go through), but I've now been invited to a Zoom reading group with Noah Guzmán and Peter Zatka-Haas. This is awesome, as it's an excuse to do the next thing I wanted to do, which is to go back through the lectures in detail (20 minutes to read, a lifetime to digest!). 

This will take a while, but I plan to develop a series of posts, one lecture at a time, similar to what I've done with Chemero (2009) and what Sabrina has done with Gibson (1979) (see The Rough Guide for links). In each post, I will attempt to (concisely) summarise the key points from the lecture. At the end, I will reflect on what I've learned from the lecture, and connect it to issues in the literature. 

More recently, I have started discussing the book on Rob Gray's Perception-Action Podcast; links below as we record. 

Turvey is a genuine gift to science, and these lectures are kind of amazing. Allons-y!

Links to posts

Lecture 1: What Kind of Systems Do We Study?

Lecture 2: Organism-Environment Dualism

• Perception-Action Podcast episode on Lectures 1 & 2: Video  Podcast

Lecture 3: Direct Perceiving, Indirect Perceiving

Lecture 4: Simulative, Projective, and Locality Assumptions

• Perception-Action Podcast episode on Lectures 3 & 4: Video  Podcast

Lecture 5: The Mechanistic Hypothesis

Lecture 6: The Cartesian Program

• Perception-Action Podcast episode on Lectures 5 & 6: Video  Podcast

Lecture 7: Empiricism and the Man in the Inner Room

The Story So Far

Lecture 8: The Space Enigmas I: Berkeley

• Perception-Action Podcast episode on Lectures 7 & 8: Video  Podcast

Lecture 9: The Space Enigmas II: Kant, the Nature of Geometry, and the Geometry of Nature

Lecture 10: The Space Enigmas III: Local Signs and Geometrical Empiricism

• Perception-Action Podcast episode on Lectures 9 & 10: Video  Podcast

Lecture 11: Doctrines of Sensations and Unconscious Inferences

Lecture 12: The Space Enigmas IV: On Learning Space Perception

• Perception-Action Podcast episode on Lectures 11 & 12: Video Podcast