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 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). 

Framing the Debate

In 2014 we published a book chapter with Eric Charles in which we argued that the most important thing psychology and neuroscience needed from people like us was a new language in which to talk about the problems we are trying to solve. Our Ecological Representations paper is part of this, and we have a much larger paper in development laying out the more complete set of conceptual tools needed to do ecological psychology across a wider range of problems.

One reason why this is important is a simple fact; we are asking psychology to change and it is up to us to clearly articulate what we want it to change into, or else nothing can happen. A related reason is that without a clear framework, we can't reformulate the questions in a useful way and we're left stuck because we can't explain something like 'theory of mind' because the actual solution is that ToM doesn't exist or need explaining. Ecological neuroscience, for example, will look very different to cognitive neuroscience.

A final reason is that the language in which psychology frames it's understanding of behaviour drives popular understanding of behaviour too. I recently came across my favourite example of this in a tweet by Alice Dreger;

My dominant eye is very blurry so my left eye has come online (it rarely does) and now I'm seeing 3D. 3D is SO WEIRD. How do you stand it?

— Alice Dreger (@AliceDreger) July 19, 2016

Dreger, for some reason, spends most of her life only using her right eye, even though her left is perfectly functional. She blogged about it here. Every now and again, something makes her left eye kick in and she suddenly has stereo vision.

What caught my eye here is her description of her experience is grounded in the myth that you need two eyes in order to perceive in 3D (I bug my students about this in class every year too). The myth is based in the standard image-based analysis of vision which I'll lay out below; but the point I want to make here is that people still describe their experience of monocular vision as 'not being able to see 3D/depth' even though this is inarguably, demonstrably not what is happening in their visual experience. It's like blind echolocators talking about how the sound creates 'an image in their minds'; this is just not the case, but this is the language psychology has provided them for talking about the perceived experience of spatial layout. What fascinates me is that it's trivial to demonstrate that monocular vision allows for 3D perception, but everyone lets the framing override their own experience. This, to me, is a big part of why our work right now is important - we will never make progress until we can reframe the debate.