Is Direct Perception Plausible? The Case for Affordances-as-Dispositions

The first post in this series laid out the rules for what makes a theory of perception direct or indirect. In order to avoid having to require organisms to somehow figure out behaviourally relevant properties (indirect perception), direct perception requires that such properties are out there already, ready and able to be detected. Such properties are a bit weird - by definition, they must be properties of objects that include some reference to the organism doing the detecting (specifically, they are impredicative properties). 

The second post laid out some reasons to think that such circularly defined properties are legitimate options for the physical world. Properties like this are required by the mathematics of the quantum scale; and so, while a bit weird, are possible. Organisms don't work with quantum properties, though, so if they only happen at that scale, this doesn't help a theory of direct perception. The key to making impredicative properties work is measurement. At the quantum scale, all properties are uncertain until measurement collapses the uncertainty of the thing measured. At the ecological scale, properties aren't uncertain in this way, but which properties are 'primary' still depends on the measurement device; to a polar planimeter, for example, the higher order property 'area' is simple and lower order properties such as 'length' must be figured out. The reverse is true of a ruler. 

We have a set of pieces now. Impredicativity requires measurement to affect which properties are immediately available to the measurer, this is possible at the ecological scale, and with the right measurement device higher-order properties can be immediately available. This establishes an in-principle case in favour of direct perception as an option. Next, if we can identify the higher-order form of behaviourally relevant properties, we will identify what kind of measurement device is required for these to be directly available. 

The main ecological hypothesis is that higher-order behaviourally relevant properties, which we call affordances, take the form of dispositional properties. This post will walk through how this works and how it fulfils what's required to support direct perception.

(As many of you know, not everyone is happy with the dispositional ontology, and propose instead that affordances are relations. I am not going to lay out the parallel case for how this ontology fulfils the requirements I have been laying out, for the simple reason that I do not think it can do any such thing and I have yet to see any successful attempt to make it work. I talk about this in this paper, currently still living in review limbo.)

What Does it Mean for Perception to be 'Direct' vs 'Indirect'?

The ecological approach is a theory of direct perception. Put simply, direct perception proposes that our perceptual experience of the world is not mediated by anything that sits between the world and that experience. Making this viable is a big challenge, however, and the idea seems preposterous on the face of it to many people. 

In this post, I want to lay out the basic idea of direct vs indirect perception, and then explain how each approach addresses the problem of how we perceive the world. There will be some big words, but I will aim here to place them in a context that supports them usefully, and focus mainly on the straight-forward ideas in play. In a future post, I will ask the question 'what do we know about how plausible direct and indirect theories of perception are?'

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.

Visual illusions and direct perception

A while back I reviewed a bunch of papers by Rob Withagen who is currently arguing that while perception is not typically based in specifying variables, it can and should still be ecological in nature. While we are also developing an account of information that goes beyond specification I still have some reservations about the details of Rob's work. That said, I do think there is a lot of overlap and I'm still interested in figuring out what that is. 

Rob's latest paper (de Wit, van der Kamp & Withagen, 2015) is about visual illusions, and how to talk about them ecologically. There is a lot of very useful stuff in here, not least the review of the many things Gibson said about illusions. After this review, the paper tries to put all of this into Rob's and Tony Chemero's evolutionary framework and uses this to formalise and tidy up what Gibson was up to. I'm adding this paper to the set I've covered from Withagen as I continue to think through these issues.

A Gibsonian analysis of linguistic information

This post is based on a talk I just gave at the Finding Common Ground Conference at the University of Connecticut. Please excuse the Power Pointy nature of some sections! You might need to Ctrl+ to see some of the images clearly.  I have made some changes from the original talk content on the basis of very useful feedback I received from other conference attendees.

What is the place of language in ecological psychology? Is language a type of direct perception? Is language comprehension direct perception? Does language have affordances?

In trying to answer these questions I discovered that some things we think of as being perceptual have a lot in common with the conventionality of language and that some language-related behaviours look a lot like perception (as typically construed). I end up suggesting that we move away from talking about 'perception' and 'language' as different types of entities and instead focus on information / behaviour relations in specific tasks.