You Cannot Perceive a Relational Affordance (A Purple Peril)

One of the more enduring arguments in ecological psychology is about the best way to formally describe affordances. The two basic approaches are that they are dispositions (Turvey, Scarantino, me) or that they are relations (Reitveld, Kiverstein, Chemero). The argument has mostly settled down into just agreeing to disagree, but I am still convinced that the relational analysis is critically flawed and I want to try and either get them to solve the problem or end the debate once and for all. I've reviewed this in a bunch of places (e.g. here, here, and here)  but this post is just setting out my challenge once and for all; you cannot perceive a relational affordance, and there is as yet no good story about how to learn new affordances.

My problem stems from this Gibson (1979) quote (we all have our favourite, but this one seems to cut to the heart of it)

The central question for the theory of affordances is not whether they exist and are real but whether information is available in ambient light for perceiving them.

Right now, the affordances-are-relations camp have no story for how these can structure light (or other energy media) and therefore create information about themselves. They are therefore, as currently formulated, not even in principle perceptible. This means affordances-as-relations is of zero use to the ecological approach. 

Bruinberg et al (2018) tried to address this problem, but as I blogged here their solution is not ecological information and it reveals that these authors do not as yet understand what information actually is. My challenge is therefore this: tell me a story in which affordances-as-relations are able to create ecological information in energy arrays, and might therefore be learned, and the debate will be back on. Until then, affordances-as-dispositions is the only account that formalises the right properties and the debate is over. 

General Ecological Information Does Not Support the Perception of Anything

One common critique of the ecological approach is how can we use perception to explain behaviour that is organised with respect to things in the world that aren't currently in our area? How do we plan for future activities, or how do we know that the closed fridge has beer? 

A recent attempt to get ecological about this comes from Reitveld & Kiverstein (2014) who propose a relational account of affordances that enables them to talk about opportunities for more complex behaviours. This account has developed into the Skilled Intentionality Framework (e.g. Bruineberg & Rietveld, 2014), where skill is an 'optimal grip' on a field of task-relevant, relational affordances. 

I have always had one primary problem with this programme of work - I don't believe that they can show how these affordances create information and thus can be perceived. I discuss this here and here, and there's comments and replies for Rietveld and Kiverstein there too. You can indeed carve the world up into their kind of entities, but if they don't create information then they cannot be perceived and they are irrelevant to behaviour. 

I was therefore excited to see a new paper from the group called 'General ecological information supports engagement with affordances for ‘higher’ cognition' (Bruineberg, Chemero & Rietveld, 2018; hence BC&R). There is a lot of excellent work in here; but their proposal for a general ecological information is, in fact, neither ecological nor information. It is a good way of talking ecologically about conventional constraints on behaviour, but it doesn't make those perceivable and so the main thesis of the paper fails. 

Do Dynamic Models Explain? (#MechanismWeek 3)

So far we have learned what a mechanism is, two ways of modelling mechanisms (functional and mechanistic) and we've identified that cognitive science is currently dominated entirely by functional models which will never actually turn into mechanistic models without a change in our research priorities.

Bechtel & Abrahamsen (2010) challenged cognitive science to make the move to mechanisms. They laid out the form of the necessary research programme (empirically decompose and localise the actual mechanism, and then model those real components), and they described all the benefits of mechanistic models we might really want to have. The main benefit is a move from mere description to proper explanation of the mechanisms we study, and this certainly seems like something we would want.

But can we do the work needed to get mechanistic models? Can we decompose cognitive systems into sensible components and model the result?  Chemero & Silberstein (2008) and Silberstein & Chemero (2010) argue we can't, because cognitive systems are nonlinear and therefore non-decomposable; it makes no sense to break them down into parts because the behaviour of the system is more than the sum of those parts. They do argue, though, dynamical models are appropriate and count as proper explanations. This post will review but ultimately reject this argument.

Dynamic Mechanistic Explanations in Radical Embodied Cognitive Science

I'm on my way back from an enactivist/embodiment conference in Warsaw. I gave a talk (slides) in which I argued that in order to make theories of distributed/embodied cognition work, you have to have something like a theory of ecological information as the glue to hold it all together. All the talks I saw that discussed any kind of plan for distributing cognition were missing this piece and desperately needed it, so I'm hoping the talk will make people realise this tool exists and can help. Drop me a line if you would like any help!

I argued specifically that information lets us propose mechanistic explanations for distributed cognitive systems. We recently came across the philosophical literature on what mechanisms are and how to make them, and it seemed immediately clear that we should be doing this (and that we already are; see below). 

It turns out, though, that some of the radical camp (specifically Chemero and Silberstein) don't think we can have distributed cognition mechanisms, but that this is ok because we still get explanations out of our dynamical models. 

This post will briefly review what dynamic mechanistic explanation is and why they are so useful (Bechtel & Abrahamsen, 2010). I'll briefly summarise the radical opposition to mechanisms, point out their answer doesn't work, then talk an example that shows we can have radical dynamic mechanistic explanatory models without giving anything up. The trick, as ever, will be to rely heavily on information as the component part that allows cognitive mechanisms to extend out over body and environment. 

Radical Embodied Cognitive Neuroscience - A Frontiers Research Topic

UPDATE: This topic is now live! We welcome all and any submissions that fit the remit. Please email Andrew if you are interested and I will add you to the contributors list, or you can also simply contribute via the Frontiers page. 

A couple of years ago, Sabrina and I were chatting about the brain and running into the problem that we just don't know enough about how it works. We realised that what we needed to do was host a conference, invite some useful people, and pick their brains for a few days. 

We've had two goes at funding such a conference; we've had a lot of interest from the academics we've contacted but no luck convincing anyone to give us any money. Over the process, however, we got Tony Chemero (author of Radical Embodied Cognitive Science) involved, and he recommended Louise Barrett to us (that's how we came across her excellent book). The four of us have been scheming for a while to try and make this a reality, and two things have developed.

First, we are going to host a workshop on Radical Embodied Cognitive Neuroscience, hopefully at the Lorentz Centre in the Netherlands. Before that can really be worth doing, however, we've realised we need a little more momentum, so we've advanced our plans and are about to announce a Research Topic at Frontiers in Psychology. We'd like to invite all interested parties to play.

The goal is simple: we want this to be a virtual conference, in effect, where people pose problems and offer solutions to the problem of developing a radical (non-representational) embodied cognitive neuroscience. We want real collaborations to come out of this, so we want people coming looking for ways to help and be helped. And we want to create a resource that we can point to to shape discussions at future workshops. 

What we need from you
I've pasted the text of the call we will run below. If you are interested in submitting something to  this, send us your name, affiliation and email address (either in the comments below or email us, psychscientists@gmail.com). At this point, this commits you to nothing; we just need a decent length list of people to initially invite to submit, to indicate that there is going to be enough interest. If you change your mind later there's no problem.

Any thoughts on the call, let us know. We all like that this call is short, direct and to the point; too many of these research topic calls are inflated by too much detail. But if there's any flags, let us and know.

If you can help us by promoting  this post on social media, that would also be excellent. We are looking to cast a wide net.

Evolution vs.Specification (Specification V)

One of Gibson's key contributions was to reveal that it was possible for the optic array to specify a meaningful property of the world. Gibson insisted that specification existed between the world and optics (each property produced one unambiguous pattern, and thus the mapping is 1:1). Specification, said Gibson, meant direct perception was possible, because picking up that one variable meant perceiving the one property that caused it. 

Turvey, Shaw, Reed & Mace (1981) formalised this idea by describing how ecological laws governed which properties of the world could be specified and identifying that these laws allowed affordances into this set. Turvey et al (hence TSM, because Reed changed his mind later on) then insisted that, in order for perception to be direct, specification also had to exist between the optics and the perceiver; an organism should only use one variable per property, and thus the mapping from world to perceiver is 1:1:1. This is a very high bar, and was put in place to defend ecological psychology from the Establishment attack (Fodor & Pylyshyn, 1981).

Withagen & Chemero (2009) think that the 1:1:1 account is incompatible with evolutionary thinking, and they aren't hot on the 1:1 account either. Specifically, they think that any given species will show individual variation in it's members ability to use information, and that in many cases species will end up using sub-optimal solutions (two important elements of evolutionary thinking). The1:1:1 bar, they say, is implausibly high and a naturalised theory of perception (one that is compatible with evolution) will instead predict the common use of non-specifying information. They also claim that this does not stop perception from being direct, so long as you allow 'directness' to live along a continuum.

I think there are some important issues here, but I think this paper's presentation is problematic. It contains no analysis of any particular information or task, and instead is full of sentences such as 'it seems more plausible to us that' and 'it is possible that'. This comes off as the kind of woolly evolutionary thinking psychology is rightly scolded for. Gibson and TSM spent a lot of time trying to make us pay less attention to what might be and more to what is.My concerns are mostly along these lines, and once I get them off my chest I want to turn in future posts to some ideas for a research programme to pursue this all in more detail.

How Information Gets Its Meaning (Specification II)

Gibson proposed that specification was required in order for perceptual information to have meaning that was tied to the world in a manner an organism could use. The concept of specification has been placed back under the microscope by recent theoretical and empirical work. Here I want to briefly summarise the theoretical argument put forth by Withagen & van der Kamp (2010), who worry that specification places too strong a constraint on what a perceiving-acting organism might find informative. They suggest that (visual) perception can still be direct with non-specifying patterns, if you stop thinking information is in the relation between the environment and the optic array but rather, in the relation between the optic array and the organism. They propose this because recent empirical work suggests that organisms can happily get around using non-specifying variables; they want to keep directness, however and they don't think Chemero's solution to the problem does the trick. I'll review the studies they cite over the next few posts; first, let's lay out the solutions they propose.

Again, I want to emphasise that this is very much a work in progress for me. I'm using these posts to come to grips with the arguments, and I don't yet endorse any of these various critiques. My goal is simply to have a clear understanding of what everyone says, so that we can evaluate those claims later on when I review some data.

Specification: What It Is, and Why We Need It (Specification I)

The first thing I need to do in a discussion of specification is explain what it is and why it's important to ecological psychology. I've tried to maintain a clear logical progression in this post, building towards the need for specification. In my next post, I'll take a first swing at explaining what specification gives us, namely a reason why information means one thing and not another.

The issue of specification comes from Gibson's (1966, 1979) analysis of visual perception, so that's where I'll start too. Most descriptions of visual perception begin with the anatomy of the eye; people note that the eye resembles a camera, and that the lens seems to focus a messy, upside down image onto the retina. The retina then pixelates that image into neural activity, and this pixelated structure then shows up in primary visual cortex (this is topographic mapping). If vision does indeed begin this way, then a huge amount of work seems to be required to take this impoverished stimulus and use it as the basis for the rich, 3D visual world we experience.

Gibson's ecological theory begins with a re-evaluation of the stimulus for vision. The first three chapters of the 1979 book are about the world and what it contains, while chapter 4 is about how this world can interact with light to produce information. Only once he lays out the information available to the organism does he begin to talk about the act of perception itself; this re-evaluation of the 'job description' for a visual system is one of his most important contributions to psychology. Gibson's reanalysis leads him to conclude that action relevant properties of the world (specifically, affordances) can be specified in the optic array, and this concept underpins the directness of his theory of perception.

The issue of specification is assumed to be critical for the success of a direct theory of perception. The traditional views propose a 'many-to-one' mapping; a given pattern of stimulation on the retina is ambiguous because it could be caused by many possible states in the world. Specification is the hypothesis that there is a 'one-to-one' mapping - a given pattern in the optic array comes from one and only one state of the world. This can happen, according to Turvey, Shaw, Reed & Mace (1981) if (and only if) the creation of information about the world is a lawful process. If the projection of world into optics is underwritten by a law and thus one-to-one, then detecting the optical pattern is equivalent to detecting the property of the world: detecting the information is perceiving the world, with no additional processing work required. Perception can be direct.

A theory of direct perception will require several elements: there must be invariant structure within the endless flow across the retina that relates 1:1 to some property of the world. To be invariant, this structure must be relational, and therefore higher order. If perception is to be direct, these higher-order invariants must be detectable as a piece, and not built out of their elements in some post-perceptual process. Only if you have all this do you have the possibility of a one-to-one mapping between the world and vision, i.e. the possibility of specification.This post lays out what this all means, and  how these pieces come together in ecological psychology.

Specification & Its Discontents

A topic that has been flying under the radar a little in Sabrina's language posts is the issue of specification. Sabrina's ecological analysis of language discusses information and what it means, but is not committed to the kind of law based account that is typically invoked in the perception-action literature. It can't - language can be used to talk about things in their absence, and it's not clear what kind of ecological laws might govern the connection between the speech event and it's meaning. Breaking specification has consequences, however, and has been a topic of some debate lately; the next few posts from me will be an in-depth look at the theoretical and empirical contributions to the debate as I try to come to terms with the idea and whether it can still support a direct theory of perception.

Affordances, Part 2: Affordances are relations between organism and environment

The idea that affordances are dispositional properties of the environment is not immediately obvious, given the way everyone talks about them. This was certainly the source of my confusion - affordances are always described as animal-relative properties of the environment, and in the classic Warren stair-climbing affordance studies Bill Warren pioneered the use of pi numbers to describe affordances. Pi numbers are a handy trick from engineering, where you characterise a relation using a ratio. This has the advantage of a) eliminating the units so you can then rescale the number in any system you like, and b) highlighting that the relation between two things remains common even when the specific details change. Warren found that judgements of climbability varied not with leg length or riser height but with the ratio. Affordances are therefore almost always discussed this way - as being about the relation between an organism and its environment. Ecological psychology eschews internal representation and computation, so this relation must be directly perceived, i.e. they must be affordances.