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.

Some Ground Rules for a Theory of Psychology

Add psychology to the list

A fairly common response to our theory post was 'here's my theory, which is designed to replace and fix all the others'. However, it's more a symptom of the problem I was discussing than a solution for everyone to have their own entirely separate theory which doesn't talk to any other work in the field (see above). One of my personal goals in science is to not be that guy. I want to see cognitive science become more integrated, not more fragmented. We have also been asked, however, and quite sensibly, what we think the solution to our problem is. The question then is how to propose a theoretical approach for psychology and cognitive science where we don't just reinvent the wheel.

Sabrina and I have been working on this for, well, the entire blog. It has been a place for our "brave attempt to think out loud about theories of psychology until we get some" since day one; we've been identifying problems but, just as importantly, solutions the whole time. The theory post identified the big picture problem we see in psychology; time to lay out some solutions.

Step one is to present a map of the blog, organised thematically to guide new readers to work we've already done here. This should also help map out the gaps in the approach, so we can focus on things to do next; feel free to point us to problems we can't yet address! (And yes, we know about episodic memory and language - we're working on it.) This post is not a comprehensive summary of past work - it's a map for you to use to find what we've done so far.

To summarise: in essence, and some minor details aside, we are advocating for Chemero's (2009) radical embodied cognitive science, with the addition of some elements he was missing (network science & task specific devices). Cognition is embodied, extended and held together by the direct perception of affordances and events; the result is a complex, nonlinear dynamical system that must be analysed as such. The brain is not the sole source of our behaviour, nor is it representing the world; it clearly plays a critical role in this system, though, and we propose that we'll need the tools of network science to describe what it's actually up to (Sporns, 2010). Methodologically, we must carefully characterise the task, the resources available to solve the task (which include brain, body and environment) and the information these resources create which can sustain the formation and control of an embodied solution. This method is Bingham's (1988) task specific device approach (the main piece Chemero was missing, I think).This approach applies to all and any behaviour you want to explain, including the hard stuff like episodic memory and language.

Critically, this approach, while new (and uncommon in insisting on a role for Gibson's ecological approach) isn't just something we invented: all these elements are active parts of modern cognitive science. The only new part is bringing it all under one roof, with the goal of getting on and getting some decent normal science under our belts.

Here's what we've covered so far. If you want more details on any point, click on the links!

Chemero (2009) Chapter 7: Affordances, etc (Pt 2)

Last time I went over affordances-as-dispositions, and Chemero's first swing at affordances-as-relations. Affordances can't be dispositions, claims Chemero, because

1. Dispositions manifest when the conditions are met; this is compulsory. But I am not currently trying to effect all the affordances in my vicinity, so they can't be dispositions. Relations are functions, and thus support malfunctions.
2. Dispositions require complements - for perception-action, the complement of an affordance is an effectivity. But what exactly is this? Body scale (e.g. leg length)? Actually, it's more likely in terms of ability (per some unpublished experiments Chemero has run); people's judgements of stair climbability are a relation between the riser height and the person's ability to step that high.
3. If affordances are properties that are directly perceived, then when two people perceive the same affordance their minds will overlap: the problem of two minds. Relations solve this problem by making the overall relation which the directly perceived affordance is part of unique to each observer.

This would be all well and good, except that 

1. Affordances and effectivities are complex dispositions, and the conditions for being realised can be a long list. In addition, I can only be one kind of effecting device at a time, so when seated I am literally not capable of complementing the climbing affordances of my stairs at that moment in time.
2. Noting that 'body scale' is an imperfect proxy for an effectivity, and then claiming that this means nothing is an effectivity makes no sense. In addition, 'abilities' are equally approximate. The issue (being careful what you claim is the actual complement of the affordance) is valid but applies equally to dispositions or relations.
3. The solution to the problem of two minds that Heft outlined and Chemero thinks supports his case lies in making the act of perception relational, not the thing perceived. The affordance does not, itself, need to be a relation.

So far, nothing has convinced me that affordances need to be relational. But to round the story out, I want to finish the chapter and address the final tweak Chemero adds: Affordances 2.0.

Chemero (2009) Chapter 7: Affordances, etc (Pt 1)

If you want perception to be direct (no 'mental gymnastics') you must identify where the content of perceptual experience comes from; when I view a chair, for example, I don't see a meaningless or random collection of surfaces or colours, I see an object that I can interact with in some ways and not others. For traditional, indirect theories of perception, this meaning is constructed internally: mental representations perform transformations (perhaps computational ones) on sensory input to infer what the input means. A theory of direct perception requires that meaning is not added to the signal; this 'enrichment' is not permitted. To solve this problem, Gibson proposed that the world, for a perceiving-acting organism, is not comprised of meaningless bits of physics and chemistry. Instead, he proposed that the world presents itself to this organism in terms of affordances, which are intrinsically meaningful for the organism and are about the possibility of behaviour.

So a theory of direct perception requires an ontology, a theory about the make-up of the world  that means it is intrinsically meaningful. Chemero wants RECS to include direct perception, therefore he needs such an ontology. He is happy with affordances; he is not, however, satisfied with the Turvey-Shaw-Mace approach which defines affordances as dispositions. This chapter will defend an extended version of his theory of affordances as relations: Affordances 2.0.

Affordances have cropped up here, er, a couple of times already - namely here, here, here, and most recently and enthusiastically here, as well as some empirical discussions here and here. The idea that affordances, not physics, is the correct ontology for a theory of direct perception also came up here. To jump ahead, I disagree with Chemero about affordances. I don't think the disposition account is flawed in the way he thinks, and I don't think relations solve the problem anyway. While I obviously agree that an affordance-based ontology is the way to go, I am so far satisfied that the dispositional account is the best current analysis, and I think that trying to make affordances relational is to confuse the world with information about the world.

I'm going to take this chapter in two parts, because this post got long; affordances are complicated things. After this chapter, I think a pause for station identification may also be in order, just to lay a few things out in response to Chapters 6 and 7, the real meat of the book. But first, Affordances 1.0 vs Affordances 1.1.

F*cking affordances - how do they work?

Over on Bounds of Cognition, Ken has been doggedly pursuing what he thinks is a critical problem with the concept of affordances as described by Gibson (1979) and expanded on by Turvey, Shaw, Reed & Mace (1981; hence TSRM). I feel the need to spend some time consolidating my responses and some ideas in one place; every time I try to lay out why the problem is ill-posed or a potential route out, Ken just says I'm clouding or avoiding the issue or throwing out red herrings.

I actually think Ken has identified one very useful critique of the affordance concept: the lack of care with which we attach '-able' to words. But Ken isn't just making a methodological point; he thinks he's shown that affordances cannot structure light in a way that can specify the affordance, and that's the argument that needs to be tackled.

Saddle up: this is going to take some time, and I'm not going to solve everything. But to get a little ahead of myself, the answer to the problem is that it's complicated.

Poverty of Stimulus and Ecological Laws

A question about a term I’ve been using is a nice segue into an important moment in the history of the ecological approach.

Poverty of stimulus is a term that came from Chomsky, but the intuition has been underpinning theories of perception for as long as there have been theories of perception. The term describes a problem, in which the information required to achieve something is not present in the environment. In language, the argument runs

1. Certain patterns of correct language use can only be learned with exposure to negative evidence (i.e. evidence about what counts as incorrect)
2. Children learning languages only encounter positive evidence (i.e. evidence about what counts as correct)
3. Children do acquire the patterns in (1).