Introducing Elliott Thomas

Sabrina and I are proud to announce our most recent joint production: Elliott Thomas Wilson Golonka, born at 16:05 GMT on the 21st of December, 2011, at St James' Hospital in Leeds to the tune of 'Fairytale of New York' (seriously, you can't escape that song this time of year, even in operating theatres!). 8lb 13oz, all fingers and toes present and correct! Thanks to everyone at St James for their sterling work, and to the ongoing midwifery support courtesy of the UK's National Health Service. NHS, we love you lots!

Elliott will be be contributing his experiences as a developing perceiving acting embodied organism to the blog (and, most likely to another blog we'll set up to nerd out about our son). We look forward to his unique insights into the processes of perceptual learning and development, and to recreating some fun experiments in the comfort of our own home.

Merry Christmas and Happy Holidays to all our readers; 2011 has been a big year for us in lots of ways and while obviously the blog is going to slow down for the next while, we're looking forward to more fun in 2012.

Andrew, Sabrina & Elliott

Leaning to the left makes you believe odd things about embodied cognition

Embodied cognition is not what you think it is. But I do understand why people think differently; it's because of the depressingly endless stream of papers published in Psychological Science that claim to have found that body posture somehow influences the contents of some cognition about the world. The latest "exciting" new finding claims that estimates of magnitude (size, amount, etc) are affected by your posture. The paper is well summarised at the Guardian for those without access to the paper (UPDATE: I am also talking to Rolf Zwaan, lead author of this paper, in the comments section there.)

It's a terrible paper, so it's apparently time for another in what might have to become a more frequent series, In which I am a bit rude about a rubbish paper and worry about how to kill papers like it. At the end, I've also talked a little about the role science journalism plays in maintaining the momentum for papers like this, via their own version of the file drawer problem. I'd be interested in people's thoughts.

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!

This is not the paternity leave policy you were looking for

So, this is a bit off the scientific/psychological beaten path, but since we get a good amount of traffic from people in the UK it seemed worth mentioning...

Image via Hammonton Photography

You might be aware that the UK government recently did something awesome by giving employed fathers the right to take up to 26 weeks off work during the first year of their child's life. This was a massive step forward from the previous Ordinary Paternity Leave policy, which gave dads a whopping 2 weeks off work. In terms of government mandated pay, the scheme is pretty close to the maternity leave policy; dads receive the lesser of £128.73 a week, or 90% of average weekly pay. One difference, is that fathers can only begin their leave after the mother takes 20 weeks of her leave.

Many employers (universities among them) offer additional pay for maternity leave to employees within certain salary band (which is great- thanks!). But, (here's where things aren't so great), some employers don't feel that this extra pay should extend equally to paternity leave (warning - I don't have national data on this; my conclusion is based on the policies I've seen from a handful of institutions). For example, a maternity leave plan might offer extra pay to mothers until 26 or 31 weeks, while fathers who start their leave at 21 weeks would receive no extra pay (beyond the statutory rate mentioned above). This means that, in practice, maternity leave policies are more financially generous than paternity leave policies. Sharing leave between parents is often more financially detrimental to a family than having the mother take the entire leave.

How Universal Is The Mind?

If someone asked you to describe the psychological aspects of personhood, what would you say? Chances are, you'd describe things like thought, memory, problem-solving, reasoning, maybe emotion. In other words, you probably list the major headings of a cognitive psychology text-book. In cognitive psychology, we seem to take it for granted that these are, objectively, the primary components of "the mind" (even if you reject a mind/body dualism, you probably accept some notion that there are psychological processes similar to the ones listed above). I've posted previously about whether the distinction between cognitive and non-cognitive even makes sense. But, here, I want to think about the universality of the "mind" concept and its relationship to the modern view of cognition.

In fact, this conception of the mind is heavily influenced by a particular (Western) cultural background. Other cultures assign different characteristics and abilities to the psychological aspects of personhood. Wierzbicka (2005) delves into this problem in detail. She argues that speakers of a particular language make assumptions about what must be universal based on their own ability to imagine doing without a certain concept. Important cross-cultural differences in meaning become lost in translation. For instance, Piaget’s “The moral judgment of the child” was translated to English by substituting the French “juste” with the English “fair.” So, English readers think they are reading about the development of fairness in children, when this was not the author’s intention.

Translation is a deep problem, but it is often ignored in psychology. Generalisations about cognition must be made in some language, but, language is specific to particular cultures. Our choice of language, then, inevitably will bias how we talk about cognition across cultures.

“If we uncritically formulate some hypothetical universals in one particular natural language, for example, English, we run the risk of distorting them by imposing on them the perspective embedded in that particular language; and the same applies to our description of cultural differences” (Wierzbicka, 2005; p. 257).

So, back to the mind and our current view of cognition. Cross-linguistic research shows that, generally speaking, every culture has a folk model of a person consisting of visible and invisible (psychological)  aspects (Wierzbicka, 2005). While there is agreement that the visible part of the person refers to the body, there is considerable variation in how different cultures think about the invisible (psychological) part. In the West, and, specifically, in the English-speaking West, the psychological aspect of personhood is closely related to the concept of "the mind" and the modern view of cognition.But, how universal is this conception? How do speakers of other languages think about the psychological aspect of personhood?

In Korean, the concept "maum" replaces the concept "mind". "Maum" has no English counterpart, but is sometimes translated as "heart". Apparently, "maum" is the "seat of emotions, motivation, and "goodness" in a human being" (Wierzbicka, 2005; p. 271). Intellect and cognitive functions are captured by the Korean "meli" (head). But, "maum" is clearly the counterpart to "mind" in terms of the psychological part of the person. For example, there are tons of Korean books about "maum" and body in the same way that there are English texts on "mind" and body.

The Japanese have yet another concept for the invisible part of the person - "kokoro"."Kokoro" is a "seat of emotion, and also, a source of culturally valued attention to, and empathy with, other people" (Wierzbicka, 2005; p. 272). To illustrate the contrast between "kokoro" and "mind", Wierzbicka gives the following example: A Japanese television programme proclaims, "The 21st century should be the age of kokoro. Let's make a point of meeting with other people" (Hasada, 2000: 110). If an English speaker declared the 21st century to be "the age of the mind" then "meeting with other people" probably would not be a priority - thinking and knowing would be. In contrast to the Korean "maum", "kokoro" is not associated with will and motivation ("hara" meaning belly serves this purpose in Japanese). But, "hara" is not associated with the psychological component of the body, the way "kokoro" is. In other words, "maum" is all about motivation and "kokoro" is all about feelings and "mind" is all about thinking.

Interestingly, Russia, which kind of sits between East and West uses "dusa" as the counterpart to the psychological part of the person. "Dusa" is often translated as "soul", but also sometimes as "heart" or "mind." "Dusa" is associated with feelings, morality, and spirituality. The "dusa" is responsible for the ability to connect with other people. This meaning seems to lie somewhat more with the Eastern conception than with the highly cognitive concept of "mind."

In a larger sense, the fact that there seems to be a universal belief that people consist of visible and invisible aspects explains much of the appeal of cognitive psychology over behaviourism. Cognitive psychology allows us to invoke invisible, internal states as causes of behaviour, which fits nicely with the broad, cultural assumption that the mind causes us to act in certain ways.

To the extent that you agree that the modern conception of "cognition" is strongly related to the Western, English-speaking view of "the mind", it is worth asking what cognitive psychology would look like if it had developed in Japan or Russia. Would text-books have chapter headings on the ability to connect with other people (kokoro) or feelings or morality (dusa) instead of on decision-making and memory? This possibility highlights the potential arbitrariness of how we've carved up the psychological realm - what we take for objective reality is revealed to be shaped by culture and language.



Hasada, Rie (2000). An Exploratory Study of Expression of Emotions in Japanese: Towards a Semantic
Interpretation. Ph.D. thesis, Australian National University..

Wierzbicka, A. (2005). Empirical universals of language as a basis for the study of other human universals and as a tool for exploring cross-cultural differences. Ethos, 33(2), 256-291. 

Theory, and Why It's Time Psychology Got One

Psychology has a problem. We have no core theory to guide our research; no analogue to the theories of evolution or relativity. When particle physicists recently found that some neutrinos had apparently travelled faster than light, it never actually occurred to them that this is what had happened. On the basis of the extraordinarily well supported theory of relativity, everyone went 'huh, that's weird - I wonder what we did wrong?', and proceeded to use that theory to generate hypotheses they could then test. It would take a lot of fast neutrinos to disprove relativity.

Psychology, though, when faced with an empirical result that violates the laws of physics, can't find any principled reason to reject the result and instead spends a lot of time squabbling about whether Bem's result might possibly be true because 'quantum'. Worse, when people do replicate the experiment and fail to support the original result, they can't get their 'null result' published. It's a bit embarrassing, really.

One of the problems of having no core theory is that you can't simply rule things out as options. Psychologists almost all consider this a strength: we can pick and choose from a variety of mechanisms which enables us to cope with our messy and erratic subject matter. Can't imagine how perception can explain a result? Just hypothesise a mental representation to fill the gap. After all, no single theory is going to account for the opportunistic and idiosyncratic behaviour of people, so why limit ourselves? We tried that with behaviourism, and it got us nowhere. Let's stay flexible.

Embodied cognition is not what you think it is

The most exciting thing in cognitive science right now is the theory that cognition is embodied. It is, in fact one of the things interested lay people know about cognitive science, thanks in part to a lot of high profile experiments that claim to show how cognition can be influenced and biased by states of the body, or that cognitive states can affect states of the body in ways that suggest abstract metaphors and concepts are grounded in the behaviour of the body. A recent blog post at Scientific American covers this ground quite nicely (although the large picture of Noam "not an embodied cognitive scientist" Chomsky hints that someone didn't actually read the piece).

The problem, however, is that this is not really what embodied cognition is about. Embodiment is not the weak claim that you can see small effects of the behaviour of the body in our mental representations of the world. Embodiment is the radical hypothesis that the brain is not the sole resource we have available to us to solve problems. Our bodies, and the meaning-filled perception of the world they allow, do much of the work required to achieve our goals, and this simple fact changes utterly what our theories of 'cognition' will look like.

Robots, Representation, & Dynamical Systems

When cognitive science tries to explain a given behaviour, it typically looks in one of two places for it's explanation. Some people go looking in the brain for the representation that encodes the solution to the task; these people typically treat the brain as the source of the observed structure in behaviour. Some of us, however, go looking in perception for the necessary access to the properties of the world that enable us to couple our resources to those in the environment. We consider the origin of behaviour to be the dynamical system formed by this coupling; the system provides a set of constraints and behaviour emerges as the constrained system works over time.

It's sometimes a little hard to tease these suggestions apart: after all, they  typically both predict that we succeed at the task at hand. When studying people, the best way to try and separate these two suggestions out is to examine how we succeed. For instance, in catching a fly ball, the brain-based prediction solution says we will run in a direct line to where we think the ball will land; the perception-based coupling solution suggests we will run along curved paths as we attempt to move so as to produce the information required. In this case, data supports the latter hypothesis, but it's not always that easy.

Sometimes, you've just got to start from scratch and build yourself a robot.

The Affordances of Everyday Things

I ramble on about affordances quite a bit; a big chunk of those posts was dedicated to figuring out whether they are relations or dispositions (answer: they're dispositions), and then there was all that arguing with Ken Aizawa about whether they are even anything at all (answer: yes, they are).

The thing I've been a little worried about is that people might see all this and come away thinking, "Why should I care one way or another?". I wanted to spend a post reminding everyone why all this talk about affordances matters, and the reason is simply this: affordances are important because they influence our behaviour, for good and ill, all day, every day. I'd like to illustrate this with a story, and a few photos I've been accumulating recently.

Review: Louise Barrett's "Beyond the Brain"

There are a lot of books about embodied cognition. Like psychology itself, the idea that cognition might not all be in the head has fractured off into about 5 distinct flavours, most of them quite annoying and pointless.There are also quite a few books about the thesis of the 'extended mind' (Clark & Chalmers, 1998) ; the idea that cognition quite literally extends into our bodies and environments, in terms of the tools we use and the objects we interact with. It's getting quite hard to find a book on these topics that isn't a) simply rehashing old ground or b) trying to come up with it's own distinct flavour of embodied, extended cognition that fixes some problem of everyone else's. I find this sort of fracturing and endless bickering quite distracting and troublesome, for reasons best expressed by xkcd. I also agree with Tony Chemero, that much of this work is still, sometimes deep down, representational. I think this is because they fail to embrace a sufficiently useful theory of information, such as that proposed by Gibson. So I often find myself reading these books finding nothing new and far too much that's depressing.

Louise Barrett's book, "Beyond the Brain: How Body and Environment Shape Animal and Human Minds" is, refreshingly, not like this at all. Barrett is a psychologist who studies animal cognition and behaviour, and her book does a lot of things very, very well. I'm not planning on a chapter by chapter book club on this, although I may at some point; Eric Charles has posted a few thoughts on the book as well, here, here, here, and here. To cut to the chase: if you are new to the area of embodied cognition, read this book. If you're familiar with the literature but want a clear, well-structured presentation of many of the key ideas, then read this book. If you're bored with the same old examples and want some new, perhaps more convincing examples of embodied cognition in action, read this book. And if you have heard some of the arguments but still think behaviour really comes from the computational activity of our complex brains, then, for the love of science, read this book.

Prospective Control I: The Outfielder Problem

A couple of posts ago I raised the distinction between prediction and prospective control. I was trying to make the point that, if you are coupled to the right information, you don't need to be mentally simulating what's happening so you can run this simulation ahead and predict what's coming up. Prediction of this sort is invoked by representational cognitive scientists to cope with things like delays in the nervous system (e.g. Changizi's 'perceiving-the-present' framework). It's a risky business (if you make a mistake, you are suddenly controlling your behaviour according to an incorrect guess), and the better solution is prospective control. This is when you couple your behaviour to information in the world that doesn't tell you about the future, but that, if you use it for a while, will get you where you want to go.

People requested some more on this topic, and so here we go. People also requested something other than the outfielder problem, but I am going to start with this problem because it is still the best example, and I'll get into some more as we go to demonstrate it's not just baseball where this works.

Introduce yourselves, dear readers

Dear readers:

We keep finding out that all kinds of people are reading our blog, when you email us, or when we say 'hey, you should totally read our blog' and you say 'I already do!'. Lots of you don't comment much, though, so we never find out who you are and we're actually quite interested.

So if you read us, take a moment to leave us a comment below. Introduce yourselves, tell us a little bit about what you do and why you're reading us, and, if you blog and whatnot yourself, feel free to leave links for people to find your stuff too.

Also, please feel free to comment on things if you want to; we both see comments on any posts, even the old ones, and we like the attention! Plus we've had some great conversations with some of you who do comment, and begun all kinds of collaborations and things, and one thing we want from the blog is to open some lines of communication on our flavour of psychology that doesn't get a lot of traction in other, more mainstream blogs.

Andrew & Sabrina

Embodied solutions to neural delays: Information and Network Motifs

One of the bugbears of direct perception is the fact of neural delays. The transmission of signals through the nervous system takes time, and this means that there is a lag between something happening (at, say, the retina) and that event having consequences in cortex, let alone behaviour. In control theory terms, delays in a system can lead to instability in that system's behaviour as you are forced to make corrections that are then incorrect and must themselves be corrected.

It's typically suggested in psychology that these delays are compensated for via computational predictions; the nervous system 'perceives the present' by taking the lagged input and using it as the basis of a guess about what's going on now (e.g. Changizi et al, 2008, plus see this post from a while back). This is a problematic idea: if the perceptual control of actions is based on a guess compensating for a variable time lag, then the stability issue remains, not to mention the consequences for mis-predicting the future. Regardless, it's not really an option for a theory of direct perception, and I want to discuss a couple of options.

Coordination dynamics and relative speed

The Bingham model of coordinated rhythmic movement makes three predictions. First, it predicts that movement stability is a function of perceptual ability, and we confirmed this in two ways (by showing how people can move stably at non-0° with transformed visual feedback (Wilson et al, 2005) and by showing that perceptual learning of 90° led to improved movement stability without practice at the movement task; Wilson et al, 2010). This prediction is also supported by recent work by Kovacs and Shea, who are busy demonstrating that transformed, Lissajous feedback breaks the classic pattern of movement stability in coordination tasks. The second prediction is that relative phase is specified by the relative direction of motion; we confirmed this by selectively perturbing various components of motion and showing selective effects on performance (Wilson & Bingham, 2008). 

The third prediction was that the detection of relative direction was conditioned on the relative speed; the latter was simply a noise term. de Rugy, Oullier & Temprado (2008) tested this prediction by using an amplitude manipulation to alter the relative speeds. Their data did not support the model predictions, and they concluded that the approach taken by the Bingham model was flawed. We recently replicated their experiment (Snapp-Childs, Wilson & Bingham, in press as of Friday; download) and identified numerous critical flaws in their design and analysis which invalidated their criticism.

Help me write a good lay summary of my coordination research

I'm writing a grant proposal, and part of the process involves a 4000 character lay summary of the project; what I'm up to, what the objectives are and who the likely beneficiaries are. The goal is for this to be in language a non-expert can understand (Research Councils use these summaries when they promote funded grants to the wider public). I am, frankly, cursed with too much knowledge, and pitching these lay summaries is always a challenge. What I would like is for people, especially non-experts, to have a look at the text below and give me feedback - are there sections that aren't popping? Sentences that aren't clear? Entire sections that seem a bit mysterious?

Please feel free to leave comments pointing out things that aren't working (and things that are, too, actually: it's good for me to get a feeling for what I'm doing right here). If you felt like spreading this around via Twitter, G+, whatever your fancy, I'd appreciate all and any feedback on this!

There's More Than One Way to Rhythmically Move a Lobster

I'm slowly working my way through Olaf Sporn's excellent book, Networks of the Mind. The purpose of this book is to introduce neuroscientists to network theory, and vice versa; I'm eavesdropping and tooling up on both. It's slow going only because it's pretty much all new territory to me, but I'm seeing a lot of potential in the overall approach to the brain, and this just confirms for me that Sporns understands what he does pretty deeply. 

Anyway, a while back, Bruce Hood tweeted the following:

Fact: in the digestive tract of the lobster, its nervous system can have 100k-200k different neural states that produce the same behavior

This struck me as an astonishing fact; to my mind, it throws the idea that hunting for the neural correlates of behaviour into serious doubt. At the very least, it needs to radically change what you expect to find. I finally found the reference for this fact in Sporns' book (Prinz, Bucher & Marder, 2004; download), and Sporns has some interesting context for this fact (which Hood undersells - see below) and why it's interesting, rather than soul-crushingly depressing. There are some interesting potential consequences relevant to my current ponderings on the brain, although it's definitely still at the 'these sound like the same sort of principle' level of analysis. 

Mirrors are Literally Windows to Another World

The other day, psychologist Tom Hartley tweeted "Your reflection is always half the size of the real thing - no matter how far from mirror. Hard to believe but true." and linked to this post in which someone demonstrates this effect. I had never quite thought about it, but realised it was of course always true: the mirror is at half the distance specified in the reflection. Then I read this post linked from the original, which reviewed an article by Lawson et al (2007) describing how people misjudge the size of objects on mirrors - specifically, they think the projection is larger than it actually is. This got me thinking about some work by Gibson on slant perception (Gibson, 1950) and then I realised that this really is an interesting topic. So I'm taking a break from the brain this week to blog about some optics instead.

What's the difference between perception and conception?

As Andrew has been tackling a new job description for the brain (part 1 and part 2), several comments have been made that suggest that his approach (and the ecological stance in general) might be fine for perception/action, but not for other types of tasks/behaviours. Later on in this post I also think about how we might be able to distinguish between association and direct access to meaning, which is another idea that has been coming up repeatedly in the comments (see here).

In this post I want to think about what makes perception different from conception (Andrew reviews William James' views on this distinction here). I will argue that both occur as networks of evolving neural activity (with perception, this network extends to the environment and the body), but these networks have different properties because they are driven by signals of differential stability. I do not think it is accurate to think of perception as something that happens in V1, for example, and conception as something that happens in SFG. If parts of the brain reverberate in a system along with parts of the brain that are directly interfacing with an energy array in the environment, it seems correct to refer to that whole system as perception. In contrast, if a network of activity appears to be relatively encapsulated with respect to external energy arrays, it seems correct to refer to that system as an act of conception. For now I will leave aside the problem of how conceptual networks develop, but I hope to return to this later.

Mirror Neurons, or, What's the Matter with Neuroscience?

One of the problems I face as I try to figure out what the brain is up to, if not representing, is that I can't rely on the neuroscience literature to back me up. The problem is that, while there has been a lot of data collected over the years, very little of it has been collected within an ecological framework. Neuroscientists are looking for how the brain represents information, not how it perceives it; they're looking to see where perception and action are integrated in the brain, not how the brain-body-environment system produces stable, functional behaviour. This matters because there's no such thing as theory-free observations - all data comes from this experiment rather than that experiment, and even simply reporting a result is laden with theoretical assumptions, even when these aren't explicitly identified. So until I can find a neuroscientist interested in collecting a little data (and I would love to hear from any such person!) I'm limited to laying out the consequences of taking the ecological route and critiquing what's out there already. 

The worst offenders, in terms of theory-laden data disguised as 'merely the observed facts', are mirror neurons. They are, I think, the text book example of what's the matter with neuroscience, and I thought it was about time to talk about them a little. For those interested, the most recent exposition of what mirror neurons are and do can be found in a recent (and currently open access) issue of Perspectives on Psychological Science: there's a brief introduction (Glenberg, 2011a), a detailed Q&A paper (Gallese et al, 2011) by five main figures in the field, and a summary (Glenberg, 2011b).(Update: recent meta analysis finds mirror type activity all over the brain, including the cerebellum!)

What Does The Brain Do, Pt 2: The Fast Response System

I want to continue thinking about the implications of the claim that the brain does not trade in representations. I'm not looking to defend this view here; we got into it a bit last time, I've talked about it here, and if you can't imagine what cognition without representation might look like, then you should read this post by Sabrina and then Radical Embodied Cognitive Science before worrying me with your lack of imagination. If you then feel like getting into it, Sabrina is tackling this topic in detail, beginning here.

If the brain isn't mentally representing, what is it doing? Last time, I got into the idea that the brain is part of a embodied cognitive system. It's in the middle of a rich information flow, with access to perceptual information about the world and ourselves, and it's a critical part of the action system, involved in our responses to that information. I talked about it as the fast response system in the set of inherent dynamical resources available for us to use to form task specific devices; I want to expand on that a little.

A selection of problems with representation

As Andrew alluded to in the comments to his last post, I'm cooking up some replies to various questions that have been raised. Being relatively time poor at the moment, I'm going to take these in small bits, rather than attempt a more comprehensive reply. The first thing I want to do is consider a few of the major issues, as I see them, with the notion of representations. As a cognitive psychologist, I spent many years endorsing a representational framework, but over time I have encountered enough problems/limitations with this approach that I consider the idea of representations to be seriously flawed. As a result, I've spent the past couple of years figuring out how to do cognitive psychology without them (but that's another post). What I want to do here are go through some of the things that have convinced me to abandon representations.

1) We don't know what we're talking about when we talk about representations

This criticism goes beyond the fact that there are multiple, competing definitions of representation. It goes beyond the fact that most cognitive psychologists are never asked to seriously wrestle with their own definition of representation, to consider its historical origins, or to consider whether there are alternative approaches to cognition. This criticism is more basic and is summed up nicely by Larry Barsalou: "We have no accounts of how propositional representations arise in the cognitive system, either innately or through experience. We haven't the faintest idea of how biological mechanisms could produce abstract propositions" (Barsalou, 1993, p. 173). Regarding this quote, Linda Smith says "When we cannot imagine how our basic ideas about cognition can possibly be realized, we ought to consider the possibility that they are wrong" (Smith & Jones, 1993, p. 181).

There's More to Us Than Our Brains - So What Does The Brain Do?

I'm not that interested in the brain.

It's hard to be this way in modern psychology. Cognitive neuroscience is where it's at, and I think I come off as  a bit of a Luddite when I try to convince people fMRI is a bit of a waste of time. Not caring much about the brain is certainly a sociological reason why ecological psychology doesn't get taken very seriously; we're just the crazy people who don't think there are mental representations, based on some work from the 50s-70s. Surely modern imaging has shown us the activity of mental representations? Clearly, the brain is the source of all behavior! Popular science writing on psychology is all cognitive and representational; most of the psychology blogging I come across is neuroscientific. What else could it be?

I've certainly spent a lot of time waving the flag against the infiltration of neuro-talk into places it doesn't yet belong; but to be honest, as I get older, I've begun to worry that I'm trying to be 'fair and balanced' in the sense Fox News is fair and balanced: relentlessly playing up one side to offset a perceived imbalance elsewhere. What I actually want to do is be actually fair and balanced: I want my own discussions about these issues to be internally balanced and coherent, giving credit where credit is actually due. I want to start teasing apart a few issues I've conflated over the years, so that my strong concerns about the relevance of fMRI  and cognitive neuroscience work stop getting swallowed up in a general dismissal of the brain's role in our lives. The brain is clearly interesting, but it's not representing, and if not that, what is it doing?

This post is therefore a first swing at integrating a lot of the things I've been blogging about for a while and doing so in a way that leaves a sensible role for the brain. I'm going to need some neuroscientists to talk to, though; I'd appreciate it if people could spread the word on this a little, because there are just some things I want to go a few rounds on with people who know what they're talking about. 

Lissajous feedback and coordination stability

Understanding the perceptual information you provide people in a task is a critical element of the perception-action analysis. Last time I talked about the new form of coordination feedback I developed to allow us to train coordinated rhythmic movements without perturbing the task dynamic. Prior to this, the most common form of augmented feedback was the Lissajous plot - these are the result of plotting the displacements of two harmonic oscillators against one another, and the unique shape associated with each relative phase can be used as a template on the screen. People can then try to move so as to make a dot trace that shape.

Lissajous plots (have a play with them in this Excel file) are transformed feedback, because they take a coordinated movement and represent it on the screen as the motion of a single dot. This type of feedback has been used extensively to train people to perform novel coordinations, but until recently no-one had thought to investigate the consequences of transforming the information about relative phase. Kovacs, Buchanan and Shea have recently begun doing exactly this, and, in line with the perception-action approach developed by Bingham and pushed at every opportunity by myself, these authors have found that Lissajous plots completely alter the nature of the task, with serious consequences for the studies that rely on it.

Visual feedback for training novel coordinations

The key feature of coordinated rhythmic movements is that not all coordinations are stable. Most other rhythms can be learned, however, which is why we can have jazz drumming. People have been training participants to perform novel coordinations (especially 90°, the least stable rhythm without training) for years now, and have been asking all the standard learning questions - how long does learning take? Does it transfer to other coordinations? 

The first real studies on learning were by Kelso and Zanone (Kelso & Zanone, 2002; Zanone & Kelso, 1992a, b, 1997). I briefly reviewed the results of these studies here, which have lead to to the dynamic pattern hypothesis. This account describes stable states as attractors in a state space defined by relative phase as the order parameter, and learning is the creation of a new attractor centred on the target novel phase. This account ran into problems quite quickly but is still alive and kicking in a modified form; stability is the governing principle now, and from this perspective the feedback displays used for training don't matter so long as they support stable action. 

However, from our perception-action standpoint, the feedback displays matter a lot, because these are what's providing the perceptual information about the coordinated movement. Early learning studies all used some kind of transformed feedback, which we could never use because it altered the overall perception-action dynamic. In order to look at action learning directly, we needed a new form of feedback. 

So I invented one.

Rates of learning and the dynamic pattern approach

One of the interesting features of coordinated rhythmic movement is that people start out with a particular pattern to their performance - there is pre-existing structure to our attempts to coordinate these movements. This structure affects our ability to learn new coordinations, and the pattern of the effects reveals a lot about the cause of this pre-existing structure. 

However, the literature is split into two incompatible accounts of learning, and trying to fix this is part of my ongoing interest in this task. The first account is the dynamic pattern approach, which was pioneered by JAS Kelso, and championed by modelling (Gregor Schöner) and behavioural studies (Pier Zanone). I'm more interested in the latter aspect, because it's the motivation for the former. I've already reviewed how this account fails, but it's still alive and well thanks to some creative history, and needs to be tackled again. The second account, which I prefer, is the perception-action account (Bingham) which developed from empirical work on visual and proprioceptive perception as well as action measures, and embodied in a model.

We haven't explicitly tackled the rate of learning issue, although we will and there is already support for our account in the literature (Wenderoth et al, 2002). But it comes up regularly in the dynamic pattern behavioural work, so it's time to work out what's going on in their data.

Chemero (2009) Chapter 9 - The Metaphysics of Radical Embodiment

The final chapter of RECS tackles the metaphysical implications of the radical stance. Gibson was a staunch realist, but there are some odd elements to entities like affordances that, to certain minds, sound like idealism or antirealism of some kind. Realism is, essentially, the claim that there is a world independent of our experience of it, and that we can have basically accurate knowledge of that external world. In modern times this reality has been equated with the description given by physics. Affordances don't belong to physics, however; whether relations or dispositions, they are, at heart, facts which span the organism and the environment. This sounds wrong to a lot of ears (as Ken's comments on that post readily show!). Chemero therefore devotes the final chapter to defending the claim that RECS can be realist; this matters, because people tend not to like idealism in their science these days, and it's going to be a standard philosophical objection to the RECS programme if not addressed.

Task Specific Devices and the Perceptual Bottleneck

I've been wanting to blog this paper, Bingham (1988; download link), for some time, and I've had the excuse to be reading it this week as I develop a grant. There's a lot here, and many of these brief points are worth posts in and of themselves. My goal here was to create a walk through of the paper, and I hope to dive into some of these issues in more detail.

This paper comes from Geoff Bingham, my PhD advisor at IU. And, like most of the good things Geoff has taught me over the years, this paper is a gift that keeps giving as I come to grips with what's in it. What it does is lay out a methodological problem (the massive redundancy and complexity of the human action system), proposes a solution (studying task-specific devices) and firmly embeds the idea that these devices are intrinsically perception-action devices (by discussing the so-called perceptual bottleneck). In effect, it lays out a way to be a productive scientist studying a hugely complex system without shying away from the complexity. This paper blew my fragile little mind when I first read it, and I'm still pulling good ideas from it today.

This paper is what I think the science of perception-action should look like. It's the piece I think Chemero (2009) is missing for his radical embodied cognitive science, and it contains (oddly without a lot of specific references) all the key ideas that have come up on this blog in a single coherent frame work (e.g. Gibson & specification; Turvey et al on the symmetry principle). Frankly, if you want to study perception-action systems from a dynamical systems perspective, this is what you have to acknowledge is the lay of the land and these are the beginnings of the tool kit you'll need.

Perceiving long distances in action scaled units

I have so many things I need to write up just now, but it's been a struggle finding the time. I hope to post on Chemero's last chapter, task-specific devices, calibration and some new coordination data soon. In the meantime, I thought I'd take advantage of the fact that I'm reading some new articles on an interesting topic, and I wanted to organise some thoughts and see if anyone had any comments!

Perception is action-scaled

Traditional theories of perception claim that we perceive the world in generic terms, and must transform that perception into a task relevant variable after picking the information up. The ecological suggestion is that the act of perception itself is directly scaled in action-relevant units, and that this perception will therefore be task-specific. In order to directly perceive action relevant properties (i.e. affordances) perception must be smart (think of the analogy of the polar planimeter).

We are capable of perceiving the distance of things in the world; but we don't perceive them as being '6m away'. Instead, the system is interested in how to reach for an object, so you need to calibrate your perception of distance in terms of, say, arm length units. Calibration is the process of placing a measurement on a scale, and the ecological approach has been interested in action relevant scales such as arm lengths (for reaching; Mon-Williams & Bingham, 2007) and leg lengths (for stair climbing; e.g. Warren, 1984). One of Chemero's points is relevant here; body scale is probably only a proxy measure for ability to perform the action and the real action scale the system is using (the effectivity) will be more complicated. But body scale is mostly where the field is at right now.

Chemero (2009) Chapter 8: Neurophilosophy Meets RECS

Chemero's book finishes with two chapters on some philosophical consequences of taking a radical, embodied approach to cognitive science. Chapter 8 is about the mind-body problem, and how various attempts to reduce cognitive science to, say, neuroscience, can be vigorously resisted via the RECS approach, without being dualist about the mind. There are many people who think cognitive science can be reduced to neuroscience (intertheoretic reduction), but one plank of any embodied approach is that this won't work. RECS is particularly committed to a more extended notion of cognition and so a strategy for resisting reduction is critical. Chemero's plan won't rely on the usual philosophical manoeuvres such as Martian pain mechanisms or zombies. Like me, Chemero is concerned that these create the impression that philosophers aren't tackling real problems; he wants the philosophical conclusions of RECS to be grounded in data, and I thoroughly endorse this approach.

Perception, Action & Dynamical Systems

Over Easter I visited the Center of Functionally Integrative Neuroscience at Aarhus University in Denmark, courtesy of the Interacting Minds group. I gave a talk, got the tour, and met some of the faculty and students - some interesting opportunities for future collaborations, I hope - thanks for the hospitality!

I wanted to lay out the basics of the talk I gave. I took the opportunity to present some ideas that have been developing as I work on this blog, reading Chemero and working on coordination experiments. There is a core of people in Aarhus interested in things ecological, as well as dynamical systems, so it was a good audience to try these ideas out and they seemed to go over well. This is also the sketch of a paper Sabrina and I are going to work on over the summer.

The take home message of the talk was simple - dynamical systems is the right kind of mindset for cognitive science, but it is not a theory of behaviour. Dynamics merely provides the right kind of modelling tools - the form of the model must be based on hypotheses about the specific kind of dynamical systems we are or else they are merely an exercise in data-fitting. Ecological psychology is the right theory, and the Bingham model of coordinated rhythmic movement is currently the only example of a genuinely perception-action dynamical systems model. My thoughts here are largely from my response to Chapter 4 of Chemero (on 'the dynamical stance') and Chapter 5, his initial attempt to use dynamics to serve as a guide to discovery which I think fails and which Chemero then replaces with ecological psychology. The description of Bingham's model comes from here.

Failing to Replicate Bem's Ability to Get Published in a Major Journal

I think Daryl Bem has done psychology an enormous favour. Possibly even two.

As you probably  know, Bem is the author of 'Feeling the future: Experimental evidence for anomalous retroactive influences on cognition and affect', a paper with claims to have found evidence for precognition by running standard psychological experiments in reverse and demonstrating small but statistically reliable effects on behaviour of stimuli which came after the response was made. I posted briefly about it here, and otherwise it's been all over all of the internet for months.

It's back on my radar because several psychologists, including Richard Wiseman, recently submitted a failure to replicate the studies to the Journal of Personality & Social Psychology (JPSP), which is where Bem published his work. As reported here, Eliot Smith, the editor, refused to even send this (and another, successful replication as well) out for review. The reason Smith gives is that JPSP is not in the business of publishing mere replications - it prioritises novel results, and he suggests the authors take their work to other (presumably lesser) journals. This is nothing new - flagship journals like JPSP all have policies in place like this. But it's not a good look, and it got me thinking.

Reading Group - Gibson (1979) Chapter 6 Part 2

So, it's been four months, but here's part 2 of Gibson '79 chapter six:

Gibson believes that events are specified in the optic array, just as stationary objects are. In this part of the chapter he describes three classes of events (changes of surface layout, changes of surface colour or texture, and changes in the existence of a surface). He goes on to discuss the types of optical disturbances that can specify these events.

Chemero (2009) - A Brief Pause to See Where I'm At

There are still a couple of chapters left for me to go over in Chemero, but the last two were the crux of the book for me, and I want to try and summarise where my analysis has left me before I go on holiday for Easter.

First, I'd like to separate out a couple of themes. First, there's the overall 'radical embodied cognitive science' programme, and second is the specific form of the 'shored up ecological psychology' that Chemero advocates as a basis for this programme. I am entirely on board with the basic idea of RECS; specifically, I think that cognition, whatever that is, is non-representational and that we can make great progress by making our science non-representational. I think Chemero has written a clear exposition of what such a radical science might look like, and why we might want to bother, and I think this makes RECS a must read for the field. 

Second, I think that Chemero is right to go to ecological psychology for a theoretical basis. The more I look, the more I have come to believe that James Gibson is about the only psychologist to have actually proposed a genuine scientific theory in psychology. A true theory provides you with tools to empirically attack novel problems in your domain, and provides you with a clear basis to interpret the results of your tests and to begin to tell a coherent story. Psychology has been chasing phenomena for most of it's scientific life, with no clear framework emerging to tell us a story about why things are the way they are. Ecological psychology is a genuine theory, and it's about a critical feature of our psychological lives: how we maintain contact with our world and move through it successfully. Regardless of what topic you're specifically interested in, you need to understand how we come to have knowledge about our environments.

Finally, though, I have problems with the proposals Chemero makes about the two pillars of an ecological psychology, affordances and information. It's these problems I want to try and sum up here, to focus the conversation a little.

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.

Chemero (2009) Chapter 6: Information and Direct Perception

In the previous chapter, Chemero laid out his first idea as to how a radical embodied cognitive science could be a science; he suggested taking a 'dynamical stance' in which researchers use simple dynamical systems models such as the HKB to drive empirical work. In this chapter, he moves towards his more recent suggestion, namely using Gibson's ecological psychology as a theoretical basis from which to make predictions and run experiments. This is a much more robust idea; sciences need theories or else they wander from phenomenon to phenomenon, which I believe to be a real issue in modern psychology and cognitive science.

Chemero has his own flavour of ecological psychology, however. He believes it stays true to Gibson's essential framework but expands it to cope with new and important issues. The two pillars of ecological psychology, information and affordances, remain. Chapter 6 is Chemero's expanded notion of information, while Chapter 7 is his updated theory of affordances as relations (which I've covered briefly before).

Chemero (2009), Chapter 5: Guides to Discovery

The dynamical stance laid out by Chemero in the previous chapter has a potential flaw (besides being a bit weak-ass) - it's not clear how it can serve as a guide to discovery. How do you do productive science taking this approach? Chemero is going to make two suggestions, only one of which I think works: first, he's going to suggest dynamical models such as the Haken-Kelso-Bunz (HKB) model can serve to stimulate empirical work even when they are entirely phenomenological. This approach is, I think, entirely incorrect, and this chapter is full of serious problems (only some of which are unique to Chemero). Second, he's going to suggest that Gibsonian ecological psychology can actually solve the problem much more robustly anyway, by serving as an underlying theory of behaviour. This will work better, and I would advocate Bingham's model of coordination as an exemplar of this, more promising route.

But first, the HKB model as guide to discovery (this chapter is largely the material from Chemero, 2000; I intend to turn this post into a paper to rebut that paper and point to the Bingham model as an alternative, so comments are especially welcome on this one). Time to get a little critical, I'm afraid.

Chemero (2009), Chapter 4: The Dynamical Stance

The problem with the theory of representation Chemero settles on in the previous chapter, as we shall see, is that it makes representation unavoidable. If there are representations, then RECS fails to get off the ground (remember, the radical bit is anti-representationalism). In this chapter, Chemero identifies a path past this problem (the 'dynamical stance'), explains why it works, but then concludes with a new problem, that of how to guide future discovery.

Chemero (2009), Chapter 3: Theories of Representation

The radical part of 'radical embodied cognitive science' is anti-representationalism. Simply put, the claim is that the brain does not internally represent states of the world in any way, nor are these the basis for our experience. It's radical because to a typical cognitive scientist, the mere suggestion is ludicrous: like suggesting you do biology without genes or particle physics without Large Hadron Colliders. But this indignation is hiding a dirty little secret: mental representations are generally just assumed to exist, because of assumptions about the poverty of stimulus we supposedly face. They are theoretical entities designed to solve a problem which, frankly, might not exist. There has been a lot of theoretical work on what it means to be a representation, but most of this has occurred in philosophy and most modern experimental cognitive psychologists don't ever engage with the issue. Sabrina has talked about this a bit already here and here and here and it's likely to keep cropping up.

Chemero's third chapter lays out some basics about what a theory of representation has to look like. If you're going to be anti-representational you need something to be against that isn't a straw man. This is unfortunately difficult because the concept of representation is a moving target: if I had a dollar for every conversation I've had that included the phrase 'Oh, that's not what I mean by representation' (even when it really is), I wouldn't need to submit the grant I should be working on just now. This chapter is therefore going to look for a 'minimal case' of representation that doesn't bug too many people but that isn't too easy a target.

Strap in, this chapter's busy.

Chemero (2009), Chapter 2: Embodied Cognition

Chemero spent Chapter 1 creating space for himself and his book in the marketplace of ideas about how we should do our cognitive science. Chapter 2 is about situating his theory in amongst the competition, with the goal of establishing exactly what a radical embodied cognitive science (RECS) is, and that it is a perfectly respectable competitor. He reviews a little history and an example study using dynamical systems that explains a  'representationally hungry' cognitive task to set things up. This is still quite preliminary work, but time well spent I think.

Chemero (2009), Chapter 1: Hegelian Arguments in Cognitive Science

The basic thesis of RECS is that cognitive science should give up on representations (the radical bit) and focus on explaining the embodiment of cognition in a complex, perceiving-acting dynamical system. Chemero spends Chapter 1 heading off the likely initial line of resistance to this thesis; namely, the argument that 'your thesis got ruled out in the 80s by [insert name here]'. Chemero labels arguments of this type 'Hegelian' and makes a case that a) they're mostly a sign of the immaturity of modern cognitive science, but most importantly b) they don't really need to convince anyone to stop trying to develop a radical, embodied cognitive science (and that the rest of the book is therefore still worth a read). I basically agree with this analysis; in fact, we started this blog to try and address the immaturity issue in (a) (in favour of some form of (b)). So we're off to a good start!

New Reading Group: Chemero (2009), Radical Embodied Cognitive Science

I thought it was time to pick up the next book I have on my list to go through here on the blog. This is Tony Chemero's book, Radical Embodied Cognitive Science (hence RECS). I've read through it once, and it inspired me to write on affordances here, here and here. My goal now is to take things a little more slowly and think about the detail.

Tony is a philosopher who's been actively engaged in things ecological for quite a while now. The goal of RECS is to lay out a) what radical embodied cognitive science is, b) propose a methodological stance in the form of dynamical systems, and then c) lay out how ecological psychology is the key theoretical structure that gives this approach it's methods for 'discovery', i.e. the ability to make predictions and do normal science. (Still curious? Check out the Wordle of the book!) Chemero's going to invoke what he describes as 'shored-up ecological psychology'; this refers to his ideas on the ontology of affordances and on information. I'm not currently all that convinced by the changes, but I'll leave the details until we get there. I'll try and entice Tony into stopping by, hopefully we can have a dialogue on some of this material (especially the later chapters on his 'shored up' version of Gibson).

I've been preparing posts on chapters for the last few months, actually, but I've waited to start posting so that I could be well ahead before I got going. This is going to let me tweak the posts with later information in mind, as well as post updates fairly regularly without crushing my schedule. I'm really enjoying this extended process, I'm coming to grips with what Tony is up to and it's been an excellent way to really study the book. My optimistic plan is to stay ahead like this, and move onto other books in the future.

I'll post on the first chapter as next Tuesday's update; I'd love it if people were reading along and commenting.

Reference

Chemero, A. (2009). Radical Embodied Cognitive Science. Cambridge, MA: MIT Press. Amazon.com, Amazon.co.uk, MIT Press e-book

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.

The Size-Weight Illusion is Functional, and It's About Throwing

My colleagues, Geoff Bingham and Qin Zhu, have recently published some fascinating data which has emerged from their work on the uniquely human skill, long-distance throwing. This is a novel and rich perception-action task which Bingham and Zhu (and recently, me) have been investigating for some time, with many interesting results. I'll get onto blogging about this project once I've caught up with the coordination studies and have had some time to get my head around the data I'm helping generate.

I wanted to blog about this new paper, though, because it's an exciting result which deserves all the attention it gets. The result is about the size-weight illusion, one of the most robust illusions around. As I've talked about before, illusions are a concern to ecological psychologists only in that they suggest the task has been incorrectly characterised. This paper presents data that suggests the size-weight illusion is actually functional, and that it reflects the readiness of the human perception-action system to throw objects long distances.

This paper has seen some activity in the popular press already (e.g. here and here): Geoff's hoping for the NYT Science section too! 

UPDATE: Geoff being interview on NPR

Identifying the Visual Information for Relative Phase

Bingham's model predicts that the information for relative phase is the relative direction of movement. The first direct test of this hypothesis was the experiment that followed on from my learning study, in which we systematically perturbed the various candidate information variables to see which affected performance in the perceptual judgement task.

I like this study a lot, if I do say so myself. It's a serious attempt to make a strong test of the model's predictions, and we invested a lot of time in the methodology. This is also that rare paper that benefited from a vigorous review process; the end result is, I think, a clear, careful, and detailed presentation of a critical result for the perception-action approach Geoff and I are developing.

Readers interested in the issue of how you can scientifically study information from an ecological perspective should certainly read the paper (Ken, that's you :); it's my go-to reference for how I believe this has to be done. The main lesson - it's hard to do this properly, but the rewards, in terms of unambiguous data, are clear.

Perceptual Learning Stabilises Action: A Test of the Bingham Model

Bingham's perception-action model was initially inspired by perceptual judgement studies (using vision and proprioception). The HKB phenomena are movement phenomena, however; simply noting that the same qualitative pattern is seen in different judgement and action studies is a good first step but only suggestive, at best. We therefore next took simultaneous judgement & action measures from a movement task where we manipulated the feedback display (Wilson et al, 2005a). For instance, when the display showed 0°, movement was stable, even when the movement was at, for example, 90°. Perception of relative phase was driving the stability of the movements.

On the basis of all this data, the model predicts that the reason 0° and 180° are easy is that the information specifying that you are moving this way is easily perceived. There is provisional evidence to support relative direction of motion as the specifying information (Bogaerts et al, 2003; Wilson et al, 2005b; Wimmers et al, 1992) with relative speed acting as a noise term. This variable certainly predicts the observed pattern, as the relative direction of motion is only stable at 0° and 180°. It is maximally variable at 90°, which would explain why movements here are also maximally unstable. The model is therefore explaining the problem with moving at 90° as a problem detecting the information required to maintain the coordination; as we saw in the case of friction, no information means unstable behaviour.

The model therefore makes a critical prediction. If we could improve people's ability to perceive 90°, they should gain the ability to move at 90° without any practice at the movement itself. All previous learning studies had entailed training people to move by having them move, with the help of various forms of transformed feedback methods (visual metronomes or Lissajous plots; more on this when I discuss feedback). The prediction, that movement stability should improve with improved perceptual ability, is a strong test of both the model and the modelling strategy in general, and the experiment to test it was the first half of my dissertation.