How to Build a Valid Measure of Behaviour

One of the main problems facing psychology as a science is the issue of validity - what is the relationship between what you measured and what you are actually interested in? One of the things I like about studying movement is how straight-forward this issue is - we're interested in the control of action, so I just measure the action! The most common directly measured kinematic variable is displacement, or position over time; you can then derive (via differentiation) the various rates of change of the previous variable (velocity, acceleration, jerk, and, I kid you not, snap, crackle, and pop). In human movement we never tend to go past jerk, and you can do pretty well with just position and it's rate of change, velocity.

This post will discuss how we start from these basic kinematics and derive a measure of coordination that is  entirely valid, covers the entire space of possible states and provides a unique number for every possible state within that space. Psychology doesn't have a lot of these kinds of variables, but you need to be able to characterise your state space to do the kind of modelling I've been describing and advocating.

Stuff on the Internet (3 December 2010)

Some things that have come our way recently that are somewhat on topic for the blog.

Science

Ed Yong has a (paywalled) piece in the New Scientist about how birds visually perceive magnetic fields. He followed up on Not Exactly Rocket Science with interviews with two scientists working on this fascinating question: Klaus Schulten and Thorsten Ritz. 

NPR covers an interesting study on the fact that blindfolded humans tend to walk in circles. This fairly robust result is not due to handedness or any obvious biomechanical asymmetry, but seems to be the result of sensorimotor drift accumulating in the system (link to paper). Without calibration by vision, our sense of direction becomes increasingly noisy. This relates nicely to some data from a study some colleagues and I really need to write up, in which we got people to misperceive which finger was receiving vibrations after an extended period without vision of the hands.

The biomechanics of pterodactyl flight. 

Baroness Greenfield continues her war on the neurological consequences of modern technology.

Cool toys...er, I mean, educational stuff

Microsoft's Kinect motion tracker uses structured infra-red light arrays to passively track multiple moving objects. Deformations in the field are robust enough to detect game-specific motions as well as faces, etc. There's apparently a lot of people using the IR fields in their art (e.g here, via BoingBoing; mildly NSFW depending on where you work) and I think these could be a fun way to teach optic arrays to students. All I need is a Kinect and an IR sensitive camera...dear Microsoft...

Hi-speed video taken from a train.

Media

I caught up on some Rationally Speaking podcasts while recuperating from surgery on my wrist; these are the ones that caught my eye:

• Experimental Philosophy - to be honest, I have yet to hear an argument why this isn't just psychology done by people who don't really know how to do psychology properly.
• Thought Experiments - they worry about basically the same things I do, but are more generally optimistic about their utility.
• Evolutionary Psychology - here they were a little less generous, which I think Sabrina would be ok with.

Newton TV: I haven't had a chance to really poke around, but what could be wrong with science videos hosted by scientists?

Blogging
There's a new blog  on being a science blogger called The Science of Blogging. We're looking forward to some good advice for broadening our reach a bit.

This editorial about the dangers of science blogging is almost entirely wrong.

What Does Coordinated Rhythmic Movement Have To Do With Anything?

In which I provide an answer to a question I get asked by everyone, including grant reviewers, students and random people who make the mistake of asking what I do for a living.

I've spent numerous recent posts talking about coordinated rhythmic movement. This is my bread-and-butter experimental task, my go-to example for studying all aspects of perception, action and learning. I'm branching out, now I have my own faculty position, but coordination is where it's at. 

The single most common question I get is "why study this? Surely it's just some fake movement task; I mean finger-wiggling, who ever even does that?" I wouldn't mind so much, but I even get this question from grant reviewers, scientists who should know the answer. Doing science properly is important, but communicating that my methods achieve this matters too, not least because today's funding climate demands it.

So, coordinated rhythmic movement: what the hell?

Life and Other Vague Categories

Awhile back I proposed that the distinction between what is cognitive and what is non-cognitive is problematic because of the types of categories we're dealing with - namely, vague artefact categories rather than clearly bounded natural kinds. I suggested that this causes important problems for the study of cognition itself (because we have no principled method for deciding what counts as cognitive) and for philosophical arguments related to cognition (e.g., the coupling-constitution fallacy) because these also depend on having some idea of what counts as cognitive.

Brief Note: Daryl Bem and Precognition

In case you missed it, the Journal of Personality and Social Psychology, a flagship APA journal, published a study by Daryl Bem containing evidence for psi (precognition). I didn't really want to post in too much detail about this study (which has been doing the rounds online all week) because I'm not that interested in being a science journalist. But I did feel it was worth posting a few links and some brief comments to this provocative paper, because it raises a lot of interesting questions about the business of doing psychological science.Should a paper on precognition be published in a major social psychology journal? How did Bem get his results? How seriously should we take what seems to be evidence for something that a lot of other science suggests is impossible?

A Perception/Action Model of Coordination

Other coordination posts are here.

The role of perception in the dynamic leading to the HKB phenomena has been made clear by the work so far. But the exact form of this dynamic had yet to be modelled; the HKB model only consists of two cosine functions superimposed on each other to produce the two attractors at 0° and 180°, and the dynamic pattern hypothesis it embodies made predictions which did not held up empirically. It was now time to take an explicitly perception/action approach to modelling the task, which means it's finally time to turn to (my PhD advisor) Geoff Bingham's model (2001, 2004a, 2004b). This model is a fully perception/action model, and the modelling strategy Bingham lays out is, I think, a masterclass in how to go about building models of this kind.

Stuff on the Internet (12 November 2010)

This will be an occasional post whenever we've accumulated enough links of interest to things on the internet. These were just two things I wanted to link to but not make full posts about.

Establishing the Role of Perception in Coordination: Proprioception and Action Measures

Other coordination posts are here.

The dynamic pattern hypothesis had led to some predictions which, when tested, turned out not to be true. Instead, it seemed that the way in which we perceive relative phase (i.e. the coordination between two things) was the limiting factor. Visual judgments, in the absence of the need to produce an action, produced results that mirrored the movement stability data.

There were two immediate objections to these results, which we addressed empirically in the following way.

On being (briefly) unimanual - and worse, right handed!

Six weeks ago I broke my left wrist playing soccer. For the first two weeks I was in the temporary cast from the Accident & Emergency ward. It was only supposed to be a couple of days, but I had to travel to the US before my appointment to get a proper cast. I therefore had this unwieldy cast on while everything was sore, rendering me effectively one handed. The real cast was lighter and gave more support, and enabled me to use my arm more; the wrist was still constrained, though, and so I still had to rely on my (non-preferred) right hand for many tasks. I'm out of the cast as of Tuesday, although I need to rehabilitate the muscles back before I'll be 100%.

The experience has been quite interesting (in between being very boring). I've observed transfer of learning, recalibration of my arm as effector, and adaptation of numerous actions to the point where I can't really remember what it felt like to do them prior to the injury. I'm going to have to spend some time going back again now the cast has come off, and these things all touch on the topics I'm interested in covering on this blog.

A caveat: the plural of anecdote is not data. I'm not trying to convince anyone of my interpretations here, just thinking about my experience through the lens of my theoretical understanding of perception/action.

Gibson vs Physics: Gibson Wins, at the Ecological Scale

One of the interesting questions that popped out of our discussions with Ken Aizawa about Runeson and the Ames Room is this: did Gibson and his followers banish physics and geometry from his psychology? And if so, is Runeson breaking this prohibition by talking geometrically about the Ames Room? And how can you banish physics anyway - what the hell?

I think I've convinced Ken that there is no such prohibition in the comments at the posts linked to above (I think). But it's a topic of fairly central importance to the ecological approach, so I wanted to summarise some of these ideas and examples here.

Visual perception of coordinated rhythmic movements

Other coordination posts are here.

Fontaine et al (1997) and Wenderoth et al (2002) had empirically established that a key prediction of the dynamic pattern hypothesis was false: learning was easier closer to 0° than it was to 180°. The HKB attractor layout did not appear to be pulling behaviour in the expected manner; what was going on?

The Ames Room and the Bower Bird

A recent study (Endler et al, 2010) has shown that bowerbirds take advantage of forced perspective (the Ames Room effect) in the construction of their bowers. This study has a few interesting things to say on the topic of the origin of the Ames Room effect and the likelihood of equivalent configurations popping up by chance. (This article got a lot of popular press when it came out: Ed Yong at Not Exactly Rocket Science covered it best here.)

Is it time to abandon the cognitive / non-cognitive distinction?

We've been having some good debates with Ken Azawa over at The Bounds of Cognition and Gary Williams at Minds and Brains. A recurring theme is where to draw the line between the cognitive and the non-cognitive. A lot hinges on this distinction. For example, whether we consider things external to the brain to be coupled with a cognitive process or to constitute a cognitive process depends on what we're willing to call "cognitive." Ken has written extensively about this on his blog, but this is a simple summary of the problem: [T]he coupling-constitution distinction comes down to a distinction between X causing, or being caused by, a cognitive process, versus X being a cognitive process.

Runeson, the Ames Room and the Irrelevance of Equivalent Configurations

Recently we’ve been discussing several topics with Ken Aizawa at his blog, The Bounds of Cognition; there are several posts brewing from the two of us on this, but some travelling (plus, for me, a broken wrist) has slowed things a little.

I want to spend some time talking about some recent discussions on aperture vision and the Ames Room. This post will go over two papers on the Ames Room; the next few will discuss some of the more interesting points about the ecological approach that came out of the discussion with Ken. This is a really rich topic, and there’s a lot of ground. First, though, we need the set up.

Learning a Novel Coordination; Things Get Interesting

Other coordination posts are here.

This will be a brief post to follow on from the last, in which I reviewed the early learning studies of Kelso & Zanone that led to the dynamic pattern hypothesis.

Is Cognition Extended?

Over the past week or two, we've been engaging philosopher of psychology Ken Aizawa on the topic of extended cognition. Ken is co-author of a book, Bounds of Cognition, in which he argues cognition is most definitely not extended in any way. We both think the other is wrong, which is always fun; I've been getting to grips with his argument and trying a few ideas out, and I wanted to take a moment to summarise where I think we're at.

Tools and Brains and Embodied Cognition

Arguing about embodiment with Ken Aizawa over the last few days has opened up a lot of topics that I hope to cover over the next little while. But it also primed me to notice this article at Scientific American by Patrick Haggard and Matthew Longo, summarising a recent paper adding to the growing literature on the neuroscience of tool use. I like this work, and it got me thinking how this relates to the embodied cognition literature; Ken, I'd be interested to hear your thoughts on this on.

Learning a Novel Coordination - The Dynamic Pattern Hypothesis

Other coordination posts are here.

Recall this image:

The HKB potential function, ~1Hz

This basic layout is supposed to describe an intrinsic state of affairs, namely that only 0°and 180°are stable coordinations (+/- 180° are identical except for which limb is lagging and which is leading). If you look at this function, you will see that potential energy is a maximum at +/90; this suggests that 90°is a maximally unstable coordination (i.e. it takes the most energy to maintain and is susceptible to perturbations which will make behaviour 'run off' towards one or other attractor). This is indeed the case, empirically; people can do it but fail to respond to the inevitable errors that accumulate and they lose the coordination very rapidly.

The question then is: can you learn to move at 90°? Is this dynamic pattern modifiable by experience?

Assume the Cow is a Sphere

One of my favourite jokes goes like this:

A physicist, an engineer, and a psychologist are called in as consultants to a dairy farm whose production has been below par. Each is given time to inspect the details of the operation before making a report.

The first to be called is the engineer, who states: “The size of the stalls for the cattle should be decreased. Efficiency could be improved if the cows were more closely packed, with a net allotment of 275 cubic feet per cow. Also, the diameter of the milking tubes should be increased by 4 percent to allow for a greater average flow rate during the milking periods”.

The next to report is the psychologist, who proposes: “The inside of the barn should be painted green. This is a more mellow colour than brown and should help induce greater milk flow. Also, more trees should be planted in the fields to add diversity to the scenery for the cattle during grazing, to reduce boredom”.

Finally, the physicist is called upon. He asks for a blackboard and then draws a circle. He begins: “Assume the cow is a sphere....”.

A brief rant about waist-to-hip ratio

This is a bit off topic, but it's a good illustration of William James' notion of the psychologist's fallacy and it addresses a pet peeve of mine.

Evolutionary psychology is becoming more and more popular and the media is one of its biggest fans.One thing that annoys me is how quickly and uncritically people latch on to these stories and use them to justify the status quo. One of the most popular stories is that men prefer women with small waists and big hips. This is measured using the Waist to Hip Ratio (WHR). The WHR is the circumference of your waist divided by the circumference of your hips. The links below will tell you that men are irresistibly drawn to women with WHRs of .70. This number is apparently imbued with evolutionary significance because prepubescent girls have WHRs close to 1 (their waists are the same size as their hips), while post-pubescent girls have WHR less than 1 (waists smaller than hips); and also because low WHRs are associated with a good hormonal balance. One thing that makes this idea attractive is that it conforms to our modern, western experience - many women who are considered to be extremely attractive have low WHRs and it's difficult to generate examples of women who are famous for their beauty, but who have high WHRs. This evolutionary angle legitimizes our society's standard of attractiveness. We assume that everyone else basically shares our own preferences (the psychologist's fallacy), so, rather than this result simply telling us something about modern, western mens' judgments of attractiveness, there is the irrisitable pull to generalise this preference to ALL men.

"Moving Through Time" and embodied cognition

In which I am a bit rude about a rubbish paper and worry about how to kill papers like it.

The term 'embodied cognition' has been checked out of the library by a lot of different people, all of whom use it to mean something different. My least favourite definition comes from the cognitive literature, which considers embodiment to be about how internal, abstract cognitive function can be 'revealed' motorically (the Barselou (2008) version of embodiment). This definition is rooted firmly in the assumption of mental representation. For me, embodiment is only interesting if it contributes in a meaningful way to what cognition is, and thus I define embodied cognition in the other direction - embodied cognition is about how cognition is shaped by the kind of perceiving-acting organism we are.

Coordination and the Haken-Kelso-Bunz Model

Other coordination posts are here.

Now we have the basics out of the way, we can explore some of the key characteristics of coordinated rhythmic movements.

Kelso's early experiments established a set of basic phenomena. Recall that, at the moment, the task is to wiggle your fingers in and out (towards the midline) at some mean relative phase and at some frequency. Moving your fingers in-phase (0° mean relative phase) has the fingers moving in the same direction at the same time, and entails the co-activation of homologous muscle groups in each hand.

Coordinated rhythmic movement. - an introduction to an experimental paradigm

I have some papers I wanted to talk about, but it occurred to me that they only make sense in a context. So I'm going to spend some time talking about the experimental task I use a lot, why it's interesting and what we can learn from it about perception and action.

***********************************

To a man with a hammer, everything looks like a nail. My hammer is coordinated rhythmic movement, and I use it to study everything I'm interested in - perception-action, learning, ageing, you name it. This task is a workhorse of the perception-action literature and has been since Kelso described it in 1981 (after the task was, as far as I can find, first described by Cohen, 1971).

Rebooting the blog

The curse of only occasionally writing a blog is that when other things intrude (like real work) the blog tends to suffer. A bunch of work plus finishing reading Heft lead to this hiatus (once Heft's covered Gibson, he moves onto Roger Barker and while Barker seems like an interesting (and very ecological) researcher his interests fall quite convincingly outwith mine. So blogging about it seemed a little pointless.).

The question is, where next? I plan to re-read Radical Embodied Cognitive Science and blog that, now that I've had time to digest it, think about it, and get more into the 'affordances-are-dispositions' vs '-are relations' argument. We may yet also write a couple of papers on that, so stay tuned.

In the meantime, I'm keen to get back into the discipline of writing a couple of times a week. I may devote one post to reviewing specific papers; I'm developing two grants using coordinated rhythmic movement and I've been reading and developing the arguments for a while now. There's an interesting tension in the literature on this, and I've finally gotten two key papers on this topic in press so I can finally begin to really get moving on this topic. I think one post a week will be on a paper by myself or someone else which I can use to highlight the various theoretical conflicts.

It's not like anyone's reading :v

Reading Group - The Problem of Time (Heft, 2000)

How big is the present? Classic theories of perception all essentially assume that 'now' is some instantaneous slice of time, and that the task of perception is to reconstruct the flow of experience from the snapshots provided by, for example, the eye. But phenomenologically, our experience clearly occurs over time, and it is not clear how you can reinsert time into a perceptual system that detects static slices (in the same way it is not clear how you can uniquely recover the third spatial dimension from a 2D retinal image). In other words, perceptual experience is 4 dimensional - three spatial and one temporal - and we are supposedly creating this from a series of two (spatial) dimensional snapshots.

 

Eye, Borg

It's been a good day for this sort of thing; shortly after my last post I came across this blog post via Gizmodo. It describes the curious case of Neil, who cannot see colour but who has learned to hear it, via a camera that encodes colours as sounds.

The Writer Who Forgot How To Read

NPR has a cute little animation (via BoingBoing) about the story of writer Howard Engel. Engel suffered a minor stroke which left him unable to read words, but he could still write (and read what he wrote for a short period, before it faded into incomprehensibility).

Fascinatingly, he has taught himself to read again using touch. By tracing a letter with his finger (or eventually with his tongue on the roof of his mouth or back of his teeth) he could identify it; he's fast enough now with his tongue that he can read about half of the subtitles in a foreign movie!

Reading Group - Gibson (1979) Chapter 5 Part 3

Chapter 5 Part 3

So far, Gibson has explained how invariant structure can emerge from changes in perspective (see here and here). How he gets down to the real problem. What are the consequences of this structure for the ambient optic array. What is it that I see, as a perceiver, that specifies things about the environment?

On why fMRI is bullshit, even when you're doing it right

I'm just back from the 11th European Workshop on Ecological Psychology and I have a few posts about things that arose there. Ecological psychology is, reassuringly, in better empirical form than I had been thinking; there are still  people doing things badly, but plenty going after things as carefully as they should be, with due attention to issues of information. So that was good.

There was one talk by John Wann on the neural control of steering in driving tasks. I like John a lot, and respect his work - he's a very careful experimentalist and not at all susceptible to fads in psychology, and his work has always included detailed use of perceptual information in sensible ways. He has recently been involved in some fMRI versions of his steering studies with a post-doc trained in imaging, and he presented this data to the conference.

Reading Group - The Problem of Two Minds (Heft, 2001, Chap 4)

I left this part of Chapter 4 as a separate post because the end discusses a problem, the problem of two minds, in some detail and it made sense to split it out. This section ties Gibson to James again by highlighting how his ecological optics can solve a problem within radical empiricism, demonstrating that they are, indeed, connected in interesting ways. This will also segue a little back into dispositions, although only briefly; I've been doing some digging and, as I suspected, the philosophical discussion of what dispositions are has moved on since Turvey (1992). Over the next little while I'll be attempting to read some of the philosophy literature, with the help of a philosopher friend of mine, with the goal of producing some papers for the philosophical and eco-psych communities.

Reading Group - Gibson (1979) Chapter 5 Part 2

Chapter 5 Part 2

In this part of Chapter 5, Gibson talks about how various relations between objects can be specified by the ambient optic array. This is important because image-based theories assume that we have to make a lot of inferences to detect, for example, that one object is partially obstructing the view of another object. In contrast, Gibson once again goes looking for regularities in the ambient optic array that can distinguish one relation between objects from another.

Reading Group - Heft (2001) on Gibson (Pt IIa)

Time for a break on affordances, and a quick check in with Heft. In the last chapter Heft laid out the key contributions Gibson made to the radical empiricist programme. In Chapter 4, Heft focuses on the specific consequences for Gibson of being a realist about relations, and continues to tie this to James via Holt. This post will cover the first half of that chapter.

Chapter 3 discussed Gibson's notion of the "mutuality between the knower and the thing known" (p.143). Chapter 4 now turns to "the context within which knowing processes transpire", i.e. the metaphysical landscape that serves as the basis for the act of perceiving. Simply put, this landscape is the rich web of relations between objects and events, which are real and perceivable. This web is the basis for the dynamic stability described by James and required for flexible but reliable behaviour.

Affordances, Part 3: Dispositions or relations - which is it?

Affordances are difficult entities to wrap your head around. We talk about them imprecisely, they seem like odd, ghostly entities that couldn't possibly exist, and even when we get precise about them, we end up with two different accounts of the kind of thing they are.

Gibson did not have a logical framework with which to express what he mean by affordances, although his verbal formulation is quite clear:

An affordance is neither an objective property nor a subjective property; or it is both if you like. An affordance cuts across the dichotomy of subjective-objective and helps us to understand its inadequacy. It is equally a fact of the environment and a fact of behaviour. It is both physical and psychical, yet neither. An affordance points both ways, to the environment and the observer.

(Gibson, 1979, p. 129)

There have been two attempts at formalising this definition, with two incompatible results: for Turvey, an affordance is a dispositional property of the environment, like solubility, which is complemented by an effectivity of an organism. For Stoffregan and Chemero, affordances are relations between the organism and environment. These are not the same and the difference matters: so which is it?

Visual Illusions Again

VSS is the Vision Science's Society conference that's held every year in Naples, FL. I couldn't make it this year, but they have a contest for the best new visual illusion that's usually a pretty good show; illusions are getting cleverer.

This is this year's winner:



There's actually visual information that something is wrong that's available before they rotate the display - 5 internet points to anyone who points it out!

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.

Affordances, Part 1: Affordances are real dispositions of the environment

It turns out I've been pretty confused about affordances for a long time. This is partly due to the fact that I don't (yet) do research on affordances and so don't spend much time thinking about them. However, it is also partly due to the fact that affordances are fucking weird and much has been written that is confused, incomplete and wrong.

I got back into thinking about affordances in detail by reading Anthony Chemero's mostly excellent new book, Radical Embodied Cognitive Science (Google Books preview). Actually, everything I've written so far is actually me getting my head in the game to go after something I think Tony has gotten needlessly wrong; for various reasons he thinks its time to lower the specification requirement for perceptual information. I think the reasons are flawed and that it's not even close to being an empirical reality that specification is not needed; but this is all material for later on.

When Tony talks about affordances, he proposes that they are relations. He contrasts this to the generally accepted Turvey formulation, that affordances are properties, specifically dispositional properties. This, it turns out, is a key internal battle that is ongoing within ecological psychology. I was initially on Tony's side: Turvey's account has always seemed wrong to me. But after some discussion with my PhD advisor, and after reading Heft's summary of what Gibson meant, I'm back on the side of affordances as properties.

Reading Group - Gibson (1979) Chapter 5

Chapter 5: The ambient optic array

This chapter is long and dense, so I’m going to go through it in two posts. Essentially, Gibson is going to make the case that light can be structured in a way that specifies things about the environment. The important thing to keep in mind is that the structure arises from relations between things ( in this case, relations between solid visual angles). Traditional optics talks about points of light falling on an object. These points of light change all the time and this creates a real mess for any perceptual systems that perceives points of light. Ecological optics talks about the relationship between solid visual angles. Although the particular conditions of light or perspective might change, the nature of these relationships is preserved. To refresh your memory see Chapter 1, 2, 3, and 4. Now, on to details...

Reading Group - Heft (2001) on Gibson

Part II of Heft moves on from James and Holt and into Gibson's ecological approach. The point of Part I, as I've discussed, was to establish the roots of Gibson in the radical empiricism of James, conveyed via the molar behaviourism of Holt. Part II is a detailed discussion of the ecological approach, specifically that laid out in Gibson (1979). I'm therefore going to leave the details of the exposition to the other reading group posts, and focus on the higher level connections and points Heft makes. I'm also going to handle Chapter 3 in two posts: this one will be a brief summary of some key points, and later this week I'll reveal how I've been mistaken about affordances for quite a while.

A Note on Holt on Visual Illusions (Heft, 2001)

This is a visual illusion. When you look at it, there appears to be a great deal of motion as things rotate in various directions. But there's no actual motion; this isn't an animated display and you can verify this by fixating the centre or touching your computer screen - no motion. I just fooled your visual system.

But Andrew, you say, you've been talking all this time about how great perception is! It's direct, functional, reflects experience, and lawful: if perception is all these things, how can it be fooled so easily by some pixels? Direct realism surely cannot handle this: perception is flawed, and readily shown not to correspond to the way things really are. Clearly this James Gibson is a mad man and we can go back to 'knowing' that perception is clearly mediated by pretty good but fallible representations.

Reading Group - Heft (2001) on EB Holt

In Chapter 2, Heft examines the life and work of James student EB Holt, who links Gibson to James by being the student of the latter and the graduate advisor of the former. Heft discusses Holt's work and frames the discussion to show how the key ideas from radical empiricism come through to feature so heavily in Gibson's psychology.

A lot of the fundamentals should now be familiar: Holt follows James in denying any type of dualism and in considering cognition to be a completely natural phenomenon. Holt is a realist, considers relations to be real and where the action is, and (eventually) considers all psychological phenomena to be the result of dynamic, time extended interactions between an active organism and a structured environment.  It's no coincidence that Gibson described himself as a 'Holtian philosophical behaviourist'!

Reading Group - Gibson (1979) Chapter 4

In this chapter Gibson really steps up the pace, so hold onto your hat. First, he shows that perception can’t be based on sensation. Then he shows that we can’t see light. Finally, he shows that we don’t see images. Here we go...

What else could it be? The case of the centrifugal govenor.

Previously, I’ve dismissed the idea of mental representation because 1) no one knows what a representation is and 2) the arguments for representation tend to be pretty weak. Now, I’d like to spend a bit of time discussing a possible alternative – a dynamical systems approach to cognition. To frame this discussion, I’m going to summarise a very handy philosophy paper by Van Gelder (1995) in which he distinguishes between a computational and dynamical solution to a particular problem (see also Andrew's post on the polar planimeter). Van Gelder has clearly picked a side - that cognition emerges from dynamical systems and that cognitive processes are evolutions in the state-space within these systems. One of the main arguments for computation is that it’s difficult to imagine what else could be going on (see footnotes p. 346 for references for this argument). So, Van Gelder wrote this paper,  not to decisively rule out computation, but to provide an answer to the question “what else could [cognition] be?”

"Smart" perceptual mechanisms

I mentioned yesterday that James' theory about pure experience being all there is, and relations being legitimate objects for perception does at one level sound crazy. Surely physics is where it's at - if you aren't talking about a physical variable, how can you be talking about anything real?

 Ecological theorists have one good example to hand, courtesy of a 1977 paper by Sverker Runeson, that might help: the polar planimeter (pictured). This is a device that measures area directly, rather than measuring the 'simpler' physical unit length and then performing the necessary computation. Runeson uses this device as an example of a 'smart' mechanism, and proposes that perception might entail such mechanisms.

Reading Group - Heft (2001) William James and Radical Empircism

This book got heavy, fast! The first full chapter discusses the metaphysics of William James (pictured in his younger, cooler days) and how it is the philosophical groundwork for Gibson. Assuming Heft's analysis of James is right, this is precisely what it is.

I won't review all the detailed argument because there is a lot of material in this chapter. What I will do is summarise the key points.

The goal of James' metaphysics (theory of the way the universe is composed) is to replace the dualism he and others like Dewey knew was (and still is) lurking at the heart of psychology. Metaphysical dualism is the assumption that there are two kinds of stuff in the universe - for Descartes it was soul and world, for psychology it was mind and body. Dualism is a major problem, if true, because of one important point - if there are indeed two types of thing in the universe, how can something of one type (e.g. a mental state) come to have knowledge about something of another type (e.g. an event in the world?). It is, in fact, impossible by definition, and for this reason any line of reasoning that entails a dualism is generally frowned upon in philosophy.

Reading Group - Gibson (1979) Chapter 3

Chapter 3

In which Gibson defines everything. See here and here for a refresher.

Here’s the crux of it:

“The world of physical reality does not consist of meaningful things. The world of ecological reality, as I have been trying to describe it, does. If what we perceived were the entities of physics and mathematics, meanings would have to be imposed on them. But if what we perceive are the entities of environmental science their meanings can be discovered” (p. 33).

It's not just us, honest

I need to put together posts on Heft and a couple of other points, but we've been noticing more and more examples of people expressing the same worry we have - that psychology is no longer a field with theories, merely phenomena. A couple of links that came our way this week:

Reading Group - Gibson (1979) Chapter 2

In the previous chapter, Gibson established the importance of the environment to perception. In this chapter, he goes into more detail about the properties of the environment that are relevant to perceivers. Gibson argues that although classical physics talks about the world in terms of bodies in space, this doesn't mean that this is a good way to talk about the environment as it applies to perception. In studying perception, it’s better to think about our environment in terms of mediums, substances, and surfaces. Two things occurred to me as I read this chapter. The first was, “Wow, I’ve never before heard the environment described in this way.” The second was, “Wow, this is so unbelievably straightforward and comprehensive, why don’t all psychologists talk about the environment in this way?”

In which I finish talking about discrete computational representations

In a previous post, I summarised Dietrich & Markman’s definition of representations and ideas about how representations get their content. While there are many flavours of representation, D&M subscribe to the discrete computational (DC) variety. To summarise the previous post: According to D&M, representations are internal mediating states that govern behaviour. Representations have relations to both the external and internal (i.e., other representations) environment. They acquire content in two ways. The first way is through correspondence, where some internal state connects to some external state. The second is through functional relations with other representations. Representations are transformed via computations.

The main purpose of this post is to summarise D&M's main arguments in favour of discrete representations so that I can refer to these in other posts. I make several comments about the quality of these arguments, but this is in no way meant to be a systematic response to their paper.

Reading Group - Gibson (1979) Chapter 1

Welcome to the first instalment of the Gibson (1979) reading group. I’m reading this for the first time, so I’m going to take things pretty slowly. If anyone is interested in following along, let me just say that Gibson is surprisingly readable. In this introductory chapter Gibson establishes the importance of the environment to the study of perception. It’s a brief chapter, but I think it’s important enough to leave it on its own.

Reading Group - Heft (2001) Intro + Prologue

This is the first post on the readings I'm doing at the moment. I'm going to be focusing on Heft (2001) while Sabrina is going to work on Gibson (1979).

Heft is a psychologist, and the goal of this book is to 'examine the historical and theoretical foundations' of Gibson. This is an excellent idea: as Heft points out, a lot of modern psychologists reject Gibson as being 'out there' and 'from out of the blue' when in actual fact his basic approach is firmly rooted in the work of William James and Edwin B Holt, Gibson's graduate advisor.

Can’t form a mental image? No big deal.

UPDATE (23/6/15) - Carl Zimmer followed up his Discover piece with an NYT article about a recent paper in Cortex naming this non-imaging 'aphantasia'. The lead researcher is Dr Adam Zeman and he's interested to hear from people who experience this; his email is a.zeman@exeter.ac.uk (tell him we sent you :)

Discover covers a really cool Neuropsychologia article about a man, MX, who lost his ability to experience mental imagery.

Mental imagery is a divisive topic in psychology. Some (most notably Kosslyn) argue that mental images are essential to many types of cognition. According to this camp, mental images are functionally similar (but not identical to) like-modality perception (Kosslyn, 2004 summarises this view nicely). Imagining an apple and seeing an apple involve similar mechanisms. Furthermore, I can use my mental image of an apple to answer questions about its properties – is it red? is it heavier than a plum? But, many other people argue that, although we might feel like we’re using pictures in our imagination to solve various problems, the real work is done by non-depictive representations (see Pylyshyn, 2003 for a good review). When we’re asked to answer questions about an apple’s properties, we can think about what it would be like to see the apple, but this doesn’t entail that the representation is depictive, in this case, pictorial.

On why fMRI is bullshit

If you want to really confuse a psychologist, tell them you don't think there are mental representations mediating behaviour. Try it - they will simply assume you must be joking, because it has never occurred to them that it might be true. This, unfortunately, is the single biggest stumbling block in talking about Gibson to cognitive psychologists, because one of the radical ideas in ecological psychology is that there isn't any need to invoke representations.

The most common counter argument comes from modern neuroscience (specifically, neuro-imaging, and in particular functional magnetic resonance imaging (fMRI)). There must be representations, your cognitive friend will cry - we've seen them via fMRI! If I present a stimulus to a person in a magnet, you can literally see the brain light up. Clearly, the triumphant cognitive type will claim, Gibson is wrong when he says there are no representations because the brain is obviously up to something.

Reading Group: Gibson (1979) and Heft (2001)

I'm going to take advantage of the fact I'm doing this blog to re-read Gibson 1979 and take notes. I'm going to post these chapter by chapter as I go, I also found a copy of Harry Heft's book in the library and I've been meaning to read it too, so I'm going to do the same for that. Posts about the books will have 'Reading Group' in the title. Feel free to read along :)

Gibson, J.J. (1979). The ecological approach to visual perception. Boston: Houghton Mifflin. Amazon.co.uk

Heft, H. (2001). Ecological Psychology in Context: James Gibson, Roger Barker and the Legacy of William James's Radical Empiricism. Mahwah, NJ: Lawrence Erlbaum. Amazon.co.uk

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).

What psychologists can learn from physicists

String theory is a really cool idea. I don’t actually understand it, of course; I’m not a physicist. But, it’s a neat to think that some of the oddness of our physical world is accounted for by this undetectable world of tiny, vibrating strings. Some physicists also seem to think that string theory is cool. But, physics has not adopted string theory and nobody’s really pushing for this, either. Why not? Well, strings are purely hypothetical entities. Maybe they exist, or maybe something completely different is going on. It doesn’t matter that they might explain some interesting stuff, they’re off the table because we can’t see or measure them. Tough. That’s physics.

Psychologists faced a very similar problem when people started thinking about theories of representation. Representations seemed to resolve thorny issues, like how we can successfully interact with the environment given inadequate information (e.g., poverty of the stimulus). It was a really cool idea; people are just like computers! But, as with strings, representations are hypothetical entities. They seem to explain certain behaviour, but we can’t see or measure them. They also aren’t the only game in town. Let go of certain assumptions (e.g., poverty of the stimulus) and the problems representations were supposed to solve look very different, or cease to look like problems at all. While physicists showed restraint in the face of their cool theory, psychologists took representation and ran with it. Although they remain poorly defined and undetectable (probably because we don’t know what we’re looking for), representations are ubiquitous in explanations of cognition.

So, what is the alternative? How about we bench the really cool idea until we’ve exhausted all the other possibilities? Let’s take the alternatives to representation seriously. Physics produces some insanely accurate predictions. Physics sent people to the moon. Psychology can’t reliably diagnose and treat depression. Some of that is down to the complexity of the subject – people are a mess. But I think that some of it is also down to method. While physics is cautious, psychology is eager.

Happy birthday, BF Skinner

Today is the birthday of Burrhus Frederic Skinner. I have a soft spot for ol’ BF, because he was right about a lot of things and refused to let the man get him down. Behaviourism gets a bad rap these days, with cognitive people the world over rolling their eyes at the idea that all behaviour can be explained by stimulus-response associations of varying kinds. But Skinner was my kind of scientist: driven by the data and refusing to indulge in the theoretical excess he saw in others.

Skinner was, in part, responding to the Freudian school of thought, that saw all human behaviour as generated by unseen drives and urges. Skinner recognised that there was no scientific evidence for the existence of these particular kinds of internal mental states mediating between the environment and our behaviour. In fact, you could account for a lot of behaviour, human and otherwise, without ever assuming any internal states, simply by recognising that behaviours can be shaped and assembled by learning via schedules of reinforcement.

Monopoly is a perfect example of embodied cognition

I teach a Matlab programming class. The main project I get people to work on is programming up a version of the game Monopoly. It’s a great project, I think, because it makes you use all the things Matlab is good at (loops, matrices, data in and output, etc). It’s a surprisingly entertaining programming project, if you’re into that sort of thing.

But I realised yesterday that Monopoly contains a perfect example of embodied cognition, and this contrast becomes abundantly clear when attempting to implement it in a computational way.

Internal representation or behavioural dynamics?

More on Gibson later, but I wanted to get to this today. Yesterday I saw a talk about eye tracking, and how people control smooth pursuit movements (the tracking movements your eyes can make when you’re following something continuously). Tracking performance is a quandary for cognitive folks, because we are often very good at it. For instance, if you ask people to track a moving stimulus and record their eye movements, they will successfully foveate the target with almost no lag or erratic need to play catch up (foveating means using the fovea, the densely packed high resolution region on the retina we rely on for precise visual perception). The lack of ‘catch-up’ is the interesting bit, and cognitive psychology thinks that it is evidence of prediction by the system. Prediction requires a predictor, which for cognitive psychology is always a representation.

The main thing I learned from this talk is this: I am a rampant ego-maniac who is convinced I am right and other people are wrong, but at least I am capable of entertaining the idea that there is another way to conceive of the task. This speaker (and at least one other person in the room) was completely unaware that their perspective entailed assumptions about the underlying mechanism and simply couldn’t conceive of another way to describe the task: for them, prediction was clearly required and therefore internal representation was clearly required.

Whose representation?

One of my pet peeves is when different groups of psychologists use one term to refer to something for which they have multiple, sometimes contradictory, definitions. When I started studying similarity, I wasted a lot of time trying to clarify what everyone meant by relations. See, for one group of people, relations occurred within a stimulus (a cat’s legs are under its body, its whiskers are on its face). For another group of people, relations occurred between two stimuli (you use a hammer to hit a nail). These are very different types of relations and they affect similarity in very different ways. But, by using that one word, relation, the literature was all muddied about how relations influenced similarity. Clarifying the terms (we now speak of structural relations vs. thematic relations) helps clarify how we think about the subject.

The word representation is used in a comparably muddied fashion. Depending on who you’re talking to, representation might refer to something symbolic, perceptual, discrete, or continuous; and these symbolic/perceptual/discrete/continuous things might be transformed or acted on via ordinary computations or differential equations.

To get to the bottom of this, I want to clarify the different ways in which representation is commonly used. Then, I want to figure out how to introduce some precision in talking about representations. This will make it much easier to discuss the problem of representation and to consider the alternatives.

Today’s installment: Discrete computational representations (based on Dietrich & Markman, 2003).

Representations are internal mediating states. Anything that changes / transforms / acts on input to a system in a way that changes / transforms output (i.e., actions) is a representation.
The authors provide four conditions for this definition.

1) There needs to be at least one system, which has internal states governing its behaviour.
2) There needs to be an environment, although this doesn’t have to be the external environment. It could just be an adjacent system.
3) Some types of relations have to exist between the system’s internal states and the environment.
4) Processes must act on the internal states to satisfy goals or solve problems. Dietrich and Markman believe that these processes are computational.

On top of these conditions, the authors argue that semantic content needs to be explicit. In other words, the authors contend that psychological-level descriptions of internal states are real and that this level is more relevant that the physical-level description. Representations and processes are more important than chemicals and neurons.

How representations get their content:

1) The relations between internal states and the environment connect particular internal states with particular external states (i.e., correspondence).
2) Representations acquire some content by virtue of the types of interactions they have with other representations (i.e., functional role).

The authors suggest that 1 contributes primarily to the content of low level DC representations like a vibrating eardrum responding to sound, while 2 contributes to higher level DC representations like “hope”, “democracy” or other abstract concepts. It’s necessary for every DC representation to have at least some content from correspondence to external states.

Now, representations could be either discrete or continuous, but Dietrich and Markman argue that they must be discrete. These terms map on perfectly to the mathematical sense of continuity/discreteness. So, discrete representations are uniquely identifiable. E.g., I have a unique cat representation that is different from all of my other representations. And, discrete representations have gaps between them. My cat representation doesn’t seamlessly transition into my tiger representation (although there may be overlap).

To sum up, this notion of representation is that they are internal mediating states that are discrete and computational. Each representation is uniquely identifiable (discrete) and the processes that act on representations are ordinary computations. From now on, when I’m talking about this type of representation, I will refer to DC (discrete computational) representations.

Dietrich, E. & Markman, A. B. (2003). Discrete thoughts: Why cognition must use discrete representations. Mind and Language, 18, 95-119.

There is no poverty of stimulus

In my last post I outlined the basic state of affairs in the study of perception up to the modern day. Cognitive science assumes a poverty of stimulus that must be overcome with internal mental representations. The content of these representations is an empirical question, and the drive in psychology ever since the ‘cognitive revolution’ of the 1960s has been to uncover the contents and format of these representations such that they can do the job apparently required.

The only non-representational cognitive psychologist in the village

Hi. I’m a cognitive psychologist, but I’m not that kind of cognitive psychologist. Specifically, I don’t believe in representations, and I reject the computational model of cognition. Yes, this makes me very unpopular. I this post I want to quickly review the dominant cognitive approach and then briefly raise several potential problems with this framework. I will go through these issues in detail in later posts, but I want to go ahead and present the big picture here.

Cognitive scientists tend to view cognition as computation. In this model, representations are data structures and cognitive processes are algorithms acting on these data structures. Input => transformation of input via manipulation of discrete symbols (representations) => output. The clear analogy is to information processing in a computer. Another way to think about representations is as internal mediating states (cf. Dietrich & Markman, 2003). For instance, when I see a cup, the stuff happening in the visual system will probably be a better match to my “cup” representation than to my “glass” representation. So, I correctly identify the object as a cup. In other words, my ability to identify an object depends on consulting a discrete, internal representation of that object.

There are a number of unresolved issues with this representational stance: First, there is no theory of what representations actually are or of what information they contain. Second, many cognitive phenomena seem to defy a computational explanation. For instance, attempts to use a computational framework to model cognitive behaviours have often failed to produce anything as flexible or interesting as what we humans get up to. Third, alternative stances (e.g., that there are no discrete representations or that they are not processed algorithmically) have not been thoroughly explored. Cognitive psychologists usually take representations for granted; their existence is assumed, rarely defined or tested. This just isn’t good science. I’m just raising these points here; in future posts I’ll lay out the evidence.

My goal is to spend some time discussing these issues and to think about alternatives to representation. As a cognitive psychologist, I could get away with not understanding or caring about perception. Honestly, it just doesn’t come up much. When it does come up (e.g., Barsalou) it’s in terms of the “sensation based theory of perception” (see previous post), which we know is outdated. In the long run, I want to discuss how it might be possible to ground the study of cognition in Gibsonian perception/action. This is risky since, at the moment, I have no idea what such a framework would look like. But, cognitive psychology needs to evolve, and this is currently my best bet on how that might happen.