Is Autism a Deficit in Invariance Detection?

If ASD is a problem detecting invariants, the world would remain a 'blooming buzzing confusion' and lead to the behaviours we see in children with ASD, claims a new paper. 

A new paper in Frontiers in Psychology (Hellendoorn, Wijnroks & Leseman, 2015) has proposed that autistic spectrum disorders might be the developmental consequence of a low level, domain general perceptual deficit, specifically the detection of invariants. They explicitly ground this hypothesis in Gibson's ecological approach and theories of embodied cognition that emphasise the key role perception plays in behaviour. This seemed like something I should evaluate, so thanks to Jon Brock for sending this my way on Twitter.

While I am very sympathetic to the basic idea, this particular implementation is too flawed to get off the ground. The authors make a critical conceptual confusion. They mix up invariant features of the world with invariant features of perceptual arrays that might serve as information for the world, and this stops the paper in it's tracks. I think an interesting exercise might be to fix this problem and then simply repeat the paper with the more careful grounding to see where you end up. 

In this post I've briefly reviewed the claims in the order in which they came up in the paper. I've focused my attention on the central hypothesis about invariant detection because that underpins everything else. I've also briefly summarised some of the cited evidence and implications as laid out by the authors, and commented on any issues I saw. This bit is briefer, because my knowledge of the specifics of ASD are limited. I am also considering a comment to Frontiers on this paper, so feedback on this welcome. If you want in on a comment or reworking of the paper, let me know!

The Information Available in Pictures

I've become fascinated with the problem of pictures and how they relate to the things they are pictures of. One reason is the regular use of pictures of objects to study how the affordances of those objects might ground cognition; this, I think, is a major problem. 

A more positive reason is that, like language, pictures contain information about something they themselves are not (see Sabrina's information taxonomy). I have a hunch that an ecological study of picture perception might help guide an ecological study of language, because the former can take more direct advantage of the work already done about how we perceive meaning in events via ecological laws but then act as a bridge, a point along the way to the conventional world of language meaning.

Finally, the topic seems to be woefully understudied in the ecological approach. There is some, however. In the comments section on my rant about using pictures to study affordances, I was pointed to the work of John Kennedy (a Gibson student, now emeritus at the University of Toronto). I have downloaded his 1974 book, 'A Psychology of Picture Perception' and am working my way through it. Matthieu de Wit then linked me to an archive of a discussion, in papers, between Gibson and Ernst Gombrich about picture perception. I thought I'd start with Gibson (1971), The Information Available in Pictures, to begin to sketch out what we know and what we don't.

The current question at hand is, can pictures provide the same information about the things they depict?

Individual Variation in the Use of Perceptual Information (Specification IV)

If it is the case that perception requires the use of specifying variables, then there should be no individual variation in what information variables people use. However, as we've already seen, such variation exists: the dynamics of a collision event produces multiple kinematic patterns in the optic array, and people judging the mass ratio of colliding balls use all of these, only one of which actually specifies which ball is heavier. Even with training, people do not always find the specifying variable. 

This is an example of how the mapping between a property in the world (mass ratio) and the optic array can be one-to-many, with consequences for perception. Figure 1 on this post shows us that there is another mapping to investigate, namely the one from a perceptual array to the organism. Can this mapping also be one-to-many?  Withagen & van Wermeskerken (2009) suggest that it can, and that again training does not necessarily help.

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

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

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

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

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

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

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.

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.

There's No Prospective Information About Friction, or, Why I Fell Over on the Ice

In which I justify why I, a healthy perceiver-actor, slipped and fell on a clearly visible icy patch, breaking my wrist for the second time, using SCIENCE.

It's been a cold, icy winter here this year, and 6 weeks ago I slipped on a patch of ice and fell entirely on my (previously broken) wrist. The ensuing physics did enough damage that I needed surgery to set the wrist with two pins, and I am only today out of the cast. These kinds of falls and injuries are very common; half of all falls  in the US are caused by insufficient friction, and the types of injuries (broken wrists and collarbones, etc) suggest reactive responses to the slip - people using their arms to try and regain a sudden, unexpected loss of balance. 

The two papers I'm going to talk about are from the lab of my favourite developmental psychologist, Karen Adolph, who has done some excellent affordance work using the transition from crawling to walking as a way to studying the changing perception-action performance of children. This research, however, asked about whether a perceiver can detect information about upcoming friction conditions and use this information for prospective control. The answer seems to be no, because there isn't any information. Given that action requires information, the absence of information might explain the often catastrophic failures of action we see on ice and other low-friction surfaces.

At least, that will be my story.

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.