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).