Function vs Structure (A Purple Peril)

One of the apparently controversial things that I say is that psychology, as a science, needs to address function before it gets worried about structure; what is the brain trying to do, vs how is it doing it? This Peril lays out the argument in a little more detail. As always, this is my current thinking not my final thinking and I am happy as ever to hear arguments for and against this proposal.

Structure (the details of how a function is implemented) is important, there is no doubt. But I see two related arguments about putting function first, or at least giving it the driver's seat in our science.

Specification and Some of Its Consequences (A Purple Peril)

Perception is how we maintain psychological contact with functionally relevant objects and events in our environments. Explaining how we do this means describing that environment in appropriate terms and investigating what information might possibly exist for that environment, given that description. The ecological hypothesis is that the correct level is dynamics, and that describing the environment this way allows there to be information that can specify those dynamics. This information can support the kind of behaviour we need to exhibit. 

This Purple Peril describes what is meant by specification, and what that implies for how information comes to mean something to an organism. There is more detail in the various links, so check those for information too.

(Re)Introducing "The Purple Perils"

'Note for a tentative redefinition of behaviour', 1975. 

James J Gibson ran an afternoon seminar for many years at Cornell. This seminar was widely attended by a variety of students, professors and visiting scholars, and Gibson used them as a place to try out new ideas, new ways of describing those ideas and generally hammer his theory as hard as he could to see where the weak and strong points were.

Before many of these seminars, he would write and distribute a note, often fairly detailed, detailing the topic of that week's meeting. These were copied as he typed by 'ditto' sheets which transferred the text onto multiple sheets of paper. The ink on these sheets was purple, and the notes became known as the Purple Perils. (There is a nearly complete archive of these online hosted by Bill Mace.) 

These Perils were never the final word on anything. They reflected Gibson's current thinking and were always up for debate. That debate often found it's way into the next week's seminar and Peril, so these were always works in progress.

I've just finished reading Ed Reed's Gibson biography (there's a couple of taster chapters here) and I've been inspired by his description of the kind of scientist Gibson was; the Perils and his seminar were good examples of the kind of rigour and openness he embraced in his science. So, in this spirit, we are going to start posting some shorter, more focused posts on specific topics and ideas from the ecological embodied cognitive science we are developing. They will reflect our current thinking on the topic, but not necessarily our final thinking, and they will not aim to solve everything, just move it forward. They will typically include some 'facts of the matter' as seen from the ecological view, and some analysis to reach some conclusions and hypotheses based on those facts. The goal is to stimulate debate and discussion and come away with a better, clearer theory. 

We would like to invite you all to come get into it with us; ask questions, challenge us, agree with us (we like this too!), talk to each other in the comments and argue/agree with each other. Keep it friendly, keep it a little focused on the topic and try to be specific, detailed and clear in your arguments. If specific parts of topics become sticking points they will likely show up in future Perils for a more focused discussion; otherwise they will be what we're trying to clarify for ourselves. If there are particular topics that are bugging you about radical embodied cognitive science, post about it here and they may show up as future Perils. "What about language then, huh? Huh?" is not something we can work with, though, sorry - be specific :)

We cannot promise to have time to do one every week (Gibson didn't have to teach anything else!) but we will post them as frequently as we have things to post. Feel free to steal the idea and host something similar on your own blogs; we will link to them here. Gibson valued a good argument above all other things in science, and I entirely agree, so please take any opportunity you see to make this a dialogue people can all take part in. 

What Kind of Thing is an Information Variable? The (Annoying) Case of Tau

The central contribution of the ecological approach is the idea of ecological information. Information variables are higher order relations that remain invariant over time as the elements of the pattern change. These relations are the kind of thing that can specify a dynamical property of the environment and support direct perception of that environment. 

This is all a little abstract. One nice, simple example is the variable tau which specifies time-to-contact (TTC). TTC is an important property of objects approaching you that, if perceived, would support you intercepting or avoiding the object. Tau is one variable that specifies TTC and therefore might get used by organisms to perceive TTC.

This post will use tau as an example of information because it's straight forward and has lots of the relevant key features. However, tau is a pain in the ass because organisms typically don't actually use it - it's too limited in its scope to be the best information. People discussing this fact sometimes says it reveals a weakness in the ecological approach. It doesn't; it just reveals a weakness in tau (and the error ecological psychologists made getting as excited as they did about it as an exemplar). It highlights a lot of useful issues, though, so I thought it was still worth the post.