Sunday 15 July 2018

You Cannot Perceive a Relational Affordance (A Purple Peril)

One of the more enduring arguments in ecological psychology is about the best way to formally describe affordances. The two basic approaches are that they are dispositions (Turvey, Scarantino, me) or that they are relations (Reitveld, Kiverstein, Chemero). The argument has mostly settled down into just agreeing to disagree, but I am still convinced that the relational analysis is critically flawed and I want to try and either get them to solve the problem or end the debate once and for all. I've reviewed this in a bunch of places (e.g. here, here, and here)  but this post is just setting out my challenge once and for all; you cannot perceive a relational affordance, and there is as yet no good story about how to learn new affordances.

My problem stems from this Gibson (1979) quote (we all have our favourite, but this one seems to cut to the heart of it)
The central question for the theory of affordances is not whether they exist and are real but whether information is available in ambient light for perceiving them.
Right now, the affordances-are-relations camp have no story for how these can structure light (or other energy media) and therefore create information about themselves. They are therefore, as currently formulated, not even in principle perceptible. This means affordances-as-relations is of zero use to the ecological approach. 

Bruinberg et al (2018) tried to address this problem, but as I blogged here their solution is not ecological information and it reveals that these authors do not as yet understand what information actually is. My challenge is therefore this: tell me a story in which affordances-as-relations are able to create ecological information in energy arrays, and might therefore be learned, and the debate will be back on. Until then, affordances-as-dispositions is the only account that formalises the right properties and the debate is over. 

My basic argument goes as follows. As you go, you should notice that the word 'relation' shows up in a lot of places. This is on purpose, and I think it is part of the confusion.

Here, crudely, is the perception-action loop.
Figure 1. A good old fashioned perception-action loop picture
The organism is a real part of the loop, as is the environment. A given perception-action event entails the organism placing themselves into some relation to the environment (acting) and detecting the ongoing consequences (perceiving). The question at hand is, where in this loop do affordances live?

This analysis (Turvey, Shaw, Reed & Mace, 1981; Turvey, 1992) places affordances in the environment. They are higher-order properties of objects and events, and they are constituted by various lower order properties (things like surfaces) being arranged in a specific spatial and temporal relation to each other.

From this point of view, to say “My coffee mug affords grasping” is to identify that the relations between the surfaces that constitute the mug make it so that when certain satisfying conditions are met (say, the presence of an appropriately sized hand) the disposition to be grasped can be manifested. The affordance disposition is constituted by the cup’s surfaces and their physical properties (the anchoring properties of the disposition; Turvey et al, 1981) but the affordance itself is a distinct, higher order property of the cup. The ecological hypothesis is that perceiving-acting organisms organise their behaviour with respect to this latter property directly, and not via internal, inferential combination of the various anchoring properties.

Dispositions come in complementary pairs. The description above includes a specification of the higher-order properties of something that isn't the coffee mug that can do the grasping. Turvey calls the organism complement of the affordance an effectivity.

So affordances are properties of the environment, and effectivities are properties of the organism. As dispositions, they co-define each other in interesting ways (Scarantino's analysis is currently the most up-to-date in terms of the ontology of dispositions, building on Mumford's definitive work on this topic) but they exist independently of each other; a coffee mug affords grasping even if there is no-one around to effect that grasp.

This analysis (Chemero, 2003, 2009) places affordances at the level of the organism-environment relation. From this point of view, affordances are what you get when you place the relata (the organism, and the environment) into a relation. In his 2009 book, Chemero went even further and proposed dynamical Affordances 2.0 in which the organism and environment causally interact in real time to create affordances that ebb and flow. 

This account is mostly positioned as a way to solve problems with the dispositional account, primarily the issue of malfunction. When the complementary pairs of a disposition are in each other's presence, they must manifest the disposition. Chemero and others worry that this means there cannot therefore be malfunctions, or errors, which clearly occur. However, given that the effectivity is always a complex dynamic that must be learned to be softly assembled, and given that there really is an element of compulsory-ness to skilled action (think about being unable to not pull that door handle, even if the sign says push), I think this problem is already solvable.

Affordances-as-relations also let you find more complex affordances; social affordances, cultural affordances, linguistic affordances. This is how the Skilled Intentionality Framework (e.g. Bruineberg & Reitveld, 2014) works to tackle these issues ecologically. 

The Problem
Refer to Figure 1. Both the organism and the (physical) environment are things that light and other energy media can interact with. The organism-environment relation is not. The relation is not constituted by surfaces, it's constituted by the spatiotemporal layout of the organism-environment system. Light (or other media) cannot bounce off a layout. This means that affordances-as-relations cannot create information about themselves, and they therefore cannot be perceived. They cannot, therefore play any role in an ecological analysis of behaviour. Affordances and effectivities can, however, and so they are at least in principle an option. 

A second, slightly more subtle issue is that the organism-environment relation does not exist prior to the relata being in the relation. In affordances 2.0, organisms co-create affordances by their causal interactions with the environment. This means that I can only create affordances using abilities I already have; so how do I learn new affordances? It can't be by being in the presence of those new affordances, because I cannot create them yet; I need to learn something else. What that is has never been laid out; but it means learning is not affordance-based and there is suddenly a need for something else in the ontology. 


  1. Perhaps I'm a little late to the party here - but I've always wondered if this debate changes if one focuses on other modes of perception other than vision? If we focus on, say, auditory affordances I wonder if this changes the dynamic of the argument? We can SEE and perhaps FEEL that we could climb some stairs, but I don't know that we can HEAR or SMELL that we can climb them. I wonder if this in someway changes the balance of dispositional/relational accounts of affordances.

    1. I do think it does, given that all the modalities/perceptual systems work on the same general principles. They are all interested in detecting higher order invariants over transformations, they are only different in which energy media they are sensitive to.