Monday, 25 July 2016

Relational Theories of Affordances are Functional, Not Mechanistic (A Purple Peril)

Everyone and their dog has a theory about how to interpret Gibson's famously vague definition of affordances;
The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or 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 behavior. It is both physical and psychical, yet neither. An affordance points both ways, to the environment and to the observer.
There are two basic flavours of theories: affordances as dispositional properties of the environment (Turvey, Shaw, Reed & Mace, 1981; Turvey, 1992) and affordances as relational features of the animal-environment system. (A recent paper has just claimed they should be best understood as events, but to be honest I don't really know what's motivating this). The two most recent and popular relational accounts are Chemero's book (Chemero, 2009; see these posts on the relevant chapter) and Rietveld & Kiverstein (2014) in a paper entitled 'A Rich Landscape of Affordances'. Their goal, like most of the relational accounts, is to handle higher-order cognition by scaling up affordances to support it (our move, in contrast, has been to expand the uses of perceptual information; Golonka, 2015Golonka & Wilson, 2016 preprint).

I am firmly in the 'affordances as dispositional properties' camp (see, for example, the discussion section of my recent throwing paper for an extended analysis). Specifically, they are dynamically defined dispositional properties of objects and events in the context of tasks. The reason is that this is the only way affordances can be the kind of thing that can create information and therefore be perceivable. They have to be 'out there' and made of things that light can bounce off, for example, and relations between organism and environments are not typically such things. In addition, if they do not exist until perceived, we need a story to explain how we come to learn to perceive them, and there is no viable ecological framework that will make this happen (Wilson et al, 2016).

Reading this material with my new mechanism glasses on has given me a new, concise way to identify the problems with these relational accounts:

Affordances-as-relations theories are all functional explanations, and not mechanistic explanations

Functional explanations are ones that take a capacity and break it down into sub-capacities in order to explain it; for example, defining an affordance as "a relation" between "a possibility for action" offered by the environment to an organism "with some set of abilities". These capacities do not point to specific real components, but describe things the system does that help constitute this other, bigger thing the system does. They are not necessarily wrong, just limited. Functional explanations have been the norm in cognitive science for as long as we've been going and many people think this is all we get. Mechanistic explanations that point to real parts and processes have many advantages but are not always possible. 

People presenting these theories want their relational affordances to do actual work in explaining behaviour, of course. But the way in which they talk reveals that if there is anything doing actual work in their accounts, it's properties of the environment. For example, Rietveld and Kiverstein defend relations this way:
We argue that the existence of affordances is not dependent on the actual engagement with an affordance of any particular individual, but affordances nevertheless have an existence that is relative to a form of life"
pg 335
This is actually a good definition of a dispositional property, except that dispositions have the additional advantage of existing prior to a particular individual coming into contact with it.

In another example,
Affordances are just aspects of a niche, so if the niche to which an affordance belongs ceases to exist so also will the affordance. Still the aspect of the material environment may well continue to offer possibilities for other forms of life in which relevant abilities are found (emphasis mine).
pg 337
This and several other examples show that it's the 'material environment' doing most of the important affordance work here.

Here's the thing to remember; Turvey's (1992; Turvey et al, 1981) dispositional analysis completely accounts for all these features. Affordances are the dispositions of the environment, but then there are effectivities, which are the complementary dispositional properties of the organism. The dispositional analysis then makes affordances and effectivities real parts that exist independently of each other, things that can be objectively defined and investigated and that therefore support the development of mechanistic models. The relational work happens when the affordance is perceived; the act of perceiving and acting on an affordance is an act of placing oneself in a relation to that affordance so that the opportunity for action it presents is taken up.

What's Limiting Affordances-as-Relations to be Only Functional?
While every camp has it's favourite Gibson quotes to back themselves up, the one constant in his contradictory and incomplete analysis of affordances is that in order for them to be interesting to a theory of behaviour, they must be perceivable. This means that must be able to create information, and this means at some point some light has to hit something and get structured by that interaction (or the equivalent for the acoustic array, etc). If affordances are properties then this can happen. If they are relations, there is as yet no story about how this occurs. Affordances-as-relations simply pick out a functional level description of an opportunity for action. This allows you to talk about things like social affordances, for example. But the cost of this is that it is as yet unclear how such relational affordances can be perceived because there is nothing identified that energy media can interact with.

So right now, affordances-as-relations accounts cannot explain how they are perceived and have their effect on behaviour. This limits them to be functional level descriptions and makes them of limited use in ecological explanations of behaviour.

Affordances-as-relations theories can only support functional explanations of behaviour, while affordances-as-dispositions accounts can support mechanistic explanations and models. In addition, relational accounts suffer from the problem that it's not clear affordance relations are real enough to support behaviour; how do these things create ecological information? All attempts to solve this problem are either unsatisfactory (Chemero simply declares it to be all good in his book) or they depend on the reality of properties in the world to work (see above). Given that we want mechanistic models, and given that constraining affordances in a way that makes them not everything but in principle perceivable then supports such models, I suggest that treating affordances as dispositional properties is an important discipline for the field to progress.

This might also account for Chemero's opposition to mechanistic modelling. His notion of affordances leads only to functional explanations, but he still wants to explain, so the burden is on him to come up with a non-mechanistic way to get good quality explanations. His solution is his dynamical explanation papers. In hindsight, all these pieces fit together nicely. However, because we believe we can get to mechanisms and that this is worth doing, it's natural for us to treat affordances as real properties, and it's a nice side-effect that this analysis has let me and others do a lot of detailed empirical affordance research.

I will highlight that I got to meet Erik Reitveld and Julian Kiverstein at EWEP14. I had a lovely chat, and we basically agree on nearly everything around the idea of scaling up ecological (and enactivist) ideas to handle complex cognition. But this problem (that affordances-as-relations create no information, are therefore not perceivable and so can, at best, support functional level analyses of behaviour) remains and I believe it's an important problem they don't actually need to suffer from. Not everything that affects our behaviour is an affordance, and this is just fine. Sabrina's development of the conventional use of information (Golonka, 2015) allows everything they want while preserving the use of real parts and processes, and so I hope we can find a way to align our activities to point in the same basic direction.


  1. Rodolfo Llinas, in his book, I of the Vortex, touches on some ideas that may relate to affordances. He points out that, as we learn to interact with various objects in our environment (climb stairs, pick up a mug of hot coffee and take a sip, shoot a basketball, ride a bike, etc.) these behaviors at first require attention but, over time are automated. The area of the brain crucial to “storing” these automated behaviors (basal ganglia) is largely inhibitory in nature. This can readily seen in such diseases as Parkinsons and Tourettes. In Tourettes, inhibition is lost. We are “primed” to act at all times and can do so in a split second if warranted. So long as the environment contains what we expect it to contain, we inhibit action unless directed by attentive behavior or are startled (think spotting a snake on a trail in the woods).

    An interesting point touched on by Llinas in his book is that speech, too, is comprised of learned, automated muscle movements in a way that is no different from skipping rope and that it is controlled by much of the same brain areas. We are inhibited from speaking, but primed to hear and recognize and understand words as they are spoken. Even when we think sub-vocally, we are still using muscles associated with speech. The is also true for reading. We only need to see a word and it's meaning is cascaded from memory.

  2. Nice post. However, I'm not sure I understand what you mean by "dispositions have the additional advantage of existing prior to a particular individual coming into contact with it." I did read the salt analogy in your earlier blog post, and also the example of the chair and "sit-on-ability" as having existed before the human and the chair came in contact with each other. All of these are nice analogies but what is a concrete example of such a disposition in cognition (i.e., something that just exists in a vacuum and pre-experience)? IF experience is a pre-requisite for establishing these so-called dispositions, then that automatically argues against the existence of dispositions prior to the organism coming in contact with its environment.

    What am I missing here?

    1. Dispositional properties come in pairs, so for example salt has the property of being soluble in water and water has the complementary property of being able to dissolve salts.

      Both these properties exist independently of each other, because they arise from features of the salt and water, respectively. Salt would still be disposed to dissolve in something like water even if there was no water because of what a salt is and how it's made.

      Affordances have a complement in effectivities. But as above, affordances and effectivities exist independent of each other because they come about because of how each thing is made.

      The disposition is then effected if the complementary pairs come into contact. The affordance is effected when an organism with the relevant effectivities perceives and acts on it.

  3. This is a long reply which we will split up in three parts.
    1. We have been excited to follow the research by Andrew Wilson and Sabrina Golonka exploring how to explain higher cognition from within ecological psychology and had an interesting discussion on some of the challenges such a project faces with Andrew at the EWEP conference in Groningen this summer. We agree with Wilson & Golonka about the crucial research program for Ecological Psychology: it needs to expand into higher cognition and there are difficult issues that need to be addressed in order to make this possible. We have started dealing with these in a paper that discusses affordances for higher cognition (Rietveld & Kiverstein, 2014, Ecological Psychology) and a paper that proposes to think of the dynamics of the brain and body in terms states of action readiness that attune to the dynamics of the sociomaterial environment and the relevant action possibilities if offers (Bruineberg & Rietveld, 2014, Frontiers in Human Neuroscience; Bruineberg, Kiverstein & Rietveld, 2016, Synthese).

    We agree however that there are interesting points of disagreement and welcome this opportunity to exchange some thoughts on these issues. Contrary to what Andrew Wilson writes in his blogpost, on our account it is not the case that affordances do not exist before they are perceived. Affordances on our definition are relations between aspects of the (socio)material environment and abilities available in a form of life. So they are defined independently of any particular individual but not independently of the abilities available in the (socio-cultural) practices that make up the form of life. When an individual dies or is born, (almost) nothing changes to the affordances available in the practice. But when a practice changes or dies out, this does change the affordances available. Learning takes then place via a process of education of attention to the affordances that are already available in the ecological niche. This learning is typically scaffolded by more established practitioners.

    We disagree mostly with the attempt by Wilson and Golonka to introduce representations in ecological psychology. In particular the neural representations seem to generate more questions than they solve. Whereas Wilson & Golonka try to deal with representation hungry problems in the end in terms of neural representations, we try to stick to the ecological adagio formulated by Mace: don’t ask what is inside the head but what the head is inside of. More precisely, we suggest, don’t only ask what is inside the head, because what is in the head are states of action readiness that are driven by the relevant affordances that an individual encounters in its tendency towards grip on the situation (see the Conclusion of our recent Synthese paper (2016)).

  4. Reply by Rietveld & Kiverstein, Part 2.

    Crucially, the papers by Wilson and Golonka presuppose the solution to one of the main problems in cognitive science: the origin of relevance in the concrete situation. It does so by presupposing “tasks” rather than explaining why one cares about one task rather than another in the particular situation. In other words, it is presupposed that people care about certain affordances, for example an obstacle to avoid, like a pole with a stop sign one navigates around (p243 in Golonka 2015). But note that someone in a tank would not care at all about a certain pole with a sign, so this aspect of the environment would not invite avoiding to him or her. We think what matters are relevant action possibilities: affordances for which the individual has some readiness to act, and that influence the self-organization of what we call the field of relevant affordances (Bruineberg & Rietveld, 2014). Another key difference between Wilson & Golonka and us is their divide between affordances and ecological information. Our relational account of affordances defines affordances relative to a form of life/ecological niche. In the human form of life, the landscape of affordances is very rich and includes possibilities for what people have typically characterized as forms of ‘higher’ cognition, and this includes for example the affordances of language. For us perceiving is “relevant affordance related action-readiness”, there is therefore no need to restrict affordances to information that is specifying and lawlike. Instead the concept of affordances can apply to everything in the (sociomaterial) environment that people can skillfully engage with.

    For now it is perhaps also good to know that with our Skilled Intentionality Framework (SIF) for 'higher' cognition we try not just to do justice to Gibson (see Rietveld & Kiverstein, 2014, Ecological Psycholog; Rietveld, 2016, Sports Medicine), but also to complementary insights from Merleau-Ponty in phenomenology (hence the emphasis on the solicitations of relevant affordances as well as responsiveness to multiple relevant affordances simultaneously, i.e. to a whole field of relevant affordances), our Wittgensteinian philosophical work on situated normativity in embodied cognition (Rietveld, 2008, Mind,), and the field of neurodynamics, including Karl Friston’s work on free energy minimization (see Bruineberg, Kiverstein & Rietveld, 2016 in Synthese, and Bruineberg & Rietveld, 2014, on the self-organization of multiple simultaneous states of action readiness in the Frontiers in Human Neuroscience special issue on Radical Embodied Cognitive Neuroscience, edited by Wilson, Golonka and Barrett).

  5. Reply by Rietveld & Kiverstein, Part 3:
    Finally, Andrew Wilson suggests that relational affordance-based accounts will have problems giving mechanistic explanations. While we have no problem with mechanistic styles of explanation we doubt that it makes sense to try to fit all ecological and dynamical styles of explanation into this box. Mechanistic explanation has its limitations when it comes to accounting for systems that resist compositional analysis which is often the case with self-organizing systems that exhibit non-linear causal behaviors. We therefore think it is important to seek methodologies that complement mechanistic explanations and we are certainly not afraid of causal explanations.

    The Frontiers and Synthese articles just mentioned sketche a framework for developing causal explanations as we see them: multiple simultaneous relevant affordance-related states of action readiness that constrain each other. This kind of dynamical explanation can do justice to nestedness of affordances in the ecological niche –something Wilson and Golonka ignore- as well as to the fact that we respond not just to one affordances at a time (!) but to a whole field of relevant affordances, which includes affordances for so-called 'higher' cognition (see also Kivertein & Rietveld, 2015, Philosophia). Moreover, we have also investigated the causal impact of Deep Brain Stimulation empirically in order to relate our affordance-based account to data on the way Deep Brain Stimulation around the nucleus accumbens impacts the behavior and experience of patients with OCD, which includes changes in certain kinds of higher cognition (Rietveld, de Haan & Denys, BBS; de Haan, Rietveld, Stokhof & Denys, 2013 Frontiers in Human Neuroscience; 2015 PLOS ONE).

    Erik Rietveld & Julian Kiverstein


    Bruineberg, J., Kiverstein, J.D. & Rietveld, E. (2016) The anticipating brain is not a scientist: The free-energy principle from an ecological-enactive perspective. Synthese. doi:10.1007/s11229-016-1239-1

    Rietveld, E. (2016) Situating the embodied mind in landscape of standing affordances for living without chairs: Materializing a philosophical worldview. Journal of Sports Medicine. doi: 1007/s40279-016-0520-2

    Rietveld, E. & Brouwers, A.A. (2016) Optimal grip on affordances in architectural design practices: An ethnography. Phenomenology and the Cognitive Sciences, doi: 10.1007/s11097-016-9475-x

    De Haan, S., Rietveld, E., Stokhof, M. & Denys, D. (2015) Effects of Deep Brain Stimulation on the lived experience of Obsessive-Compulsive Disorder patients: In-depth interviews with 18 patients. PLoS ONE 10(8), pp. 1-29. doi:10.1371/journal.pone.0135524.

    Kiverstein, J. & Rietveld, E. (2015) The Primacy of Skilled Intentionality: On Hutto & Satne’s The Natural Origins of Content. Philosophia 43 (3), pp. 701-721

    Rietveld, E. & Kiverstein, J. (2014) A rich landscape of affordances. Ecological Psychology 26 (4), pp. 325-352.

    Bruineberg, J. & Rietveld, E. (2014) Self-organization, free energy minimization, and optimal grip on a field of affordances. Frontiers in Human Neuroscience 8 (599), pp. 1-14.

    De Haan, S., Rietveld, E., Stokhof, M., & Denys, D. (2013). The phenomenology of deep brain stimulation-induced changes in OCD: an enactive affordance-based model. Frontiers in Human Neuroscience, 7 (653), pp. 1-14.

    Rietveld, E., De Haan, S. & Denys, D (2013), Social affordances in context: What is it that we are bodily responsive to? Invited commentary article on Leo Schilbach et al. BBS, Behavioral and Brain Sciences, p. 436.