We have started our seminar meetings on the subject of space and cognition, and a big deal of the debate will be centered in the concept of affordance. On theoretical issues, we plan to combine research in neurophenomenology with the experimental tradition in philosophy of science, as well as the paradigm of distributed cognotion. Practically we'd like to establish a set of principles which could be used to analyse how the spatial distribution of research instruments and objects can be improved in order to facilitate the cognitive process in scientists.
To do so, a key concept is affordance. And our first discussion will deal with the basic ambiguity this term has in philosophical and psychological literature. Are affordances physical or relational? According to the creator or the Term, J.Gibson, we should consider affordance as physical properties that object can have, and humans can perceive them. However this does clash with a more phenomenological approach, from the cognitive readings of Heidegger by Dreyfuss to what emerges from system theory and the way it is been used, for example, by Norman.
This entry from the Encyclopedia at Interaction-Design.org presents a brief but excelent explanation of the main differents between the two conceptions.
Here you find some notes from Gibson himself on how affordances can be classified, showing again the more physicalist approach to the subject. You can also check the notes of Gibson on a reclassification of affordances, as well as this interesting reflection on the differences between perception and proprioception.
My own view on the subject is clearly towards a relational position. First of all, affordances only makes sense as long as there is a user who can find the affordance useful for something. Secondly, from an embodied mind framework, the mind makes the thermometer as well as the thermometer makes the mind.