The name Affordance (Gibson, 1979), concerns the relationship between the visuo-motor system of living organisms and the spatio-temporal distribution of electromagnetic energy to which the different visual systems are sensible, it has his root in the evolutionary process. Don Norman (1988) at that time in theoretical disagreement with Gibson was nevertheless charmed by the essence of the affordance concept: the electromagnetic distribution of energy have privileged handling modalities, they afford specific actions. Norman re-conceptualized the Affordance according to his cognitive psychology root and made of it part of the answer to his questions of that days: How do we manage to face a world populated by thousands of objects that may be we meet only once in our life? When we encounter an artefact that we never saw before how do we know what it does and what we can do with it? Affordances belonged to the answer: the perceptual appearance of a device can provide the proper suggestions for it use. The relational essence was safe also in the cognitive perspective.
The Affordance concept got smoothly into the design domain, but far from being a unitary and unanimous concept it waved between the Cognitive psychology of Norman and the Ecological psychology of Gibson. Which is, to me, just the beginning of the story. The %u201Copportunities for privileged modalities of action for a given animal%u201D, was a less intriguing aspect of Gibson%u2019s idea, a more fascinating, specially considering the time it was proposed (the %u201970), was the collapse of distinction between perception and action. The end of the distinction between perception and action is crucial to appreciate properly the Gibsonian concept of affordance. Let%u2019s see why, and also why this is just the start of the story up today. The interaction between the features of the handle with that of the human visuo-motors system as a whole determine the affordance. When I grasp the vertical cylindrical bar with the extended arm I am in propitious condition for pulling, when I put my hand on the flat horizontal bar it is easier to push. It is straightforward to figure out that if an handle of given shape and dimension will afford pulling it will depend from the characteristics of a given person, that is from her/his height, hand dimension, physical strength, etc. But we are just facing the first step of a long journey. How does a phone afford calling? Or, a computer checking mail? The examples quoting pulling, throwing, falling, concern all actions we can perform almost since ever (both from a phylogenetic and from an ontogenetic point of view). The action we perform through the thousands of artefacts that populate our environment (do you remember Norman%u2019s questions?) are still rooted in motor acts such as pushing, grasping, touching, pulling etc. but no one learns about the external would just learning the motor pattern for typing numbers on the phone, or the motor pattern for getting a ticket from an automatic ticket machine, or for stroking on the keyboard of a computer. The story goes that in our brain do exist areas dedicated to motor coordination and even neurons that fires only when a specific motor patter is executed (motor neuron), but do exists neurons that fires when we grasp an object with the left hand, with the right hand or with our mouth. These neurons do not codify movements but goals - they codify grasping. When they become active, their firing tells to the individual: %u201Cgrasp%u201D. The discovery of these neurons was a surprise for the same researchers coordinated by Giacomo Rizzolatti. The existence of these neurons gave the same ontological dignity to visual stimuli produced by physical reality, such as the existence of vertical and horizontal bar in the visual field and to the psychological construct of the grasping or throwing goals. To continue in the following post%u2026 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Posted from the new ixda.org http://www.ixda.org/discuss?post=27380 ________________________________________________________________ Welcome to the Interaction Design Association (IxDA)! To post to this list ....... [EMAIL PROTECTED] Unsubscribe ................ http://www.ixda.org/unsubscribe List Guidelines ............ http://www.ixda.org/guidelines List Help .................. http://www.ixda.org/help
