*Creating Affording Situations*

In Psychology and Human-Computer Interaction, the concept of 'affordance' relates to the ways in which a person's action is performed in response to their perception of the environment [34–37]. Gibson [36] introduced the term affordance into psychology, suggesting that we perceive the world in term of opportunities for action. What an object affords is determined by the physical properties of the objects (e.g., shape, orientation, size), and by the action capabilities of the agent and by the intention that the use of this object will support. Affordance effects for graspable objects can be manipulated by changing the size of the object, orientation, location and congruence. The spatial location of the handle influences stimulus identification in neglect patients, extinction patients and healthy participants. The end state comfort effect can be seen with participants having an uncomfortable grip at the beginning, then ending an action with a comfortable grip [39]. Participants who choose a grasp which was consistent with the end state comfort had a quicker reaction and movement time. Thus, an affordance is the relationship between an individual's ability to act and the opportunities provided to that person in the given situation in pursuit of a given intention. That is, a cup of particular dimensions can be grasped by a person of particular abilities in the context of performing a task with a particular intended goal: a person with hemiparesis might struggle to use a pinch grasp on a small teacup handle; a person with tremor might find it difficult to raise a full cup to their mouth (without spillage). A person laying the table will pick up the cup differently than a person who intends to drink from it.

From this perspective, one can consider coaching in terms of the form of encouragement of, and support for, actions which are appropriate to a given context (defined by objects, person's abilities and intentions). We aim to create 'affording situations' in which the appropriate action is subtly cued by the objects that the person needs to use. In this way, cueing is embedded naturally into the familiar world of the person's home, and coaching is a matter of responding to these cues.

The manner in which a person interacts with an object can be used to infer the physical and cognitive difficulties they might be experiencing in performing the task. As the person interacts with the object, data (from sensors on the object) will be used to define the nature of the atomic tasks being performed and, from these data, the intended outcome can be inferred. Having inferred a possible outcome, objects can modify their state to invite or cue subsequent actions, or provide feedback on the task as it is performed.

The concept of affording situations is intended to highlight the importance of context in understanding affordance; it is not simply a matter of saying that a 'jug affords lifting or pouring'. While these are actions that are, of course, possible with the jug, in order to know that this particular jug can be lifted or poured by this particular person, one also needs to know the capabilities of the person. Furthermore, in order to know whether either lifting or pouring is an appropriate action to make, one also needs to know the intention of the person (or the intention that could be plausible in that situation). Our aim is to develop technology that can recognize and interpret these contextual factors and use these to discern the plausibility of actions in a given sequence. We can then adapt the technology to provide cues that are intended to encourage the user to perform these actions. In this manner, coaching becomes a matter of creating the situations in which users of objects can learn to associate an object with an action, and an action with an intention, and an intention with a desirable outcome.
