Aghillo

Affordance theory was originally developed by James Gibson, a psychologist interested in perception. Affordances were originally defined as ‘action possibilities’ between an animal and its environment. Specifically, the term affordance (clues in the environment) was used to indicate an action possibility that was sensed in an immediate, direct way with no sensory processing required. As an example of this construct, a slide control or push button would, it is claimed, be directly understandable and require no sensory processing. Affordances always exist as a relationship between an organism and its environment. Whilst looking to scramble up a steep, grassy slope trees afford grip to haul you up, rocks afford grip to propel. They also have to be usable, affordances do not exist if they cannot by physically used through lack of height for example. This notion of direct, immediate access to the ‘meaning’ of an affordance without sensory processing is obviously appealing to designers of products. It was popularised in human computer interface circles after Donald Norman used the concepts in Psychology of Everyday Things.

In Norman’s view of interface design the notion of affordance was used alongside conceptual models and conventions to aid a designer. However, as interest in affordances grew he became concerned that discussion about them in hci circles was wandering further and further away from his original intention. Norman has expressed his dissatisfaction on this and distinguishes conceptual models, real affordances, perceived affordances, constraints and conventions.
Conceptual models provide the logic for how an interface works and provide a base for reasoning about possible actions in an interface. Real affordances are all the affordances that physically exist, but may not actually provide access to a designer’s intention. Perceived affordances are those that the designer has managed to make readily accessible and understandable to the user of the interface. Constraints exist in physical and logical form – an example of a physical constraint would be where a section of a monitor does not provide cursor feedback so it’s clear that no actions are possible in that areas. A logical constraint allows reasoning to be made about possibilities for example where a user is asked to click on five locations, but only four are visible. The user knows logically that another location must exist and can look for it using, e.g., scroll bars. Scroll bars are in turn examples of cultural conventions which have become to be accepted within communities. They are understood precisely because of their ubiquitous nature which has developed over time.

Norman is very clear on his wish to see these different aspects of interface design clearly separated out to help analysis and subsequent design. It is clear how an individual designer’s role can be much stronger in the development of intended perceived affordances of a product (they can have direct influence on this) whilst it is more difficult to change cultural constraints (at least in the short term).

When one thinks of traditional interaction with computing technology the vision that tends to be immediately conjured-up is that of a typical personal computer. A box containing all the essential digital technologies such as processor, memory and hard disk; a graphical screen for display, the visual output, perhaps speakers for audio output; for input the traditional image is that of keyboard and mouse. Interaction takes place though key presses, through button presses using the mouse, and output takes place through the screen and speakers as previously mentioned.
However, interactions do not need to be like that. In the world of tangible interaction effort has been made to connect digital data with physical representations so that control of any underlying data is effected through direct manipulation of physical objects. It is a world where computer scientist meets product designer; where artists meet robotics experts. This is an area where cross-disciplinary skills will be required in abundance.
This need to work across discipline boundaries, to integrate different skills, is highlighted in [Baskinger & Gross 2010] where the authors point out that ‘Tangible interaction practitioners, researchers, and educators integrate knowledge from many areas. They draw upon traditional design, engineering, computing, and robotics in a mashup of skills and methods—thinking and making in physical form, electronics, and code’. This phrase is particularly noteworthy as it identifies the types of skills, working practices and perhaps challenges that are sure to emerge as a possible new discipline takes shape.

The Hit Me Interactive Lamp was designed by Carnegie Mellon students Henry Julier, Justin Rheinfrank, Amanda Ip, and Michael Cruz-Restrepo. It responds directly to different touches. If finger tips are pressed on the lamp then this is reflected through individual leds lighting up and a corresponding pattern appearing. If the palm of a hand is placed over the lamp then it responds with a diffuse glow. The lamp also responds to the length of time it is touched – so quick touches result in lights flashing, prolonged touching ensures the lamp stays on.

These paper robots were designed by Greg Saul from Carnegie Mellon and Victoria University of Wellington. They make use of special materials called ‘Shape-Memory-Alloys’ for actuators, gold leaf printed circuits and embedded microchips for intelligence and can be programmed to respond to light, sound or on-line chat. Their designer was interested in ‘using new technologies, materials and information channels to create systems instead of designs or perhaps more accurately designs that are a dialogue between the user and the designer with computer program as mediation’.

These examples are interesting and embody, in simple ways, the types of knowledge and skills that are required in this area.