Visible interactive elements (as and when they are necessary) – If we are unable to see or find the operable parts, how are we going to establish what we can do? Ensure the parts necessary for a particular task are made available and are made apparent at the appropriate time.
Accurate Conceptual Models
Don Norman defined conceptual models as, “mental simulations of devices that enable users to judge the means of operation and possible uses”. An alternative definition provided by Jeff Johnson and Austin Henderson (2002) in Conceptual Models: Core to Good Design states a conceptual model is “…a high-level description of how a system is organized and operates”. When faced with an object, a person must determine what they can do with it and how they can carry out these possible functions.
Natural Mapping
(wherever possible) – Norman stated natural mappings occur where objects have obvious functions or affordances. A natural mapping occurs at a primitive level and trades on our state as innately spatial beings. When we have achieved familiarity with the spatial qualities of an object we can then map these to new demands, leading to new intuitive spatial mappings. It is through this process we learn how to manipulate our environment; a notion that forms the basis of behavioral learning theory, which acknowledges the human ability to extrapolate information derived from one situation to another. This is especially important when designing tangible devices used for the purpose of interacting with and manipulating characters, events, and elements within a graphical user interface.
Visible Results
When we interact with physical objects this usually brings about some change in its perceptible state. For example, when we push a button on a remote control we can feel the depression, hear the click, and (depending on how much our finger or thumb obscures the device) see it sink within the surrounding plastic body. These changes inform us that our actions have had some effect on the object. Graphical objects (i.e. those found in graphical user interfaces) must also change in response to interaction, as this helps users determine whether their actions have induced some effect in the programme, system, software or application.
Proportional and Meaningful Feedback
This is tied with the need for visible results, as not only must objects, both physical and graphical, change as a result of users’ interactions, they must also inform the user, in a meaningful way, whether their actions have been successful or not. This is much less of an issue when dealing with physical objects, as there is a natural, intuitive relationship between real-world object-human interaction and the changes that occur in the object’s state(s). However, graphical objects have no ‘natural’ state, which means any changes must be designed and programmed. Therefore, it is essential that graphical objects are designed to support behavioral processing in the same way physical objects in the real world. So they must provide us with sufficient perceptual information on which to gauge the effectiveness of our interaction(s).
