Research Summary Pt. 4 Usability and Multiplexing



Feedforward is the idea in user interface design that a function is able to give some indication of what will happen when we interact with it. How we do this is really at the will of the designer, and we must have a keen understanding of signifiers, affordances and information display in order to manage this. In tangible products Djajadiningrat et al note:

“For a control to say something about the function that it triggers, we need to move away from designs in which all controls look the same.”


Mapping is the relationship between how information is carried across physical and digtial mediums. For example if a row of switches operates a row of lights in the same order, this might be considered a natural mapping, as the spatial relationship of the switches matches the spatial relationship of the lights. 

Difficulties occur when we begin to map abstract concepts we cannot physically interact with Djajadiningrat et al highlight

“Natural mapping falls short when dealing with abstract data that has no physical counterpart.”


Contraints are the ways in which physical controls offer specific limitations with how a system is used. If we think about our Mercedes and Tesla examples, we can see these emerging. The driving experience is already very defined, yet there are additional constraints imposed by digital systems and methods of control.


Multiplexing is the concept of allowing mulitple methods of input to happen with one device. Maybe the best example of this concept is a computer mouse click. We can move the device and a click will have a different effect on the system, we can double click and that will have another effect again, or we can click and drag.

These different gestures create multiple methods of input possible with one modality of interaction. Multiplexing breaks down into two main methods. Spatial, and Time Based Multiplexing

Spatial Multiplexing


Time Based Multiplexing