From early cave paintings to ancient writings through television and computational media, humanity continually demonstrates a proclivity to abstract our symbolic capacities onto two-dimensional substrates. The application of this insight by Doug Engelbart and others laid the foundation for any number of advances in interface design, from the two-dimensional arrangement of pixels in graphical user interface, to the x/y coordinates that a technology like a mouse and cursor depends upon, finally to touchscreen design.
The principle, however, that computational interfaces in their current iteration consist of screens constructed of rows of “picture elements,” or pixels, which respond to programmed signals which indicate color, darkness, and position easily recedes from the forefront of conscious thought when using even the most basic functioning interfaces. The WordPress interface used for this course, for example, functions primarily as a text input program. However, as students write their weekly reflections, one can only assume that it is only upon the rarest occasion that they consider how every keystroke signals to the computer and the website interface, triggering a complex sequence of commands which finally result in “lighting up” the set of pixels correlated with the letter-form which they typed. Conversely, when one presses the backspace key, they do not really “erase” the previous character, they simply trigger the command which communicates that the correlating pixels ought to return to the previous state of the background color (white in this case). The same goes for functions like bold, italics, text alignments, and even hyperlinks. While other affordances may also be triggered by something like hyperlinks, the immediate, human-perceptible change (i.e. black text to blue, underlined text) is nothing more than a sequence of commands correlating to tiny elements of light arranged on an x/y axis.
The difficulty in interface design, to which I find myself continually returning, is that as people become more and more accustomed to the abstracted designs of an interface, the less and less they have to think about the black-boxed system of physical phenomena which ultimately underlay the entire process. Certainly, in cases like pixels, which only concerns the most basic, and fundamental level of an interface design, the stakes are relatively low. However, in many cases, designed interfaces which hide the physicality of computing only leads to confusion about the limits of computational media and promotes a perception that the digital is the same as the magical.
Martin Irvine, From Cognitive Interfaces to Interaction Designs with Touch Screens