Information Technology Reference
In-Depth Information
Figure 3.1.
The “fl ying wedge”: A plot is a progression from the possible
to the probable to the necessary.
The shape of potential over time in human-computer interaction is
similar to the “fl ying wedge.” In a play, the result of this successive for-
mulation is a completed plot—a
whole action
. What is the human-computer
equivalent? As we noted previously, a “whole” human-computer interac-
tion can be described, using the broad defi nition of a whole action, as hav-
ing a beginning, middle, and end and being composed of incidents (one or
more) that are parts of that whole. Thus, playing a computer game until it
ends (or I end it) or a “session” with an ongoing computer game can be a
whole action, and a “session” with my word processor can be a whole ac-
tion (even if I don't fi nish the chapter I'm writing).
With adequate magnitude along the temporal axis, human-computer
activities can be seen to formulate potential in the same way that drama
does—as a progression from possibility to probability to necessity. The
opening display (which may or may not be multisensory) begins the pro-
cess of delimiting potential. Every action taken by an agent, including both
human and computer-based agent(s), creates further possibilities and con-
straints as the activity takes shape (see Figure 3.2). Thinking about things
this way helps us to focus on how incidents can be arranged and caus-
ally linked. A human-computer activity, unlike a play, may be formulated
uniquely every time it is performed. The source of variability is people,
through their choices and actions, which in turn refl ect different goals,
