TW%SU-AI@sri-unix.UUCP (01/31/84)
From: Terry Winograd <TW@SU-AI>
[Reprinted from the SU-SCORE bboard.]
Talkware Seminar (CS 377)
Date: Feb 6
Speaker: Thomas P. Moran, Xerox PARC
Topic: Command Language Systems, Conceptual Models, and Tasks
Time: 2:15-4
Place: 200-205
Perhaps the most important property for the usability of command language
systems is consistency. This notion usually refers to the internal
(self-) consistency of the language. But I would like to reorient the
notion of consistency to focus on the task domain for which the system
is designed. I will introduce a task analysis technique, called
External-Internal Task (ETIT) analysis. It is based on the idea that
tasks in the external world must be reformulated in to the internal
concepts of a computer system before the system can be used. The
analysis is in the form of a mapping between sets of external tasks and
internal tasks. The mapping can be either direct (in the form of rules)
or "mediated" by a conceptual model of how the system works. The direct
mapping shows how a user can appear to understand a system, yet have no
idea how it "really" works. Example analyses of several text editing
systems and, for contrast, copiers will be presented; and various
properties of the systems will be derived from the analysis. Further,
it is shown how this analysis can be used to assess the potential
transfer of knowledge from one system to another, i.e., how much knowing
one system helps with learning another. Exploration of this kind of
analysis is preliminary, and several issues will be raised for
discussion.