User-computer
dialogues are typically one-sided, with the bandwidth from computer to user far
greater than that from user to computer. The movement of a user’s eyes can
provide a convenient, natural, and high-bandwidth source of additional user
input, to help redress this imbalance. We therefore investigate the
introduction of eye movements as a computer input medium. Our emphasis is on
the study of interaction techniques that incorporate eye movements into the
user-computer dialogue in a convenient and natural way.
This chapter
describes research at NRL on developing such interaction techniques and the
broader issues raised by non-command-based interaction styles. It discusses
some of the human factors and technical considerations that arise in trying to
use eye movements as an input medium, describes our approach and the first eye
movement-based interaction techniques that we have devised and implemented in
our laboratory, reports our experiences and observations on them, and considers
eye movement-based interaction as an exemplar of a new, more general class of
non-command-based user-computer interaction.
In searching for
better interfaces between users and their computers, an additional mode of
communication between the two parties would be of great use. The problem of
human computer interaction can be viewed as two powerful information processors
(human and computer) attempting to communicate with each other via a
narrow-bandwidth, highly constrained interface. Faster, more natural, more
convenient (and, particularly, more parallel, less sequential) means for users
and computers to exchange information are needed to increase the useful
bandwidth across that interface. On the user’s side, the constraints are in the
nature of the communication organs and abilities with which humans are endowed;
on the computer side, the only constraint is the range of devices and
interaction techniques that we can invent and their performance.
Current technology has been stronger in the
computer-to-user direction than user-to-computer, hence today’s user-computer
dialogues are typically one-sided, with the bandwidth from the computer to the
user far greater than that from user to computer. We are especially interested
in input media that can help redress this imbalance by obtaining data from the
user conveniently and rapidly. We therefore investigate the possibility of
using the movements of a user’s eyes to provide a high-bandwidth source of
additional user input. While the technology for measuring a user’s visual line
of gaze (where he or she is looking in space) and reporting it in real time has
been improving, what is needed is appropriate interaction techniques that
incorporate eye movements into the user-computer dialogue in a convenient and
natural way.
An interaction
technique is a way of using a physical input device to perform a generic task
in a human-computer dialogue. Because eye movements are so different from
conventional computer inputs, our basic approach to designing interaction
techniques has been, wherever possible, to obtain information from the natural
movements of the user’s eye while viewing the display, rather than requiring
the user to make specific trained eye movements to actuate the system. We
therefore begin by studying the characteristics of natural eye movements and
then attempt to recognize corresponding patterns in the raw data obtainable
from the eye tracker, convert them into tokens with higher-level meaning, and
then build dialogues based on the known characteristics of eye movements. In
addition, eye movement-based interaction techniques provide a useful exemplar
of a new, non-command style of interaction.
Some of the qualities
that distinguish eye movement based interaction from more conventional types of
interaction are shared by other newly emerging styles of human-computer
interaction that can collectively be characterized as ‘‘non command-based.’’ In
a non-command-based dialogue, the user does not issue specific commands;
instead, the computer passively observes the user and provides appropriate
responses. Non-command-based interfaces will also have a significant effect on
user interface software because of their emphasis on continuous, parallel input
streams and real-time timing constraints, in contrast to conventional
single-thread dialogues based on discrete tokens. We describe the simple user
interface management system and user interface description language
incorporated into our system and the more general requirements of user
interface software for highly interactive, non-command styles of interaction.
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