Human-computer interaction (HCI) is fundamentally an
information-processing task. In interacting with a computer, a
user has specific goals and subgoals in mind. The user initiates
the interaction by giving the computer commands that are directed
toward accomplishing those goals. The commands may
activate software programs designed to allow specific types of
tasks, such as word processing or statistical analysis to be performed.
The resulting computer output, typically displayed on a
screen, must provide adequate information for the user to complete
the next step, or the user must enter another command to
obtain the desired output from the computer. The sequence of
interactions to accomplish the goals may be long and complex,
and several alternative sequences, differing in efficiency, may be
used to achieve these goals. During the interaction, the user is required
to identify displayed information, select responses based
on the displayed information, and execute those responses. The
user must search the displayed information and attend to the appropriate
aspects of it. She or he must also recall the commands
and resulting consequences of those commands for different
programs, remember information specific to the task that is being
performed, and make decisions and solve problems during
the process. For the interaction between the computer and user
to be efficient, the interface must be designed in accordance with
the user’s information processing capabilities.