Lesson 03: Human Computer Interaction

Lesson Objectives

Human computer interaction (HCI) is a growing field of study. Models assist HCI workers in decision making. This lesson describes two well known HCI models. Good human computer interaction work and design leads to favorable results including increasing worker productivity and satisfaction, reducing costs, and reducing errors. Good HCI is clearly imperative to a successful design process.

After reading this lesson, you should be able to:

• Identify the characteristics of human-computer interaction.
• Identify behavioral and cognitive user characteristics.

Human computer interaction (HCI) is the study of human interaction with computer interfaces and the development of computer based interfaces to support effective user-computer tasks and interaction. Human computer interaction work involves the detailed study of users' tasks, goals, and behaviors when using computer systems and interfaces.

HCI workers develop new computer applications and interface, and then test and evaluate new interactive computer devices and interfaces. For example, when designing a Web search engine interface, an HCI worker seeks to understand how users look for information on the Web, how users decide what action to take, and what information do users need to plan a strategy for performing the task.

HCI workers must decide what information users need to perform a HCI task. They also consider the cognitive effort involved in a task (the number of mental transformations), how to display information on a computer interface so that it is most comprehensible and perceptible to the user. For example, HCI workers examine how to design more effective word processors and Web search engines.

HCI Model: Foley

Foley (1980) provides a comprehensive HCI model that includes the following four levels:

The first stage is the conceptual level understanding of the user's mental model of the HCI task. Users may have different mental images of the HCI task. For example, users have very different mental pictures of the Web. If you ask people to draw a picture of the Web, these pictures might include the following very different representations: hierarchy, telecom, library system, network, and 3-D web. Another example is that some users equate using a word processor with a typewriter interaction; a computer keyboard is similar to a typewriter keyboard.

The semantic level understanding includes the meaning of the user's input to the computer and the computer's output to the user. The input-output feedback loop between user and system only works effectively if the computer understands the user's input and the user understands the system's output. This can be a problem if the system's output is culturally based. For example, Americans understand the "trash" icon, but the British use the word garbage and may not understand the "trash" icon.

In the syntactic level, there is an understanding of how the words used are assembled into meaningful sentences that instruct the computer to perform a certain task. HCI works well when users can express their needs in meaningful sentences to the computer. For example, users often have problems expressing their information need to a Web search engine.

The fourth level, the lexical level, includes understanding user's mechanisms when structuring their interaction with the computer. A user's interaction with a computer is structured by the person who developed the interface. If the interface does not allow the user to structure their interaction in a user friendly way, the system interaction may not be satisfactory. For example, when looking for information, people often ask questions of other people. Many Web search engines do not allow the user to ask the computer a question in natural human language or conversation style. A classic site that does allow questions is the Ask Jeeves site.

Norman (1988) provides the following goal-oriented staged model of user's interaction with a computer:

1. Forming the goal of the HCI interaction: User's interact with a computer to solve a problem or achieve a goal. For example, a user's goal may be to find information about motor boats by using a Web search engine.
2. Forming the intention of the HCI interaction: Having established a goal for their interaction with a computer, users must form an intention to use the computer.
3. Specifying the HCI action to be performed: An interface must clearly specify the actions users need to perform. For example, if the user does not clearly understand the correct commands or instructions to conduct an interaction with a Web search engine, their HCI interaction may fail.
4. Executing an action with the computer: A user's HCI interaction must be error free and achieve the correct action. For example, the interface must provide effective help systems.
5. Perceiving the systems state through feedback: The computer output must be in a form that the user is able to see the feedback. System responses must be visible and readable by the user. The size of text and images must be large enough to read.
6. Interpreting the systems state through feedback: The computer output must be in a form that the user is able to understand the feedback. System responses must be comprehensible and understandable by the user. Many computer responses to users input are incomprehensible and are often ignored by users.
7. Evaluating the systems output: Users must be able to evaluate the systems output correctly and effectively. For example, most Web search engines display the results of a user's query as a list of Web sites. Frequently, users do not understand the structure of this Web site list, and how it is ranked and determined by the system.

Good HCI Work and Design

Solid HCI work serves as the foundation to obtaining the following results. Good human computer interaction work and design is important for obtaining these measurable outcomes:

• Increasing worker productivity
• Increasing worker satisfaction and commitment
• Reducing training costs
• Reducing errors during interface interaction
• Reducing production costs

Increase in Worker Productivity, Satisfaction, and Commitment

Good human computer interaction work and design is important for increasing worker productivity. If workers have problems using computer interfaces, due to poor design, their work effectiveness can be reduced. Effectively designed interfaces that offer customization for users can increase user's work satisfaction. For example, a military fighter plane must have highly effective HCI interfaces to allow pilots to make quick and effective decisions and actions.

Good human computer interaction work and design is important for increasing worker satisfaction. Improved interfaces design can lead to increased worker satisfaction and allow users to achieve their work goals.

Good human computer interaction work and design is important for increasing job commitment by reducing worker turnover. Poor quality interfaces can lead to stress and strain on users both mentally and physically. Users may experience sore muscles or eye strain due to poor HCI interfaces and computer design. Workers may leave their jobs if they are dissatisfied with their HCI experience.

Reduction in Training Costs, Errors, and Production Costs

Good human computer interaction work and design is important for reducing training costs. Poor HCI interfaces may require extensive and expensive user training. Good interfaces with effective online or manual training documents and user system guides can help users to master their system interaction quickly. For example, commercial pilots learn to fly airplanes using computer-based cockpit simulators.

Good human computer interaction work and design is important for reducing errors during interface interaction. Effective interfaces and user training can reduce errors in system use. For example, an effective retail interface can reduce the time taken to complete a sale. Also, most of the problems that led to the Pennsylvania Three Mile Island nuclear power plant disaster were due to poorly designed computer systems.

Good human computer interaction work and design is important for reducing production costs. Effective interfaces allow workers to produce better quality products and services. For example, an effective Website can assist users to view products and services offered by companies, including better customer services.

Lesson Wrap-Up

Two classic models of HCI help us recognize the behavior and needs of users. The Foley model of HCI provides four levels of user understanding. The Norman model of HCI provides a goal-oriented staged model. As you now know, good HCI is important for obtaining measurable outcomes. Well designed computer interfaces can save time, money, and lives. Airline pilots, for example, need well designed computer interfaces to successfully accomplish their jobs.

Now that you have completed this lesson, you should be able to:

• Identify the characteristics of human-computer interaction.
• Identify behavioral and cognitive user characteristics.

Additional Human-Computer Interaction Readings:

Carroll, J. M. (Ed.). (2003). HCI models, theories, and frameworks towards a multidisciplinary science. San Francisco: Morgan Kaufmann.

Dix, A., Finlay, J., Abowd, G., & Beale, R. (1999). Human-computer interaction. (2nd ed.) London: Prentice Hall.

Foley, J. D. (1980). The structure of interactive command languages. In R. A. Guedj, P. ten Hagen, F. R. Hopgood, H. Tucker, & D. A. Duce (Eds.), Methodology of interaction (pp. 227-234). Amsterdam: North-Holland.

Morville, P., & Rosenfeld, L. (2002). Information architecture for the world wide web (2nd ed.). Sebastopol, CA: O'Reilly.

Norman, D. A. (1988). The psychology of everyday things. New York: Basic Books.