The dialogue of Interaction Design exists between a person and a product, system or service. This dialogue is both physical and emotional in nature, and is manifested in form, function and technology. While Interaction Designers frequently work on projects related to computing, the field in and of itself has nothing inherently to do with computers. Instead, the field is best thought of in terms of a methodology, and the major contribution an Interaction Designer can provide in a business setting is a strong process that connects people, technology, and the emotional qualities of sensory data (generally pertaining to aesthetics). One can consider the results of this process as the design of human behavior. The methodology is usually characterized by several distinct phases. For example, an Interaction Design project may begin with understanding, move to a phase of generative synthesis, progress through creation and testing, and end with implementation or “execution”.

Usable, Useful and Desirable

Many practitioners engaged in human-centered design activities have adopted the platitude that designed products should be “usable, useful and desirable”. Liz Sanders, former Vice President at Fitch RichardsonSmith, coined this phrase in an effort to illustrate the necessity of converging perspectives in research 22. The three terms are closely linked, but each implies a quite separate facet of design. While many reference these three traits as goals of design activities, it is rare to find a product that fulfills two of the three characteristics; a product that touches all three is a rare gem of design.

Usable implies a strong and close connection between the functionality of the product and the abilities of the end user. People—or “users”, in a more clinical sense—have limits that impede their ability to perform. These limits include memory, perception and cognition. Many are innate, and rarely do users consider the boundaries (or existence) of these limitations. Nor should they—most people are busy enough without having to consider how many units may be currently stored in short term memory or how bright a stimulus is shining. Usable implies that users can understand the purpose of a product, can form strong understandings of how the product will work for them, and can deduce how to go about manipulating the product in order to achieve a goal. Very often, usability is tied to learnability: how quickly can one understand a novel system? Additionally, usability is frequently judged according to metrics such as “number of errors” or “time on task”. This is statistically relevant data when considering a system as technology, but clearly does little to address or track the more emotional issues of happiness or joy.

Useful generally refers to the match between a system’s functionality and the goals the user has in mind. Goals can be thought of as end results that someone may wish to accomplish. Products provide utility only when they allow the user to successfully meet the requirements he has (implicitly or explicitly) defined. For example, a user may wish to write a letter to all of the friends he has not communicated with in “a long time.” An email system may or may not provide an easy way to accomplish this goal. If the system behaves in a usable fashion, but simply does not allow this user to achieve this task, it has not proven to be useful. Computers are bad at dealing with human utterances like “a long time”, yet humans achieve a great deal of usefulness out of these ill-formed phrases. Usefulness is often considered after the fact, as marketing attempts to persuade us that we require more utility in our lives. Advertising pitches features of a product, and packaging of consumer electronics frequently alludes to the number of features. While the naive may be persuaded by a large quantity of functions presented by a product, some quickly learn that all of the functionality in the world is useless if the useful functions aren’t present.

Desirability is the fleeting idea associated with emotions—that a product may successfully fill an emotional, or subjective (and often superficial) niche within an audience. Physical product designers—or Industrial Designers—have long understood the importance of creating objects of beauty and desire. Consider the extra amount of money someone may pay for a Jaguar or a BMW. While the engine is probably superior to that of a Honda of a Ford, most users will rarely venture under the hood to find out. Instead, the aesthetic—or sensory experience—of the vehicle appeals to users on a level that is innate, passionate, and frequently illogical.

This section describes the three facets of Interaction Design, and the Interaction Design Process. It begins with a discussion of the procedural focus of Interaction Design as it pertains to designing what people want and need. The role of intuition is examined as compared to the necessity for ethnographic user research. This is followed by an investigation into the role aesthetics play in the development of Interaction Design solutions, specifically with regard to brand and identity. Finally, the role technology plays in the development of Interaction Design solutions is examined, with attention placed on the relatively new subfield of Information Architecture as applied to the design of technology-driven products.

22. The phrase “usable, useful and desirable” was first presented in a Design Management Institute article authored by Liz Sanders. The article was entitled “Converging Perspectives: Product Development Research for the 1990s”, in Volume 3, No 4, Fall, 1992.