Treu’s approach to human-computer interface design and evaluation has the goal of systematizing these processes. He favors an engineering approach in order to provide for timely consideration of alternative techniques.

The first book, User interface design, begins with a brief historical overview and definition of terms in Part 1. Following this, in Part 2, Treu presents six chapters about the “prerequisite knowledge areas” for human-computer interface (HCI) design. These areas are user capabilities and limitations; computer applications and tasks; computer capabilities and limitations; interaction characteristics and options; representation models and methods; and supportive tools and techniques. Treu uses a definitional presentation to systematize the language of HCI development. A key element in this approach is the use of a “symbolic functional view” to consolidate the factors affecting decision-making during design. This feature is described as a “functionlike mapping of various inputs to a design decision into the desired outcomes, or design features.” It is presented as a formula, which Treu translates as “For each (the nth) decision, we require the HCI designer to have a wealth of KNOWLEDGE and to use relevant PRINCIPLES and FACTORS in order to decide on the FEATURES that are most appropriate and desirable. …” At the end of each chapter, the “symbolic functional view” is updated based on the information developed in the chapter.

Parts 3 and 4 apply the knowledge identified in Part 2 to a design process. Chapters on design terms and decision constructs; design approaches and methods; and design objects, modules, and models present a general design process. Two chapters follow that consider network-oriented and adaptive design as special-purpose applications of the general model. Of particular value is Table 9.1, a list of user-oriented design principles, which presents desirable characteristics and briefly describes their purposes.

The second book, User interface evaluation, is a partner to Treu’s book on design. Following two chapters that recap the main points of the design book, Treu again develops “the materials deemed prerequisite for the development and use of methodology for objective measurement and evaluation of user interfaces.” In three chapters about supportive tools and techniques, interface structures, and basic measures of performance, Treu lays the groundwork for measuring the efficiency and effectiveness of interfaces. A key element in Treu’s structured approach is distinguishing several types of interface structures. Treu’s structures identify the conceptual, logical, and physical patterns that underlie the user and computer models. They were developed based on both human and computer memory elements, with the emphasis on structures that are at the intersection of the two sets. For example, the S-structure, which represents sets of objects represented by sets of features, is considered basic to both human and computer memory, and is the basis of many information retrieval systems that use Boolean combinations of query terms. Interface structures are emphasized by their appearance in leading roles in three chapters--one for their introduction and explication, and two to extend the concept.

Treu places measurement in a distinguished role as well. The subject is developed extensively in Part 3. Treu provides three useful tables that note 30 quantitative measures based on time, length, volume, multiplicities, and rates for tasks and events commonly found in human-computer interaction. In a later chapter, he develops a method for tailoring measures to a project. Part 4 of the book considers four special topics--the two mentioned above as extending the concept of interface structures, and two that consider the user directly, stress and user satisfaction, and interaction and mental involvement.

A number of features are provided as learning aids for the reader. Each book contains a page that outlines the organization and chapter titles for both volumes, giving the reader the chance to build a framework for the new material. Each part begins with a brief overview of each chapter and its role in the developing theme. These are useful for both learning and reviewing. Each chapter begins with an illustration of the part of the design or evaluation system to be examined (thus highlighting its relationship to other system components), and finishes with a series of exercises, constructed to require thought and interaction with the new material in the chapter.

Noticeable for its absence is an easy way to find the definitions of the many terms introduced and used in these texts. The physical separation of the design and evaluation material is unfortunate, since it fosters a mental separation that is at odds with the integrated consideration of all factors during design.

Treu, consistent with his goal of presenting a structured approach to design and evaluation, presents abstractions of those processes. In spite of several examples from his personal experience, these abstractions may not be easily applied to a real problem by a beginning student of design and evaluation. For this reason, the most suitable audience for these volumes might be advanced undergraduates and graduate students, who have a firm foundation in software engineering practices and theory and are able to extend their knowledge to the specialized area of human-computer interfaces and interaction. The two-volume set is a good read for working professionals as well, and is recommended for serious students of the theory of evaluation.