Implications For Interface Design Research Articles

How should fitts' law be applied to human-computer interaction?

The paper challenges the notion that any Fitts' Law model can be applied generally to human-computer interaction, and proposes instead that applying Fitts' Law requires knowledge of the users' sequence of movements, direction of movement, and typical movement amplitudes as well as target sizes. Two experiments examined a text selection task with sequences of controlled movements (point-click and point-drag). For the point-click sequence, a Fitt's Law model that used the diagonal across the text object in the direction of pointing (rather than the horizontal extent of the text object) as the target size provided the best fit for the pointing time data, whereas for the point-drag sequence, a Fitts' Law model that used the vertical size of the text object as the target size gave the best fit. Dragging times were fitted well by Fitts' Law models that used either the vertical or horizontal size of the terminal character in the text object. Additional results of note were that pointing in the point-click sequence was consistently faster than in the point-drag sequence, and that pointing in either sequence was consistently faster than dragging. The discussion centres around the need to define task characteristics before applying Fitts' Law to an interface design or analysis, analyses of pointing and of dragging, and implications for interface design.

The use of icons, earcons, and commands in the design of an online hierarchical menu

Important goals for interface designers are to determine when it is beneficial to use iconic or command-based menus and how these traditional menu systems can be enhanced by the use of sound. To investigate this topic, 28 subjects were asked to maneuver through one of four different implementations of an interactive software package in order to execute a target command using either an iconic or command-based menu with or without the use of sound. The sounds descended in pitch as the depth of the menu increased, and were used as an auditory cue to code the location of a particular menu item. The results indicate that icons were more easily remembered than commands, but that commands were easier to locate under the highest level branch of the menu. The results also indicate a trend toward faster performance times with the use of command-based menus in comparison to iconic-based menus designed with the same structure. However, there was no difference in performance within iconic or command-based menus when sound was included in the user interface. Implications for user interface design are discussed. >

Interface design: An educational perspective

Until recently, computer use was confined to a small group of highly trained users. However, the widespread introduction and acceptance of microcomputers in the workplace has created a need for interfaces which are responsive to many different types of users. The authors propose that an iterative design process is essential to developing adaptable easy-to-use interfaces. Supportive evidence is given from CAI design. Similarities between interfaces and CAI are described. Lessons learned from CAI and implications for interface design are presented.

Performance, preference, and visual scan patterns on a menu-based system: implications for interface design

This study was conducted to provide evidence for the nature of visual search processes with menus, and to derive design principles for menu-based natural language (MBNL) interfaces to databases. The effects of window size, window activity, and query length were investigated. It was found that longer queries were performed faster with single active windows, but multiple active windows were rated as more 'natural'. Query times increased with query length, as did eye fixation frequencies, fixation durations, and dwell times. Errors were most likely to occur on the longest query. Fixation durations also varied with window size. However, visual behavior depended on the area being viewed and on the interaction between window activity and query length. In contrast with previous studies, it was also found that menus were not scanned randomly. However, scanpaths were less deterministic with multiple active windows and became even more unconstrained as query length increased. User interface design recommendations were derived from the findings.

Direct Manipulation, Direct Engagement, and Direct Perception: What's Directing What?

The term “direct” has been used quite liberally in recent discussions of human performance and human-machine systems. Shneiderman (1983) discusses “direct manipulation”; Hutchins, Hollan and Norman (1986) discuss “direct engagement”; and Gibson (1979) discusses “direct perception”. This paper will compare these different uses of the term direct and will examine the implications for interface design.

The Society's Lecture 1987 The Use of Models in Human-Computer Interface Design

A user-centred approach to human-computer interface design requires that the designer has appropriate tools to aid in the design process and employs iterative design procedures which incorporate user evaluations. The concept of using models of the user as an interface design tool is discussed, and several approaches to user modelling are described. These approaches are divided into the broad categories of conceptual and quantitative models. Conceptual models deal primarily with representations of users1 cognitive processes, structures and strategies. Quantitative models include performance, ergonomic, computer simulation and statistical models. Examples of both a conceptual and a quantitative model are provided to illustrate human-computer interface design implications. Some unresolved issues pertaining to both categories of models are discussed, and recommendations are made to improve modelling as an interface design tool.

DESIGN STRATEGIES FOR UPGRADING HUMAN PERFORMANCE IN COMPUTER SYSTEMS

A new approach to errors management has emerged in human factors in computer systems. A slogan for the approach was formulated by Norman (1983): "There are no errors: all operations are iterations toward a goal." At the same time, the reality of human errors---actions that deviate from some standard of desired performance and violate some tolerance limits of the systems-still exists. The new "no-errors" approach needs a new conceptual framework to represent the traditional "errors" reality and the activities equivalent to errors management in a different, non-traditional, way. This paper offers such a conceptual framework and its human/computer interface design implications.