Mark C. Detweiler

Iconic reference: evolving perspectives and an organizing framework

Abstract Icons are now routinely used in human-computer interactions. Despite their widespread use, however, we argue that icons are far more diverse and complex than normally realized. This article examines some of the history behind the evolution of icons from simple pictures to much richer and more complex representational devices. Then we develop and present a new framework that distinguishes: (1) different kinds of sign relations; (2) different kinds of referent relations; and (3) differences between sign and referent relations. In addition, we highlight a fundamental symmetry between icons and symbols, and use this framework to raise a number of basic questions about the kinds of representational issues and challenges designers will need to consider as they create the next generation of icons for user interfaces.

Alphabetic Input on a Telephone Keypad

With the growing use of the telephone as an input device, human factors designers need more human performance data on how quickly and accurately users can learn and execute alternative data-entry input strategies, as well as indications of what strategies users prefer. This study assesses five different strategies for entering alphabetic codes from a telephone keypad.

The Effects of Display Layout on Monitoring and Updating System States

Information-display issues are described in the context of a complex memory-updating task similar to Yntemas (1963). Subjects performed the updating task with two types of graphic interfaces. In one condition, the interface provided invariant spatial information which could be used to support task performance; in the second condition, the same information was presented in a single spatial location. The results suggest that 1) the mapping effect (one-to-many vs. many-to-one) found by Yntema did not occur when the response sets being updated were composed of the same response alternatives; 2) the type of screen layout used to support the updating task had a large impact on both accuracy and time to respond; and 3) the type of screen layout used interacted with the tasks cognitive demands, including length of lag between an update and a response, and the number of variables being monitored. These results suggest that the design of information displays requires consideration of the abstract representational requirements of the task being supported.

The Effects of Response Alternatives on Keeping Track Performance

A keeping-track task was used to explore the role of interference in dynamically updating memory. Subjects performed a keeping-track task in which all monitored attributes either shared four response alternatives, or were distributed such that each monitored attribute had its own unique set of four states. The response alternatives were distributed differently on the computer keyboard in these two conditions. Results suggest that the mapping effect seen in Yntema and Meusers (1960) original experiments is best explained by interference: Accuracy was lowest when all attributes shared the same four states. Spatially distributing the response alternatives benefited accuracy when subjects kept track of multiple attributes with unique response sets, but having to choose from many response keys led to increased response times. These data suggest that keeping-track performance is sensitive to interference from shared attribute sets and to how the response environment is designed.

Do Human Factors Color Recommendations have any Practical Value

This study surveyed 342 directory-assistance (DA) operators regarding the text and background colors they used to display directory listings on their computer workstations. Color combinations were observed in use, recorded, and scored based on independent, published subjective ratings of color comfort and edge sharpness. Operators also answered a questionnaire that included information about: how often they changed colors and if they had experienced eye problems. No relationships were found between self-reported eye problems and observed color choices. However, operators using color combinations that were scored low on either comfort, edge sharpness, or both, were more likely to change the colors on their screens more frequently. This result provides evidence that independent ratings can provide practical guidance in making color recommendations.