Donald R. Gentner

Timing of Skilled Motor Performance: Tests of the Proportional Duration Model.

Historically, theories of motor control have been based on either central or peripheral mechanisms. This article examines a current, expfieit, central theory accounting for the observed flexibility in motor performance: the generafized motor program with a multiplicative rate parameter. Reanalysis of data from a variety of motor skills reported in the literature and a detailed study of skilled typewriting show that a generalized motor program with a multiplicative rate parameter generally does not fit observed performance. Instead, the data support a composite model of motor control in which performance is determined by both central and peripheral mechanisms.

Lexical, sublexical, and peripheral effects in skilled typewriting ☆

Abstract It is generally accepted that expert typewriting performance is strongly affected by the sequence of letters being typed, but there is controversy about the importance of units larger than single letters, such as digraphs or words. We studied expert typists transcribing prose texts and random words. Analyses of interstroke intervals demonstrated the presence of digraph frequency, word frequency, and syllable boundary effects, in addition to the expected effects of movement difficulty. Word frequency and syllable boundary effects function primarily at the perceptual level, whereas digraph frequency and physical difficulty effects function primarily at the motor level.

A Glossary of Terms Including a Classification of Typing Errors

A common terminology is essential when working in any area, and the study of typing is no exception. To aid ourselves and others, we have compiled a glossary of basic definitions useful in the description of the phenomena of typing. The glossary, which also contains a categorization of errors, has proved useful in several ways. Not only does it keep our terms consistent, but it has provided a framework for the description and classification of a number of typing errors. We hope this glossary will be of independent use, perhaps leading to standardization of the typing terms used throughout the typing literature.

Interfaces for consumer products: “how to camouflage the computer?”

INTRODUCTION User interfaces for consumer products are notoriously bad. The increase of computing power in consumer products, from personal computers and diaries, televisions, video and audio products to kitchen machines provides increasingly more functionality that is theoretically available but not practically accessible to users. Most HCI research is devoted to applications for which the computing systems are clearly present and usable to the trained. In contrast, the users of consumer electronics products do not expect to need computer skills to interact with their TV sets or car stereo’s. In consumer products, the computing systems are embedded and hidden from the users by the user interface. Their user interfaces have at least a dual function: platform for the quality of the human-computer interaction and carrier of the system’s attractiveness and purchasing appeal.

Design models for computer-human interfaces

Computer-human interface design has been recognized as a distinct field for only a little more than a decade, but the design of interfaces to control mechanical devices has a much longer history. The interface-design models used in these mechanical systems play similar roles in computer systems, despite the obvious differences between the two types of systems. There are many ways to control a given mechanism. Whether consciously or unconsciously, every interface designer chooses a model that forms the basis for how the mechanism is controlled. Two principal approaches are the engineering model and the user-task model. There is no best way to design a user interface, however. Interface designers must be aware that a user interface can be based on any of several models, that each model has its advantages, and that their job is to choose the approach most suitable for the project at hand. We examine the models underlying computer-human interface designs by considering a wide variety of systems, including many from areas outside of computing. These noncomputer examples can be instructive because they are simpler and thus clearer. They also provide some helpful detachment and perspective for those of us who are immersed in computers.