Number of co-authors:15
Number of publications with 3 favourite co-authors:Detlef Rhenius:2Carolanne Fisher:1Jr. Alvah C. Bittner:1
Gerhard Deffner's 3 most productive colleagues in number of publications:Penelope Sanderson:19Harry L. Snyder:8Jr. Alvah C. Bittn..:7
Civilization advances by extending the number of important operations which we can perform without thinking of them.
-- Alfred North Whitehead
Read the fascinating history of Wearable Computing, told by its father, Steve Mann
Read Steve's chapter !
Has also published under the name of:
"Gerhard P. Deffner"
Publications by Gerhard Deffner (bibliography)
Lauretta, Donna and Deffner, Gerhard (1996): Experimental Evaluation of Dialogue Styles for Hybrid Telephone-Based Interface. In Behaviour and Information Technology, 15 (1) pp. 51-56.
This paper describes empirical research evaluating dialogue styles used in telephone-based interfaces that incorporate both touch-tone and speech input. Task completion time, selection frequency, proportion of spoken commands, proportion of prompt interruptions, and user preference were obtained for four different dialogue styles. These styles varied with respect to (1) prompt style (whether explicit command information was presented in prompts or not presented in prompts), and (2) presentation order (function stated first versus command information stated first in prompts). Results provide a basis for a discussion of the strengths and weaknesses of different dialogue styles and their implications for selecting a preferred style.
© All rights reserved Lauretta and Deffner and/or Taylor and Francis
Deffner, Gerhard and Yuasa, Mashiho (1994): Understanding Perceived Image Quality: New Applications for Verbal Protocol Methodology. In: Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting 1994. pp. 1090-1093.
The present study investigated the effectiveness of 'cued retrospective verbalization' used in combination with eye-movement recordings as memory aids to study image quality evaluation of display products. That is, recordings of eye movements during image quality judgments were played back as cues for recalling and verbalizing thoughts which occurred during prior image evaluation. The study also examined the consistency of subjects' image quality evaluation responses over time and whether retrospective verbalization influenced and altered subsequent preference. The experiment consisted of two sessions separated by a 60-hour interval. Subjects in the experimental condition performed retrospective verbalization in both sessions whereas subjects in the control condition did so only in the second session. Judgments of perceptual quality were stable over time, and there was no indication that cued retrospective verbalization influenced subsequent perceptual evaluation. Moreover, subjects in the experimental condition stated the same critical image characteristics for the reasons of their preferences if they had not changed their choices between the two sessions. When there were changes in preference over time, their verbalization protocol indicated clear shifts of attention from one critical image characteristic to another. Cued retrospective verbalization appears to be an effective tool to examine the processes of display image quality.
© All rights reserved Deffner and Yuasa and/or Human Factors Society
Burns, Rae and Deffner, Gerhard (1993): Interactive Media for Communication/Advertising -- A Feasibility Study and First Trial. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 635-639.
This paper describes the development and refinement of the 'Interactive Guide', a multimedia application designed to explore the potential use of interactive media for communication/advertising. The domain selected for this empirical evaluation was radial keratotomy, a surgical procedure to correct nearsightedness. Starting from an analysis of patient information needs, we conducted iterative cycles of design, review, and testing which focused on topic selection, presentation styles and usability. Usage data and feedback from subjects have been very encouraging, pointing to the potential of this approach to establish a new style of information delivery.
© All rights reserved Burns and Deffner and/or Human Factors Society
Brennan, Paul, Deffner, Gerhard, Lawrence, Debbie, Marics, Monica, Schwab, Eileen and Franzke, Marita (1991): Should We or Shouldn't We Use Spoken Commands in Voice Interfaces?. In: Robertson, Scott P., Olson, Gary M. and Olson, Judith S. (eds.) Proceedings of the ACM CHI 91 Human Factors in Computing Systems Conference April 28 - June 5, 1991, New Orleans, Louisiana. pp. 369-372.
The current usefulness of voice recognition seems suspect given today's level of commercial voice recognition technology. The panel will discuss what improvements are necessary to make voice recognition an acceptable input medium for general consumer applications.
© All rights reserved Brennan et al. and/or ACM Press
Deffner, Gerhard and Melder, Karl (1990): User Acceptance and Preference for Advanced Voice Services Feature and Dialogue Styles. In: D., Woods, and E., Roth, (eds.) Proceedings of the Human Factors Society 34th Annual Meeting 1990, Santa Monica, USA. pp. 194-197.
The experiment evaluates several alternatives for the design of user dialogues of a telephone system which integrates advanced features to accelerate access to telephone services and also Spoken Speed Dial, Call Answering and Call Delivery. In the experiment, subjects placed phone calls and relayed pieces of information. The dialogue they then encountered presented them with experimental variations of dialogue styles and provided an opportunity to use the Spoken Speed Dial feature. Subjects made 16 call attempts in the first phase of the experiment, and their preferences for dialogue features were recorded between trial blocks and at the end of the experiment. In a second phase, subjects were the recipients of Call Delivery of various types. The results show clear preference for verbal prompts, the usability of Spoken Speed Dial, conflicting attitudes towards the extra step of recording the recipient's name in Call Answering, and a preferred mode of Call Delivery.
© All rights reserved Deffner and Melder and/or Human Factors Society
Deffner, Gerhard, Snyder, Harry L., Bittner, Jr. Alvah C., Fisher, Carolanne, Rhenius, Detlef and Sanderson, Penelope (1990): Verbal Protocols as a Research Tool in Human Factors. In: D., Woods, and E., Roth, (eds.) Proceedings of the Human Factors Society 34th Annual Meeting 1990, Santa Monica, USA. pp. 1145-1147.
Verbal protocols have been used for many years in different research contexts, but there still is no clear consensus about the validity of the technique and methods for maximizing validity in an applied setting; how to standardize the collection and analysis of protocols; and last but certainly not least, whether the resulting data is worth the effort. This panel discussion is a companion to a symposium at this conference which presents empirical studies and human factors applications of verbal protocol techniques. The panel will focus in more depth on issues raised in that earlier session, with the goal of providing guidance for practical applications of the technique.
© All rights reserved Deffner et al. and/or Human Factors Society
Rhenius, Detlef and Deffner, Gerhard (1990): Evaluation of Concurrent Thinking Aloud Using Eye-Tracking Data. In: D., Woods, and E., Roth, (eds.) Proceedings of the Human Factors Society 34th Annual Meeting 1990, Santa Monica, USA. pp. 1265-1269.
In a series of studies we address the two questions of: 1) Do verbalizations reflect concurrent thought, and 2) Does concurrent thinking aloud differ from normal thinking? The design of experimental tests was based upon Ericsson and Simon's model of thinking aloud, incorporating variation of how information is represented in short term memory. Eye-movement recordings were used as a source of additional data, allowing us to go beyond a mere analysis of solution time and accuracy. Comparing verbalizations and eye-movement data, we arrived at a positive answer to the first of our initial questions. The second question was approached on several levels, always involving a comparison of 'think-aloud groups' with silent controls. We found no differences with respect to accuracy, but longer solution times in think-aloud groups. In a final experiment, the influence of thinking aloud on concurrent task performance could be narrowed down to an effect which only persists through the early stages of familiarization with tasks. We conclude that concurrent verbalization is a viable tool in the study of cognitive processes.
© All rights reserved Rhenius and Deffner and/or Human Factors Society
Deffner, Gerhard and Ahrens, Reinhard (1989): On the Use of a Primitive Formal Language and Ill-Defined Quantifiers in Knowledge Acquisition. In: Proceedings of the Human Factors Society 33rd Annual Meeting 1989. pp. 356-360.
This paper describes a tool for knowledge acquisition and its empirical evaluation. The main characteristics are the use of a highly restricted language allowing for the expression of rules by means of cards and their combination. In order to assess the feasibility of the approach, subjects were trained in the use of a computer simulation that only gave them very general, unspecific, feedback about the internal workings of the system. It was their newly gained knowledge about how to control the system that was probed in a subsequent knowledge acquisition step. We observed substantial accuracy and also demonstrated its validity in a comparison against prior performance.
© All rights reserved Deffner and Ahrens and/or Human Factors Society
Show this list on your homepage
Join the technology elite and advance:
Changes to this page (author)10 Feb 2010: Modified26 Jun 2007: Added
26 Jun 2007: Added
26 Jun 2007: Added
26 Jun 2007: Added
26 Jun 2007: Added
26 Jun 2007: Added
28 Apr 2003: Added
Page maintainer: The Editorial Team