Number of co-authors:21
Number of publications with 3 favourite co-authors:Kapil Chalil Madathil:5Anand K. Gramopadhye:4Reshmi Koikkara:3
Joel S. Greenstein's 3 most productive colleagues in number of publications:Andrew T. Duchowsk..:21Anand K. Gramopadh..:16Richard A. Tyrrell:6
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Joel S. Greenstein
Current place of employment: Clemson University
Department of Industrial Engineering
Publications by Joel S. Greenstein (bibliography)
Juang, Kevin A., Ranganayakulu, Sanjay and Greenstein, Joel S. (2012): Using System-Generated Mnemonics to Improve the Usability and Security of Password Authentication. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 506-510. Available online
Due to fundamental human nature, it is exceedingly difficult for people to generate secure passwords on their own. System-generated random passwords can be secure but are often unusable, which is why most passwords are still created by humans. Research has been done to try to leverage the security of system-generated passwords but improve their usability through the use of mnemonics, or memory aids. We developed a simple system for automatically generating mnemonics and conducted a study to compare it with user-generated mnemonic and no mnemonic conditions. We found that participants remembered their passwords significantly better using the system-generated mnemonic condition compared to the other conditions. We also found that participants gave our system the highest overall usability ratings.
© All rights reserved Juang et al. and/or Human Factors and Ergonomics Society
Madathil, Kapil Chalil, Koikkara, Reshmi, Dorlette-Paul, Melissa, Ranganayakulu, Sanjay, Greenstein, Joel S. and Gramopadhye, Anand K. (2012): An investigation of format modifications on the comprehension of information in consent form when presented on mobile devices. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 921-925. Available online
A major challenge associated with converting paper-based consent to electronic versions is to assure that the level of comprehension offered by the electronic consenting systems is not reduced. A randomized between-subject trial comparing patient comprehension with four different electronic consenting formats of the same consent information presented on an Apple iPad was conducted using a non-clinical sample of 32 participants. The formats were Text-Based, text-based with Text Being Read out, Video-Based and Video-Based with Subtitles. The participants were asked to read and complete a consent form in one of the formats. The participants were subsequently asked to complete a semantic comprehension quiz, the NASA Task Load Index and the computer system usability questionnaire (CSUQ). Upon completing the questionnaires, the participants took part in a retrospective think-aloud session to understand any difficulties they had using the consent forms. Statistically significant differences among the formats were found for task completion time, the mental demand and frustration sub-components of the NASA-TLX, and the comprehension quiz. Video with subtitles to convey consent information appears to be the best format among the formats tested for electronic consent presentation.
© All rights reserved Madathil et al. and/or Human Factors and Ergonomics Society
Wismer, Andrew J., Madathil, Kapil Chalil, Koikkara, Reshmi, Juang, Kevin A. and Greenstein, Joel S. (2012): Evaluating the usability of CAPTCHAs on a mobile device with voice and touch input. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 1228-1232. Available online
The usability of text-based CAPTCHAs, featuring distorted letters, and image-based CAPTCHAs, featuring pictures, was explored on an Apple iPad. Five conditions were explored: Confident CAPTCHA with either voice or touch input, ESP-PIX with voice or touch input, and Google's CAPTCHA with touch input. Usability was analyzed in terms of performance, perceived usability, workload, and preference rankings. Results showed that CAPTCHAs involving touch input scored better in almost every measure than CAPTCHAs involving voice input. In particular, Confident Touch is recommended based on preference and perceived performance, whereas ESP-PIX Touch is recommended for its short completion time. When image-based CAPTCHAs are not feasible, Google's CAPTCHA is a satisfactory alternative based on usability ratings.
© All rights reserved Wismer et al. and/or Human Factors and Ergonomics Society
Madathil, Kapil Chalil and Greenstein, Joel S. (2011): Synchronous remote usability testing: a new approach facilitated by virtual worlds. In: Proceedings of ACM CHI 2011 Conference on Human Factors in Computing Systems 2011. pp. 2225-2234. Available online
This study proposes a new methodology for conducting synchronous remote usability studies using a three-dimensional virtual usability testing laboratory built using the Open Wonderland toolkit. This virtual laboratory method is then compared with two other commonly used synchronous usability test methods: the traditional lab approach and WebEx, a web-based conferencing and screen sharing approach. A study was conducted with 48 participants in total, 36 test participants and 12 test facilitators. The test participants completed 5 tasks on a simulated e-commerce website. The three methodologies were compared with respect to the following dependent variables: the time taken to complete the tasks; the usability defects identified; the severity of these usability defects; and the subjective ratings from NASA-TLX, presence and post-test subjective questionnaires. The three methodologies agreed closely in terms of the total number defects identified, number of high severity defects identified and the time taken to complete the tasks. However, there was a significant difference in the workload experienced by the test participants and facilitators, with the traditional lab condition imposing the least and the virtual lab and the WebEx conditions imposing similar levels. It was also found that the test participants experienced greater involvement and a more immersive experience in the virtual world condition than the WebEx condition. These ratings were not significantly different from those in the traditional lab condition. The results of this study suggest that participants were productive and enjoyed the virtual lab condition, indicating the potential of a virtual world based approach as an alternative to the conventional approaches for synchronous usability testing.
© All rights reserved Madathil and Greenstein and/or their publisher
Madathil, Kapil Chalil, Koikkara, Reshmi, Gramopadhye, Anand K. and Greenstein, Joel S. (2011): An Empirical Study of the Usability of Consenting Systems: iPad, Touchscreen and Paper-based Systems. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 813-817. Available online
While much research has been conducted on the software system architecture needed for capturing and managing patient consents and research permissions in health care facilities, limited information is available on the usability of such capture systems. Typically, a general consenting process involves the patients indicating their choices and then signing/initialing to verify these preferences. This study proposes four new ways of capturing these consents/research permissions using Apple iPad and touchscreen-based systems, investigating their feasibility and usability by comparing them to the conventional paper-based consenting process. Fifteen participants completed the consenting process using five capture systems: iPad-based system with pagination and scrolling interfaces, touchscreen-based system with pagination and scrolling interfaces and the paper-based system. After each consenting condition, the participants completed the NASA Task Load Index (NASA-TLX), the computer system usability questionnaire (CSUQ), and a post-test subjective questionnaire ranking the consenting systems based on preference. Statistically significant differences among the consent capture systems were found for all dependent variables except for task completion time. The iPad and touchscreen systems with pagination interfaces were preferred.
© All rights reserved Madathil et al. and/or HFES
Juang, Kevin A. and Greenstein, Joel S. (2011): Evaluating the Usability and Security of Input Masking Techniques. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1120-1124. Available online
The human remains the weakest link in computer security, and one popular method of breaching security is shoulder surfing: looking at a user's screen or keyboard as he or she enters sensitive input. Various masking techniques exist to hide text from shoulder surfers; the most common of these replaces entered text with bullets. Existing research focuses on how to improve the shoulder surfing resistance of bulletmasking, at a heavy cost to usability. We developed Purloin: an input masking technique designed to maintain the same level of security while increasing usability. We recruited pairs of participants (filling both user and shoulder surfer roles) and tested five different masking techniques on objective measures of usability and security, subjective measures of usability and workload, and user preference. We found that Purloin performed near the top in both usability and security and received the highest overall preference ranking. Bullet-masking was equally secure but less usable. The other masking techniques performed significantly worse than Purloin in either usability, security, or both.
© All rights reserved Juang and Greenstein and/or HFES
Ozkan, Necmettin Firat and Greenstein, Joel S. (2011): Effects of 2D Online and 3D Virtual World Meeting Spaces on the Performance of a Concept Selection Task by Engineering Design Teams. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1676-1680. Available online
This research investigates engineering design teams' performance of a concept selection task in three meeting spaces: face-to-face, 2D online and 3D virtual world. Cisco Systems' WebEx and Sun Microsystems' Wonderland were used as the 2D online meeting space and the 3D virtual world, respectively. Twenty-four two-person design teams were formed and randomly assigned to one of the three meeting spaces. The teams performed a cell-phone concept selection task in the meeting space to which they were assigned. Four dependent variables were measured: task completion time, team satisfaction, self-evaluated process quality and expert-evaluated process quality. Following data collection, one-way ANOVA was used to analyze each variable to determine the differences, if any, among the meeting spaces. ANOVA results did not support rejection of the null hypothesis for any variable. These results suggest that 3D virtual worlds support design concept selection as well as 2D online meeting spaces and that both of these technologies are viable alternatives to co-located meetings when it is difficult or expensive to bring team members together for a co-located meeting.
© All rights reserved Ozkan and Greenstein and/or HFES
Ranade, Rachana S. and Greenstein, Joel S. (2010): Effectiveness of Team-building and Teamwork in Virtual Worlds. In: Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting 2010. pp. 532-536. Available online
Given the increasing importance of globalization and collaboration, this research investigates the possibility of training globally dispersed teams using the virtual world Second Life. Three meeting conditions, the 3D virtual world Second Life, a combination of face-to-face and Second Life and face-to-face were evaluated. Thirty randomly assigned 3 person teams performed an ice-breaker session and then a team-building activity in each meeting condition. Four dependent variables were measured: task completion time; quality of task performance; subjective satisfaction with the process based on group cohesiveness, perception of the process and satisfaction with the outcome; and subjective satisfaction with the communication modality. Following data collection, univariate analyses were used to analyze each dependent variable to determine the differences, if any, among the meeting conditions. The results did not show significant differences for performance and subjective satisfaction with the process across the meeting conditions; however they did show significant results for subjective satisfaction with the communication modality. The Second Life and face-to-face conditions were rated more highly than the combination condition. This study indicates that the participants found the virtual world productive, enjoyed the experience of using this environment and believed that they could communicate and collaborate in it effectively. Even though participants indicated little previous experience with Second Life, this study found that it has potential as an alternate team meeting space. Cost analyses suggest that in the long run the expense of using a virtual meeting space will be lower than the cost of using face-to-face meetings for globally dispersed teams. Future research could include looking at larger group sizes, other types of team work, different team-building activities, or the effect of features of the virtual meeting space on team performance and user experience.
© All rights reserved Ranade and Greenstein and/or HFES
Madathil, Kapil Chalil, Alapatt, Githin F. and Greenstein, Joel S. (2010): An Investigation of the Usability of Image-based CAPTCHAs. In: Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting 2010. pp. 1249-1253. Available online
Objective: This research investigates the usability of image-based CAPTCHAs using performance, eyegaze and subjective measures. Background: Several forms of image-based CAPTCHAs have recently been developed. Few studies have been conducted to examine their usability. Method: Twenty participants received training using four different CAPTCHAs: Asirra, ESP-PIX, SQ-PIX and IMAGINATION. The participants were then asked to complete the CAPTCHA challenge using five CAPTCHAs of each type. The participants were subsequently asked to complete the computer system usability questionnaire (CSUQ) and the NASA Task Load Index test. Upon completing all the tasks, the participants completed a final post-test subjective questionnaire ranking the CAPTCHAs based on preference. Results: Statistically significant differences among the CAPTCHAs were found for all dependent variables other than task completion time. Conclusion: Participants preferred Asirra and ESP-PIX to the other two CAPTCHAs.
© All rights reserved Madathil et al. and/or HFES
Sadasivan, Sajay, Greenstein, Joel S., Gramopadhye, Anand K. and Duchowski, Andrew T. (2005): Use of eye movements as feedforward training for a synthetic aircraft inspection task. In: Proceedings of ACM CHI 2005 Conference on Human Factors in Computing Systems 2005. pp. 141-149. Available online
Aircraft inspection is a vital element in assuring safety and reliability of the air transportation system. The human inspector performing visual inspection of an aircraft is the backbone of this process and training is an effective strategy for improving their inspection performance. Previous studies have shown offline feedback training to be effective in improving subsequent visual inspection performance. Because experienced inspectors are known to adopt a better inspection strategy than novices, providing visualization of experts' cognitive processes a priori can accelerate novices' adoption of the experts' strategy. Using eye tracking equipment, we record the point of regard of an expert inspector performing an inspection task in a virtual reality simulator. Analysis of their eye movements leads to a visualization of their scanpaths and allows us to display the inspector's visual search (hence cognitive) strategy. We show how providing this type of scanpath-based feedforward training of novices leads to improved accuracy performance in the simulator coupled with an observed speed-accuracy tradeoff. We contend that the tradeoff results from trained novices adopting a slower paced strategy through increased fixation durations, suggesting trained novices learn a more deliberate target search/discrimination strategy that requires more time to execute.
© All rights reserved Sadasivan et al. and/or ACM Press
Duchowski, Andrew T., Cournia, Nathan, Cumming, Brian, McCallum, Daniel, Gramopadhye, Anand K., Greenstein, Joel S., Sadasivan, Sajay and Tyrrell, Richard A. (2004): Visual deictic reference in a collaborative virtual environment. In: Duchowski, Andrew T. and Vertegaal, Roel (eds.) ETRA 2004 - Proceedings of the Eye Tracking Research and Application Symposium March 22-24, 2004, San Antonio, Texas, USA. pp. 35-40. Available online
Greenstein, Joel S. (1995): Introducing Human-Centered Design Early in the Engineering Curriculum. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 389-393.
This paper focuses on the development and implementation of a cross-disciplinary, project-driven course on human-centered design. The sophomore-level course is required of all students in the industrial engineering major. The course prerequisites are a part of the college-wide freshman engineering curriculum, enabling students in other engineering majors to take the course as well. The primary objective of this course is to introduce the product development process and human-centered methodologies for designing engineering systems into the engineering curriculum. Additional objectives are to: * Let the students experience the product development process through a semester-long, real-world design project. * Prepare students to work with other specialists in the kind of cross-functional design teams employed in engineering practice. * Educate students to focus early and continually on the customers and users of their products. * Use a variety of writing and speaking activities to achieve active participation in the educational process, team building, and a class environment dedicated to professional success. * Enhance retention of engineering students by emphasizing collaborative learning and the product development process early in the curriculum.
© All rights reserved Greenstein and/or Human Factors Society
Turek, Robert O. and Greenstein, Joel S. (1991): Stars, Polygons and Clusters; An Investigation of Polygon Displays. In International Journal of Man-Machine Studies, 35 (6) pp. 807-824.
One technique for displaying multi-variate quantitative data is to represent the values graphically in the form of a polygon or star. This allows the observer to view the complex data quickly, as a whole. Such displays have been used in various applications, for data exploration and presentation, and in status displays; they are also suited to categorization and identification tasks. For polygon displays to be reliably used, they should be capable of being interpreted consistently. An experimental investigation was undertaken to ascertain the effect of certain visual features of the display on the consistency with which untrained participants categorized data presented as polygons. The independent variables included background information, shading of figure and form. Two sets of data were used; the participants performed a categorization task on both sets of data. The results of the categorization task were analysed for consistency with standard clustering algorithms and for consistency across individuals. The results of the analysis that have implications for display design include the level of clustering consistency achieved by the participants, the interaction effects of the visual variables on consistency, and the effect of distinctive visual patterns on human judgments of similarity.
© All rights reserved Turek and Greenstein and/or Academic Press
Greenstein, Joel S. and Baijal, Anish (1989): An Investigation of Techniques for Occasional Numeric Data Entry. In: Proceedings of the Human Factors Society 33rd Annual Meeting 1989. pp. 310-314.
This work tested six techniques for the occasional entry of unstructured numeric data in the context of a primarily mouse-based, cursor-positioning, human-computer dialogue. Two of the techniques used a separate keypad for numeric data entry. The other four techniques used the mouse already being used for the cursor positioning dialogue. The keypad techniques were more efficient than the mouse techniques for all of the numeric sequence lengths considered. There were no significant differences in efficiency between the two keypad techniques. Among the mouse-based techniques, an approach based on a displayed image of a calculator keypad was consistently among the most efficient.
© All rights reserved Greenstein and Baijal and/or Human Factors Society
Arnaut, Lynn Y. and Greenstein, Joel S. (1988): Human factors considerations in the design and selection for computer input devices. In: Sherr, Sol (ed.). "Computer graphics: technology and applications". Academic Press
Arnaut, Lynn Y. and Greenstein, Joel S. (1987): An Evaluation of Display/Control Gain. In: Proceedings of the Human Factors Society 31st Annual Meeting 1987. pp. 437-441.
Two studies were conducted to evaluate the adequacy of identifying the optimum display/control gain for an interface as a method of control-display interface optimization. The first study examined the effects of changes in both the maximum control input and the display width on target acquisition performance with a touch tablet and a trackball. The second study evaluated the effects of changes in the display amplitude, the display target width, and the control amplitude. Results from both studies indicate that gain is an insufficient specification for performance. In addition, the inadequacy of Fitts' Law in this context is discussed.
© All rights reserved Arnaut and Greenstein and/or Human Factors Society
Greenstein, Joel S., Arnaut, Lynn Y. and Revesman, Mark E. (1986): An Empirical Comparison of Model-Based and Explicit Communication for Dynamic Human-Computer Task Allocation. In International Journal of Man-Machine Studies, 24 (4) pp. 355-363.
When both a human and a computer in a system are capable of performing the same tasks, task responsibilities may be allocated between them dynamically. This study compared two methods of human-computer communication for dynamic task allocation: explicit and model-based communication. With explicit communication the human directed the computer and the computer did not perform any actions on its own. With model-based communication the computer employed a model of the human which predicted the human's actions and the computer used this model to work on its own. Subjects performed a process monitoring task using both of these allocation methods. In addition, in half the trials subjects had knowledge of the computer's actions and in the other half they did not. The results indicated that overall system performance was always better under model-based communication, although human performance alone was better with explicit communication. In addition, overall system and human performance were higher when the human had knowledge of the computer's actions.
© All rights reserved Greenstein et al. and/or Academic Press
Greenstein, Joel S. and Lam, Siu-Tong (1985): An Experimental Study of Dialogue-Based Communication for Dynamic Human-Computer Task Allocation. In International Journal of Man-Machine Studies, 23 (6) pp. 605-621.
The allocation of tasks between human and computer and the merits of a dynamic approach to this allocation are discussed. Dynamic task allocation requires efficient human-computer communication. This communication may be accomplished in an implicit, model-based, or explicit, dialogue-based, manner. A framework for the study of dialogue-based human-computer communication is introduced and a study exemplifying the use of the framework is presented. This study investigated the effects of two input media and four task allocation strategies on the performance of a human-computer system. The task environment represented a simplified version of an air traffic control scenario wherein computer aid could be evoked by the human controller to accomplish task sharing between the human and the computer. Dedicated function keys proved to be a more effective input medium than the standard Sholes QWERTY keyboard in terms of both objective performance and subjective preference measures. Of the task allocation strategies considered, spatial assignment, contingency-based assignment, and assignment by designation achieved the highest levels of overall system performance, while temporal assignment achieved a significantly lower level of performance. Subjective ratings indicated an overall preference for assignment by designation, followed by spatial assignment and contingency-based assignment. Spatial assignment was the most powerful, but the least specific strategy. Assignment by designation was the least powerful strategy, but the most specific and most flexible strategy.
© All rights reserved Greenstein and Lam and/or Academic Press
Lam, Siu-Tong and Greenstein, Joel S. (1984): The Effects of Input Medium and Task Allocation Strategy on Performance of a Human-Computer System. In: Shackel, Brian (ed.) INTERACT 84 - 1st IFIP International Conference on Human-Computer Interaction September 4-7, 1984, London, UK. pp. 195-200.
The allocation of tasks between human and computer, and the merits of a dynamic approach to this allocation are discussed. Dynamic task allocation requires efficient human-computer communication. This communication may be accomplished in an implicit or explicit manner. A conceptual framework for the study of explicit human-computer communication is introduced and a study exemplifying the use of the framework is presented. This study investigated the effects of two input media and four task allocation strategies on the performance of a human-computer system. The task environment represented a simplified version of an air traffic control scenario wherein computer aid could be evoked by the human to accomplish task sharing between the human and the computer.
© All rights reserved Lam and Greenstein and/or North-Holland
Revesman, Mark E. and Greenstein, Joel S. (1983): Application of a Model of Human Decision Making for Human/Computer Communication. In: Smith, Raoul N., Pew, Richard W. and Janda, Ann (eds.) Proceedings of the ACM CHI 83 Human Factors in Computing Systems Conferenc December 12-15, 1983, Boston, Massachusetts, United States. pp. 107-111.
When a human and computer perform similar tasks in parallel, it is important that an effective line of communication exist between the two entities. Since overt communication may add to the human's workload, an implicit method of communication is suggested in which the computer has a model of human performance on which to base actions. A two-stage model of human performance is employed in an experimental situation in which both a human and a computer act as decision makers. Results indicate that the implementation of a model significantly improves the human's performance and the overall system performance, without degrading the computer's performance. Research into additional experimental and real-world situations is suggested.
© All rights reserved Revesman and Greenstein and/or ACM Press
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