Publication statistics

Pub. period:2006-2012
Pub. count:14
Number of co-authors:25


Number of publications with 3 favourite co-authors:

Mira Dontcheva:
Diana Joseph:
Joel Brandt:



Productive colleagues

Krzysztof Z. Gajos's 3 most productive colleagues in number of publications:

Mary Czerwinski:80
Jacob O. Wobbrock:71
Robert C. Miller:42

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Krzysztof Z. Gajos


Publications by Krzysztof Z. Gajos (bibliography)

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Kim, Juho, Malley, Benjamin, Brandt, Joel, Dontcheva, Mira, Joseph, Diana, Gajos, Krzysztof Z. and Miller, Robert C. (2012): Photoshop with friends: a synchronous learning community for graphic design. In: Companion Proceedings of ACM CSCW12 Conference on Computer-Supported Cooperative Work 2012. pp. 271-272. Available online

Photoshop with Friends is an online community of learners exchanging just-in-time help on graphic design tasks. The system attempts to provide an interactive, visual, context-aware, and personalized mode of learning. Developed as a Facebook application, Photoshop with Friends allows users to help each other in live sessions, with built-in screen sharing, recording, and voice chat support. Major design decisions are guided by two laboratory studies that identified challenges in learning graphic design skills on the web.

© All rights reserved Kim et al. and/or ACM Press

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Gajos, Krzysztof Z., Hurst, Amy and Findlater, Leah (2012): Personalized dynamic accessibility. In Interactions, 19 (2) pp. 69-73. Available online

In this forum we celebrate research that helps to successfully bring the benefits of computing technologies to children, older adults, people with disabilities, and other populations that are often ignored in the design of mass-marketed products.

© All rights reserved Gajos et al. and/or Lawrence Erlbaum Associates

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Jayatilaka, Lahiru G., Bertuccelli, Luca F., Staszewski, James and Gajos, Krzysztof Z. (2011): Evaluating a pattern-based visual support approach for humanitarian landmine clearance. In: Proceedings of ACM CHI 2011 Conference on Human Factors in Computing Systems 2011. pp. 453-462. Available online

Unexploded landmines have severe post-conflict humanitarian repercussions: landmines cost lives, limbs and land. For deminers engaged in humanitarian landmine clearance, metal detectors remain the primary detection tool as more sophisticated technologies fail to get adopted due to restrictive cost, low reliability, and limited robustness. Metal detectors are, however, of limited effectiveness, as modern landmines contain only minimal amounts of metal, making them difficult to distinguish from the ubiquitous but harmless metallic clutter littering post-combat areas. We seek to improve the safety and efficiency of the demining process by developing support tools that will enable deminers to make better decisions using feedback from existing metal detectors. To this end, in this paper we propose and evaluate a novel, pattern-based visual support approach inspired by the documented strategies employed by expert deminers. In our laboratory study, participants provided with a prototype of our support tool were 80% less likely to mistake a mine for harmless clutter. A follow-up study demonstrates the potential of our pattern-based approach to enable peer decision-making support during landmine clearance. Lastly, we identify several design opportunities for further improving deminers' decision making capabilities.

© All rights reserved Jayatilaka et al. and/or their publisher

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Noronha, Jon, Hysen, Eric, Zhang, Haoqi and Gajos, Krzysztof Z. (2011): PlateMate: crowdsourcing nutritional analysis from food photographs. In: Proceedings of the 2011 ACM Symposium on User Interface Software and Technology 2011. pp. 1-12. Available online

We introduce PlateMate, a system that allows users to take photos of their meals and receive estimates of food intake and composition. Accurate awareness of this information can help people monitor their progress towards dieting goals, but current methods for food logging via self-reporting, expert observation, or algorithmic analysis are time-consuming, expensive, or inaccurate. PlateMate crowdsources nutritional analysis from photographs using Amazon Mechanical Turk, automatically coordinating untrained workers to estimate a meal's calories, fat, carbohydrates, and protein. We present the Management framework for crowdsourcing complex tasks, which supports PlateMate's nutrition analysis workflow. Results of our evaluations show that PlateMate is nearly as accurate as a trained dietitian and easier to use for most users than traditional self-reporting.

© All rights reserved Noronha et al. and/or ACM Press

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Jayatilaka, Lahiru G., Bertuccelli, Luca F., Staszewski, James and Gajos, Krzysztof Z. (2010): PETALS: a visual interface for landmine detection. In: Proceedings of the 2010 ACM Symposium on User Interface Software and Technology 2010. pp. 427-428. Available online

Post-conflict landmines have serious humanitarian repercussions: landmines cost lives, limbs and land. The primary method used to locate these buried devices relies on the inherently dangerous and difficult task of a human listening to audio feedback from a metal detector. Researchers have previously hypothesized that expert operators respond to these challenges by building mental patterns with metal detectors through the identification of object-dependent spatially distributed metallic fields. This paper presents the preliminary stages of a novel interface -- Pattern Enhancement Tool for Assisting Landmine Sensing (PETALS) -- that aims to assist with building and visualizing these patterns, rather than relying on memory alone. Simulated demining experiments show that the experimental interface decreases classification error from 23% to 5% and reduces localization error by 54%, demonstrating the potential for PETALS to improve novice deminer safety and efficiency.

© All rights reserved Jayatilaka et al. and/or their publisher

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Gajos, Krzysztof Z., Weld, Daniel S. and Wobbrock, Jacob O. (2010): Automatically generating personalized user interfaces with Supple. In Artificial Intelligence, 174 (12) pp. 910-950. Available online

Today's computer-human interfaces are typically designed with the assumption that they are going to be used by an able-bodied person, who is using a typical set of input and output devices, who has typical perceptual and cognitive abilities, and who is sitting in a stable, warm environment. Any deviation from these assumptions may drastically hamper the person's effectiveness-not because of any inherent barrier to interaction, but because of a mismatch between the person's effective abilities and the assumptions underlying the interface design. We argue that automatic personalized interface generation is a feasible and scalable solution to this challenge. We present our Supple system, which can automatically generate interfaces adapted to a person's devices, tasks, preferences, and abilities. In this paper we formally define interface generation as an optimization problem and demonstrate that, despite a large solution space (of up to 10^1^7 possible interfaces), the problem is computationally feasible. In fact, for a particular class of cost functions, Supple produces exact solutions in under a second for most cases, and in a little over a minute in the worst case encountered, thus enabling run-time generation of user interfaces. We further show how several different design criteria can be expressed in the cost function, enabling different kinds of personalization. We also demonstrate how this approach enables extensive user- and system-initiated run-time adaptations to the interfaces after they have been generated. Supple is not intended to replace human user interface designers-instead, it offers alternative user interfaces for those people whose devices, tasks, preferences, and abilities are not sufficiently addressed by the hand-crafted designs. Indeed, the results of our study show that, compared to manufacturers' defaults, interfaces automatically generated by Supple significantly improve speed, accuracy and satisfaction of people with motor impairments.

© All rights reserved Gajos et al. and/or Elsevier Science

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Spaulding, Aaron, Gajos, Krzysztof Z., Jameson, Anthony, Kristensson, Per Ola, Bunt, Andrea and Haines, Will (2009): Usable intelligent interactive systems: CHI 2009 special interest group meeting. In: Proceedings of ACM CHI 2009 Conference on Human Factors in Computing Systems 2009. pp. 2743-2746. Available online

The AI and HCI communities have often been characterized as having opposing views of how humans and computers should interact" observes Winograd in Shifting Viewpoints. It is time to narrow this gap. What was once considered the forefront of artificial intelligence (AI) research can now be found in commercial products. While some have failed, others, such as face detection in digital cameras or product recommendation systems, have become so mainstream they are no longer thought of as artificial intelligence. This special interest group provides a forum to examine the apparent gap between HCI and AI communities, to explore how intelligent technologies can enable novel interaction with computation, and to investigate the challenges associated with understanding human abilities, limitations, and preferences in order to drive the design of intelligent interactive systems.

© All rights reserved Spaulding et al. and/or ACM Press

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Gajos, Krzysztof Z., Wobbrock, Jacob O. and Weld, Daniel S. (2008): Improving the performance of motor-impaired users with automatically-generated, ability-based interfaces. In: Proceedings of ACM CHI 2008 Conference on Human Factors in Computing Systems April 5-10, 2008. pp. 1257-1266. Available online

We evaluate two systems for automatically generating personalized interfaces adapted to the individual motor capabilities of users with motor impairments. The first system, SUPPLE, adapts to users' capabilities indirectly by first using the ARNAULD preference elicitation engine to model a user's preferences regarding how he or she likes the interfaces to be created. The second system, SUPPLE++, models a user's motor abilities directly from a set of one-time motor performance tests. In a study comparing these approaches to baseline interfaces, participants with motor impairments were 26.4% faster using ability-based user interfaces generated by SUPPLE++. They also made 73% fewer errors, strongly preferred those interfaces to the manufacturers' defaults, and found them more efficient, easier to use, and much less physically tiring. These findings indicate that rather than requiring some users with motor impairments to adapt themselves to software using separate assistive technologies, software can now adapt itself to the capabilities of its users.

© All rights reserved Gajos et al. and/or ACM Press

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Gajos, Krzysztof Z., Everitt, Katherine, Tan, Desney S., Czerwinski, Mary and Weld, Daniel S. (2008): Predictability and accuracy in adaptive user interfaces. In: Proceedings of ACM CHI 2008 Conference on Human Factors in Computing Systems April 5-10, 2008. pp. 1271-1274. Available online

While proponents of adaptive user interfaces tout potential performance gains, critics argue that adaptation's unpredictability may disorient users, causing more harm than good. We present a study that examines the relative effects of predictability and accuracy on the usability of adaptive UIs. Our results show that increasing predictability and accuracy led to strongly improved satisfaction. Increasing accuracy also resulted in improved performance and higher utilization of the adaptive interface. Contrary to our expectations, improvement in accuracy had a stronger effect on performance, utilization and some satisfaction ratings than the improvement in predictability.

© All rights reserved Gajos et al. and/or ACM Press

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Wobbrock, Jacob O. and Gajos, Krzysztof Z. (2008): Goal Crossing with Mice and Trackballs for People with Motor Impairments: Performance, Submovements, and Design Directions. In ACM Transactions on Accessible Computing, 1 (1) p. 4. Available online

Prior research shows that people with motor impairments face considerable challenges when using conventional mice and trackballs. One challenge is positioning the mouse cursor within confined target areas; another is executing a precise click without slipping. These problems can make mouse pointing in graphical user interfaces very difficult for some people. This article explores goal crossing as an alternative strategy for more accessible target acquisition. In goal crossing, targets are boundaries that are simply crossed by the mouse cursor. Thus, goal crossing avoids the two aforementioned problems. To date, however, researchers have not examined the feasibility of goal crossing for people with motor difficulties. We therefore present a study comparing area pointing and goal crossing. Our performance results indicate that although Fitts' throughput for able-bodied users is higher for area pointing than for goal crossing (4.72 vs. 3.61 bits/s), the opposite is true for users with motor impairments (2.34 vs. 2.88 bits/s). However, error rates are higher for goal crossing than for area pointing under a strict definition of crossing errors (6.23% vs. 1.94%). We also present path analyses and an examination of submovement velocity, acceleration, and jerk (the change in acceleration over time). These results show marked differences between crossing and pointing and almost categorically favor crossing. An important finding is that crossing reduces jerk for both participant groups, indicating more fluid, stable motion. To help realize the potential of goal crossing for computer access, we offer design concepts for crossing widgets that address the occlusion problem, which occurs when one crossing goal obscures another in persistent mouse-cursor interfaces. This work provides the motivation and initial steps for further exploration of goal crossing on the desktop, and may help researchers and designers to radically reshape user interfaces to provide accessible goal crossing, thereby lowering barriers to access.

© All rights reserved Wobbrock and Gajos and/or ACM Press

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Wobbrock, Jacob O. and Gajos, Krzysztof Z. (2007): A comparison of area pointing and goal crossing for people with and without motor impairments. In: Ninth Annual ACM Conference on Assistive Technologies 2007. pp. 3-10. Available online

Prior work has highlighted the challenges faced by people with motor impairments when trying to acquire on-screen targets using a mouse or trackball. Two reasons for this are the difficulty of positioning the mouse cursor within a confined area, and the challenge of accurately executing a click. We hypothesize that both of these difficulties with area pointing may be alleviated in a different target acquisition paradigm called "goal crossing." In goal crossing, users do not acquire a confined area, but instead pass over a target line. Although goal crossing has been studied for able-bodied users, its suitability for people with motor impairments is unknown. We present a study of 16 people, 8 of whom had motor impairments, using mice and trackballs to do area pointing and goal crossing. Our results indicate that Fitts' law models both techniques for both user groups. Furthermore, although throughput for able-bodied users was higher for area pointing than for goal crossing (4.72 vs. 3.61 bits/s), the opposite was true for users with motor impairments (2.34 vs. 2.88 bits/s), suggesting that goal crossing may be viable for them. However, error rates were higher for goal crossing than for area pointing under a strict definition of crossing errors (6.23% vs. 1.94%). Subjective results indicate a preference for goal crossing among motor-impaired users. This work provides the empirical foundation from which to pursue the design of crossing-based interfaces as accessible alternatives to pointing-based interfaces.

© All rights reserved Wobbrock and Gajos and/or ACM Press

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Gajos, Krzysztof Z., Wobbrock, Jacob O. and Weld, Daniel S. (2007): Automatically generating user interfaces adapted to users' motor and vision capabilities. In: Proceedings of the ACM Symposium on User Interface Software and Technology October 7-10, 2007, Newport, Rhode Island, USA. pp. 231-240. Available online

Most of today's GUIs are designed for the typical, able-bodied user; atypical users are, for the most part, left to adapt as best they can, perhaps using specialized assistive technologies as an aid. In this paper, we present an alternative approach: SUPPLE++ automatically generates interfaces which are tailored to an individual's motor capabilities and can be easily adjusted to accommodate varying vision capabilities. SUPPLE++ models users. motor capabilities based on a onetime motor performance test and uses this model in an optimization process, generating a personalized interface. A preliminary study indicates that while there is still room for improvement, SUPPLE++ allowed one user to complete tasks that she could not perform using a standard interface, while for the remaining users it resulted in an average time savings

© All rights reserved Gajos et al. and/or ACM Press

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Gajos, Krzysztof Z., Long, Jing Jing and Weld, Daniel S. (2006): Automatically generating custom user interfaces for users with physical disabilities. In: Eighth Annual ACM Conference on Assistive Technologies 2006. pp. 243-244. Available online

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Gajos, Krzysztof Z., Czerwinski, Mary, Tan, Desney S. and Weld, Daniel S. (2006): Exploring the design space for adaptive graphical user interfaces. In: Celentano, Augusto (ed.) AVI 2006 - Proceedings of the working conference on Advanced visual interfaces May 23-26, 2006, Venezia, Italy. pp. 201-208. Available online

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