Jeremiah D. Still

Enhancing Multi-user Interaction with Multi-touch Tabletop Displays Using Hand Tracking

A rear-projection multi-touch tabletop display was augmented with hand tracking utilizing computer vision techniques. Touch detection by frustrated total internal reflection is useful for achieving interaction with tabletop displays, but the technique is not always reliable when multiple users in close proximity simultaneously interact with the display. To solve this problem, we combine touch detection and hand tracking techniques in order to allow multiple users to simultaneously interact with the display without interference. Our hope is that by considering activities occurring on and above a tabletop display, multiuser interaction will become more natural and useful, which should ultimately support collaborative work.

Examining working memory load and congruency effects on affordances and conventions

Although there is a debate about whether designers should draw a distinction between perceptual affordances and cultural conventions, there are few behavioral studies. We examined the impact of working memory load and expected button-to-action mapping congruency on affordances and conventions. The findings suggest both sides of the debate are correct. Learned conventions were found to structure responses towards expected actions, just like affordances, but affordance-based interactions were not affected by memory load while convention-based actions were. Therefore, designers ought to employ perceptual affordances when possible and when not feasible they ought to reuse established conventions. Additionally, evidence is presented that violating expected affordance-based and convention-based button-to-action mappings caused a similar performance cost. We believe that after the initial learning period, conventions play a critical role in the perception of a designs available actions just as perceptual affordances do.

An Empirical Investigation of Affordances and Conventions

There is a debate in the literature concerning whether a distinction between affordances and cultural conventions ought to be drawn. It is possible that in the absence of affordances users develop conventions to resolve interaction ambiguity. We explored whether a difference between affordances and conventions existed through a button pressing task. Our results show that affordances exist when the spatial button configuration is congruent with directional cues. When affordances were not available, most participants demonstrated consistent button-to-action mapping that sometimes represented a convention. Additionally, there was no difference in response time in the affordance and convention conditions.

Designing Intuitive Interactions: Exploring Performance and Reflection Measures

Intuitive interactions are supported by users’ implicit and explicit learning experiences. But, determining user knowledge can be difficult. With many options available for eliciting that knowledge, we tested the effectiveness of two methods – performance and reflection. Users were presented with simple interactions that had varying levels of intuitiveness (affordance, convention, bias). They were asked to perform the interaction or to describe how the interaction should be designed. These methods of knowledge elicitation produced inconsistent results; sometimes they produced the same result (affordance-based interactions), sometimes the opposite (convention-based interactions). Furthermore, when both methods were used, results obtained from the second measure were often contaminated by completion of the first measure. Carryover effects were present regardless of which measure was completed first. These results indicate that the method used to elicit knowledge should be selected based on the type of interaction that is being investigated and multiple measures should be used with caution.

Human-centered authentication guidelines

Purpose Despite the widespread use of authentication schemes and the rapid emergence of novel authentication schemes, a general set of domain-specific guidelines has not yet been developed. This paper aims to present and explain a list of human-centered guidelines for developing usable authentication schemes. Design/methodology/approach The guidelines stem from research findings within the fields of psychology, human–computer interaction and information/computer science. Findings Instead of viewing users as the inevitable weak point in the authentication process, this study proposes that authentication interfaces be designed to take advantage of users’ natural abilities. This approach requires that one understands how interactions with authentication interfaces can be improved and what human capabilities can be exploited. A list of six guidelines that designers ought to consider when developing a new usable authentication scheme has been presented. Research limitations/implications This consolidated list of usable authentication guidelines provides system developers with immediate access to common design issues impacting usability. These guidelines ought to assist designers in producing more secure products in fewer costly development cycles. Originality/value Cybersecurity research and development has mainly focused on technical solutions to increase security. However, the greatest weakness of many systems is the user. It is argued that authentication schemes with poor usability are inherently insecure, as users will inadvertently weaken the security in their efforts to use the system. The study proposes that designers need to consider the human factors that impact end-user behavior. Development from this perspective will address the greatest weakness in most security systems by increasing end-user compliance.

A Rapid Serial Visual Presentation Method for Graphical Authentication

We propose a Rapid Serial Visual Presentation (RSVP) graphical authentication method that is suited for multi-touch mobile devices. This method presents degraded pictures of everyday objects in a temporal stream. Considering all the other authentication methods employ a spatial visual search, our method is unique (i.e., searching across time versus space). A temporal method of presentation is used to decreases login times down to 14 s and to allow login with a simple touch of the screen. By degrading the images, over-the-shoulder attackers are prevented from easily capturing the passcode. This study shows that all participants could successfully login at least once when allowed up to three attempts. After becoming familiar with the RSVP authentication method, participants took on the role of an attacker. Notably, no one was able to identify the passcode. The RSVP method offers a memorable, usable, quick, and secure alternative for authentication on multi-touch mobile devices.

Subliminal Techniques: Considerations and Recommendations for Analyzing Feasibility

ABSTRACT In an attempt to provide users with more information while maintaining a calm ubiquitous environment, researchers have investigated the possibility of presenting information “subliminally.” The authors explores the historical issues associated with examining perception without awareness with special emphasis on the difficulty associated with ensuring stimuli have been presented below the participant’s subjective threshold of awareness. It may be possible to circumvent this issue by taking a results-oriented approach. However, the advancement of subliminal techniques requires stronger experimental evidence that information is actually being presented below the subject threshold of awareness and gaining the desired effect on user performance. The authors offers three considerations that help designers weigh the costs and benefits of employing a subliminal technique. The authors also offers three recommendations that help designers present information below the subjective threshold of awareness and measure their users’ awareness of the information.

Graphical Authentication Resistance to Over-the-Shoulder-Attacks

Graphical passwords offer advantages for memorability over conventional alphanumeric passwords, but in some cases they have been vulnerable to over-the-shoulder-attacks (OSA). Thus, many second-generation graphic based schemes are specifically designed to be resistant to OSA. This is often achieved by not having users select targets directly, but by adding cognitive operations to create seemingly random response patterns. This study takes the first step to directly compare three prototypical graphical password schemes to determine their relative resistance to OSAs employing a within-subjects design. We found that schemes requiring cognitive operations in response to target patterns were superior to direct selection of targets. Convex Hull Click was most secure, followed by What You See is What You Enter, while Use Your Illusion showed high vulnerability to OSA. In addition, we discuss a diversity of previous measurements, which are meant to examine security strength of new approaches. We highlight the need for standard OSA resistance measures depending on threat model needs.

Web page attentional priority model

Designing an interface that is both information rich and easy to search is challenging. Successfully finding a solution depends on understanding an interface’s explicit and implicit influences. A cognitively inspired computational approach is taken to make the implicit influences apparent to designers. A saliency model has already been shown to predict the deployment of attention within web page interfaces. It predicts regions likely to be salient, based on local contrast stemming from the bottom-up channels (e.g., color, orientation). This research replicates these previous findings and extends the work by proposing a web page-specific attentional priority (AP) model. This AP model includes previous interaction experience history, manifested as conventions, within the already valuable saliency model. These sources of influence automatically nudge our attention to regions that usually contain useful visual information. This research shows that, by integrating spatial conventions with a saliency model, designers can better predict the deployment of attention within web page interfaces.

Using a Mobile Application to Help Visually Impaired Individuals Explore the Outdoors

Visually impaired individuals face a variety of challenges when navigating outdoors, including uneven terrain, unexpected obstacles, safety concerns, and reliance on others for information. The goal of this study was to understand further the navigational needs of visually impaired individuals and to develop a mid-fidelity prototype to address these needs. Through interviews with visually impaired users and accessibility professionals, researchers found that present technology leads to an incomplete understanding of the trail and harmful situations. Currently, there is no known technology available that integrates real-time updates with static trail information for individuals navigating outdoors. In response, a mobile prototype was proposed, integrating user-provided updates with static trail information in a format that caters to all users. Our usability testing showed visually impaired users made few errors using the prototype and were satisfied with their experience.