Vassilis-Javed Khan

On the use of virtual environments for the evaluation of location-based applications

User experience (UX) research on pervasive technologies faces considerable challenges regarding todays mobile context-sensitive applications: evaluative field studies lack control, whereas lab studies miss the interaction with a dynamic context. This dilemma has inspired researchers to use virtual environments (VEs) to acquire control while offering the user a rich contextual experience. Although promising, these studies are mainly concerned with usability and the technical realization of their setup. Furthermore, previous setups leave room for improvement regarding the users immersive experience. This paper contributes to this line of research by presenting a UX case study on mobile advertising with a novel CAVE-smartphone interface. We conducted two experiments in which we evaluated the intrusiveness of a mobile location-based advertising app in a virtual supermarket. The results confirm our hypothesis that context-congruent ads lessen the experienced intrusiveness thereby demonstrating that our setup is capable of generating preliminary meaningful results with regards to UX. Furthermore, we share insights in conducting these studies.

Picassopass: a password scheme using a dynamically layered combination of graphical elements

In this paper a new graphical password scheme is presented using a dynamic layered combination of graphical elements. It has unique capabilities in terms of low memory burden due to a story based approach, while at the same time being very resistant to shoulder surfing threats. The results of a security evaluation confirm shoulder surfing resistance.

Inferring A Player's Need For Cognition From Hints

Player behavior during game play can be used to construct player models that help adapt the game and make it more fun for the player involved. Similarly in-game behavior could help model personality traits that describe peoples attitudes in a fashion that can be stable over time and over different domains, e.g., to support health coaching, or other behavior change approaches. This paper demonstrates the feasibility of this approach by relating Need for Cognition (NfC) a personality trait that can predict the effectiveness of different persuasion strategies upon users to a commonly used game mechanic -- hints. An experiment with N=188 participants confirmed our hypothesis that NfC has a negative correlation with the number of hints players follow during the game. Future work should confirm if adherence to hints can be used as a predictor of behavior in different games, and to find other game mechanics than hints, that help predict user traits.

Evaluating Ubiquitous Systems with Users (Workshop Summary)

Evaluating ubiquitous systems with users can be a challenge, and the goal of this workshop was to take stock of current issues and novel approaches to address this challenge. In this paper, we report on the discussions we had during several plenary and small-group sessions. We first briefly review those evaluation methods that we identified as being used in ubiquitous computing, and then discuss several issues and research questions that emerged during the discussion. These issues include: data sources used for evaluation, comparing ubiquitous systems, interdisciplinary evaluation, multi-method evaluation, factoring in context and disengaged users.

Does location congruence matter? A field study on the effects of location-based advertising on perceived ad intrusiveness, relevance & value

We investigate the effect of location-congruent mobile messages on perceived intrusiveness, value, and relevance through a field experiment using the Experience Sampling Method (ESM). We developed a mobile application for undergraduate students, featuring campus news and information concerning class schedules. This application also included daily ads for the University restaurant, which were either location-(semi)congruent or location-incongruent. Immediately after viewing the ads the app presented a short questionnaire to the participants for a period of four weeks, thereby measuring their perceived intrusiveness, relevance and value of these ads. During these four weeks daily ads were sent to 40 students, resulting in 107 responses from 23 participants. The results show that our participants perceived location-(semi)congruent ads as significantly more valuable and relevant, whereas no significant results were found for perceived intrusiveness. By investigating LBA in a field-study based on ESM utilizing participants own smartphone devices this study corroborates the presumed effects of location-(semi)congruency on marketing relevant ad perceptions. Field experiment examines how individuals react to Location-Based Ads (LBAs).In situ data collection via ESM using a context-triggered sampling design.Location (semi)congruency has a positive influence on perceived relevance and value.LBA has no significant influence on perceived ad intrusiveness.Intra-individual variations are significant with all three dependent variables.

Efficient navigation in virtual environments: A comparative study of two interaction techniques: The Magic Wand vs. the Human Joystick

Whether it is for entertainment, training, medical, architectural, among other purposes, virtual environments are having a salient, real impact into many facets of our lives. A common user interaction task within such environments is movement. Several solutions have been proposed in the past for different environments. We are presenting a novel variation of two known interaction techniques and evaluate them in terms of efficiency and user experience in an immersive, virtual supermarket. Results indicate that although one is more efficient than the other they do not differ in terms of experiential aspects.

Pervasive awareness

We are interested in systems that support awareness between individuals, by exchanging information that is automatically captured and presenting it to members of their social network. Here we demonstrate a principle for the operation of these systems which we describe as pervasive awareness: awareness information is aggregated opportunistically as mobile devices carrying some information migrate across space and cluster dynamically. We present a minimal demonstration of the principle where qualitative location information is used to select information offered by context capture devices (for the demonstration these are cameras).

Smart Home Control using Motion Matching and Smart Watches

This paper presents a prototype of a smart home control system operated through motion matching input. In motion matching, targets move continuously in a singular and pre-defined path; users interact with these targets by tracking their movement for a short period of time. Our prototype captures user input through the motion sensors embedded in off-the-shelf smartwatches while users track the moving targets with their arms and hands. The wearable nature of the tracking system makes our prototype ideal for interaction with numerous devices in a smart home.

How Creative is the Crowd in Describing Smart Home Scenarios

Internet of Things (IoT) is recently attracting vendors like Google, Homey, and Samsung that have already brought to the market a plethora of devices and services supporting smart home automation. However, recent studies have shown that end-users having little knowledge of the features and possibilities of IoT devices, face difficulties in conjuring up meaningful use scenarios that combine such devices. Therefore, they fail to anticipate useful configurations beyond those provided by vendors and hence missing out on the vast potential of the IoT. We present an on-going investigation that explores the potential of sourcing IoT-relevant scenarios from a popular microtask-crowdsourcing platform, and a preliminary evaluation of such scenarios with respect to their originality and practicality. This work paves the way for the automated leverage of crowdsourced user scenarios to support IoT end-users.

Using TEMPEST: End-User Programming of Web-Based Ecological Momentary Assessment Protocols

Researchers who perform Ecological Momentary Assessment (EMA) studies tend to rely on informatics experts to set up and administer their data collection protocols with digital media. Contrary to standard surveys and questionnaires that are supported by widely available tools, setting up an EMA protocol is a substantial programming task. Apart from constructing the survey items themselves, researchers also need to design, implement, and test the timing and the contingencies by which these items are presented to respondents. Furthermore, given the wide availability of smartphones, it is becoming increasingly important to execute EMA studies on user-owned devices, which presents a number of software engineering challenges pertaining to connectivity, platform independence, persistent storage, and back-end control. We discuss TEMPEST, a web-based platform that is designed to support non-programmers in specifying and executing EMA studies. We discuss the conceptual model it presents to end-users, through an example of use, and its evaluation by 18 researchers who have put it to real-life use in 13 distinct research studies.