Marios Belk

Do human cognitive differences in information processing affect preference and performance of CAPTCHA

Abstract A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a widely used security defense mechanism that is utilized by service providers to determine whether the entity interacting with their system is a human and not a malicious agent. Common design practices of current CAPTCHA schemes barely take into account cultural, contextual, and individual cognitive characteristics and abilities of users. Motivated by recent research which underpins the necessity for designing more user-friendly CAPTCHA, this paper investigates the effect of users’ cognitive styles and cognitive processing abilities towards preference and task performance of CAPTCHA challenges. In the frame of the reported research, two user studies were conducted. The first study (n=131) explored the effect of users’ cognitive styles (Verbal/Imager) on user preference and task performance of two complementary types of CAPTCHA mechanisms; text-recognition and image-recognition. The second study (n=125) explored the effect of users’ cognitive processing abilities (speed of processing, controlled attention, working memory capacity) on task performance in regards with different levels of complexity of both text-recognition and image-recognition CAPTCHA. Analysis of results revealed interaction effects of users’ cognitive processing characteristics towards preference and performance of CAPTCHA, suggesting that individual differences at such an intrinsic level are important to be considered for designing more usable and user-centric CAPTCHA challenges.

iHIP: Towards a User Centric Individual Human Interaction Proof Framework

A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a widely used Human Interaction Proof mechanism to protect on-line services against automated software agents. Nowadays, there is a consensus among researchers, practitioners and users that current design approaches of CAPTCHA need to be improved in order to provide a fair trade-off solution between security and usability. In this paper, we propose a shift from a generic Human Interaction Proof (HIP) to a more user-friendly Individual Human Interaction Proof (iHIP) approach by incorporating a dynamic and extendable human and technology factor based user-centric framework. Such an approach provides an alternative point of view to current state of the art practices aiming to deliver the best-fit CAPTCHA to each individual by taking into consideration contextual and behavioral interaction data.

Security for Diversity: Studying the Effects of Verbal and Imagery Processes on User Authentication Mechanisms

Stimulated by a large number of different theories on human cognition, suggesting that individuals have different habitual approaches in retrieving, recalling, processing and storing verbal and graphical information, this paper investigates the effect of such processes with regard to user performance and preference toward two variations of knowledge-based authentication mechanisms. In particular, a text-based password authentication mechanism and a recognition-based graphical authentication mechanism were deployed in the frame of an ecological valid user study, to investigate the effect of specific cognitive factors of users toward efficiency, effectiveness and preference of authentication tasks. A total of 145 users participated during a five-month period between February and June 2012. This recent study provides interesting insights for the design and deployment of adaptive authentication mechanisms based on cognitive factors of users. The results and implications of this paper are valuable in understanding and modeling user interactions with regard to authentication mechanisms.

Influences of Users' Cognitive Strategies on Graphical Password Composition

Recent research reveals interaction effects among human cognitive processing factors, interaction device types and user authentication schemes towards security of user created graphical keys. Aiming to investigate how different visual behaviors of individuals with varying cognitive strategies affect the security aspects of graphical user authentication (GUA) across device types, this paper reports preliminary results of a user study (N=51) on graphical password composition using a recognition-based GUA scheme. Results reveal differences on key strength and complexity, as well as on gaze-based entropies between users with different cognitive strategies, which can be used for the design of user-adaptive GUA schemes.

A Personalization Method Based on Human Factors for Improving Usability of User Authentication Tasks

Aiming to ensure safety of operation to application providers and improve the usability of human computer interactions during authentication, this paper proposes a two-step personalization approach of user authentication tasks based on individual differences in cognitive processing as follows: i) recommend a textual or graphical user authentication mechanism based on the users’ cognitive styles of processing textual and graphical information, and ii) recommend a standard or enhanced authentication key strength policy considering the users’ cognitive processing abilities. The proposed approach has been applied in a four month ecological valid user study in which 137 participants interacted with a personalized user authentication mechanism and policy based on their cognitive characteristics. Initial results indicate that personalizing the user authentication task based on human cognitive factors could provide a viable solution for balancing the security and usability of authentication mechanisms at the benefit of both application providers and end-users.

Employing virtual worlds for HCI education: a problem-based learning approach

In this paper we describe our experience focused on teaching an introductory course in HCI by employing a 3D virtual world. Our main pedagogical philosophy is presented which claims that problem-based learning activities are necessary for HCI education. To this end, appropriate new interactive media such as virtual worlds that can support these activities must be embedded in the educational procedure. The learning activities and the interactive tools that were used are presented. Key findings and educational implications are discussed.

Human-centred web adaptation and personalization

According to a recent claim by IBM, every day we create 2.5 quintillion bytes of data – so much that 90 % of the data in the world today has been created in the last two years alone. These data come from a variety of sources and in diverse formats creating an ecosystem that apart from the many benefi ts and opportunities it offers, generates a number of problems and complications that might hinder and disorient people in their daily interaction with online information. In this respect, non-personalized systems and applications fail to meet the needs and goals of different users. The necessity for adaptation and personalization of today’s fast growing and dynamic computing systems, content and services is now even more recognizable since they can offer alternative solutions that could adequately support the increasing multi-purpose requests and desires of users. This chapter overviews the major infl uential dimensions and aspects around this uncontrolled and vague ever-expanding digital reality, and tries to sketch the shift of viewpoints towards new research challenges in creating adaptive and personalized interactive systems that consider the human in the ‘centre’. Main aim is to provide a fi rst understanding of the context and dynamics around adaptation and personalization, and motivate the reader to appreciate the role of the user and individual differences in the design and development process of such systems.

Studying the Effect of Human Cognition on Text and Image Recognition CAPTCHA Mechanisms

This paper investigates the effect of individual differences in human cognition on user performance in CAPTCHA tasks. In particular, a three-month ecological valid user study was conducted with a total of 107 participants who interacted with a text-recognition and an image-recognition CAPTCHA mechanism. The study included a series of psychometric tests for eliciting users’ speed of processing, controlled attention and working memory capacity, with the aim to examine the effect of these cognitive processes on the efficiency and effectiveness of user interactions in CAPTCHA tasks. Preliminary results provide interesting insights for the design and deployment of adaptive CAPTCHA mechanisms based on individual differences in cognitive processing since it has been initially shown that specific cognitive processing abilities of individuals could be a determinant factor on the personalization of CAPTCHA mechanisms.

Security and Usability in Knowledge-based User Authentication: A Review

This paper presents a comprehensive review of state-of-the-art research works in knowledge-based user authentication, covering the security and usability aspects of the most prominent user authentication schemes; text-, pin- and graphical-based. From the security perspective, we analyze current threats from a user and service provider perspective. Furthermore, based on current practices in authentication policies, we summarize and discuss their security strengths based on widely applied security metrics. From the usability point of view, we present and discuss the usability of each authentication scheme in regards with task performance and user experience. The analysis reveals that although a plethora of alternative user authentication schemes have been proposed in the literature and users interact differently with the various alternatives, online service providers do not yet adopt alternatives to text-based solutions. We further discuss and identify areas for further research and improved methodology with the aim to drive this research towards the design of sustainable, secure and usable authentication approaches.

CogniWin – A Virtual Assistance System for Older Adults at Work

This paper presents an innovative virtual assistant system, which aims to address older adults’ needs in a professional environment by proposing promising and innovative virtual assistance mechanisms. The system, named CogniWin, is expected to alleviate eventual age related memory degradation and gradual decrease of other cognitive capabilities (i.e. speed of processing new information, concentration level) and at the same time assist older adults to increase their learning abilities through personalized learning assistance and well-being guidance. In this paper we describe the overall system concept, the technological approach, the methodology used in the elicitation of user needs, and describe the first pre-trials’ evaluation.