10 results on '"Avouris, Nikolaos"'
Search Results
2. Computer-Supported Collaborative Concept Mapping: Study of Synchronous Peer Interaction
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Komis, Vassilis, Avouris, Nikolaos, and Fidas, Christos
- Published
- 2002
- Full Text
- View/download PDF
3. Eye Gaze-driven Prediction of Cognitive Differences during Graphical Password Composition
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Katsini, Christina, Fidas, Christos, Raptis, George E., Belk, Marios, Samaras, George, Avouris, Nikolaos, and Belk, Marios [0000-0001-6200-0178]
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Password ,Recall ,Computer science ,User modeling ,05 social sciences ,Cognition ,02 engineering and technology ,Service provider ,Affect (psychology) ,Human–computer interaction ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,Eye tracking ,0501 psychology and cognitive sciences ,050107 human factors ,Cognitive style - Abstract
Evidence suggests that individual cognitive differences affect users' memorability, visual behavior, and graphical passwords' security. Such knowledge denotes the added value of personalizing graphical password schemes towards the unique cognitive characteristics of the users. However, real-time and accurate cognition-based predictive user models are necessary to reach such a breakthrough. In this paper, we present the results of such an attempt, where an in-lab eye-tracking study was conducted with 36 participants who completed a recall-based graphical password composition task. We adopted a credible cognitive style theory, and investigated a variety of eye-tracking metrics to predict participants' cognitive styles. Results' analysis reveals that inferring individual cognitive differences in real-time during graphical password composition is feasible within a few seconds and that specific eye-tracking metrics correlate stronger with certain cognitive style groups. The findings further support the vision of incorporating real-time adaptive mechanisms in graphical password schemes for the benefit of service providers and end-users.
- Published
- 2018
4. Influences of Human Cognition and Visual Behavior on Password Strength during Picture Password Composition
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Katsini, Christina, Fidas, Christos, Raptis, George E., Belk, Marios, Samaras, George, Avouris, Nikolaos, and Belk, Marios [0000-0001-6200-0178]
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Password ,Elementary cognitive task ,Computer science ,05 social sciences ,Perspective (graphical) ,C850 ,Cognition ,02 engineering and technology ,Password strength ,Human–computer interaction ,0202 electrical engineering, electronic engineering, information engineering ,Eye tracking ,020201 artificial intelligence & image processing ,0501 psychology and cognitive sciences ,050107 human factors ,I140 ,Cognitive style - Abstract
Visual attention, search, processing and comprehension are important cognitive tasks during a graphical password composition activity. Aiming to shed light on whether individual differences on visual behavior affect the strength of the created passwords, we conducted an eye-tracking study (N=36), and adopted an accredited cognitive style theory to interpret the results. The analysis revealed that users with different cognitive styles followed different patterns of visual behavior which affected the strength of the created passwords. Motivated, by the results of the first study, we introduced adaptive characteristics to the user authentication mechanism, aiming to assist specific cognitive style user groups to create more secure passwords, and conducted a second study with a new sample (N=40) to test the adaptive characteristics. Results strengthen our assumptions that adaptive mechanisms based on users' differences in cognitive and visual behavior uncover a new perspective for improving the password's strength within graphical user authentication realms.
- Published
- 2018
5. Influences of users' cognitive strategies on graphical password composition
- Author
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Katsini, Christina P., Fidas, Christos A., Belk, Marios, Avouris, Nikolaos M., Samaras, George S., and Belk, Marios [0000-0001-6200-0178]
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Scheme (programming language) ,Computer science ,Human engineering ,02 engineering and technology ,Affect (psychology) ,Human–computer interaction ,020204 information systems ,Cognitive Strategy ,Graphical user authentication ,0202 electrical engineering, electronic engineering, information engineering ,0501 psychology and cognitive sciences ,Composition (language) ,050107 human factors ,computer.programming_language ,Password ,Human cognitive differences ,Authentication ,Eye tracking ,Cognitive password ,05 social sciences ,Cognition ,User authentication ,User authentication scheme ,Usable security ,Cognitive processing ,Interaction devices ,Eye-tracking ,computer - Abstract
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. Copyright © 2017 by the Association for Computing Machinery, Inc. (ACM). Part F127655 2698 2705 Conference code: 127655 Cited By :3
- Published
- 2017
6. Preface
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Pivec, Maja, Gründler, Josef, Admiraal, Wilfried, Alemi, Minoo, All, Anissa, Almeida, Ana, Amresh, Ashish, Arnab, Sylvester, Ask, Kristine, Avouris, Nikolaos, Awwal, Nafisa, Hauge, Jannicke Baalsrud, Badau, Dana, Barata, Ana, Barendregt, Wolmet, Basaiawmoit, Rajiv, Bellotti, Francesco, Blanchfield, Peter, Borit, Melania, Boskic, Natasha, Boyle, Liz, Brady, Mairead, Bratitsis, Tharrenos, Brinch, Sara, Brom, Cyril, Brooks, Anthony, Brown, David, Brox, Ellen, Busch, Carsten, Caldeira, Carlos, Callies, Sophie, Cardoso, Tiago, Carron, Thibault, Casimir, Rommert, De Castro, António Vieira, Chang, Maiga, Charalambis, Dimitris, Charles, Darryl, Charlier, Nathalie, Chee, Yam San, Chen, Ming-Puu, Chiarello, Fabio, Connolly, Thomas, Crockett, Larry, Darwish, Tamer, Sigurdardottir, Helga, Deliyannis, Ioannis, Demirbilek, Muhammet, Sigurdardottir, Helga Dis, Duin, Heiko, Dyer, Ronald, Edgar, David, Ejsing-Duun, Stine, Escudeiro, Paula, Felicia, Patrick, Fesakis, Georgios, Figueira, Ana Paula, Fotaris, Panagiotis, Fujimoto, Toru, George, Sebastien, Georgiadis, Panagiotis, Gerodetti, Natalia, Giannakoulopoulos, Andreas, Gjedde, Lisa, Goebel, Stefan, Gomez-Martin, Pedro Pablo, Gouscos, Dimitris, Grigoriadou, Maria, Guralnick, David, Guttormsgaard, Vibeke, Habgood, Jacob, Hainey, O., Hanghoj, Thorkild, Hawlitschek, Anja, Hemben, Terseer, Hlavacs, Helmut, Hommedal, Silje Hole, Hollins, Paul, Idrus, Rozhan, Wang, Alf Inge, Ismail, Marina, Jans, Ruben, Juzeleniene, Saule, Kalavassis, Fragiskos, Kalogiannakis, Michail, Karakostas, Anastasios, Katzlinger-Felhofer, Elisabeth, Ketamo, Harri, Ketelhut, Diane Jass, Kickmeier-Rust, Michael, Kiili, Kristian, Koeppen, Veit, Kolås, Line, Kordaki, Maria, Korkut, Safak, Kourti, Evangelia, Ken, Li, Lukosch, Heide, Macleod, Hamish, Magnussen, Rikke, Majgaard, Gunver, Marchetti, Emanuela, Marques, Bertil, Marty, Jean-Charles, Marzantowicz, Lukasz, Mehm, Florian, Meimaris, Michail, Michel, Christine, Moffat, David, Montero-Fleta, Begoña, Moseley, Alexander, Mota, Dulce, Mozelius, Peter, Nadolski, Rob, Nelson, Brian, Neville, Karen, Annie W. Y., Ng, Nixon, Darren, Nocchi, Susanna, Broin, Daire O., O'Mullane, John, Skevik, Trond Olav, Øygardslia, Kristine, Panagouli, Dimitra, Papagiannakis, George, Papakonstantinou, George, Papastergiou, Marina, Peachey, Paul, Peirce, Neil, Perez-Sabater, Carmen, Pfeiffer, Alexander, Pimenidis, Elias, Piramuthu, Selwyn, Plohn, Trygve, Popescu, Maria-Magdalena, Poskiene, Audrone, Poylymenakou, Angeliki, Reis, Rosa, Retalis, Simos, Rito, Pedro, Rogers, Gregory, Rossiou, Eleni, Roussou, Maria, Rugelj, Joze, Salajan, Florin, Santorineos, Manthos, Sardone, Nancy, Schneider, Etienne, Shabalina, Olga, Shah, Samir, Siepermann, Markus, Sillaots, Martin, Silseth, Kennet, Sim, Gavin, Sime, Julie-Ann, Skoumpourdi, Chrysanthi, Soebke, Heinrich, Stansfield, Mark, Steinicke, Martin, Stewart, Ian, Tang, Stephen, Thomas, Andre, Tomos, Florica, Trivedi, Uday, Tsiatsos, Thrasyvoulos, Tunstall, Richard, Vahed, Anisa, Vallance, Michael, Van Eck, Richard, Van Oostendorp, Herre, Van Rosmalen, Peter, Vaz De Carvalho, Carlos, Verhagen, Harko, Voulgari, Iro, Weitz, Charlotte Lærke, Wendel, Viktor, Westera, Wim, Westin, Thomas, Whitton, Nicola, Williams, Dorothy, Wilson, Amanda, Wilson, Andrew, Wong, Yoke Seng, Zaharias, Panagiotis, and Zorina, Aljona
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Human-Computer Interaction ,Computer Networks and Communications ,Artificial Intelligence ,Control and Systems Engineering ,Software ,Computer Graphics and Computer-Aided Design ,3304 - Published
- 2017
7. Mutually Coordinated Anticipatory Multimodal Interaction
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Nijholt, Anton, Reidsma, Dennis, van Welbergen, Herwin, Akker, Rieks, Ruttkay, Zsofia, Esposito, Anna, Bourbakis, Nikolaos G., Avouris, Nikolaos, and Hatzilygeroudis, Ioannis
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Computer science ,media_common.quotation_subject ,METIS-251104 ,Turn-taking ,HMI-MI: MULTIMODAL INTERACTIONS ,EC Grant Agreement nr.: FP6/033812 ,Multimodal interaction ,Human–computer interaction ,Perception ,Synchronization (computer science) ,IR-62066 ,EWI-11601 ,Virtual actor ,media_common - Abstract
We introduce our research on anticipatory and coordinated interaction between a virtual human and a human partner. Rather than adhering to the turn taking paradigm, we choose to investigate interaction where there is simultaneous expressive behavior by the human interlocutor and a humanoid. We have designed various applications in which we can study and specify such behavior, in particular behavior that requires synchronization based on predictions from performance and perception. We have some preliminary observations – based on the literature and in analogy with our applications – on the role of predictions in conversations. Architectural consequences for the design of virtual humans are presented.
- Published
- 2008
8. A SURVEY OF TOOLS SUPPORTING DESIGN AND EVALUATION OF WEBSITES BASED ON MODELS OF HUMAN INFORMATION INTERACTION.
- Author
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KATSANOS, CHRISTOS, TSELIOS, NIKOLAOS, and AVOURIS, NIKOLAOS
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WEB design ,SCIENTIFIC surveys ,HUMAN-computer interaction ,COMPUTER simulation ,COMPUTER algorithms ,HYPERLINKS ,DATA structures - Abstract
This paper presents and discusses a survey of existing tools to support design and evaluation of websites, with special emphasis on improving the information navigation process. The amount of information of today's websites, the continuous evolution of the medium and the heterogeneity of typical users' profiles, make the website design task particularly hard. The presented tools are mainly based on recent models of Web usage behavior, and involve various natural language and semantic similarity modeling methods. Validation studies of the presented tools have shown that they can support effectively various phases of the website design lifecycle including information structuring, hyperlink evaluation and assessment of alternative designs. In this paper, existing techniques are discussed, the aspects of Web design that (should and) could be better supported are identified and suggestions are made on extensions of existing approaches to better support the usability evaluation process. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
9. Heterogeneity of learning material in synchronous computer-supported collaborative modelling
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Fidas, Christos, Komis, Vassilis, Tzanavaris, Spyros, and Avouris, Nikolaos
- Subjects
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STUDENTS , *PROBLEM solving , *DECISION making , *COMPUTER systems - Abstract
This paper examines the effect of heterogeneous resources, available to students, during computer-supported collaborative problem solving. A study of collaborative modeling has been conducted in the frame of an authentic educational activity in a secondary school. The students involved were provided with sets of primitive resources of varying degrees of heterogeneity to be used during synchronous computer-mediated modeling activities. Analysis of students'' peer interaction and of the produced solutions revealed that, contrary to our expectations, the group with heterogeneous resources produced solutions of similar quality to those of the reference group, although they were more active, they exchanged more messages, they were involved in deeper discussions and collaborated more for building the constituent parts of the solution. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
10. Προσαρμοσμένη εύχρηστη ασφάλεια: εξατομίκευση μηχανισμών ταυτοποίησης χρηστών και CAPTCHA με βάση τις ατομικές τους διαφορές στην γνωστική διεργασία της πληροφορίας
- Author
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Belk, Marios R., Samaras, George, Παττίχης, Κωνσταντίνος, Δικαιάκος, Μάριος, Γερμανάκος, Παναγιώτης, Αβούρης, Νικόλαος, Pattichis, Constantinos, Dikaiakos, Marios, Germanakos, Panagiotis, Avouris, Nikolaos, Dimitrova, Vania, Πανεπιστήμιο Κύπρου, Σχολή Θετικών και Εφαρμοσμένων Επιστημών, Τμήμα Πληροφορικής, and University of Cyprus, Faculty of Pure and Applied Sciences, Department of Computer Science
- Subjects
HUMAN COGNITIVE PROCESSING CHARACTERISTICS ,Computers -- Access control ,USABLE SECURITY ,ΜΟΝΤΕΛΟΠΟΙΗΣΗ ΧΡΗΣΤΩΝ ,ADAPTATION AND PERSONALIZATION SYSTEMS ,Adaptive computing systems ,User interfaces (Computer systems) ,ΕΥΧΡΗΣΤΗ ΑΣΦΑΛΕΙΑ ,Human-computer interaction ,ΜΗΧΑΝΙΣΜΟΙ ΤΑΥΤΟΠΟΙΗΣΗΣ ΧΡΗΣΤΩΝ ,ΑΛΛΗΛΕΠΙΔΡΑΣΗ ΑΝΘΡΩΠΟΥ-ΥΠΟΛΟΓΙΣΤΗ ,ΓΝΩΣΤΙΚΕΣ ΔΙΕΡΓΑΣΙΑΣ ΑΤΟΜΩΝ ,Computer security ,USER MODELING ,Individual differences ,ΜΗΧΑΝΙΣΜΟΙ ΔΙΑΧΩΡΙΣΜΟΥ ΑΝΘΡΩΠΟΥ-ΜΗΧΑΝΗΣ ,ΣΥΣΤΗΜΑΤΑ ΠΡΟΣΑΡΜΟΓΗΣ ΚΑΙ ΕΞΑΤΟΜΙΚΕΥΣΗΣ ,Computer users ,CAPTCHA ,ΑΤΟΜΙΚΕΣ ΔΙΑΦΟΡΕΣ ΧΡΗΣΤΩΝ ,USER AUTHENTICATION - Abstract
Includes bibliography (p. 237-258). Number of sources in the bibliography: 394 Thesis (Ph. D.) -- University of Cyprus, Faculty of Pure and Applied Sciences, Department of Computer Science, 2015. The University of Cyprus Library holds the printed form of the thesis. Η αλληλεπίδραση ανθρώπου-υπολογιστή μετατοπίζεται από παραδοσιακούς υπολογιστές και αυτόνομες εφαρμογές, προς την αλληλεπίδραση χρηστών με φορητές υπολογιστικές συσκευές και εφαρμογές που υποστηρίζονται από το υπολογιστικό νέφος. Σε αυτό το πλαίσιο, το θέμα της ασφάλειας διαδραστικών συστημάτων κερδίζει ολοένα και περισσότερο την προσοχή ερευνητών και εμπειρογνωμόνων, όχι μόνο από τεχνικής άποψης, αλλά επίσης από την πλευρά της ευχρηστίας. Η κοινότητα ασφάλειας έχει κατανοήσει τη ζωτική σημασία της «εύχρηστης ασφάλειας» (usable security), η οποία εστιάζεται κυρίως στο σχεδιασμό συστημάτων ασφαλείας που να είναι εύχρηστα και φιλικά προς το χρήστη. Οι κυρίαρχες αλληλεπιδράσεις ανθρώπων με συστήματα ασφαλείας στον Παγκόσμιο Ιστό σχετίζονται κυρίως με την ταυτοποίηση χρηστών (user authentication) και το διαχωρισμό μεταξύ ανθρώπων-μηχανών μέσω μηχανισμών CAPTCHA. Ο σχεδιασμός και η ανάπτυξη αυτών των μηχανισμών αντιπροσωπεύει ένα υπαρκτό πρόβλημα μεταξύ ασφάλειας και ευχρηστίας, το οποίο προκύπτει κυρίως από αντιφατικούς στόχους και απαιτήσεις που δημιουργούνται μεταξύ των διαφόρων εγγενών εμπλεκομένων παραγόντων. Από τη μία πλευρά, ειδικοί σε θέματα ασφάλειας αυξάνουν συνεχώς τα επίπεδα της ασφάλειας των μηχανισμών ταυτοποίησης χρηστών και CAPTCHA, ενώ από την άλλη, οι τελικοί χρήστες απαιτούν διαφάνεια, προσαρμοσμένες και φιλικές λύσεις που δεν θα αποτελούν εμπόδιο στην εκτέλεση των καθημερινών τους διεργασιών. Παράλληλα, οι πάροχοι υπηρεσιών από κοινού με εμπειρογνώμονες σε θέματα ευχρηστίας, προσπαθούν να αναδείξουν μια βιώσιμη ισορροπία μεταξύ της ασφάλειας και της ευχρηστίας με σκοπό την αύξηση της αποδοχής υπηρεσιών και εφαρμογών από τους χρήστες. Στο πλαίσιο αυτό, η έρευνα σχετικά με τέτοιου είδους μηχανισμούς ασφαλείας αποτελεί προτεραιότητα τα τελευταία χρόνια, με στόχο την ανάπτυξη μηχανισμών που να προσφέρουν υψηλά πρότυπα ασφαλείας και ταυτόχρονα να διατηρούν την απρόσκοπτη αλληλεπίδραση με τους νόμιμους χρήστες. Επί του παρόντος, η ανάπτυξη μηχανισμών ταυτοποίησης χρηστών και CAPTCHA ακολουθεί κυρίως το μοντέλο «ένας-σχεδιασμός-για-όλους». Κατ’ επέκταση, ο ίδιος τύπος μηχανισμού κοινοποιείται σε όλους τους χρήστες χωρίς να λαμβάνεται υπόψη ότι οι χρήστες έχουν διαφορετικά χαρακτηριστικά, πολιτισμικό και γνωστικό υπόβαθρο. Έχοντας κατά νου ότι οι αλληλεπιδράσεις ανθρώπου-υπολογιστή όσον αφορά τους μηχανισμούς ταυτοποίησης χρηστών και CAPTCHA εκτελούνται κυρίως σε γνωστικό επίπεδο, που περιλαμβάνουν την αντίληψη, την αναγνώριση, μνήμη και σκέψη, η παρούσα διδακτορική διατριβή υποστηρίζει ότι ανθρώπινοι γνωστικοί παράγοντες μπορούν να προσφέρουν μια στρατηγική προοπτική για την εξέταση μηχανισμών ταυτοποίησης και CAPTCHA, πλαισιωμένη από θεωρίες ατομικών διαφορών γνωστικής επεξεργασίας. Στα πλαίσια της διατριβής αυτής επιχειρείται να επανεξεταστεί ο ορισμός της «εύχρηστης ασφάλειας», προτείνοντας μια εναλλακτική προσέγγιση του προβλήματος η οποία ωθείται από την έρευνα σε μοντελοποίηση χρηστών, προσαρμογή και εξατομίκευση συστημάτων αλληλεπίδρασης και ατομικών διαφορών. Κύριος στόχος είναι η εξατομίκευση και βελτίωση της ευχρηστίας μηχανισμών ταυτοποίησης και CAPTCHA λαμβάνοντας υπόψη τα μοναδικά χαρακτηριστικά της γνωστικής επεξεργασίας των χρηστών. Οι στόχοι της διατριβής είναι: (i) Να εξεταστεί η επίδραση γνωστικών παραγόντων στις προτιμήσεις χρηστών και ευχρηστίας διαφόρων μηχανισμών ταυτοποίησης και CAPTCHA, που υποστηρίζεται από μια σειρά έγκυρων μελετών, βασισμένες σε ποσοτικές και ποιοτικές μετρήσεις, (ii) να προταθεί ένα γνωστικό μοντέλο χρηστών, και να μοντελοποιηθεί ένας μηχανισμός προσαρμογής τύπου και πολυπλοκότητας μηχανισμών ταυτοποίησης και CAPTCHA, και (iii) να προταθεί ένα πλαίσιο εξατομίκευσης PAC (Personalized Authentication and CAPTCHA), που προτείνει την καλύτερη δυνατή απόφαση προσαρμογής μηχανισμών ταυτοποίησης χρηστών και CAPTCHA. Computer-human interaction is nowadays shifting from traditional desktop computers and standalone applications towards mobile computing devices and cloud-based oriented applications and services, mainly triggered by developments in network communication technologies. Within this realm, security issues of interactive systems are gaining more than ever the attention not only from a technical and security perspective but also from the user’s point of view. The security community has come to understand the critical importance of usable security, which is primarily focused on designing secure systems that people can use. The predominant user security interactions over the World Wide Web are commonly related to user authentication and CAPTCHA mechanisms. Design and development of user authentication and CAPTCHA represents a cross-roads priority problem, between security and usability, which emerge from contradictory requirements posed by different stakeholders, inherent to the function and purpose of each security mechanism. On the one hand, security experts increase continuously the security levels of user authentication and CAPTCHA, while on the other, end-users demand transparent, adaptable and user-friendly solutions. In parallel, service providers together with user experience experts, try to find a viable equilibrium among security and usability in order to increase the acceptability of services and applications. In this context, research on these security mechanisms has received significant attention lately, aiming to offer high security standards and at the same time to maintain a seamless interaction for the legitimate users. Currently, deployment of user authentication and CAPTCHA mechanisms follow a “one-size-fits-all” paradigm. The same type of text-based password and text-recognition CAPTCHA is communicated to all users neglecting the fact that users have different cultural and cognitive backgrounds, and interact in different contexts of use. Bearing in mind that human-computer interactions with regard to user authentication and CAPTCHA mechanisms are in principal cognitive tasks that embrace perception, recognition, remembering and reasoning, this research work builds on the promise that human cognitive factors offer a widely ignored but very strategical perspective for examining user authentication and CAPTCHA tasks framed by theories of individual differences in human cognitive processing. Henceforth, this work attempts to revisit the definition of usable security by advocating an alternative approach which is driven by research in the intersection of User Modeling, Adaptation and Personalization, and Individual Differences. Main focus is to personalize and improve the usability of user interactions in authentication and CAPTCHA according to the unique cognitive processing characteristics of users. The high-level objectives of the thesis are: (i) Investigate the effects of human cognitive factors on user preference and task performance of different user authentication and CAPTCHA mechanisms, supported by a number of ecological valid user studies, and quantitative and qualitative metrics; (ii) propose a formalization of a cognitive factor-based user model and an adaptation engine for personalizing user authentication and CAPTCHA tasks on design type and complexity; and (iii) propose PAC (Personalized Authentication and CAPTCHA), a personalization framework that recommends the “best-fit” decision based on the aforementioned formalizations.
- Published
- 2015
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