Nikolaos M. Avouris

University of Patras | UP · ECE - Division of Electronics and Computers

This paper presents CALEND_AR, a hybrid calendar application that uses augmented reality technologies to blend physical and digital calendars. The study investigates user preferences and motivations for using physical or digital calendars and explores the need for a hybrid solution that incorporates both. It comprehensively describes the applicatio...

A major concern in mixed-reality (MR) environments is to support intuitive and precise user interaction. Various modalities have been proposed and used, including gesture, gaze, voice, hand-recognition or even special devices, i.e. external controllers. However, these modalities may often feel unfamiliar and physically demanding to the end-user, le...

The worldwide shift to distance learning at Higher Education Institutions (HEIs) during the COVID-19 global pandemic has raised several concerns about the credibility of online academic activities, especially regarding student identity management. Traditional online frameworks cannot guarantee the authenticity of the enrolled student, which require...

The credibility of online examinations in Higher Education is hardened by numerous factors and use-case scenarios. This paper reports on a longitudinal study, that spanned over eighteen months, in which various stakeholders from three European Higher Education Institutions (HEIs) participated, aiming to identify core threat scenarios experienced du...

One of the main challenges of massive open online courses (MOOCs) is the effective facilitation of learners in the course forum. The more learners participating in the forum, the more difficult it is for instructors to provide timely support. The effective intervention of teaching assistants (TAs) can play a crucial role in mitigating this issue; h...

Dual-language or multiple-language keyboards are widely used in many parts of the world, where users need to type in more than one scripts. During use of such keyboards, ‘input mode errors’ often occur when the user types in one language mode while the keyboard layout is set to a different one. These errors, along with frequent switching between in...

A correction to this paper has been published: https://doi.org/10.1007/s00521-021-05904-z

Information overload in MOOC discussion forums is a major problem that hinders the effectiveness of learner facilitation by the course staff. To address this issue, supervised classification models have been studied and developed in order to assist course facilitators in detecting forum discussions that seek for their intervention. A key issue stud...

There is evidence that the visual behavior of users when creating graphical passwords affects the password strength. Adopting a cognitive style perspective in the interpretation of the results of recent studies revealed that users, depending on their cognitive style, follow different visual exploration paths when creating graphical passwords which...

Α major issue that concerns course instructors of massive open online courses (MOOCs) is the low retention ratio of learners. One of the key factors of this problem is the lack of support and interactivity in MOOC discussion forums. The support provided to learners in MOOC forums is critical to retain their motivation. Teaching assistants (TAs) pla...

Cultural heritage (CH) institutions attract wide and heterogeneous audiences, which should be efficiently supported and have access to meaningful CH content. This introduces numerous challenges when delivering such experiences, given that people have different cognitive characteristics which influence the way we process information, experience, beh...

Massive Open Online Courses (MOOCs) are delivered through dedicated platforms that provide educational opportunities to a large number of learners around the globe. The discussion forum is a key part of a MOOC platform. Structured communication between learners or between learners and instructors can take place through the forum. This communication...

People use various techniques and tools to perform spatial navigation tasks, such as asking a local person for instructions in order to reach a destination or creating a detailed route plan for their trip through technology-mediated tools. Novel technologies, such as augmented reality, have been introduced to improve the performance and enhance the...

The heterogeneity of the audience of cultural heritage (CH) institutions introduces numerous challenges to the delivery of meaningful CH content. People with diverse cognitive characteristics are engaged with varying CH activities (e.g., games, guided visits) and considering that cognitive characteristics define the way we process information, our...

Two-factor authentication (2FA) provides an extra layer of security as it requires two pieces of evidence to be provided to an authentication mechanism before granting access to a user. However, people do not prefer 2FA; a reason for this is that 2FA requires performing extra actions. In this late-breaking work, we present UltraSonic Watch which pr...

Information architecture forms the foundation of users' navigation experience. Open card sorting is a widely-used method to create information architectures based on users' groupings of the content. However, little is known about the method's cross-study reliability: Does it produce consistent content groupings for similar profile participants invo...

The heterogeneity of the audience of cultural heritage institutions introduces numerous challenges to the delivery of the content. Considering that people differ in the way they perceive, process, and recall information and that their individual cognitive differences influence their experience, performance, and knowledge acquisition when performing...

In the cultural heritage domain, games have been used to engage users into an active state of learning through immersive and playful interactions that include visually enriched interaction contexts. There is evidence that individual differences in the inherent way people search, process, analyze, comprehend, store, and retrieve visual information i...

Graphical password composition is an important part of graphical user authentication which affects the strength of the chosen password. Considering that graphical authentication is associated with visual search, perception, and information retrieval, in this paper, we report on an eye-tracking study (N=109) that aimed to investigate the effects of...

Inclusion of social good in computer science education has been proposed as an approach that demonstrates computing's social relevance and potential for positive societal impact, thus providing students with a motivating vision over the subject. This is particularly important in the context of human-computer interaction courses that can relate to r...

The purpose of this paper is to explore the characteristics of teaching assistants' interventions in Massive Open Online Courses (MOOCs). The study of interaction patterns in MOOCs can inform the design and development of mechanisms for more effective learning. We performed an analysis of teaching assistants' interactions in two different MOOCs in...

This paper presents the landscape of introductory courses in computing across Greek higher education institutions. The survey is based on publicly available data on courses and textbooks, obtained by the eudoxus.gr higher education courses/textbooks website. Research questions addressed include: (a) the approaches used and technologies applied in d...

This paper reports on innovative teaching interventions in the frame of Internet of Things (IoT) design ideation classes. A card-based gamification approach has been applied in two different engineering masters courses. The participating students had already a good understanding of IoT technologies and they were asked to produce innovative designs...

Discussion forums are considered important tools for promoting learning in Massive Open Online Courses (MOOCs). They involve learner to learner and learner to instructor discussions. An interesting research question is related to the effect of the subject matter on the characteristics of social networks of MOOCs’ discussion forums. Being motivated...

This paper reports on our experience of applying a cards-based ideation method and tool in a design for Internet of Things (IoT) workshop. In this workshop, master students of engineering participated, who had a good understanding of IoT technologies. The workshop run for two years, and has produced some interesting findings in terms of applicabili...

This paper reports on the analysis of the design of two location-based games using micro-narratives. The two games were commissioned to two historic regions of Greece, Tzoumerka and Movemvasia. In both we applied the notion of linking micro-narratives to specific locations. The objective of both games was to introduce the players through the short...

In this paper, we introduce a two-step method for estimating the strength of user-created graphical passwords based on the eye-gaze behaviour during password composition. First, the individuals' gaze patterns, represented by the unique fixations on each area of interest (AOI) and the total fixation duration per AOI, are calculated. Second, the gaze...

Nowadays, technological advances introduce new visualization and user interaction possibilities. Focusing on the user authentication domain, graphical passwords are considered a better fit for interaction environments which lack a physical keyboard. Nonetheless, the current graphical user authentication schemes are deployed in conventional layouts,...

Comprehension of visual content is linked with the visitor's experience within cultural heritage contexts. Considering the diversity of visitors towards human cognition, in this paper, we aim to investigate whether cognitive characteristics are associated with the comprehension of cultural-heritage visual content. We conducted a small-scale eye-tra...

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...

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 a...

Mixed-reality environments introduce innovative human-computer interaction paradigms assisted by enhanced visual content presentation which require from end-users to perform excessive cognitive tasks related to visual attention, search, processing, and comprehension. In such visually enriched interaction realms, individual differences in perception...

This paper discusses two user studies to investigate whether human cognitive differences affect user interaction and visual behavior within recognition-based graphical authentication tasks. In order to increase external validity, we conducted the studies with separate user samples. In the first study (N = 82) which embraced a longitudinal and ecolo...

The objective of this course, is to introduce the participants to location-based games and to the challenges relating to designing them. Key characteristics of this new genre are introduced first, followed by a design framework and a set of design guidelines. Examples of location-based games will be presented and typical design patterns as extracte...

Image-based rendering and reconstruction (IBR) approaches minimize time and costs to develop video-game assets, aiming to assist small game studios and indie game developers survive in the competitive video-game industry. To further investigate the interplay of IBR on developers’ efficiency, game performance, and players’ gaming experience we condu...

This paper investigates the trade-off between security and usability in recognition-based graphical authentication mechanisms. Through a user study (N=103) based on a real usage scenario, it draws insights about the security strength and memorability of a chosen password with respect to the amount of images presented to users during sign-up. In par...

Recent research provides evidence that individual differences in human cognitive styles affect user performance and experience in diverse application domains. However, state-of-the-art elicitation methods of cognitive styles require researchers to apply explicit, in-lab, and time-consuming "paper-and-pencil" techniques, rendering real-time integrat...

Common design practices of current cultural heritage activities barely take into account the contextual, cultural, and cognitive characteristics of visitors. Bearing in mind that information processing is substantial in such activities, this paper investigates the interplay among human cognitive differences and cultural heritage gaming activities t...

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 authentica...

Recent research provides evidence that individual differences on human cognitive strategies affect user performance and experience in diverse application domains. However, state-of-the-art elicitation methods of human cognitive strategies require from researchers to apply explicit, in-lab, and time-consuming "paper-and-pencil" techniques, compromis...

This paper discusses our experience with designing and implementing a new Introduction to Computing course that aims both to introduce students to programming and at the same time to cover key concepts of Computer Science using a hands-on experiential approach. The redesign of the course has put more emphasis on using Python as a tool for studying...

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....

Being the windows to the soul, eyes reveal information about individuals' feelings, emotions and behaviour, affecting various cognitive tasks, such as focus of attention, spatial cogni-tion and navigation, cognitive load, etc. With the increased use of computer systems, complex information is visualized and communicated through visual interfaces as...

Based on a large number of different cognitive theories on information processing procedure, suggesting that individuals have different approaches in the way they forage, retrieve, process, store and recall information, this paper investigates the effect of field dependence/ independence with regards to visual attention of gamers in the context of...

Stimulated by a large number of different theories on human cognitive processing, suggesting that individuals have different habitual approaches in retrieving, recalling, processing and storing information, this paper investigates the effect of field dependence/independence with regards to game players' performance in the context of a cultural heri...

Retrieving, recalling, processing, organising and storing information are integral parts of the human information seeking process and many socio-cognitive theories suggest that the approach of the seekers is closely related to their cognitive processing styles and abilities. The aim of this study is to investigate the impact of wholistic-analytic c...

The majority of existing Learning Management Systems (LMS) support collaborative learning throughunstructured, general purpose collaboration workspaces that provideeducators with semantically poor low-level data about learners’ interactions. Educators in turn, labourto process and interpret this kind of data, and consequently, are not ableto interv...

This paper reports the results of a study of software development organizations' approach towards usability, conducted on software development organizations in Greece, extending a survey conducted in Southern Italy in 2011. The results show that the organization performing usability evaluation is nearly the same in both countries as well as the key...

This is an overview of game-related research of the HCI Group of the University of Patras. We are active in the area of location-based mobile games, with an interest at games that can enrich the cultural experience in open spaces (like city centres) and in museums aiming to actively engage citizens and/or visitors with cultural spaces. Over the pas...

This is an overview of game-related research of the HCI Group of the University of Patras. We are active in the area of location-based mobile games, with an interest at games that can enrich the cultural experience in open spaces (like city centres) and in museums aiming to actively engage citizens and/or visitors with cultural spaces. Over the pas...

Although problem-based learning (PBL) has many advantages, it often fails to connect to the real world outside the classroom. The integration with the laboratory setting and the use of information and communication technologies (ICTs) have been proposed to address this deficiency. Multi-user virtual environments (MUVEs) like Second Life (SL) are 3D...

Οι διαδραστικές τεχνολογίες έχουν διεισδύσει σε μεγάλο βαθμό στην καθημερινή μας ζωή. Η περιοχή της επιστήμης που είναι γνωστή ως Επικοινωνία Ανθρώπου-υπολογιστή (Human-computer interaction, HCI) έχει ως αντικείμενο την μελέτη το σχεδιασμό, ανάπτυξη και αξιολόγηση Διαδραστικών Υπολογιστικών Συστημάτων (interactive computer systems), δηλαδή συστημάτ...

Περίληψη “Open Courses”, has been a large scale initiative to develop open courseware in Greek higher education. As the project has come to its end, a first evaluation of the outcomes is attempted in this paper at the level of one of the participating universities. The University of Patras has been a major partner in this project. It has been the...

(authors' copy) The analysis and evaluation of computer-supported collaborative activities is a complex and tedious task. However, it is necessary in order to support collaborative scenarios, to scaffold the collaborative knowledge building and to evaluate the learning outcome. Various automated techniques have been proposed to minimize the worklo...

Effective and efficient approaches are required in order to develop and maintain cultural heritage applications and services that meet user requirements and expectations. This is particularly relevant to cultural heritage mobile applications which support interaction experiences among a variety of stakeholders and diverse contexts of use. In this c...

Engaging museum visitors through game playing is an approach that has been used extensively by many museums and cultural institutions. Location-based games, facilitated by mobile technologies, have been already implemented in various museums, archaeological, historical, cultural, science, art galleries, etc. However a particularly hard case to impl...

Mobile technology has been used for indoors and outdoors applications related to Cultural Heritage over many years. Mobile applications in museums and other sites of culture can satisfy visitors' needs through the provision of contextualized contents and services. Personalization of these services is necessary as the amount of available information...

INTERACT is among the world’s top conferences in Human-Computer Interaction. Starting with the first INTERACT conference in 1990, this conference series has been organised under the aegis of the Technical Committee 13 on Human-Computer Interaction of the UNESCO International Federation for Information Processing (IFIP). This committee aims at devel...

This paper describes TaggingCreaditor, a content authoring tool for location-based games. This tool is implemented both as a mobile and desktop application, which offers the possibility to end users to easily create, edit and/or mix content for these games. TaggingCreaditor has been designed to support a number of location-based games for learning...

In this paper we discuss the difficulty of museum visitors to engage and relate with cultural objects focusing mainly on pieces of contemporary art. We present Taggling a location based game designed to support learning in the Macedonian Museum of Contemporary Art. The results of a qualitative user study with volunteers helped us to outline the lea...

This paper presents a mobile augmented reality application, that was designed with the objective of visitors, to experience the historical center of old Zakynthos, Greece, that was destroyed after an earthquake, and allow the users to re-live the atmosphere and life of the historic place. Special attention is given to the mental model of the landma...

When people interact with digital artefacts they perceive their pragmatic and hedonic qualities. In the case of interacting with mobile devices and applications, users seek utility as they try to satisfy certain needs, but at the same time they have certain feelings and emotions when, for example, they feel attached to their personal phone and/or t...

This paper presents the integration of a real time evaluation method of collaboration quality in a monitoring application that supports teachers in class orchestration. The method is implemented as an automatic rater of collaboration quality and studied in a real time scenario of use. We argue that automatic and semi-automatic methods which provide...