Embodying photorealistic personalized avatars that closely resemble their users has recently become technologically achievable in virtual reality (VR). While previous work highlighted several benefits of personalization, its impact on emotions, a central VR element, remains underexplored. Given their high production cost, assessing the added value of photorealistic personalized avatars is essential before their adoption as a design feature. To address this, we designed and validated (n=302) four virtual environments (VEs) that induce emotions in different quadrants of Russell’s Circumplex Model. Using these VEs, we systematically investigated the impact of avatar type (no avatar, generic avatar, personalized avatar) on perceived emotions and physiological responses (n=51). Generic avatars enhanced valence, arousal, embodiment, presence and selected physiological measures, while personalized avatars further amplified these effects and additionally increased heart rate variability, a marker of self-regulation. Our study demonstrates that photorealistic personalized avatars markedly enhance VR’s capacity to foster emotional engagement.

Healthcare artificial intelligence (HAI) robots could alleviate the current healthcare provision crisis. However, their successful deployment rests on achieving and responsibly calibrating appropriate patient trust in them. Over two user studies, we systematically investigate trust formation in and usage intentions for HAI robots. We first investigate manipulations of visual appearance in a passive observation study without healthcare-specific situational context (n=87) and then in a realistic VR scenario depicting a medical consultation with a HAI robot (n=177) that introduces such situational context (diagnosis and treatment severity). Results show that within a healthcare context, a unique combination of (i) situational (diagnosis and treatment severity), (ii) robot (perceived competence) and (iii) user characteristics (personality and attitudes) determine trust and ultimately influence usage intentions for HAI robots. Furthermore, our results emphasize the absence of HAI visual appearance effects on trust. Our findings support and inform a human centred design approach of HAI robots.

Article 5 of the European Union’s Artificial Intelligence Act is intended to regulate AI use to prevent potentially harmful consequences. Nevertheless, applying this legislation practically is likely to be challenging because of ambiguously used terminologies and because it fails to specify which manipulation techniques may be invoked by AI, potentially leading to significant harm. This paper aims to bridge this gap by defining key terms and demonstrating how AI may invoke these techniques, drawing from insights in psychology and behavioural economics. First, this paper provides definitions of the terms “subliminal techniques”, “manipulative techniques” and “deceptive techniques”. Secondly, we identified from the literature in cognitive psychology and behavioural economics three subliminal and five manipulative techniques and exemplify how AI might implement these techniques to manipulate users in real-world case scenarios. These illustrations may serve as a practical guide for stakeholders to detect cases of AI manipulation and consequently devise preventive measures. Article 5 has also been criticised for offering inadequate protection. We critically assess the protection offered by Article 5, proposing specific revisions to paragraph 1, points (a) and (b) of Article 5 to increase its protective effectiveness.

There is great potential for adapting Virtual Reality (VR) exergames based on a user’s affective state. However, physical activity and VR interfere with physiological sensors, making affect recognition challenging. We conducted a study (n=72) in which users experienced four emotion inducing VR exergaming environments (happiness, sadness, stress and calmness) at three different levels of exertion (low, medium, high). We collected physiological measures through pupillometry, electrodermal activity, heart rate, and facial tracking, as well as subjective affect ratings. Our validated virtual environments, data, and analyses are openly available. We found that the level of exertion influences the way affect can be recognised, as well as affect itself. Furthermore, our results highlight the importance of data cleaning to account for environmental and interpersonal factors interfering with physiological measures. The results shed light on the relationships between physiological measures and affective states and inform design choices about sensors and data cleaning approaches for affective VR.

VR exergaming is a promising motivational tool to incentivise exercise. We present a novel VR exergaming method called social interactive feedforward. The player competes with an 'enhanced model' of one of their friends in a real-time VR environment, showing improved performance levels in a way the player can relate to. Social interactive feedforward was tested in a cycling-based VR exergame and players competed with enhanced models of themselves, their friend, and a stranger moving at the same enhanced pace. Results show that friend-modelled social interactive feedforward improves performance and intrinsic motivation the most. This indicates that the mere association of the enhanced model with their friend results in a rapid improvement in performance and motivation which implies that social feedforward was successfully elicited by using an enhanced friend's model. This widens the application of self-modelled feedforward to a wide range of social options which enables players to also reap the benefits of socialising in addition to feedforward benefits.

Presence is one of the most studied and most important variables in immersive virtual reality (VR) and it influences the effectiveness of many VR applications. Separate bodies of research indicate that presence is determined by (1) technical factors such as the visual realism of a virtual environment (VE) and the field of view (FoV), and (2) human factors such as emotions and agency. However, it remains unknown how technical and human factors may interact in the presence formation process. We conducted a user study (n=360) to investigate the effects of visual realism (high/low), FoV (high/low), emotions (focusing on fear) and agency (yes/no) on presence. Counter to previous assumptions, technical factors did not affect presence directly but were moderated through human factors. We propose TAP-Fear, a structural equation model that describes how design decisions, technical factors and human factors combine and interact in the formation of presence.

Personality characteristics can affect how much presence an individual experiences in virtual reality, and researchers have explored how it may be possible to prime users to increase their sense of presence. A personality characteristic that has yet to be explored in the VR literature is imaginative suggestibility, the ability of an individual to successfully experience an imaginary scenario as if it were real. In this paper, we explore how suggestibility and priming affect presence when consulting an ancient oracle in VR as part of an educational experience – a common VR application. We show for the first time how imaginative suggestibility is a major factor which affects presence and emotions experienced in VR, while priming cues have no effect on participants’ (n=128) user experience, contrasting results from prior work. We consider the impacts of these findings for VR design and provide guidelines based on our results.

Street harassment is a widespread problem that can constrain people’s freedom to enjoy public spaces safely, along with many other negative psychological impacts. However, very little research has looked at how immersive technology can help in addressing it. We conducted three studies to investigate the design decisions, ethical issues and efficacy of an immersive simulation of street harassment: an online design study (n=20), an interview study with experts working in the area (n=9), and a comparative lab study investigating design, ethics and efficacy (n=44). Our results deepen understanding of the design decisions that contribute to a realistic psychological experience, such as the effects of screen-based video vs passive VR vs interactive VR. They also highlight important ethical issues such as traumatisation and potential for victim blaming, and how they can be approached in an ethical manner. Finally, they provide insights into efficacy in terms of perceived usefulness, competence and empathy.

Arguably one of the most important characteristics of virtual reality (VR) is its ability to induce higher feelings of presence. Still, research has remained inconclusive on how presence is affected by human factors such as emotion and agency. Here we adopt a novel design to investigate their effects by testing virtual environments inducing either happiness or fear, with or without user agency. Results from 121 participants showed that the dominant emotion induced by a virtual environment is positively correlated with presence. In addition, agency had a significant positive effect on presence and, furthermore, moderated the effect of emotion on presence. We show for the first time that the effects of emotion and agency on presence are not straightforward but they can be modelled by separating design factors from subjective measures. We discuss how these findings can explain seemingly conflicting results of related work and their implications for VR design.

User experience estimation of VR exergame players by recognising their affective state could enable us to personalise and optimise their experience. Affect recognition based on psychophysiological measurements has been successful for moderate intensity activities. High intensity VR exergames pose challenges as the effects of exercise and VR headsets interfere with those measurements. We present two experiments that investigate the use of different sensors for affect recognition in a VR exergame. The first experiment compares the impact of physical exertion and gamification on psychophysiological measurements during rest, conventional exercise, VR exergaming, and sedentary VR gaming. The second experiment compares underwhelming, overwhelming and optimal VR exergaming scenarios. We identify gaze fixations, eye blinks, pupil diameter and skin conductivity as psychophysiological measures suitable for affect recognition in VR exergaming and analyse their utility in determining affective valence and arousal. Our findings provide guidelines for researchers of affective VR exergames.

Customised avatars are a powerful tool to increase identification, engagement and intrinsic motivation in digital games. We investigated the effects of customisation in a self-competitive VR exergame by modelling players and their previous performance in the game with customised avatars. In a first study we found that, similar to non-exertion games, customisation significantly increased identification and intrinsic motivation, as well as physical performance in the exergame. In a second study we identified a more complex relationship with the customisation style: idealised avatars increased wishful identification but decreased exergame performance compared to realistic avatars. In a third study, we found that 'enhancing' realistic avatars with idealised characteristics increased wishful identification, but did not have any adverse effects. We discuss the findings based on feedforward and self-determination theory, proposing notions of intrinsic identification (fostering a sense of self) and extrinsic identification (drawing away from the self) to explain the results.

The field of game research is still very young. As such, unlike many research fields, it lacks an established or widely accepted set of methods and techniques. Methods are often taken from other fields while new tools tailored specifically to games are still emerging. We used a conceptual content analysis approach to review the methodology of papers published from 2013 to 2018 in four major publication venues related to game research: CHI Play, the Digital Games Research Association conference, the International Conference on the Foundations of Digital Games, and the Games and Culture journal. We searched the papers to find all occurrences of words or phrases related to methods, tools or participants. The process was iterative as new keywords were found and informed subsequent searches. For instance, the names of specific questionnaires used by game researchers were found while searching for survey. Our findings offer an overview of the methods, tools and recruitment strategies currently used for game research. Through this review, we aim to contribute to the development of a set of well defined and commonly understood methods for game research.

Users are increasingly able to move around and perform tasks in virtual environments (VEs). Such movements and tasks are typically represented in a VE using either a first-person perspective (1PP) or a third-person perspective (3PP). In Virtual Reality (VR), 1PP is almost universally used. 3PP can be represented as either egocentric or allocentric. However, there is little empirical evidence about which view may be better suited to dynamic tasks in particular. This paper compares the use of 1PP, egocentric 3PP and allocentric 3PP for dynamic tasks in VR. Our results indicate that 1PP provides the best spatial perception and performance across several dynamic tasks. This advantage is less pronounced as the task becomes more dynamic.

Human performance augmentation through technology has been a recurring theme in science and culture, aiming to increase human capabilities and accessibility. We investigate a related concept: virtual performance augmentation (VPA), using VR to give users the illusion of greater capabilities than they actually have. We propose a method for VPA of running and jumping, based on in place movements, and studied its effects in a VR exergame. We found that in place running and jumping in VR can be used to create a somewhat natural experience and can elicit medium to high physical exertion in an immersive and intrinsically motivating manner. We also found that virtually augmenting running and jumping can increase intrinsic motivation, perceived competence and flow, and may also increase motivation for physical activity in general. We discuss implications of VPA for safety and accessibility, with initial evidence suggesting that VPA may help users with physical impairments enjoy the benefits of exergaming.

Virtual environments for gaming and simulation provide dynamic and adaptive experiences, but, despite advances in multisensory interfaces, these are still primarily visual experiences. To support real-time dynamic adaptation, interactive virtual environments could implement techniques to predict and manipulate human visual attention. One promising way of developing such techniques is to base them on psychophysical observations, an approach that requires a sound understanding of visual attention allocation. Understanding how this allocation of visual attention changes depending on a user’s task offers clear benefits in developing these techniques and improving virtual environment design. With this aim, we investigated the effect of task on visual attention in interactive virtual environments. We recorded fixation data from participants completing freeview, search, and navigation tasks in three different virtual environments. We quantified visual attention differences between conditions by identifying the predictiveness of a low-level saliency model and its corresponding color, intensity, and orientation feature-conspicuity maps, as well as measuring fixation center bias, depth, duration, and saccade amplitude. Our results show that task does affect visual attention in virtual environments. Navigation relies more than search or freeview on intensity conspicuity to allocate visual attention. Navigation also produces fixations that are more central, longer, and deeper into the scenes. Further, our results suggest that it is difficult to distinguish between freeview and search tasks. These results provide important guidance for designing virtual environments for human interaction, as well as identifying future avenues of research for developing “attention-aware” virtual worlds.

Exergames commonly use low to moderate intensity exercise protocols. Their effectiveness in implementing high intensity protocols remains uncertain. We propose a method for improving performance while maintaining intrinsic motivation in high intensity VR exergaming. Our method is based on an interactive adaptation of the feedforward method: a psychophysical training technique achieving rapid improvement in performance by exposing participants to self models showing previously unachieved performance levels. We evaluated our method in a cycling-based exergame. Participants competed against (i) a self model which represented their previous speed; (ii) a self model representing their previous speed but increased resistance therefore requiring higher performance to keep up; or (iii) a virtual competitor at the same two levels of performance. We varied participants' awareness of these differences. Interactive feedforward led to improved performance while maintaining intrinsic motivation even when participants were aware of the interventions, and was superior to competing against a virtual competitor.

A key requirement for a sense of presence in Virtual Environments (VEs) is for a user to perceive space as naturally as possible. One critical aspect is distance perception. When judging distances, compression is a phenomenon where humans tend to underestimate the distance between themselves and target objects (termed egocentric or absolute compression), and between other objects (exocentric or relative compression). Results of studies in virtual worlds rendered through head mounted displays are striking, demonstrating significant distance compression error. Distance compression is a multisensory phenomenon, where both audio and visual stimuli are often compressed with respect to their distances from the observer. In this paper, we propose and test a method for reducing crossmodal distance compression in VEs. We report an empirical evaluation of our method via a study of 3D spatial perception within a virtual reality (VR) head mounted display. Applying our method resulted in more accurate distance perception in a VE at longer range, and suggests a modification that could adaptively compensate for distance compression at both shorter and longer ranges. Our results have a significant and intriguing implication for designers of VEs: an incongruent audiovisual display, i.e. where the audio and visual information is intentionally misaligned, may lead to better spatial perception of a virtual scene.

End-user Service Composition (EUSC) is defined as service composition where the person who creates the composite service also uses it. We derived requirements for EUSC tools using a custom method based on the scenario-based requirements analysis method. Ten participants were given scenarios, a demonstrator application and examples of EUSC tools before being interviewed. Analysing their responses, we elicited 139 requirements across topics including service “types” (e.g. pervasive services), composition flow (i.e. control/data flow) and the use of templates in composition. This is the first published work to have used a robust requirements analysis method in EUSC, adapted specifically to take account of prior work on EUSC. Some of our requirements validate those found in prior research or current EUSC tools but many are unique to our findings. The requirements found in this work inform and inspire the development of future EUSC tools, and the methodology is easily adapted for application in other domains.

We aim to contribute to the development of tactile-based pedestrian navigation systems that help users to navigate urban environments with minimal attention to the user-device interface. This paper describes the design and evaluation of a prototype and reports findings from (i) a lab-based study that directly compared features of two widely researched forms of tactile display: a waist belt and a back array; and (ii) a field evaluation which compared our prototype tactile-based navigation system (TactNav) with a visual mobile maps application (Nokia Maps™). Lab results indicated that the waist belt afforded significantly better performance than the back array across a wide range of metrics. Field results indicated that users' performance with the tactile-based system was equivalent to that with the visual-based system in terms of accuracy while route completion time was significantly faster with the tactile-based directional display.

We describe a novel methodology that examines perceptions of urban space, and present a study using this methodology that explores people’s perceptions of their neighbourhood. Previous studies of spatial cues have involved a variety of tasks such as pointing and sketching to externalise participants’ internal spatial maps. Our methodology extends these approaches by introducing mobile technologies alongside traditional materials and tasks. Participants use mobile phones to carry out self-guided neighbourhood tours. We collected rich qualitative data from 15 participants during two workshops and a self-directed neighbourhood tour. Our study highlights the use of public and private landmarks, differences in spatial maps of rural versus urban dwellers, and individual variance in orientation strategies. These themes suggest guidelines for the design of technologies with personalised spatial profiles.

In this paper we investigate how decisions made while using a granular access control mechanism for sharing photographs are influenced by contextual factors and properties relating to the identities of contacts. We develop analytical models using logistic regression to understand relationships between variables that affect sharing decisions. We also investigate how predefined, static groups for privacy control cope with the challenge of sharing large amounts of content associated with numerous different contexts, and test whether they need to be adjusted to suit particular contexts.

Wearable tactile navigation displays may provide an alternative or complement to mobile visual navigation displays. Landmark information may provide a useful complement to directional information for navigation, however, there has been no reported use of landmark information in tactile navigation displays. We report a study that compared two tactile display techniques for landmark representation using one or two actuators respectively. The single-actuator technique generated different vibration patterns on a single actuator to represent different landmarks. The dual-actuator technique generated a single vibration pattern using two simultaneous actuators and different pairs of actuators around the body represented different landmarks. We compared the two techniques on four measures: distinguishability, learnability, short term memorability and user preference. Results showed that users performed equally well when either technique was used to represent landmarks alone. However, when landmark representations were presented together with directional signals, performance with the single-actuator technique was significantly reduced while performance with the dual-actuator technique remained unchanged.

The shared online calendar is the de facto standard for event organisation and management in the modern office environment. It is also a potentially valuable source of context, provided the calendar event data represent an accurate account of 'real-world' events. However, as we show through a field study, the calendar does not represent reality well as genuine events are hidden by a multitude of reminders and 'placeholders', i.e. events that appear in the calendar but do not occur. We show that the calendar's representation of real events can be significantly improved through data fusion with other sources of context, namely social network and location data. Finally, we discuss some of the issues raised during our field study, their significance and how performance could be farther improved.

Users of social networking sites often want to manage the sharing of information and content with different groups of people based on their differing relationships. However, grouping contacts places a significant configuration burden on the user. Automated approaches to grouping may have the potential to reduce this burden, however, their use remains largely untested. We investigate people's rationales when grouping their contacts for the purpose of controlling their privacy, finding six criteria that they commonly considered. We assess an automated approach to grouping, based on a network clustering algorithm, whose performance may be analogous to the human's use of some of these criteria. We find that the similarity between the groups created by people and those created by the algorithm is correlated with the modularity of their network. We also demonstrate that the particular clustering algorithm, SCAN, which detects hubs and outliers within a network can be beneficial for identifying contacts who are hard to group or for whom privacy preferences are inconsistent with the rest of their group.

Moving human-computer interaction off the desktop and into our cities requires new approaches to understanding people and technologies in the built environment. We approach the city as a system, with human, physical and digital components and behaviours. In creating effective and usable urban pervasive computing systems, we need to take into account the patterns of movement and encounter amongst people, locations, and mobile and fixed devices in the city. Advances in mobile and wireless communications have enabled us to detect and record the presence and movement of devices through cities. This article makes a number of methodological and empirical contributions. We present a toolkit of algorithms and visualization techniques that we have developed to model and make sense of spatial and temporal patterns of mobility, presence, and encounter. Applying this toolkit, we provide an analysis of urban Bluetooth data based on a longitudinal dataset containing millions of records associated with more than 70000 unique devices in the city of Bath, UK. Through a novel application of established complex network analysis techniques, we demonstrate a significant finding on the relationship between temporal factors and network structure. Finally, we suggest how our understanding and exploitation of these data may begin to inform the design and use of urban pervasive systems.

With an ever increasing number of mobile services, meaningful audio notifications could effectively inform users of the incoming services while minimising undesired and intrusive interruptions. Therefore, careful design of mobile service notification is needed. In this paper we evaluate two types of audio (auditory icons and earcons) as mobile service notifications, by comparing them on 4 measures: intuitiveness, learnability, memorability and user preference. A 4-stage longitudinal evaluation involving two lab experiments, a field study and a web-based experiment indicated that auditory icons performed significantly better in all measures. Implications for mobile audio notification design are presented.

This paper concerns the problem of phishing attacks in ubiquitous computing environments. The embedding of ubiquitous services into our everyday environments may make fake services seem plausible but it also enables us to authenticate them with respect to those environments. We propose physical and virtual linkage as two types of authenticating evidence in ubiquitous environments and two protocols based on them. We describe an experiment to test hypotheses concerning user responses to physical and virtual linkage with respect to fake Wi-Fi hotspots. Based on our experience we derive an improved protocol for authenticating spontaneously accessed ubiquitous services.

There are academic and commercial drivers for context-awareness to play a prominent role in the future of mobile services. Implementing a complete model of context remains an unsolved problem, however, some contextual elements such as person, time and place are relatively easy to identify. We develop a simple context model incorporating personal, temporal and spatial dimensions and apply it to a context-aware text messaging service. We report a field study of the service, investigating how applying these fundamental contextual constraints to messages can affect the nature of communication between participants. The results suggest that although contextual constraints are not appropriate for all types of message content, they increase opportunities for situated chat in public spaces, improve group awareness between peers and facilitate conversations between people, some of whom would not otherwise communicate with each other.

Users of public Wi-Fi networks risk being tricked into connecting to `evil twin' access points set up by attackers to launch man-in-the-middle attacks. We present a system which employs post hoc validation of an anonymous Diffie-Hellman key exchange undertaken as part of an 802.1X/EAP-TTLS network association process. Our system utilises an additional secure auxilliary channel to run a modified version of the interlock protocol based on physical evidence in the network location. By using keying information generated during the network joining process, we allow spontaneous network users to detect man-in-the-middle attacks as well as avoiding the need for pre-shared keys. We report on implementations of our system which utilise physical evidence of authenticity in the alternative forms of public displays and 2D barcodes embedded in the environment and read by mobile phones.

Within the creativity community, researchers and practitioners have developed and studied various support tools and environments. It is important to learn from these tools and environments, identifying requirements for improving the future support of creativity in design. In this paper, we focus on support for generating and interacting with external representations to facilitate shared understanding and common ground amongst stakeholders. In considering external representations, we distinguish between artifacts provided by the tools and boundary objects created by the participants. We evaluate the use of a particular creativity support tool: the Envisionment and Discovery Collaboratory (EDC). From this evaluation we identify requirements for future tools and environments to support creative design.

Nearly 50 years of empirical research has suggested that social influences have an inhibiting effect on creativity in collaborating groups such as design teams. This suggests that design teams may not be as creative as they could be, resulting in a negative impact on the design process. In this paper we investigate the effect of group composition on creativity in terms of divergent thinking, in order to determine how best to support the creative process in design and the development of design environments. We present some novel results about 'group think', showing that real groups foster refinement of ideas while nominal groups foster duplication of ideas.

The Human-Computer Interaction community has long been concerned with design. Terms such as 'creativity' and 'innovation' are frequently used when referring to the design process and in this paper we examine what creativity is with respect to design. Design is often a collaborative and, therefore, a social activity. We review the evolution of definitions of creativity, leading to our proposal of a unified definition, we present a theoretical account of why social creativity should in principle be more productive than individual creativity. We explain findings to the contrary in terms of three social influences on creativity and suggest that research in supporting design should focus on mitigating the effects of these social influences on the creativity of design teams.

Journal Article The social implications of emerging technologies Get access Vassilis Kostakos, Vassilis Kostakos * * Corresponding authors Search for other works by this author on: Oxford Academic Google Scholar Eamonn O'Neill, Eamonn O'Neill Search for other works by this author on: Oxford Academic Google Scholar Linda Little, Linda Little * * Corresponding authors Search for other works by this author on: Oxford Academic Google Scholar Elizabeth Sillence Elizabeth Sillence Search for other works by this author on: Oxford Academic Google Scholar Interacting with Computers, Volume 17, Issue 5, September 2005, Pages 475–483, https://doi.org/10.1016/j.intcom.2005.03.001 Published: 01 September 2005

In this paper we discuss a real world problem encountered during recent fieldwork: that of providing information in public settings when the information has both public and private components. We draw on our ethnographic studies in the waiting area of a busy hospital Emergency department. Despite evidence that lack of information can lead to stress, problem behaviours and poor levels of satisfaction with treatment, little information was made available to patients. We review the types of information needed and propose how the theoretical concepts of public, social and private information spheres relate to public spaces such as the Emergency department waiting area. We argue how the further theoretical concept of interaction spaces may be used in conjunction with these information spheres to inform interaction design for public settings.

(1999). Introduction to This Special issue on Representations in Interactive Systems Development. Human–Computer Interaction: Vol. 14, Representations in Interactive Systems Development, pp. 1-7.

Participatory design (PD) and task analysis (TA) have each been widely promoted as amerlioratives to the problems of developing systems hat meet users' requirements. However, PD methods have tended to focus on design per se, rather than also promoting user-developer cooperation in upstream analysis activities. TA methods have promoted these upstream activities but largely failed to involve users directly in the analysis and modeling work. Hence, there is a need for a broader approach encourages user–developer cooperation throughout systems analysis and design activities. This article examines the support for user-developer interaction provided by representations of users' tasks and software designs in 2 real-world software development projects that followed a task-based cooperative development approach. In the course of the system deve1oprnenat work, h e representations were called on to serve a number of different purposes. Task model and paper prototype representations facilitated the development s f cowmen ground among h e members of the development team through h e provision of an external shared model of the object of the development activity and helped to delimit an interaction space in which the cooperative activity was conducted. Weaknesses of the representations as supports for cooperative development included users' reluctance physically to amend the representations and the very strength of common ground developed between the participants that was not explicitly represented in the external models.

An automated system has been developed for use in the characterization and modeling of MOS transistors. The system, consisting of automatic testing, a dynamic data base, and device parameter extraction, has been applied to process characterization and device modeling. The data base handles storage and retrieval of the data. Parameter extraction is based on optimization with constraints.