The impact of animated interface agents: a review of empirical research

Over the last years, the animation of interface agents has been the target of increasing interest. Largely, this increase in attention is fuelled by speculated effects on human motivation and cognition. However, empirical investigations on the effect of animated agents are still small in number and differ with regard to the measured effects. Our aim is two-fold. First, we provide a comprehensive and systematic overview of the empirical studies conducted so far in order to investigate effects of animated agents on the user's experience, behaviour and performance. Second, by discussing both implications and limitations of the existing studies, we identify some general requirements and suggestions for future studies.     

Detecting emotional state of a child in a conversational computer game

The automatic recognition of user’s communicative style within a spoken dialog system framework, including the affective aspects, has received increased attention in the past few years. For dialog systems, it is important to know not only what was said but also how something was communicated, so that the system can engage the user in a richer and more natural interaction. This paper addresses the problem of automatically detecting “frustration”, “politeness”, and “neutral” attitudes from a child’s speech communication cues, elicited in spontaneous dialog interactions with computer characters. Several information sources such as acoustic, lexical, and contextual features, as well as, their combinations are used for this purpose. The study is based on a Wizard-of-Oz dialog corpus of 103 children, 7–14 years of age, playing a voice activated computer game. Three-way classification experiments, as well as, pairwise classification between polite vs. others and frustrated vs. others were performed. Experimental results show that lexical information has more discriminative power than acoustic and contextual cues for detection of politeness, whereas context and acoustic features perform best for frustration detection. Furthermore, the fusion of acoustic, lexical and contextual information provided significantly better classification results. Results also showed that classification performance varies with age and gender. Specifically, for the “politeness” detection task, higher classification accuracy was achieved for females and 10–11 years-olds, compared to males and other age groups, respectively.     

The effects of animated pedagogical agents in an English-as-a-foreign-language learning environment

Animated pedagogical agents (APAs) have frequently been used as a powerful addition to learning environments, since APAs have been known to facilitate learning. APAs can present various features, such as voice, movements, gestures and pointing, and researchers have sought to verify specifically which features of agents effectively contribute to learning. Previous studies have studied these features by comparing different degrees of agent embodiment in the evaluation of the image effect (i.e., students learn more when learning systems have visual APAs), the embodied agent effect (i.e., fully embodied agents that deliver instruction aurally and use gestures to improve learning outcomes in text-only learning systems), the modality effect (i.e., oral instruction contributes to the learning process), and the expressiveness effect (i.e., fully embodied agents promote more effective learning than static ones). Some of these studies have investigated the image, embodied agent and modality effects in the same learning environment, but they were not the same studies that investigated the expressiveness effect. The expressiveness effect allows us to separate the movements of the agent from its other features, such as the agent's image, so investigating this effect is as important as investigating the other effects. We are not aware of any studies that investigated all of these four effects within the same learning system, nor that evaluated any of these effects in language learning environments. Accordingly, this paper describes the design, implementation, and analysis of an APA designed to evaluate the abovementioned effects. The APA was integrated into a computer-assisted language learning (CALL) system to teach English as a foreign language to Brazilian students. A total of 72 Brazilian undergraduate students were divided into four groups, each of which used a different version of the APA in the same CALL system: no agent, a voice-only agent, a static agent, or a fully embodied agent. We compared students’ gain scores (i.e., difference between pre- and posttest scores) across groups to evaluate each of the four effects. Though the outcomes of our study supported the presence of the embodied agent and modality effects, we were not able to demonstrate the image or expressiveness effects in the experiment. Our results indicate that the voice of the agent might contribute more positively to learning than movements, gestures and pointing.     

The affective outcomes of using influence tactics in embodied conversational agents

In this study, we highlight the theoretical underpinnings of human impression management tactics and link them to current research in embodied conversational agents. Specifically, we incorporated impression management behaviors into an embodied conversational agent in order to show that different influence strategies affect user perceptions, and how those perceptions might be moderated by user gender. We programmed the agent to use two human impression management techniques (ingratiation and self-promotion) and had the agent interact with 88 users. After the interaction, users reported their perceptions of the system’s power, trustworthiness, expertise, and attractiveness. The impression management techniques altered users’ perceptions and these perceptions were moderated by gender differences.     

Controlled invariance of ellipsoids: linear vs. nonlinear feedback

Several equivalent conditions or statements for set invariance were obtained for systems with one saturating actuator in a recent paper. In particular, it was shown that the existence of a nonlinear feedback that makes an ellipsoid invariant is equivalent to the existence of a feedback linear inside the ellipsoid that makes it invariant. In this paper, we will show that this equivalence property holds conditionally for systems with multiple saturating actuators. We will provide a criterion to check if the largest ellipsoid made invariant by nonlinear feedback can also be made invariant by a feedback linear inside the ellipsoid. Numerical examples reveal that this criterion is usually satisfied. The equivalence of other set invariance conditions will also be investigated.     

The effects of speech–gesture cooperation in animated agents’ behavior in multimedia presentations

Until now, research on arrangement of verbal and non-verbal information in multimedia presentations has not considered multimodal behavior of animated agents. In this paper, we will present an experiment exploring the effects of different types of speech–gesture cooperation in agents’ behavior: redundancy (gestures duplicate pieces of information conveyed by speech), complementarity (distribution of information across speech and gestures) and a control condition in which gesture does not convey semantic information. Using a Latin-square design, these strategies were attributed to agents of different appearances to present different objects. Fifty-four male and 54 female users attended three short presentations performed by the agents, recalled the content of presentations and evaluated both the presentations and the agents. Although speech–gesture cooperation was not consciously perceived, it proved to influence users’ recall performance and subjective evaluations: redundancy increased verbal information recall, ratings of the quality of explanation, and expressiveness of agents. Redundancy also resulted in higher likeability scores for the agents and a more positive perception of their personality. Users’ gender had no influence on this set of results.     

The TRAINS project: a case study in building a conversational planning agent

Abstract

The TRAINS project is an effort to build a conversationally proficient planning assistant. A key part of the project is the construction of the TRAINS system, which provides the research platform for a wide range of issues in natural language understanding, mixed-initiative planning systems, and representing and reasoning about time, actions and events. Four years have now passed since the beginning of the project. Each year a demonstration system has been produced that focused on a dialogue that illustrates particular aspects of the research. The commitment to building complete integrated systems is a significant overhead on the research, but it is considered essential to guarantee that the results constitute real progress in the field. This paper describes the goals of the project, and the experience with the effort so far.     

Analysts and clients in organisational contexts: a conversational perspective

This paper takes a conversational perspective on the issue of analyst–client interaction, concentrating on how social and organisational contexts impact on the verbal process of defining a new information system. It has been suggested that organisational agendas are built from talk at the interactional level (Boden, 1994), and this paper seeks to explore the relationship between social and organisational contexts and the process of early requirements gathering. Analysts and clients were asked about their aims, their professional role, and other issues that arose in their interactions with each other as part of a larger study in early requirements gathering. The paper discusses three themes from three case studies that can be seen to be embedded in the social and organisational context of early requirements gathering—how the issues to be discussed during the interaction were put forward, professional relationships, and the overall organisational context in which the interaction takes place. Some observations are made about the varying social and organisational contexts of early requirements gathering and the role of individual differences, and the possibility of using typical contexts as ‘repertoire building research’ (Schön, 1983) to flow into practice.     

Linguistically-tailored video feedback increases total and positive emotional expression in a structured writing task

A strength of computer-based interventions is the capacity to tailor to individual differences, but most studies have tailored to self-report, rather than linguistic, data. The purpose of the present study was to develop and evaluate the effects of linguistically-tailored feedback on an Internet-based expressive writing intervention. Two hundred eighty-one participants were asked to engage in 3 days of expressive writing and were randomly assigned to one of 3 feedback conditions: control (no feedback), simple (feedback about levels of emotional expression), and directive (simple feedback + suggestions for emotional processing). A Perl-based implementation of Linguistic Inquiry and Word Count (LIWC) was developed in order to provide dynamic feedback to participants based on levels of emotional expression identified in their writing. This implementation provided near-perfect correlations with standard LIWC output, r’s = .98-1.00. Positive and total, but not negative, emotional expression increased over time for those who received simple or directive feedback. These findings suggest that linguistically-tailored feedback has the potential to alter patterns of engagement in computer-based interventions. However, additional research is needed to identify the most effective types of feedback in order to enhance immediate effects on writing and longitudinal effects on relevant outcomes.     

The effects of simulating human conversational style in a computer-based interview

A computer interview involves a program asking questions of the user, who responds by providing answers directly to the computer. Using a computer interview has been shown to be an effective method of eliciting information, and particularly personal information which many people find difficult to discuss face to face. While the simulation of some of the characteristics of human–human communication seems to enhance the dialogue, it appears to be the absence of others, such as being non-judgmental, unshockable, completely consistent, and unendingly patient, that gives computer interviewing its particular effectiveness.

The work reported in this paper investigated the effect of simulating in a computer interview two techniques which good human interviewers use: empathy and grouping questions. Thirty nine interviewees answered 40 questions on a computer, in combinations of human-like or computer-like question styles, and presented in either a logical or a random order.

They found the use of the human interviewer technique in the wording of questions made the computer interviews more interesting and enjoyable, than when blunt, direct questioning was used, and they answered honestly more often to the human-like style.

This investigation has shown that a computer interview can be made more effective by simulating the human interviewer technique of empathising with interviewees and softening those questions which are of a sensitive nature. It seems therefore that it is the combination of the right non-human characteristics with the right human characteristics that can produce a successful computer interview. The question for further research is which are the right characteristics in each case, given the purpose of the interview.     

Designing motivational agents: The role of praise, social comparison, and embodiment in computer feedback

The present study draws on theories of attribution, social comparison, and social facilitation to investigate how computers might use principles of motivation and persuasion to provide user feedback. In an online experiment, 192 participants performed a speed-reading task. The independent variables included whether or not the verbal feedback from the computer involved praise, whether the objective feedback showed that the participants were performing better or worse from their peers, and whether or not the feedback was presented by an on-screen agent. The main dependent variables included a subjective measure of participants’ intrinsic motivation and an objective measure of their task persistence. Results showed that providing participants with praise or comparative information on others’ performance improved intrinsic motivation. When praised, participants whose performances were comparatively low persisted in the task longer than those whose performances were comparatively high did. Additionally, the mere presence of an embodied agent on the screen increased participants’ motivation. Together, these results indicate that praise and social comparison can serve as effective forms of motivational feedback and that humanlike embodiment further improves user motivation.     

Forwarders vs. centralized server: an evaluation of two approaches for locating mobile agents

This paper evaluates and compares the performance of two approaches for locating an agent in a mobile agent environment. The first approach dynamically creates a chain of forwarders to locate a moving agent, whereas the second one relies on a centralized server to perform this task. Based on a Markov chain analysis, we compute the performance of each scheme (time to reach an agent, number of forwarders) and compare them first with simulations and second with experimental results obtained by using ProActive, a Java library. Depending on the system parameters we identify the best scheme and observe that over a LAN the server yields the best performance, whereas the forwarders yield the best performance over a MAN.     

CBR for the management and reuse of image-processing expertise: a conversational system

The development of an image-processing (IP) application is a complex activity, which can be greatly alleviated by user-friendly graphical programming environments. The major objective of the work described in this paper is to help IP experts reuse parts of their applications. A first step towards knowledge reuse has been to propose a suitable representation of the strategies of IP experts by means of IP plans (trees of tasks, methods and tools). This paper describes the CBR module of an interactive system for the development of IP plans. After a brief presentation of the overall architecture of the system and its other modules, the authors explain the distinction between an IP case and an IP plan, and give the selection criteria and functions that are used for similarity calculation. The core of the CBR module is a search/adaptation algorithm, whose main steps are detailed: retrieval of suitable cases, recursive adaptation of the selected one and memorization of new cases. The system’s implementation is presently completed; its functioning is described in a session showing the kind of assistance provided by the CBR module during the development of a new IP application.     

The integration of scheduling and control: Top-down vs. bottom-up

The flexible operation of continuous processes often requires the integration of scheduling and control. This can be achieved by top-down or bottom-up approaches. We compare the two paradigms in-silico using an air separation unit as a benchmark process. To demonstrate the top-down paradigm, we identify data-driven models of the closed-loop process dynamics based on a mechanistic model and use them in scheduling calculations that are performed offline. The resulting target trajectories are passed to a linear model predictive control (LMPC) system and implemented in the process. To demonstrate the bottom-up paradigm, we define an economic nonlinear model predictive control (eNMPC) scheme, which performs dynamic optimization using the full model in closed-loop to directly obtain the control variable profiles to be implemented in the process. We provide implementations of the process model equations as both a gPROMS and a Modelica model to encourage future comparison of approaches for flexible operation, process control, and/or handling disturbances. The performance, advantages, and disadvantages of the two strategies are analyzed using demand-response scenarios with varying levels of fluctuations in electricity prices, as well as considering the cases of known, instantaneous, and completely unknown load changes. The similarities and differences of the two approaches as relevant to flexible operation of continuous processes are discussed. Integrated scheduling and control leverages existing infrastructure and can be immediately applied to real operation tasks. Both operation strategies achieve successful process operation with remarkable economic improvements (up to 8%) compared to constant operation. eNMPC requires more computational resources, and is – at the moment – not implementable in real-time due to maximum optimization times exceeding the controller sampling time. However, eNMPC achieves up to 2.5 times higher operating cost savings compared to the top-down approach, owing in part to the more accurate modeling of key process dynamics.     

Signal recognition: Both components of the short time Fourier transform vs. power spectral density

A new feature representation approach was generalised and used for Gaussian recognition. The generalised approach consists of simultaneously using two new recognition features — real and imaginary Fourier components —taking into account the covariance between features. Generalisation of the approach improves recognition effectiveness. An advanced time-frequency technique, the short time Fourier transform, was considered. Covariance and the correlation coefficient between the proposed features were obtained for the first time for arbitrary stationary signals. The recognition effectiveness between the generalised approach and power spectral density was compared. It was shown that power spectral density is not an optimal feature, and represents only a particular case of the generalised approach. The use of power spectral density is optimal if simultaneously the correlation coefficient between Fourier components is equal to zero, and the standard deviations of components are equal. Use of the generalised approach provides an increase in effectiveness in comparison with power spectral density.     

Narrowing power vs efficiency in synchronous set agreement: Relationship, algorithms and lower bound

The k-set agreement problem is a generalization of the uniform consensus problem: each process proposes a value, and each non-faulty process has to decide a value such that a decided value is a proposed value, and at most k different values are decided. It has been shown that any algorithm that solves the k-set agreement problem in synchronous systems that can suffer up to t crash failures requires rounds in the worst case. It has also been shown that it is possible to design early deciding algorithms where no process decides and halts after rounds, where f is the number of actual crashes in a run (0≤f≤t).This paper explores a new direction to solve the k-set agreement problem in a synchronous system. It considers that the system is enriched with base objects (denoted has [m,?]_SA objects) that allow solving the ?-set agreement problem in a set of m processes (m<n). The paper makes several contributions. It first proposes a synchronous k-set agreement algorithm that benefits from such underlying base objects. This algorithm requires rounds, more precisely, rounds, where . The paper then shows that this bound, that involves all the parameters that characterize both the problem (k) and its environment (t, m and ?), is a lower bound. The proof of this lower bound sheds additional light on the deep connection between synchronous efficiency and asynchronous computability. Finally, the paper extends its investigation to the early deciding case. It presents a k-set agreement algorithm that directs the processes to decide and stop by round . These bounds generalize the bounds previously established for solving the k-set agreement problem in pure synchronous systems.     

The emotional impact of cyberbullying: Differences in perceptions and experiences as a function of role

Research is accumulating to confirm adverse consequences of cyberbullying. Less is known about the perceptions, expectations and reactions of those involved as a function of their different roles (e.g., as bullies, victims, bully-victims) and how this relates to their experiences of traditional bullying. We examined whether cyberbullies' beliefs about the impact of their actions reflects the impact as reported by cybervictims themselves. We tested also whether the emotional reactions to cyberbullying differed depending upon whether the victim was or was not also a victim of traditional bullying behaviours. Participants were 1353 Spanish adolescents. Approximately 8% reported experiences of cyberbullying (compared to 12% reporting experiences of traditional bullying). Cyberbullies believed that their victims would experience more discomfort than cybervictims actually reported experiencing. Those who had experienced victimization in both traditional and cyber contexts evaluated cyberbullying as having greater negative impact than did those who had experienced victimization only in cyber contexts. Perceptions differed according to role and the context(s) in which bullying has been experienced. Findings are discussed in relation to the ways in which technologically delivered aggression may differ from traditional bullying.     

HT-7低杂波电源反馈控制系统的设计与实现

介绍了在HT-7托卡马克装置中低混杂波电流驱动(LHCD)的高压源反馈控制系统。该系统通过PLC与PC并行处理的方式,对等离子体参数进行反馈控制,很好地实现了延长等离子体电流持续时间的目的,同时又有效地保证了高压源与LHCD系统的运行安全。本文给出了反馈控制系统的控制方法、软硬件的实现以及运行情况。