Agneta Gulz
email: agneta.gulz@lucs.lu.se

Benefits of Virtual Characters in Computer Based Learning Environments: Claims and Evidence

Pedagogical theory of today gives high priority to social components of learning. Within the field of computer supported learning there are many attempts to acknowledge this. One approach involves the addition of virtual characters to electronic learning environments. Such character enhanced systems are the focus of the present article. Firstly, a systematic overview is given of pedagogical benefits that have been proposed in the literature regarding character enhancement of electronic learning environments, for example increased motivation, stimulation of particular learning activities, enhanced flow of communication and fulfillment of a need for deeper personal relationships in learning. Secondly, I examine the empirical results presented in the literature with respect to the proposed positive pedagogical effects. Based on these reviews, I finally discuss possible directions for continued research and design in the field from a pedagogical point of view. I propose a research agenda for the near future and conclude with some reflections on a longer-term perspective.

'keep a learner's exploration going '. Johnson et al. (2003) underline the same potential of animated agents, namely to promote students' curiosity.

.

 likewise lift forward the possibility that an animated agent can draw a student's attention to specific aspects of a virtual world.

INTRODUCTION

Today, central pedagogical theories in various ways influenced by Vygotsky highlight the importance of social aspects for successful learning. It is emphasized that knowledge is socially constructed and that teaching as well as learning processes are inherently social, involving interaction, communication, negotiating and sharing (c.f. Vygotsky, 1987). Furthermore, it is pointed out that learning has emotional as well as cognitive facets. Specifically within the field of educational technology, many researchers and practitioners emphasize the role of social dimensions, and the importance of having technically supported learning situated in a social context. Articles and conferences in abundance address themes such as: 'social learning in multimedia,' 'socially interactive agents for learning,' 'enabling social presence in virtual environments,' 'personalized web companions,' 'artificial social actors,' 'learning companion agents,' 'character enhanced systems,' 'computer animation and social agents,' 'computersupported social interaction,' 'the sociability of computer-supported collaborative learning environments,' and so on (e.g. [START_REF] Knoll | Learning to work in global virtual teams[END_REF][START_REF] Hietala | The Competence of Learning Companion Agents[END_REF]Höök et al., 2001;[START_REF] Kapoor | Towards a Learning Companion that Recognizes Affect Proceedings of Emotional and Intelligent II: The Tangled Knot of Social Cognition[END_REF]Kreijns & Kirschner, 2002;[START_REF] André | From adaptive hypertext to personalized web companions[END_REF][START_REF] Dowling | The Socially Interactive Pedagogical Agent within Online Learning Communities[END_REF] Conference on Computer-supported social interaction, 2003; International conference on computer animation and social agents, 2003).

As can be noted in these citations, one important approach is that of adding various kinds of virtual characters to electronic learning systems. Some environments harbour so called animated pedagogical agents (e.g. Cassell et al., 1994;[START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF][START_REF] Paiva | Vincent, an autonomous pedagogical agent for on-the-job training[END_REF]Cassell & Thorisson, 1999;[START_REF] Shaw | Pedagogical Agents the Web[END_REF][START_REF] Johnson | Animated pedagogical agents: Face-to-face interaction in interactive learning environments[END_REF][START_REF] Lester | Deictic and emotive communication in animated pedagogical agents[END_REF][START_REF] Kort | An Affective Model of Interplay Between Emotions and Learning: Reengineering Educational Pedagogy -Building a Learning Companion[END_REF], whose social character can be expressed by movements, gestures, facial expressions as well as voice, dialogue, etc. Other environments make use of virtual agents or characters that are not, or only to a limited extent, animated. One example of the latter is the Agneta & Frida system [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF], where voices, looks, humour and dialogues are used to express the characters' personalities and inner lives. Similarly, the personalities of [START_REF] Hietala | The Competence of Learning Companion Agents[END_REF] learning companion agents are comprised of a name, a picture and a personal voice and manner of speech (which is exploited as a central social feature). 1 Common to all systems is that a social context is created inside the computer (c.f. [START_REF] Hietala | The Competence of Learning Companion Agents[END_REF], and that the technology provides an already populated social arena. Such learning environments may be called intrinsically social, in contrast to extrinsically social learning environments. In the latter, all social agency and all social activities are supplied by the human users of the system. The role of the technological system is to provide room and support for the activities. Here we find the rapidly growing area of computer supported cooperative learning (CSCL), with different kinds of support for discussion groups, on-line debates, chats, forums, arenas, etc. [START_REF] Koschman | CSCL: Theory and Practice of an Emerging Paradigm[END_REF]Dillenbourg, 2000).

Intrinsically and extrinsically social learning systems differ most markedly with respect to the case of a single individual user. An extrinsically social system, in fact, requires more than one user; otherwise, there will not be any social interaction. In an intrinsically social learning system, on the other hand, social interactivity can take place independently of any other human presence than that of one student. 2,3 There are also other differences between the two approaches in terms of constraints and potentials. Today, extrinsically social systems are commercially more widespread, whereas a majority of intrinsically social systems have the status of research prototypes. This is probably due to the fact that the architecture of an extrinsically social system is less complex, in the sense that there is little or no advanced artificial intelligence in the system. Potentially, however, intrinsically social systems may offer more possibilities to ensure the pedagogical quality of the social activities taking place in the learning environment. As an example, in letting children learn and practice language skills and storytelling by interacting and playing with a virtual peer -as in the case of the virtual learning companion Sam [START_REF] Ryokai | Virtual peers as partners in storytelling and literacy learning[END_REF] -it is possible to provide just the right amount of challenge in making the storytelling of the companion more advanced than the child's, but not too advanced. In other words, it is possible to ensure that a particular child or group of children gets appropriate, and high-quality, scaffolding. 4 In general, it is possible to modify the role, behaviour or expertise of a virtual fellow learner, for instance from that of an active leader to a weaker companion or even a passive observer, depending on a teachers' evaluation of whether the learner requires more or less guidance (c.f. [START_REF] Dowling | The Role of the Human Teacher in Learning Environments of the Future[END_REF][START_REF] Hietala | The Competence of Learning Companion Agents[END_REF].

In an extrinsically social learning system, on the other hand, the particular combination of roles, goals, status and expertise that happens to be there among students in a group (c.f. Dillenbourg, 2000), may be decisive for the pedagogical quality of the group interaction. Different combinations are more or less favourable from a pedagogical point of view, and in practical situations these factors are very hard to control. In general, one cannot order particular roles or expertise or pedagogical strategies from human beings, while virtual characters may be tailored for particular purposes, as regards teaching strategies (troublemaker, challenger, cooperator), roles (coach, instructor, companion), visualization, and so on. This leaves room to provide a student with more tailored learning situations.

In this review article I focus on intrinsically social learning systems and will use the term character enhanced learning systems (c.f. [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF]. The two main questions addressed are the following: (i) what are the arguments in favour of character enhancement of computer based learning environments? and (ii) what are the empirical results with respect to these arguments? The structure of the paper is as follows: Firstly, I present the kinds of benefits of character enhancement that have been proposed in the literature: increased motivation, increased comfort with learning tasks, stimulation of particular learning activities, enhanced flow of information and communication, fulfilling the need for deeper personal relationship in learning and improved achievement in terms of memory, problem solving and understanding. Secondly, the empirical results presented in literature with respect to the argued positive effects are examined. In the literature surveys, I attempt to cover as many as possible of the major studies from the mid 1990's that are relevant to the questions examined. Thirdly, in a final part possible directions for continued research in the field of character enhanced computerized learning environments are discussed. I propose a near time research agenda and conclude with some reflections on a longer-term perspective.

CHARACTER ENHANCEMENT OF COMPUTER BASED LEARNING MATERIALS AND ENVIRONMENTS -PROPOSED GAINS

What is gained, from a pedagogical point of view, by enriching computer based learning materials and environments with virtual social characters? This section presents a survey of six kinds of positive effects that have been proposed: (i) increased motivation, (ii) increased sense of ease and comfort in a learning environment, (iii) stimulation of essential learning behaviours, (iv) increased smoothness of information and communication processes, (v) the fulfillment of a need for personal relationships in learning, and (vi) gains in terms of memory, understanding and problem solving. There are, of course, as several researchers point out (e.g. [START_REF] André | Presenting through Performing: the Use of Multiple Lifelike Characters in Knowledge-Based Presentation Systems[END_REF][START_REF] Dehn | The impact of animated interface agents: a review of empirical research[END_REF] potential relations between different kinds of gains. In a particular section I will address this issue.

Increased motivation

A frequently presented argument in favour of character enhancement5 is that it will increase students' motivation to stay on in a learning environment and engage in the learning activities. Some different factors are proposed to produce the increased motivation: Learners may experience the environment and activities as more entertaining [START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF] or as more likeable [START_REF] Sproull | When the Interface is a Face[END_REF]. As the environment becomes more social, the user's engagement will increase [START_REF] Walker | Using a human face in an interface[END_REF][START_REF] Sproull | When the Interface is a Face[END_REF][START_REF] Moundridou | Evaluating the persona effect of an interface agent in a tutoring system[END_REF].

Lester and his colleagues [START_REF] Elliott | Lifelike Pedagogical Agents and Affective Computing: An Exploratory Synthesis[END_REF]Lester et al., 1997aLester et al., , 1997b[START_REF] Lester | Animated pedagogical agents in knowledge-based learning environments[END_REF] emphasize that the addition of animated agents makes the computer more lifelike and that this increases its motivational impact. 6 They hold that the presence of lifelike characters in interactive learning environments, 'can have a strong positive effect on students' perception of their learning experience' (my italics, Elliott et al.,ibid.,p. 4). The researchers name this the persona effect, and argue that 'the motivational benefits derived from the persona effect are compelling' (Elliott et al.,ibid.,p. 4).

Several researchers (e.g. [START_REF] Lee | Integration of Various Emotion Eliciting Factors for Life-like Agents[END_REF][START_REF] Ball | Emotion and personality in a conversational agent[END_REF][START_REF] Lester | Deictic and emotive communication in animated pedagogical agents[END_REF][START_REF] Massaro | Developing and evaluating conversational agents[END_REF][START_REF] Kort | An Affective Model of Interplay Between Emotions and Learning: Reengineering Educational Pedagogy -Building a Learning Companion[END_REF][START_REF] Takeuchi | Learning Enhancement in Web Contents through Inter-Agent Interaction[END_REF] point to the ability of social characters and agents to show and elicit emotion as a central factor behind the hypothesized increased motivation.7

Increased sense of ease and comfort with the learning tasks and the learning environment

Another argument for character enhancement of computer based learning environments is that the addition of a social character, or a set of social characters, can make the learner feel more comfortable and more at ease with the learning tasks and the learning environment. [START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF] propose that 'the presence of Persona may […] take away the fear of failure that some students experience with regard to particular educational material' (p. 63).

Stimulation of certain essential learning activities

It has also been proposed that certain crucial learning activities are stimulated or supported in character enhanced learning environments, for instance explorative activities. According to [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF] several studies show that the addition of characters encourages exploration of information materials, and a motive behind their own system (ibid.) is that the characters in the Agneta & Frida-system will encourage exploration. Similarly, the Affective Learning Companion by Picard and her colleagues (e.g. [START_REF] Kort | An Affective Model of Interplay Between Emotions and Learning: Reengineering Educational Pedagogy -Building a Learning Companion[END_REF][START_REF] Kapoor | Towards a Learning Companion that Recognizes Affect Proceedings of Emotional and Intelligent II: The Tangled Knot of Social Cognition[END_REF] has as a main goal to

Enhanced flow of information and communication

Some researchers hold that a central gain when adding social characters to a pedagogical interactive system is an improved flow of information and communication (e.g. Cassell & Thorisson, 1999;[START_REF] Shaw | Pedagogical Agents the Web[END_REF]. An animated social character that gives feedback in the form of gazes, smiles or nods, or which points and demonstrates with its body, opens up for rich and smooth interaction. Human beings are accustomed to interact with other social actors, that is, other humans, and the more one can resemble such information and communication processes in a learning environment, the better the attained flow of information will be. An underlying idea is that the naturalness of interaction between human beings, and the bandwidth of multi-modal interaction that we are capable of, is to be emulated or recreated in artificial actors. According to Shaw et al. (ibid.) the main motive of working with pedagogical agents is to 'make it possible to more accurately model the kinds of dialogs and interactions that occur during apprenticeship learning and one-to-one tutoring [where] factors such as gaze, eye contact, body language and emotional expression can be modelled and exploited for instructional purposes' (p. 283). [START_REF] Massaro | Developing and evaluating conversational agents[END_REF] reason along similar lines: As animated characters can provide many sources of valuable and effective information in a natural manner, this will facilitate and enrich the interaction between human and machine in a learning context. And Oviatt and Adams (2000) whose research is driven by the long-term overall goal of developing robust interfaces for children 'that make effective use of animated characters for purposes like education' (p. 321), hold that with 'social interfaces' it will be possible to obtain more transparent, high bandwidth and relatively natural multi-modal communication.

Fulfilling the need for deeper personal relationship in learning

A social context can make possible and support interactive and cooperative activities of different kinds, but it can do more: it can also make deeper personal relations possible. [START_REF] Bickmore | Social Dialogue is Serious Business[END_REF] advocates what he calls relational agents, which are computational artefacts designed to build and maintain long-term, social-emotional relationships with their users. He holds that 'humans have a need to engage in substantive and deep social interaction, not only in what we call social contexts but also in explicitly task-oriented contexts'. In education, he maintains, 'the establishing of personal relationships is absolutely crucial' (p. 1). The proposal, thus, is that personal relationships in a deeper sense, not a more shallow social interaction, is the prime value that can be gained from character enhancement of computer based learning environments. Such deeper personal relationships are essential in order to achieve outcomes of significant benefits for users of computers, in particular in learning contexts. (See also [START_REF] Bickmore | Subtle Expressivity Relational Agents[END_REF]) Also [START_REF] Moreno | The case for social agency in computer-based teaching: do students learn more deeply when they interact with animated pedagogical agents[END_REF] propose that a main value in a pedagogical animated agent lies in it acting as a 'personal tutor' (p. 183, my italics).

Positive effects on learning achievements in terms of memory, problem solving and understanding

Finally, positive effects in terms of improved memory, problem solving, knowledge transfer or understanding are proposed as potential gains of character enhancement. Lester et al. (1997a) propose that virtual animated characters, in addition to their significant motivational benefits, increase students' problem-solving effectiveness. Similarly, [START_REF] Johnson | Evaluation of user Interaction: The Case of Agent Adele[END_REF] describe animated pedagogical agents as a promising means for making computer-aided learning more efficient in that agents may scaffold learning activities such as problem solving. [START_REF] Moreno | The case for social agency in computer-based teaching: do students learn more deeply when they interact with animated pedagogical agents[END_REF] suggest that a social agency environment built around an animated pedagogical agent, will encourage learners to make a stronger effort to understand a material and thus results in increased understanding and an improved capacity for knowledge transfer.

Potential relations between effects

There are potential relations between several of the discussed effects or gains, and some authors discuss such relations. Specifically, the possible relations between motivational gains and activity gains and, in turn, between activity gains and achievement gains have been pointed out. 'A greater entertainment value of a tutoring system might lead the student to interact with a system more frequently, thus eventually leading to superior learning achievements' (Dehn & van Mulken, 2000, p. 17). [START_REF] Moundridou | Evaluating the persona effect of an interface agent in a tutoring system[END_REF] state that an increase in students' motivation may show positive results in learning outcomes in the long run, and [START_REF] André | Presenting through Performing: the Use of Multiple Lifelike Characters in Knowledge-Based Presentation Systems[END_REF], as well, suggest that people possibly learn more about a subject matter because they are willing to spend more time with a system. Indeed there is intuitive appeal in the argument that if a learning environment or material is found engaging -that is, experienced as involving, interesting or as having impact -it is likely that users will become more active, stay on longer and produce more, which may, in turn, have effects on learning achievements. The first part in the argument, namely that there is a relation between motivation and activation, gets support from the theory of intrinsic motivation [START_REF] Keller | Motivational design of instruction[END_REF][START_REF] Malone | Toward a theory of intrinsically motivating instruction[END_REF]. However, in empirical studies it is necessary to sort out which effects are measured and which related effects are only hypothesized.

EMPIRICAL RESULTS WITH RESPECT TO THE PROPOSED POSITIVE EFFECTS

Increased motivation

The concept of motivation is complex, and empirical studies have to exploit some or other operationalization of it. One possible measurement is the length of time that learners spend with a character enhanced versus a neutral system, where longer time spent is interpreted as higher motivation. However, a prerequisite is that there is no specific task that the learners are asked to accomplish. If there is such a specific task, a longer time spent could also be interpreted as it being more difficult to understand or work within the environment. [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF] compared the average time spent by a group of eighteen participants who used a character enhanced system called Agneta & Frida (the 'with A&F' group) and a group of twenty participants who used the system without characters (the 'without A&F group'). The participants were told to look around and check out a collection of web links about movies, and the study was set up with the intention to allow subjects to feel free to do what they wanted and stay as long as they wanted. The subjects in the 'with A&F group' spent on the average 27.4 minutes with the system versus 20.7 minutes on the average for subjects in the 'without A&F group'. The difference is not significant as the standard deviation is large, but the tendency is towards the 'with A&F group' spending longer time.

A study that deserves particular attention is [START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF] of the use of an exercise adoption program involving a virtual trainer agent, named Laura. The Laura project, exceptionally, deals with long-term interaction within a learning context; the virtual trainer agent being designed to interact repeatedly with users during several weeks. Participants in the study were during four weeks able to log in as often as they liked and spend as much time as they liked viewing educational pages related to the training program. One of Bickmore's hypotheses was that the group that used the exercise adoption program with the virtual trainer would log in more frequently and would view a larger number of educational pages than the group that used a version of the program without the virtual trainer. The hypothesis was partly supported. There was a significant difference, in the hypothesized direction, in the number of pages viewed, but no difference in the numbers of log-ins.

A number of studies use questionnaires or interviews, where participants are questioned about their experiences, to measure the motivational effects of character enhancement. Many of these studies give support to the hypothesis that character enhanced systems are experienced as more entertaining, likeable or engaging. Some results regard explicitly pedagogical applications (Lester et al., 1997b;[START_REF] Lester | Animated pedagogical agents in knowledge-based learning environments[END_REF][START_REF] Moreno | The case for social agency in computer-based teaching: do students learn more deeply when they interact with animated pedagogical agents[END_REF][START_REF] Moundridou | Evaluating the persona effect of an interface agent in a tutoring system[END_REF][START_REF] Johnson | Evaluation of user Interaction: The Case of Agent Adele[END_REF]. Other results regard other kinds of information and knowledge applications [START_REF] Takeuchi | Situated facial displays: towards social interaction[END_REF][START_REF] Koda | Agents with faces: the effects of personification[END_REF][START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF][START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF][START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF] 8 .

In sum, a number of studies support the proposal that the use of social characters in knowledge-based systems of various kinds may have a considerable motivational impact. Many users experience these systems as more lively and engaging (c.f. [START_REF] André | Presenting through Performing: the Use of Multiple Lifelike Characters in Knowledge-Based Presentation Systems[END_REF]. However, three qualifications should be made.

First, with the exception of [START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF] virtual trainer study, there are to date no studies on long-term effects of character enhanced learning systems (c.f. [START_REF] Dehn | The impact of animated interface agents: a review of empirical research[END_REF]. Thus, little is known about motivational effects in the long run: what happens when a learner over a long period of time is given possibilities to use such systems and to choose to return or not return to them?

Second, the positive results concerning motivational effects derive from (i) comparisons between groups of subjects, with one but not the other group using a character enhanced version of a system, and from (ii) studies where a group of subjects are asked to compare a character enhanced version of a system with a non character enhanced version. When taking a more finegrained perspective that looks at individual results, one finds a subgroup of subjects who do not appreciate the character enhanced systems. For instance, [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF], report that a third of the eighteen participants tended to express negative views about the character enhancement, finding them irritating or disturbing, and not fun. These participants also, not surprisingly, expressed comparatively little willingness to use the system again. In related research, [START_REF] Tholander | Design and Evaluation of an Apprenticeship Setting for Learning object-Oriented Modelling[END_REF] report that out of the two groups who got to use an assistant in a modelling task, one group believed that the assistant provided useful information while the other group thought it was in their way. In a study by [START_REF] Gulz | Spatially Oriented and Person Oriented Thinking -Implications for User Interface Design[END_REF] participants were asked to choose between two interfaces -a socially elaborated interface and a spatially elaborated interface -to an information system about books, and asked to give reasons for their choices. From the motivations given, it was clear that social enrichment was appreciated by some (e.g. 'I chose it because it is more personal, about people, individuals', 'I find a social context more stimulating to explore' and 'It's more natural and easy for me to relate to the people than to the park') but disliked by others (e.g. 'I don't want to know things about those people' and 'The people only complicate things'). It seems, in sum, that character enhancement can evoke strong reactions -positive as well as negative.

Third, not only do we find divergence in motivational effects in individuals, there is also evidence that motivational effects vary with the kind of content or subject dealt with in the learning environment in question. In a study by [START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF] the character-enhanced system -the PPP Persona system -was experienced as more entertaining than the system without the PPP Persona, when the function of the system was to explain a technical device. But when the function of the system was that of introducing fictitious employees of a research institute, there was no difference in entertainment ratings between the character enhanced and the system that was not character enhanced. [START_REF] Dehn | The impact of animated interface agents: a review of empirical research[END_REF] speculate that the reason for this discrepancy can be that, if a system is visually attractive from the start, as they argue was the case with the employee introducing application, character enhancement might not make any difference as concerns motivational effects.

Increased sense of ease and comfort with the learning tasks and learning environment

An important result in Mulken et al.'s (1998) study was, that the mere presence of a character in a technical presentation appeared to influence the subjects' perception of the difficulty of both the presentation and the recall test. Subjects who had used the character enhanced version judged the technical presentation as significantly less hard to understand than subjects who had used the system without character enhancement. Subjects who had used the character enhanced version also rated the recall test as significantly less difficult than subjects who had used the unenhanced version. However, there were no actual performance differences between the groups, neither in comprehension nor in recall. [START_REF] Moundridou | Evaluating the persona effect of an interface agent in a tutoring system[END_REF], similarly, found that students who worked with an agent version of an intelligent tutoring system, found the maths problems that they solved significantly less difficult than students working with the intelligent tutoring system without an agent, despite the fact that the performance of both groups of students was similar.

This effect -an increased sense of ease and comfort with a learning task and environmentis of course interesting from a pedagogical point of view. However, as with the motivational effect, discussed above, we have no reason to believe it to be a panacea. Rather, empirical evidence indicates that there is significant individual variation also as regards the effect of an increased sense of ease and comfort with a learning task and environment. In the Höök et al.'s study (ibid.) some of the subjects did not feel at ease but were stressed, irritated and disturbed by the characters. [START_REF] Rickenberg | The effects of animated characters on anxiety, task performance, and evaluations of user interfaces[END_REF] used a series of Likert Scales (for instance 'I felt relaxed', 'I felt strained') to assess anxiety vs. relaxation in subjects who used a system with a monitoring and interacting animated character, and found large individual variation among subjects. The results can be summed up by the following passage from [START_REF] André | Presenting through Performing: the Use of Multiple Lifelike Characters in Knowledge-Based Presentation Systems[END_REF]: '[…] there is no "standard user". Rather, the members of a user population can differ widely with regard to personality and individual preferences for a certain style of acquiring new information. In fact, some people feel less comfortable when being approached directly by an agent' (p. 1). Additionally, it is unclear whether effects of increased comfort in a learning environment depend upon the character of the environment and tasks [START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF].

Stimulation of particular essential learning activities

Is there evidence that explorative activities, attention, cooperative activities or reflection is positively affected by character enhancement of computer based learning environments? [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF] compared the time spent and the number of sites explored by subjects who used the character enhanced Agneta & Frida system and by subjects who used the system without character enhancement. They conclude that their 'study showed that the Agneta & Frida system encouraged subjects to explore more of the space and to stay longer in the space' (my italics; p 208). 9Regarding studies on the effects of character enhancement on attention and concentration, there is no concensus on how to measure attention and on how to interpret different measurements (c.f. [START_REF] Dehn | The impact of animated interface agents: a review of empirical research[END_REF][START_REF] Moundridou | Evaluating the persona effect of an interface agent in a tutoring system[END_REF]. [START_REF] Takeuchi | Situated facial displays: towards social interaction[END_REF] interpret the longer response time in users in the character condition when playing a card game, as compared to users in the non-character condition, as an indication of a lower degree of attentiveness. The authors conclude that the character distracts users from the game. [START_REF] Sproull | When the Interface is a Face[END_REF], on the contrary, interpret the longer time taken by subjects in the character enhanced condition when answering psychological test items as reflecting a higher degree of attentiveness. Their conclusion is that people are more attentive to a task presented by a character than to one presented by a textual display. An issue that is closely related to the conflicting interpretations of time spent with respect to attention and learning, and that is discussed by several researchers, is the following: When does attentiveness to a character help a student focus on the learning tasks and activities as such, and when does it function as a distractor? (e.g. [START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF][START_REF] Rickenberg | The effects of animated characters on anxiety, task performance, and evaluations of user interfaces[END_REF][START_REF] Moreno | The case for social agency in computer-based teaching: do students learn more deeply when they interact with animated pedagogical agents[END_REF][START_REF] Craig | Animated Pedagogical Agents in Multimedia Educational Environments: Effects of Agent Properties, Picture Features, and Redundancy[END_REF] In a study by Tholander et al. (1999b) a distracting effect was indicated. Ten pairs of students were asked to perform a modelling task within the area of object-oriented analysis. Two pairs were supplied with a virtual pedagogical assistant, two pairs given a pattern library, two pairs supplied with an expert track, two pairs supplied with all three tools and two pairs given no tool. An observation of the groups that used all the tools was that the virtual assistant had a tendency to take too much attention away from the other two tools.

Moundrido and Virvou ( 2002) applied the criterion of 'longer time spent, but not too long'numerically spelt out -to stand for higher attentiveness in a study, where students worked with mathematical problems. No difference in attentiveness was found between students using character enhanced and non character-enhanced systems. [START_REF] Craig | Animated Pedagogical Agents in Multimedia Educational Environments: Effects of Agent Properties, Picture Features, and Redundancy[END_REF], who measured attentiveness during a short time span, found no difference in so called split attention effects between a character condition and a characterless condition.

In the Tholander et al. (ibid.) study described above, one hypothesis was that the virtual assistant would help subjects spend more time and effort to critically reflect upon their model and evaluate their solutions. However, the study gave no clear evidence that this was the case. Sometimes when the assistant commented on some important aspects of the domain that needed to be covered in the model, the students would indeed evaluate and reflect on their model. But sometimes comments were a source of confusion.

As concerns cooperative behaviour, it is, on the one hand, obvious that a character enhanced system offers extended possibilities for cooperation compared to a corresponding system without characters. The issue is rather whether -and how -it is possible to obtain cooperative behaviour of a sufficient naturalness and quality in a character enhanced computerized learning system. In a study by Keissler and Sproull (1997), three different character enhanced conditions as well as the condition of real human-human interaction were compared with respect to cooperation. The human partner, a confederate, communicated through desktop video. One character was based on an image of the confederate's face, another character was based on an image of a pet dog, and the third character was based on a cartoon drawing of a dog. The result was that participants cooperated highly and equally often with the person-like character and the confederate (the real person), but significantly less with the other two characters.

In sum, the evidence as regards positive influence of character enhanced environments on certain important learning behaviours is rather mixed. Furthermore, most evidence consists of single studies rather than a series of studies, systematically approaching an issue. It is therefore not possible to generalize the results to other kinds of systems, other learning situations and other instantiations of character enhancement. In particular, long-term learning is rarely addressed in the studies.

Enhanced flow of information

The proposed gain of enhanced and more natural communication takes the rich and smooth communicative processes in human-human learning as its starting point. Character enhanced computerized learning environments, it is suggested, offer the promise of modelling or emulating (aspects of) this. The empirical studies that relate to the proposal are, in general, design and development oriented.

Evaluations with respect to the claim are carried out in different forms. Sometimes they involve comparisons between a particular learning environment with and without animated characters, but more frequently a character enhanced environment evaluated as such (e.g. [START_REF] Massaro | Developing and evaluating conversational agents[END_REF], sometimes being compared to the human-human interaction case (e.g. Oviatt & Adams, 2000). In other studies several different character enhanced environments are compared (e.g. Cassell & Thorisson, 1999). [START_REF] Massaro | Developing and evaluating conversational agents[END_REF] describe a study where the animated character Baldi -a computeranimated talking head -functions as a classroom tutor for language training for children with hearing loss. The study showed that Baldi helped the children to correctly interpret auditory speech, in other words, helped to increase the smoothness of dialogue interaction.

Oviatt and Adams (2000) compared childrens' conversing and interacting with a set of animated characters to childrens' conversing with adult human beings. Results were that the childrens' speech when directed at the animated characters was significantly more repetitive and clearer or more hyper-articulated, than was their speech when directed at an adult human. This may, according to the authors, indicate that the children view their computer partner as a kind of 'at-risk' listener. In other words, the interaction, in terms of conversation with the characters in this environment, did not attain the smooth and natural conversational pattern that is achieved in interaction with another (adult) human being.

Cassell and Thorisson (1999) compared three different animated agents that communicated with learners about the solar system. One agent just provided answers to questions. The second agent in addition to this also produced emotional responses, for instance smiling when addressed by the user. The third agent, defined as the most communicative agent or the discoursesupporting agent, was similar to the first but additionally turned head and eyes towards the user when expecting a request, etc. The hypothesis was that the flow of interaction would be smoother with the third agent than with the two others, in the sense that the user would make a smaller number of repetitions and hesitations, and that there would be less communicational overlaps. The result did indeed show that the relative number of repetitions was significantly lower in the interaction with the third agent. Also when subjects were asked to rate the smoothness of the interaction, the condition with the third agent was rated significantly higher than the other two conditions. However, contrary to the expectations, the number of hesitations and overlaps was significantly higher in the interaction with the third agent. The authors explain the unexpected result by arguing that a larger number of overlaps and hesitations might in fact be an indicator of a more natural interaction.

In sum, a number of studies have been conducted, but they differ, among other things, in the kind of evaluation or comparison that is used. Compared to the case of 'no character' at all, it seems fair to say that character enhancement brings about an improvement in communication. Compared to the human-human-case, on the other hand, there is a long way still to go.

Fulfilling the need for deeper personal relationships in learning

The claim that character enhancement can be used to fulfil a need for deeper personal relationships in learning is, just as the claim that it can increase naturalness of communication, closely related to a modelling endeavour. The starting point is the existence of personal relationships in human-human learning, and attempts are made to recreate or emulate (aspects of) such relationships.

Among studies related to the proposal are the following. Oviatt et al. (2000) use the terminology of 'new friends' when reporting on how absorbed the six-to-ten-year old children in their study sometimes were with the animated characters (pp. 339-340). The researchers also report signs of social relations: 'children spoke directly to the animals using personal pronouns, and approximately one-third of all the content exchanged involved social questions initiated by the child about the animated character's name, birthday, personal characteristics, friends, and family life' (p. 339). Subjects in Höök et al.'s (2000) study were asked whether the Agneta and Frida characters 'feel like friends' on a scale from 1 to 7, where 1 stands for 'not at all' and 7 stands for 'very much'. Nine out of eighteen participants gave ratings between five and seven. Tim Bickmore, who is one of the leading proponents of the idea that computer based environments can and should make room for deeper social relations, worked during several years with the development of the animated character REA, a real estate agent. Among the mechanisms in the building of personal relationships that were studied in the REA projects was that of 'small talk'. An interesting result [START_REF] Bickmore | Social Dialogue is Serious Business[END_REF] with respect to this was the indication of significant individual differences: many participants felt strongly about their like, and many felt strongly about their dislike of small talk with an animated character.

In the later developed agent, the virtual trainer agent Laura [START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF], more sophisticated relational and social attributes are being modelled10 . Specifically there is development of so called relational cues, something that is assumed be important in the building of human relationships. Over time, the following cues develop in Laura: more frequent eyebrow raises, hand gestures and communicative head-nods; less frequent gaze-aways; more frequently coming close. Results of a between-subjects experimental design [START_REF] Bickmore | Subtle Expressivity Relational Agents[END_REF][START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF] indicated that when the virtual coach used these relationship building strategies, users reported more liking, trusting and respect for the agent, and reported an increased desire to continue working with it, compared with users in the so called non-relational condition. Some participants in the study explicitly stated, for instance, that "My relationship with Laura is very important to me" (Bickmore, 2003, p. 189) or that "Laura and I care about each other" (ibid., p. 189). But there were also participants who expressed quite a different attitude, for instance declaring that "I felt like I was talking to a robot, to a machine" (ibid., p. 186) or that "[ ] I liked all of the software except for the animated conversation thing" (ibid., p. 185).

In sum, it has been demonstrated that people can develop some different kinds of personal relationships to virtual characters11 in educational contexts. It has also been shown, though, that reactions and attitudes towards such a personal relation aspect differ considerably between individuals [START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF]. We conclude this section with an attempt to relate these two findings to [START_REF] Reeves | The Media Equation: How People Treat Computers, Televisions and New Media Like Real People and Places[END_REF] influential media equation, i.e. that a computer, and even more so an anthropomorphic projection such as a computer character, is treated as a social actor by human users [START_REF] Nass | Computers are social actors[END_REF]. In a series of studies, Nass, Reeves and co-workers have shown that human beings transfer social expectations and strategies used in the encounter of human beings to the case when there is a computer instead of a person in front of us.

The first finding, that people, who interact with a virtual character endowed with various social attributes, describe their relation to the character in terms of a personal relationship, is of course compatible with [START_REF] Reeves | The Media Equation: How People Treat Computers, Televisions and New Media Like Real People and Places[END_REF]. The finding however goes beyond what Reeves Nass actually speak about. Their focus is on how people behave in front of a computer and what this tells us about peoples' strategies and expectations. They are not concerned with the extent to which people explicitly declare that they experience a friendship, a personal relationship or the like.

It is more of an open question whether the second finding, concerning the considerable differences in how individuals react to and express their attitudes towards virtual characters, is compatible or not with the Nass and Reeves' framework. What we have is that, given a particular virtual character, endowed with more or less sophisticated social cues, some individuals willingly respond by being social in return and seemingly appreciating the situation, whereas others react with repudiation and, as soon as they can, shut the computer or the animated character off. The question is whether this pattern of differences has some correspondence in the non-virtual world. Is there a media equation or not in this respect?

Positive effects on learning achievement in terms of memory, problem solving, and understanding Lester et al. (1997b) hold that their study 'demonstrates that animated pedagogical agents can yield important educational benefits in the form of improved problem solving' (p. 23). This conclusion is, however, problematic, as the actual study involves only five conditions where different kinds of agents are compared with one another and no condition without an animated pedagogical agent. [START_REF] Graesser | Intelligent tutoring systems with conversational dialogue[END_REF] compare the learning results of students who used an intelligent tutoring system with the pedagogical agent AutoTutor to the learning results of students in a control condition who read yoked chapters in the book. Given the conditions that are compared, the outcome that 'that Autotutor improves learning by .5 standard deviation units' (p. 4) does thus not have any bearing upon the issue of whether character enhancement has positive effects on learning.

A number of studies provide negative evidence for the hypothesis that character enhancement has beneficial effects on memory, problem solving and understanding. [START_REF] Van Mulken | The persona effect: how substantial is it?[END_REF] showed no positive effect of an animated character on comprehension and recall in learning new information, for neither technical information nor non-technical information. There was also no positive effect on problem solving. [START_REF] Höök | Evaluating users' experience of a character-enhanced information space[END_REF] found no difference between subjects using the character enhanced system and subjects using the system without characters, in terms of how much they remembered of web page content. [START_REF] Moundridou | Evaluating the persona effect of an interface agent in a tutoring system[END_REF] present 'the not encouraging finding […] that the presence of an interface agent did not manage to improve the short-term learning outcomes significantly' (p. 260). [START_REF] Moreno | The case for social agency in computer-based teaching: do students learn more deeply when they interact with animated pedagogical agents[END_REF] compared subjects who learned about botanical physiology by interacting with an animated pedagogical agent who spoke to them, with subjects who received identical graphics and explanations as on-screen text without a pedagogical agent. No differences were found on retention tests.

A positive result, though, comes from the same set of studies by [START_REF] Moreno | The case for social agency in computer-based teaching: do students learn more deeply when they interact with animated pedagogical agents[END_REF]. On a transfer test where students were asked to apply what they had learned to solve new, relatively difficult, problems, the group who had used the character enhanced system outperformed the group that had used the system without the animated pedagogical agent. The authors speculate that the animated pedagogical agents may 'personalize the learning task and help students feel a positive personal relationship with the agent' which 'promotes interest in the learning task […] More motivated students try harder to make sense of the presented material than do less motivated students. They are also more likely to form coherent mental models that enable them to apply what they learned to challenging new problem-solving situations ' (ibid., p. 193, my italics). Even though this chain of explanation may be intuitively appealing, it remains basically speculative. [START_REF] Craig | Animated Pedagogical Agents in Multimedia Educational Environments: Effects of Agent Properties, Picture Features, and Redundancy[END_REF] present a result that in some respects parallels that of Moreno et. al.'s. In the study the three conditions, no agent, an agent without gesture and an agent with gestures were compared. No differences were found on a retention task, but on transfer questions there was a significant positive effect from the agent with gestures condition over the two other conditions. Craig et al. (ibid.) point out, however, that their study involves very brief information delivery and that it is 'not clear whether similar findings would be obtained in longer term learning sessions' (ibid., p. 433). [START_REF] Ryokai | Virtual peers as partners in storytelling and literacy learning[END_REF] in discussing a study of young children, who play and tell stories together with the virtual peer Sam, as compared to children who play and tell stories without Sam, make a similar reservation. The comparisons indeed suggest that children who played with the virtual peer told stories that more closely resembled the virtual peer's linguistically advanced stories. 'However the duration of the study is not sufficient to conclude that the children actually learned these behaviours from Sam' (p. 202).

CONCLUSION AND DISCUSSION

Summing up, none of the suggested pedagogical benefits of character enhancement discussed in the article is supported by unambiguous evidence. Instead, evidence is rather scattered and sometimes contradictory. Studies diverge in their methods of evaluation: character vs. noncharacter; character vs. human being; character version 1 vs. character version 2, etc. Many studies are pilot studies, and thus, their results are difficult to generalize. A particularly significant shortcoming of current evidence is that most studies leave us without knowledge of what happens when learners are involved in repeated interactions with social characters over a longer period of time. As a result we know little about potential effects of character enhancement of computerized learning environments in ecologically valid contexts.

The fact that we are left with such uncertainty, in spite of about a decade of intense research and development within the field, can be interpreted as reflecting the field's complexity. Also, it can be argued that we are still at a very early stage in the development of character enhanced systems, and consequently it is too early to go into evaluations of potential benefits of these kinds of learning environments. We have to await systems that are built for long-term real use and leave short-time lab studies behind. Evaluations today are bound to give uncertain results.

Even though these lines of argument are sound, it is important to acknowledge that there are several systems out there in the market place. Character enhancement of pedagogical systems is far from a pure R&D-phenomenon, which, in turn, entails some responsibility for the research domain. The following questions may, for instance, be posed:

• Is there anything in the hitherto collected knowledge that can be immediately applied in order to improve the character enhanced learning systems that are produced today? • Are there any of the proposed pedagogical gains that seem sufficiently promising to merit focused, systematic research also in a shorter time perspective? These issues will be briefly addressed below, followed by some reflections on a longer time perspective.

Research agenda in a shorter time perspective

Two of the potential pedagogical benefits from character enhancement that have been discussed above differ, in our opinion, somewhat from the rest: (i) increased motivation and (ii) increased sense of ease and comfort with tasks and learning environments. These proposed benefits are not so strongly associated with an idea of re-creating or emulating the human case, and are therefore less bound to having to await technological progress that can make emulation of the human case possible. They are of interest also given the aim of developing as successful character enhanced systems as possible today, and merit to be the focus of systematic studies in the near future. Among the critical parameters that ought to be involved in such short term studies, we propose the following: different pedagogical roles and strategies of virtual characters; aspects of visualization; user diversity; and repeated interactions over longer periods of time. Below I discuss why I hold that these parameters should be put on the short term research agenda.

Different pedagogical roles and strategies of virtual characters

Virtual characters can take on several kinds of roles: more authoritative ones as instructors, guides or coaches and less authoritative ones as different kinds of companions (c.f. [START_REF] Chou | Redefining the learning companion: the past, present, and future of educational agents[END_REF]. An instructor or coach may, furthermore, use active and intervening strategies or be more passive, only responding to requests for assistance by the learner. A companion may, for instance, be competitive, collaborative or act as a troublemaker (c.f. [START_REF] Chou | Redefining the learning companion: the past, present, and future of educational agents[END_REF]. Systematic, comparative research on the potentials of roles and strategies, as to how and when they affect motivation and comfort with tasks in users, would be useful. I propose large-scale studies that systematically compare effects in terms of motivational impact (and also learning achievements, when possible) between different roles/strategies in virtual characters. For instance, when and for which learners does the strategy of opportunistic teaching that is implemented in some pedagogical agents [START_REF] Shaw | Pedagogical Agents the Web[END_REF][START_REF] Lester | Animated pedagogical agents in knowledge-based learning environments[END_REF] have positive effects on motivation and sense of comfort and when is it found to be irritating, pushy or tactless? (C.f. [START_REF] Tholander | Design and Evaluation of an Apprenticeship Setting for Learning object-Oriented Modelling[END_REF][START_REF] Johnson | Interaction Tactics for Socially Intelligent Pedagogical Agents[END_REF]Gulz et. al., 2004).

Specifically we need to systematically address possible variations due to age, gender, and culture, in order to provide guidelines as to what pedagogical roles and strategies in virtual characters are worth having and to elaborate in different learning contexts. Such guidelines would be useful both for continued research and for development of environments to be used commercially.

Aspects of visualization; realism vs. iconization; choice of face, body and clothing; visual style; animation vs. still graphics

To date very little research has dealt with the visual aspects of virtual characters. With respect to the potential of character enhanced systems to motivate and to increase the impact of learning activities on users, this research gap deserves to be filled out. In the case of people interacting with real people, there is ample evidence that interpretations of appearance and observable physical cues profoundly affect both beliefs and behaviour. The visual appearance of a human being produces an impression of personality, which initiates a set of attitudes and expectations in others (e.g., [START_REF] Mcarthur | Judging a book by its cover: a cognitive analysis of the relationship between physical appearance and stereotyping[END_REF][START_REF] Kalick | Physical attractiveness as a status cue[END_REF][START_REF] Branham | Creating physical personalities for agents with faces: modelling trait impressions of the face[END_REF]. One of the few studies that address the visual appearance of virtual characters by Lee & Nass (1998), demonstrates that this factor seems critical for how people access virtual characters as well. The authors argue, that the visual appearance influences peoples' preferences in terms of looking at and even interacting with a virtual character. Within the related domain of computer games, Gard (2002), in discussing the design of computer game characters, claims that 'a person's first impression of a character will almost certainly come not from what they do, think, or say, but what they look like. If the character makes a good first visual impression, players will likely stay focused on it, allowing you to further entice them with the character's personality ' (p. 4-5).

Not only do human beings form impressions of someone's personality based on physical appearance, these impressions also persist and deepen over time [START_REF] Mathes | The effects of physical attractiveness and anxiety on heterosexual attraction[END_REF]. Relatedly, [START_REF] Gard | Building character[END_REF] claims that even though our opinions on a person's personality may be reformed after a while, it will 'for a long time […] still [be] filtered through our preconceptions based on our first impressions. So to create a really good character, you have to control all of the visual clues that people use to judge each other and establish a clear, unified message to make players interested in -and ultimately like -your character.' (p. 3).

An implication of all that has been said above is that if the goal of virtual characters is to motivate, engage and adequately impact learners -and/or to increase a learner's sense of ease and comfort with tasks -visual appearance ought to be carefully articulated in research and development of such characters. For more detailed arguments, see Gulz & Haake (submitted).

Regarding realism versus iconization (e.g. cartoonish) in visual rendering -which is a variable that can be manipulated only in the virtual, not the real world -we find diverging claims with respect to how this choice affects a character's impact and ability to involve (Gulz & Haake, submitted) but few corresponding empirical studies. However, empirical studies would be useful in order to sort out the issue and be able to provide guidelines both for continued research and for developing environments for commercial use. One variable to consider in such empirical studies is that of different user groups. There may well be differences between cultures and sub-cultures in response to realistic versus iconic animated agents (c.f. O 'Neill Brown, 1997;[START_REF] Baylor | Which Pedagogical Agent do Learners Choose? The Effects of Gender and Ethnicity[END_REF].

Learner/user diversity

As repeatedly indicated above, the field needs systematic research of differences between groups of people in attitudes and reactions towards virtual social characters in general, as well as towards particular instantiations of virtual social characters.

That there is variability in how virtual social characters are received by learners has repeatedly been demonstrated. Indeed a straight-on application of research results so far would be to convey knowledge of this state of affairs to designers of character enhanced learning environments. On such a general level, two kinds of design solutions could, furthermore, be suggested. The first solution accounts for the fact that some people but not others seem to appreciate virtual characters. It consists in offering both character enhanced and characterless alternatives. Paraphrasing [START_REF] Laurel | Interface Agents: Metaphors with Character[END_REF] on 'good interfaces': '[good learning environments] allow for more than one way of doing things. Only users who want to use agents should have them, others should have other choices' (p. 209). The second design solution provides room for variation and choice within the framework of character enhancement. An example is Hietala and Niemirepo's (1998) teams of teacher and learner companions that the student can choose from. The different companions have different levels of competence, personalities, voices and ways in which they interact. Another example is [START_REF] André | Presenting through Performing: the Use of Multiple Lifelike Characters in Knowledge-Based Presentation Systems[END_REF] presentation teams, with multiple presenters with complementary characters and role castings. These different characters may to some extent account for the different interest profiles of a diverse audience. There are also pedagogical benefits in letting different characters present different and incompatible points of view, pairs of arguments and counter arguments, or alternative conclusions and suggestions. A further merit of this kind of design solution is that it acknowledges both the idea that sociocommunicative aspects are essential for learning, and the idea that it is individuals, with varying minds, that bring about socio-communicative phenomena in all their richness and multitude.

But we still need to be better informed on what differences between groups of people are relevant in a certain context, in order to provide an adequate set of character strategies, roles, looks, etc. to choose from. In order to reach this, systematic studies of parameters such as age, culture, gender, learning styles are required.12 For instance, in studying the effects of different roles and strategies, and effects of the visualization of characters -as mentioned above -we need to chart out for which learners increased motivation and sense of ease and comfort with learning environments can be established.

Repeated interactions over extended periods of time with character enhanced systems

Finally, efforts to conduct longitudinal studies would strengthen the research field and its applicability. It is not wear-and-tear-systems that constitute the vision and provide the impetus for the work on character enhanced learning systems, and the questions and answers that are of pedagogical interest are not to be found in one-time or short-term interactions between a student and a system.

One may not have to go to the other end of the time scale, towards the vision that [START_REF] Chou | Redefining the learning companion: the past, present, and future of educational agents[END_REF] present as 'the creation of a lifelong learning companion, one that is like a friend and stays with a student from childhood to adulthood' (p. 266) but there is a large time-scale spectrum inbetween. [START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF] sets an example in his pioneering study of students who use the Laura system on a daily basis during several weeks. 13 Notably, this is also a study where a wellbalanced combination of quantitative and qualitative research methods is applied.

However longitudinal studies in the field of character enhanced learning systems are resource-demanding. They cannot be conducted on the basis of a dummy environment but require a system that is sufficiently developed and sufficiently rich to be able to stand up to longer time use. For one thing, too much repetitiveness in interaction must be avoided, something that [START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF] emphasizes as one of the main challenges for the development of pedagogical agents. He underlines that 'several subjects said [the repetitiveness in interaction with the exercise coach Laura] had a significant negative impact on their engagement with the system and motivation to exercise' (Bickmore,ibid.,p. 192). Nevertheless, the field is calling for more long-term interaction studies.

Hopefully we will see increased possibilities to re-use parts or modules of character enhanced systems in different implementations and studies. Access to usable freeware is likely to increase. And researchers working on studies where for various reasons it is not feasible to work longitudinally, may nevertheless contribute by discussing possibilities to extend the studies in question to a 'repeated interactions situation'.

Research agenda in a longer term perspective

It would be unwise to single out any particular research issues or approaches as more relevant than others in a long term perspective and attempt to guess which lines of research will contribute more than others to future successful learning environments. With this caveat, I nevertheless want to highlight two of the possible benefits of character enhancement discussed in the article: that of obtaining smoother communication and that of fulfilling the need for deeper social relationships in learning. Both proposals are associated with the idea of emulating human-human interaction and human-human relationships, and related research is clearly design and development oriented. It is also often visionary and acknowledges the fact that the systems built today are only prototypes, or belong to the very first generations of computerized learning environments. In view of this, it seems unlikely that the role of character enhanced computerized learning environments in the short time, will depend upon the extent to which these claims are fulfilled. 14 On the other hand, the outcomes of these lines of research may have a major long-term impact on the fate of computer based learning environments. Given the high priority that pedagogical theory gives to social and communicative components of learning, the extent to which it will or will not be possible to provide socially rich, deep, smooth and natural communicative processes in computer based learning environments, may turn out to be decisive. With a less successful outcome, computer based learning may remain what it is today for many educators and students: a sometimes practical choice, yet a kind of learning that is far from the real thing, namely human face-to-face learning. Character enhancement will then continue to be mostly an ornamental addition to jazz up this second choice, and cheer up (some) learners. With a more successful outcome, character enhancement may indeed help computer supported learning develop into a genuine virtual alternative to human face-to-face learning environments.

Not all virtual characters are embodied in the sense that there is a visualization of them. In this text, however, we focus on embodied virtual characters.

Additionally, though, it may be possible for several human learners to collaborate and interact with respect to such a learning environment.

There are also hybrid systems such as a pedagogical agent system designed to support multi-user collaborative exercises[START_REF] Shaw | Pedagogical Agents the Web[END_REF].

And, for instance, make sure that the more advanced participants in a group -the 'help-teacher-studentsthemselves are being challenged and getting appropriate scaffolding.

In the following, I will use the term 'character enhancement' as a short form for 'character enhancement of computer based environments'.

An experience of the computer as more lifelike may, in turn, produce an experience of the learning environment and activities as more entertaining, likeable or engaging.

Emotional aspects may, in turn, produce an experience of the system environment and activities as more entertaining, engaging and likeable.

Even though the latter do not focus on educational dialogue and interaction, they involve many elements such as the presentation of materials, and guidance through materials, that are important aspects of educational applications.

Höök et al. (ibid) also refer to the studies by van Mulken et al.(1998) andLester et al. (1997b) as studies that support the idea 'that characters encourage exploration of a given information space in relation to learning and creativity' ( p. 196).

Or rather, in one of the implementations of the agent.

As well as to other kinds of computer artefacts, such as Tamaguchis.

In contrast to only addressing such issues as an aside to a main study.

[START_REF] Bickmore | Relational Agents: Effecting change through Human-Computer Relationships[END_REF] himself suggests, however that the study should be repeated over a longer period of time with a much larger population

Acknowledgements

This work was partially supported by a research grant from the Swedish Science Council (Vetenskapsrådet). I also would like to thank three anonymous reviewers for highly valuable comments on a previous version of this paper. Likewise, I am grateful for valuable suggestions from Christian Balkenius, Petra Björne and Annika Wallin, all at Lund University Cognitive Science and Magnus Haake at the Department of Design Sciences, Lund Institute of Technology.


Care -Making the Affective Leap: More Than a Concerned Interest in a Learner's Cognitive Abilities

This commentary addresses the issues of 'care' in intelligent learning systems more precisely, elaborating and extending the definition to include recent research from neuroscience and education on the affective aspects of learning. It reflects on the association of profound empathy with care and in what ways the systems described in this issue illustrate features of profound empathy. It concludes that though they all include some features of profound empathy they all lack an elaborate definition of 'care' which means their ability to reproduce it is limited and they tend to focus more heavily on the cognitive rather than the affective nature of care. However it concludes that there are exciting opportunities ahead in the field if we consider the affective nature of learning and care more seriously.

INTRODUCTION

Although John Self regards care as a serious factor in the design of intelligent tutoring systems in the paper to which this issue is dedicated, he chose not to explore the concept of 'care' in any depth apart from arguing that such systems adapt to learners needs and 'care about what the students knows, misunderstands, wants to do etc' p352 (Self,1999). This brief commentary will argue that John Self's emphasis on care is even more fundamental to learning than perhaps even he acknowledges, though through working with John I suspect 'care' is intuitive to his way of thinking. It will also argue that the nature of care is more complex than having a concerned interest in some aspect of a student's cognitive understanding, though that indeed is a vital part of care. John urges precision in his original article and if we are to bask in the glow of the term 'care' as he suggests and harness its emotional and moral power in our research then we need to begin to define it more precisely and elaborately. This might help us to understand to what extent our systems do really 'care' and give pointers to ways in which we might improve them. Though the articles in this special issue show many 'caring' features, none of them define the term except with reference to John Self's article. In order then to develop increasingly understanding systems, which take into account learning contexts perhaps we can begin to elaborate our definition of care. [START_REF] Noddings | Caring -a Feminine Approach to Ethics and Moral Education[END_REF] describes caring thus:

CARE, INTERACTION AND LEARNING

Caring is largely reactive and responsive. Perhaps it is even better characterised by receptive. The onecaring is sufficiently engrossed in the other to listen to him and to take pleasure or pain in what he recounts. Whatever she does for the cared-for is embedded in a relationship that reveals itself as engrossment and an attitude that warms and comforts the cared for ( p19).

Caring involves stepping out of one's own personal frame of reference and into the other's. When we care we consider the other's point of view, his objective needs and what he expects of us. Our attention, our mental engrossment is on the cared -for, not on ourselves. Our reasons for acting, then, have to do with the other's wants and desires and with the objective elements of his problematic situation (p.24).

Genuine care therefore is an engrossing developmental process, which encompasses affect as well as cognition. From [START_REF] Noddings | Caring -a Feminine Approach to Ethics and Moral Education[END_REF] we gain this idea of care as empathy, as 'receptivity', to be open to someone's feelings and feel 'with' someone, to share a feeling and an understanding. From [START_REF] Murdoch | The Sovereignty of Good[END_REF] we gain the concept of 'loving attention'. Vygotsky reminds us of the importance of the united nature of affect and cognition and of the inadequacy of a merely cognitive approach:

When we approach the problem of the interrelation between thought and language and other aspects of mind, the first question that arises is that of intellect and affect. Their separation as subjects of study is a major weakness of traditional psychology, since it makes the thought process appear as an autonomous flow of 'thoughts thinking themselves' segregated from the fullness of life, from personal needs and interests, the inclinations and impulses of the thinker. (E)very idea contains a transmuted affective attitude toward the bit of reality to which it refers. (Vygotsky, 1986 p 10).

My thesis argues that an attitude of care in teaching and learning emerges through profound empathy in one to one empathic relationships [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF]. Showing that you care profoundly provides precisely the right climate in which students learn most effectively. The learner's achievements consist of both personal and academic development and are continually inter-linked. The degree of empathy shown by the tutor or system can also affect the degree of empathy shown by the student and the student's ability to share with and learn from others. The constraints of the context also appear to be powerful factors in the ability of the tutor to employ their empathy to best effects and meet the needs of their students [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF].

Best argues that emotions have been largely neglected in British mainstream education [START_REF] Best | The development of Affective Education in England[END_REF] and the increasingly mechanistic approach to teaching and the prescribed and extensive nature of the curriculum in recent years have not helped. However it is surprising that rich holistic findings of previous international psychological research into learning [START_REF] Rogers | Empathic: an unappreciated way of being[END_REF]Purkey 1972;[START_REF] Aspy | Towards a Technology for Humanising Education[END_REF] and also recent developments in neuroscience about the significance of affect (Damasio,1994;1999;Goleman, 1996) are often ignored when we consider some aspects of computer based learning at an international level. Vygotsky's warning about the separation of affect and cognition are seen clearly in the field. Our user models nearly always address cognition and though our agents increasingly address affective issues we seem to mainly separate the two, almost as if affect is quite separate and too ephemeral for some research to contemplate. The findings from neuroscience reaffirm the emphasis placed on affect by the older psychological literature and suggest strongly that all learning is affective in nature [START_REF] Damasio | Descartes Error[END_REF].

In combination these two fields of research help us to understand how empathy works and how the emotional engagement of intense multi-sensory interaction allows us to envisage and process our environment more intensively and gain alternative perspectives. Emotions seem to be central to decision making and also to learning and memory. Though the complex systems described in this issue succeed in creating more understanding models and touch here and there on the role of affect and the significance of care in teaching and learning they do not take either seriously in a theoretical sense. [START_REF] Damasio | The Feeling of What Happens: Body, Emotion and the Making of Consciousness[END_REF] explains the importance of high levels of engagement in learning, emphasising the role of the human's own sense of body and self in relation to the world he or she perceives and learns about.

He explains how the intensity of focus and engagement created by multi-sensory interaction engages the mind deeply and each interaction reinforces the person's sense of self, because the image of self in the brain has to be recreated at each interaction. Such intense engagement stimulates the whole brain and body because the memory of the interaction is mapped both in the brain at an emotional level but also throughout the body and is remembered as a feeling. Hence all interaction and the learning associated with it is affective in nature.

Provided interaction is mainly of a positive nature the brain will remain curious and open to the environment. A continuing, positive sense of self will produce a constant positive feeling throughout the body, which leads to greater openness and willingness to engage in interaction. Babies brains grow when they feel cared for [START_REF] Winkley | Towards the Human School -principles and practice[END_REF]. Conversely, negative affect tends to produce a shutting down of self, a withdrawal, stimulating protection and defence. In our intelligent systems therefore we need to create this frequent positive interaction and subsequent good feeling. This may come from both the learning itself and the learning context, crucially incorporating the affective relationships with the tutor and with peers. [START_REF] Damasio | The Feeling of What Happens: Body, Emotion and the Making of Consciousness[END_REF] explains how intense engagement with the world around us helps us to process and understand that world. Dewey also rejected Cartesian dualism (Biesta and Vandestraeten, 1997) and saw interaction as a transaction in which both the organisms and the environment were implicitly involved. Intense interaction with other humans also produces emotional engagement. Leal explains how the shared interactions between parents and infants produce intense emotion for the young child [START_REF] Leal | The Caring relationship[END_REF] and this is how our sense of self grows and our learning occurs.

All along it has been clear to educators that the experience of 'selfhood' is not a purely 'instinctual' or 'cognitive' affair' but is an early construction, contextualised in a primitive matrix of desires motives and intentions involving 'selves' and 'others' in a continuum of successful instances of social-emotional integration (Leal, 2002 pg. 3) Our awareness is heightened the more we interact and through this we 'know' and process other objects and people much more intimately. This 'knowing' of a person both emotionally and cognitively begins to sound very much like empathy, 'the power of mentally identifying oneself with (and so fully comprehending) a person or object of contemplation' (The New Oxford English Dictionary, 1993 edition). This empathic approach towards others deployed over time results in a moral concern of care for the others [START_REF] Noddings | Caring -a Feminine Approach to Ethics and Moral Education[END_REF][START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF].

Vygotsky's zone of proximal development (1978) must therefore involve affective assessment and scaffolding. This makes the tutors or the intelligent system's task very complex. If a tutor is unable to scaffold learning encompassing emotional as well as cognitive responses, the student may flounder around in internal confusion. Some direction, support and intervention is vital to move students on at sufficient pace, to help motivate and encourage them in their tasks and thinking. Formative assessment which is at the very heart of learning needs to be both emotional and cognitive, both personal and academic. [START_REF] Noddings | Caring -a Feminine Approach to Ethics and Moral Education[END_REF] argues that time is needed for real caring relationships to develop, not only through the taught curriculum but through the normal conversations and interactions which take place between people. Sometimes these may be lengthy conversations but other times they may be simple interactions that affirm and recognise students as valued people and their importance should not be underestimated [START_REF] Watson | Education, Assumptions and Values[END_REF]. Such 'off-task' interaction is more likely to enhance liking and feeling of community than purely task-related engagement (Klein cited in [START_REF] Clark | Schools as learning communities: transforming education[END_REF]. Face-to-face interaction is more likely to produce positive sentiments between people. Relationships and a sense of community are destroyed by the 'I-it relationship', which reduces other people to the status of objects [START_REF] Clark | Schools as learning communities: transforming education[END_REF]. Human relationships are central to a positive learning atmosphere (DFES, 1989) and are the source of the higher levels of intellect [START_REF] Vygotsky | Mind in Society[END_REF]. They motivate and reassure students (Rudduck, 1996).

A key feature of profound empathy in teaching and learning is the development of positive emotions and interactions which create the ambience for learning which enables and fosters open communication, [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF]. Profound empathy incorporates a deep understanding of self and others which appreciates all existing and historical relationships and their impact on learning. It includes the ability to empathise with all students and to take responsibility for their needs. Empathic tutors have a richly adaptive and integrated concept of themselves and others, which creates a strong moral concern. These factors in combination have particular effects. They build a positive learning climate by increasing positive interaction and communication. They build a student's esteem and self-worth, create emotional links between tutor and student and build trust and security which leads to an emulation of empathy thus increasing the positive ambience. This emotional closeness enables the tutor to discover hidden factors, which might enhance or inhibit learning.

CARE, COMPUTERS AND INTELLIGENT TUTORING SYSTEMS

The taxonomy of empathy in Cooper's thesis [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF] also reveals the advantages of the computer over the classroom teacher when it comes to care in that it offers more opportunity for intensive one -to one interaction. A more equal, multi-media, interactive and mutually responsive relationship has the potential to provide greater focus, engagement and greater care. Typically the classroom teacher's ability to empathise and care for students is reduced in the educational system. Large classes, lack of time, and the more animalistic environment created by competition, testing and league tables and the rigidity of the curriculum impact on the quality of empathy available in the classroom. Equally, the nature of individuals and groups with which teachers work, limit the ability of teachers to empathise sufficiently with students. Many of the features of profound empathy can be seen in these systems though significantly none display many features. Perhaps Bull's article reveals the greatest potential to reproduce high quality care. The computer in this instance can offer fast response times, 'just in time' or 'contingent' support (Wood, 1998[START_REF] Wood | Scaffolding, contingent tutoring and computer supported learning[END_REF] and can search for a 'ready, willing and able helper' thus supporting human collaboration. The system does seriously consider affective issues, though does not really address them theoretically. The proposal that the agent know the person as deeply and broadly as possible is a feature of profound empathy but the interaction has to be reciprocal and encompass off task interaction as well as on-task interaction (Klein in [START_REF] Clark | Schools as learning communities: transforming education[END_REF][START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF]. The importance of off-task conversation and trust and the generation of positive emotions is currently being explored in agent technology (Bickmore and Cassell;[START_REF] Bickmore | How about this weather?' -Social Dialogue with Embodied Conversational Agents[END_REF][START_REF] Wood | Scaffolding, contingent tutoring and computer supported learning[END_REF][START_REF] Kapoor | Towards a learning companion that recognises affect[END_REF]. Trust is built through mutuality and sharing [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF], and the student needs to share emotional understanding with its tutor for the highest levels of learning.

Both computer based learning systems and traditional educational systems lack many features of profound empathy, which might be addressed in the future. The values on which the potential 'learning community' are based may not coincide with those which support a learning community. The introduction of market values into the relationships into Bull's community for example is likely to reduce the level of empathy to a functional rather than profound level [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF] and encourage the I-it relationship rather than the human one (Clarke, 1996;[START_REF] Marx | Manifesto of the Communist Party[END_REF]. The labelling of banned individuals in Bull's community may also restrict the capacity of the community to learn.

The idea of sharing and trust and mutual open communication is powerfully addressed by Dimitrova. This is also strong aspect of profound empathy but the issue of more overt emotional exchange and its effect is not addressed. The system values the learners existing understanding and the tutor/student relationship is more equal, more collaborative, an important feature of profound empathy, which leads to deeper understanding on both sides. The system supports reflective learning but does not consider students' feelings about learning like an empathic human tutor.

The significance of differential treatment for learners, which Katz identifies and the need for different reflection is also an aspect of profound empathy. Their feeling about their learning and the development of positive emotions is also touched on when she considers assessment and motivational issues in the general dialogues. However it is the cognitive or 'instructional' dialogues which are the focus for the study even though the high significance of a positive ambience in motivating learners to learn has always been acknowledged in educational circles [START_REF] Aspy | Towards a Technology for Humanising Education[END_REF]. In Cooper's thesis (2002) experienced teachers stress the human, caring side of teacher/student interaction. Moreover the effects of care reproduce themselves and support collaborative work and the caring ambience generally.

Tedesco's project MarCo considers decision making and the intervention of an artificial mediator to support group planning interactions around conflicts. This is also an aspect of empathy. Young children felt that a caring teacher intervened in situations of conflict allowing a 'fair' classroom in which everyone was valued [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF]. Damasio would argue that complex decision making for individuals is also at base an emotional issue (1999). This emotional aspect is not really addressed yet it is a vibrant area of theory in agent research and references to Damasio's work abound in last years proceedings of the AISB for example (AISB, 2001). The concept of multi-modal communication in literacy research [START_REF] Kress | Multimodal Discourse: the modes and media of contemporary communication[END_REF] and situated learning [START_REF] Lave | Situated learning[END_REF] invite the study of a holistic appreciation of learning. This takes into account the complexity of multi-media interaction within a given context to which we have significant emotional responses.

Tedesco also refer to the importance of the quality of the communication in group interaction, but how is this quality assured? The degree of controversy and the power relations in the group can have a powerful effect for different members and the quality of communication is enhanced by profound empathy, which includes emotional exchange between tutor and student and between students. Can we assume all participants are acting in a rational, coherent fashion in their exchanges or are there anxieties at work in discussions? Are people coming to the discussion empty-minded or do they bring their historical selves, their perceptions of others and previously acquired emotional baggage with them? What is the mediator doing to assuage anxiety as a human mediator might? Does the structure of the dialogue games ensure people listen to each other or merely hear each other? Listening involves emotional engagement and motivation coupled with connectivity to one's own understanding not just a technical auditory or textual absorption process.

Similarly in the area of cognitive dissonance, in order to accept the inadequacy of our previous understanding we have to make an emotional leap and have the confidence to reassess our previous thinking. If we feel reasonably secure and that we are functioning in a climate of trust, which permits failure and openness, we can make such leaps with relative impunity. However if we feel threatened or anxious we find it harder to listen to new ideas or adapt our old ones [START_REF] Hoban | Teacher learning for Educational Change[END_REF]. In this respect the emotional climate has to be addressed in order to ensure such systems work effectively.

CONCLUSIONS

Empathy it seems is the ability to create a rich mental model of others which relates directly to our own experiences and feelings. This model is simultaneously affective and cognitive in nature. Teachers without empathy neglect emotion and focus too heavily on whole group, subject and curriculum and in the process can lose the motivation of their students [START_REF] Cooper | Teachers as moral models? The role of empathy in teacher/pupil relationships[END_REF]. Profoundly empathic tutors or artificial systems that try to imitate them are increasingly recognising and valuing the role of the affective in interaction and learning and utilising this knowledge to enhance the learning process for all students. The increasingly complex systems described here address several aspects of profound empathy in interactions but perhaps do not address as yet the truly affective and holistic nature of learning. We are beginning to acknowledge and value the role of affect which is at the heart of a caring approach in intelligent systems but perhaps we can be enthused by the prospect that we all have still an exciting and extensive journey to make along this particular research roller-coaster.