The experiment presented in this paper investigated the effects of different kinds of reminders on adherence to automated parts of a cognitive behavioural therapy for insomnia (CBT-I) delivered via a mobile device. Previous studies report that computerized health interventions can be effective. However, treatment adherence is still an issue. Reminders are a simple technique that could improve adherence. A minimal intervention prototype in the realm of sleep treatment was developed to test the effects of reminders on adherence. Two prominent ways to determine the reminder-time are: a) ask users when they want to be reminded, and b) let an algorithm decide when to remind users. The prototype consisted of a sleep diary, a relaxation exercise and reminders. A within subject design was used in which the effect of reminders and two underlying principles were tested by 45 participants that all received the following three different conditions (in random order): a) event-based reminders b) time-based reminders c) no reminders. Both types of reminders improved adherence compared to no reminders. No differences were found between the two types of reminders. Opportunity and self-empowerment could partly mediate adherence to filling out the sleep diary, but not to the number of relaxation exercises conducted. Although the study focussed on CBT-I, we expect that designers of other computerized health interventions benefit from the tested opportunity and self-empowerment principles for reminders to improve adherence, as well.

In this paper, we address the issue how an ambient intelligent system can coach people in doing progressive muscle relaxation exercises. Such a system could help many people in dealing with their stress-related problems like poor sleep. We develop a formal model of progressive muscle relaxation, formalize the different steps of the practice of relaxation and show how these can be assisted by an ambient system. The model can be used as a basis on top of which concrete coaching applications can be developed.

In this paper, we address the issue how a computing system can coach people in doing progressive muscle relaxation exercises. Such a system could help many people in dealing with their stress-related problems like poor sleep. We develop a formal model of progressive muscle relaxation, provide examples of typical instantiations of the model and identify how different coaching activities have their effects on the model. The model can be used as a basis on top of which concrete coaching applications can be developed.

Smart phones could become a great support technology for several behavioural therapies. In order to support target behaviour whenever the therapist is not available, build-in persuasive strategies can motivate users to adhere to their therapy. Several scholars have described persuasive strategies and how to implement them in different degrees. This paper gives an overview of the most important persuasive strategies and maps them on Cognitive Behaviour Therapy for Insomnia principles to derive some first high-level requirements of a virtual sleep coach.

This paper advocates a new science of intelligence, one that is holistic, multi-disciplinary, oriented to crucial values as health and well-being and able to contribute to the solution of real-world problems. As a starting point we study the interplay between two research disciplines that until now have been hardly related to each other: Ayurveda and multi-agent systems. We consider some possible results of the cross fertilisation like for instance the application of ayurvedic knowledge to improve the skills of practical reasoning agents.

This paper studies semantic efficiency measures for ambient intelligence. We follow an agent-based approach and investigate how large quantities of information can be efficiently handled. We will show how to dynamically set up a communication network between agents, which aims to minimize the communication load. The approach is based on a formal ontological notion of informativeness, on quantitative measures such as information gain and on the proper use of interaction mechanisms such as Publish/Subscribe. We also present experimental results that were obtained using our prototyping tool called Ubismart.

This paper proposes a decentralized approach for modeling information flow in ambient environments. We study how query and notification mechanisms can be used to reduce the amount of information exchanged between agents. We will propose qualitative criteria which state whether querying a concept is appropriate given the logical structure of an agent’s knowledge base. Furthermore, we will propose quantitative criteria which state which concept is most likely to be most informative, given an agent’s information needs and its experience with past events.

The successful application of ubiquitous computing in crisis management requires a thorough understanding of the mechanisms that extract information from sensors and communicate it via PDA's to crisis workers. Whereas query and subscribe protocols are well studied mechanisms for information exchange between different computers, it is not straightforward how to apply them for communication between a computer and a human crisis worker, with limited cognitive resources. To examine the imposed cognitive load, we focus on the relation of the information supply mechanism with the workflow, or task model, of the crisis worker. We formalize workflows and interaction mechanisms in colored Petri nets, specify various ways to relate them and discuss their pros and cons.

This paper studies the use of agent communication in ubiquitous computing. This application domain allows us to investigate the efficient handling of large quantities of information in agent-based systems. We will present an approach to dynamically set up a communication network between agents which aims to minimize the communication load. The approach is based on a formal ontological notion of informativeness, on quantitative measures such as information gain and on the proper use of interaction mechanisms such as Publish/Subscribe. We also present experimental results which have been obtained using our prototyping tool called Ubismart.

Intelligent user interfaces provide smooth interaction with the user, possibly by employing an embodied conversational agent. This paper argues that human-agent interaction improves by provoking alignment of coordination devices. Thereby we concentrate on eye behaviour. We show that automatic alignment of eye behaviour, described for human-human interaction (Pickering & Garrod, 2004), carries over to human-agent interaction. We experimentally investigate the role of alignment of eye behaviour and attention on the fluency of interaction and user-perception in human-agent interaction. A pilot study of interactions between humans and the embodied conversational agent iCat ( (Philips Research Technologies)) indicates that an agent that simulates eye contact and attention, provokes more eye contact from the user which increases fluency of interaction and perceived alertness of the agent. INTRODUCTION In order to realize intelligent interaction between humans and computers, human-human interaction may be mimicked, and an embodied conversational agent (ECA) may be employed in the interface. In this conversational metaphor for intelligent user interfaces, the conversational agent may be more or less human-like. The question how human-human interaction comes about has many answers. Starting point here is the view of Clark ( (Clark, 1996)) that dialogue is a joint activity, which is carried out in coordination by the dialogue participants. Participants are coordinated in a cooperative dialogue just as participants in any successful joint activity, such as dancing, are coordinated. Some aspects of human-human interaction have been shown to carry over to human-agent communication (cf. (Bartneck, 2003), (Zanbaka, Goolkasian, & Hodges, 2006)). Our goal here is to investigate alignment of eye behaviour in this respect. HUMAN-HUMAN INTERACTION Natural human-human interaction is composed of communicative acts and physical actions. Communicative acts may be verbal (cf. ( (Searle, 1969)) or non-verbal acts. One may distinguish between dialogue management acts versus content acts. Content acts are directly related to the 1 See (Hutchkins, 1989) for other possible metaphors for interface design. content of the interaction, e.g. information exchange or, in general, the task at hand, whereas dialogue management acts are concerned with the interaction itself, and directed to managing the flow of interaction. Examples of dialogue management acts are greetings, signals providing feedback on attention and processing, and error signaling. See (Bunt, 2000) for an extensive taxonomy of dialogue management acts. The flow of interaction The flow of interaction in a dialogue is determined by the interplay between the participants by means of their communicative acts and actions. Thereby dialogue management acts play an important role. The main subjects of managing the flow of interaction are turn-taking, timing, feedback, perceptual contact, dialogue structuring, and social obligations management. For instance, it is common in dialogue that one of the participants has the floor (by speaking or acting), whereas the other participant’s contributions are limited to feedback by dialogue management acts, preferably expressed in such a way that they do not interfere with the speaker / actor. Employing these ‘backchannel cues’, i.e. listener responses that (dis)confirm interest and understanding without interrupting the flow of dialogue, multiple modalities are advantageous, such as nodding (or shaking), eye contact, short vocal utterances such as ‘yes’, ‘uhhuh’, etc. Viewing human dialogue as an ongoing joint activity, dialogue management acts are acts by which participants coordinate the next step in their ongoing joint activity. Dialogue management acts are coordination devices: they are employed to coordinate the interaction. See (Clark, 1996) for other coordination devices. Automatic alignment (Dijksterhuis & Bargh, 2001) argue that social behaviour is based for an important part upon direct links between perception and behaviour: much social behaviour is automatically triggered by perception of actions of others. The majority of routine social behaviour follows the ‘perceptionbehaviour expressway’ ( (Dijksterhuis & Bargh, 2001)), i.e. a direct linking between perception and action. These findings are based on research on mirror neutrons in the neuropsychological literature. There is evidence for automatic links controlling speech, facial expressions, gestures, posture and other nonverbal behaviour. For instance, in the literature on speech it has been established that participants in a cooperative dialogue align with regard to their dialect, speaking rate and pausing frequency (cf. (Street, 1984), (Cappella & Planalp, 1981)); furthermore dialogue participants may mimic foot shaking and nose rubbing carried out by a person with whom they interact ( (Chartrand & Bargh, 1999)); and it has recently been established that dialogue participants involved in a cooperative task automatically converge their posture ( (Shockley, Santana, & Fowler, 2003)). Pickering & Garrod ( (Garrod & Pickering, 2004), (Pickering & Garrod, 2004)) have applied the findings on the perception-behaviour expressway to their theory of human dialogue. They agree with Clark ( (Clark, 1996)), that dialogue is a joint activity which involves cooperation between dialogue participants in a way that establishes a joint meaning of the dialogue as a whole, but they add automatic alignment, a device that facilitates language processing in dialogues. To come to a joint understanding, participants align their representational models at various levels: words, syntactic, semantic, situational alignment. So, the flow of interaction in human dialogue is managed largely by dialogue management acts, and is partly determined by non-conscious automatic processes. It has, as far as we know, not been investigated whether automatic alignment carries over to agent-human interaction. Eye behaviour Eye behaviour serves many functions in human interaction (cf. ( (Argyle & Cook, 1976), (Leathers, 1997)). Like other communicative acts, eye signals may be used as content acts and as dialogue management acts. To contribute to the content of the interaction, a speaker may communicate beliefs, intentions or affective state by means of eye behaviour, e.g. express (un)certainty on a topic or express emotional state. A hearer may indicate degree of attentiveness (paying attention/ interest / arousal / intimacy) by means of his/her eye behaviour. In addition, eye behaviour may indicate the relationship between participants (power / status / impression management). See (Poggi, Pelachaud, & Rosis, 2000) for an extensive typology of meanings of 2 (Chartrand & Bargh, 1999) refers to the non-conscious mimicry of behaviour in human interaction as the chameleon effect. eye behaviour. As for managing the flow of interaction, eye behaviour is efficient in structuring the dialogue (e.g. stress certain information by eye behaviour) and in turntaking ( (Vertegaal, Shell, Chen, & Mamuji, 2006), (Bunt, 2000)): e.g. looking away is a means for a speaker to keep the floor. Resuming eye contact, sometimes referred to as gaze, with a dialogue partner is a way to pass the turn to the hearer. Asking for a turn may be done by widely opening the eyes, comparable to taking breath for starting to speak. Eye behaviour may also be employed to ‘ask for’ feedback. Like other behaviour, eye behaviour, especially dialogue management acts, seems partly determined by automatic alignment. HUMAN-AGENT INTERACTION Several studies suggest that users in interaction with embodied conversational agents behave as they normally do in social interaction, and apply ‘social heuristics’ (cf. (Reeves & Nass, 1998) and (Rickenberg & Reeves, 2000)). ECAs may inhibit different embodiments with different degrees of anthropomorphisation. As for embodiment, (Bartneck, 2003) studies the difference between robotic versus screen embodiment, and shows effects of social facilitation in that embodied robotic characters seem to have a stronger social facilitation effect than embodied screen characters. When ECAs show human-like appearances and behaviour, users tend to ascribe human characteristics to them or ‘anthropomorphise’ them. The question how the degree of anthropomorphisation of an embodied agent influences interaction is still open. (Beun, Vos, & Witteman, 2003) shows that the mere presence of an ECA in the interface, independent of the human-like character, has positive influence on retainability of information by the user. Carry over In recent studies, it has been shown that several aspects of human interaction carry over to the interaction between humans and human-like ECAs. For instance, (Zanbaka, Goolkasian, & Hodges, 2006) shows effects of gender with regard to persuasiveness in that subjects may be more persuaded by agents of the opposite sex. Rickenberg & Reeves ( (Rickenberg & Reeves, 2000)) indicate that employing an embodied agent in the interface may increase the perceived presence of the user. Some aspects of eye behaviour were shown to carry over to human-agent interaction: (Garau, Slater, Bee, & Sasse, 2001) shows that adding eye gaze to an ECA improves the ‘communication experience’ of subjects, but only when eye gaze is related to the conversational flow (e.g. turn taking) and inferred from the audio stream. (Garau, Vinayagamoorthy, Brogni, Steed, & Sasse, 2003) found that ‘low-antropomorfic’ agents are adversely affected by adding eye gaze, whereas adding eye gaze to ‘high-anthropomorphic’ agents shows significant interaction effects on the perceived quality of interaction. So, more eye gaze control only leads to higher perceived quality of communication if the anthropomorphic degree is high. FOCUS OF THIS STUDY The focus of this study is on alignment of eye behaviour as dialogue control acts in human-agent interaction. Since we can control th

A computational framework is presented for the generation of elementary speech acts to establish conceptual alignment between a computer system and its user. This article clearly distinguishes between 2 phases of the alignment process: message interpretation and message generation. In the interpretation phase, presuppositions are extracted from the user's message and compared with the system's semantic model of the application domain, which is represented in Type Theory. Subsequently, in the generation phase, a feedback message at the conceptual level is produced to resolve detected discrepancies and avoid potential discrepancies as a result of quantity implicatures. A conversational strategy is provided that is based on Gricean maxims and a differentiation of various types of information states of the system, such as private and common beliefs about the domain of discourse.

The importance of agent communication for multi-agent systems is, of course, beyond any doubt. However, the importance of research in this area seems less obvious. After several years with lots of discussions about standard agent communication languages and possible semantics for them it seems people have the feeling that all the issues in this area are settled. Despite some criticism on FIPA ACL this seems to be the de facto standard for agent communication. Especially after the JADE platform (which is probably the widest used in academic circles) was made FIPA compliant. However, there is still a wide gap between being able to parse and generate messages that conform to the FIPA ACL standard and being able to perform meaningful conversations.Inordertoforceorevenjustsupportagentstoperformmeaningfulconversations some form of a shared semantics of the communication process is needed. Since it is impossible to verify compliance of agents based on internal structures of the agents (that cannot be inspected) the semantics should be based on concepts that are externally observable. Hence the growing interest in the use of social concepts that can be observed and verified outside the agents. In thecontextofthese developmentswe are happyto presentthis specialissue.The papers selected for this special issue on agent communication are based on presentations at the Agent Communication workshop of 2004, held in New York. They clearly indicate the general trend in the past few years towards the use of social concepts in defining the semantics of agent communication. Especially “social commitments” and deontic concepts such as “obligations” seem to become a central element in this respect. In three of the four papers in this special issue social commitments form the basis of the theory discussed in that paper. The fourth paper is based on the use of obligations and permissions. The paper of Fornara et. al. discusses the use of “institutions” as an abstract set of rules that describe how social commitments are changed based on communication

Communication in heterogeneous Multi-Agent Systems (MASs) is hampered by the lack of shared ontologies. Ontology negotiation offers an integrated approach that enables agents to gradually build towards a semantically integrated system by sharing parts of their ontologies. This solution involves a combination of a normal agent communication protocol with an ontology alignment protocol. For such a combination to be successful, it must satisfy several criteria. This paper discusses the goals and requirements that are important for any ontology negotiation protocol. Furthermore, we will propose some implementations that are constructed according to these criteria.

This paper presents a framework for the generation of coherent elementary conversational sequences at the speech act level. We will embrace the notion of a cooperative dialogue game in which two players produce speech acts to transfer relevant information with respect to their commitments. Central to the approach is that participants try to achieve some sort of balanced cognitive state as a result of speech act generation and interpretation. Cognitive states of the participants change as a result of the interpretation of speech acts and these changes provoke the production of a subsequent speech act. Describing the properties and the dynamics of the mental constructs that constitute the participants’ cognitive states, such as beliefs and commitments, in relation to the various dialogue contributions is an essential aspect of the game. Although simple in its basic form, the framework enables us to produce abstract conversations with some properties that agree strikingly with coherence structures found in, for instance, Conversation Analysis.

In open heterogeneous multi-agent systems, communication is hampered by lack of common ontologies. Ontologies may differ in naming conventions, granularity and scope. In such an environment, the agents must possess the right conversational skills to effectively exchange information even when the speaker's ontology is only approximately translatable to the hearer's ontology. Furthermore, the agents must be able to autonomously establish an ontology translation by exchanging parts of their ontologies. In this paper, we propose a layered communication protocol in which the agents gradually build towards a semantically integrated system by establishing minimal and effective common ontologies. We tested our system, called ANEMONE, on a number of heterogeneous news agents. We show how these agents successfully exchange information on news articles, despite initial difficulties caused by heterogeneous ontologies.

Communication in open heterogeneous multi agent systems is hampered by lack of shared ontologies. To overcome these problems, we propose a layered communication protocol which incorporates techniques for ontology exchange. Using this protocol, the agents gradually build towards a semantically integrated system by establishing minimal and effective shared ontologies. We tested our approach, called ANEMONE, on a number of heterogeneous news agents. We show how these agents successfully exchange information on news articles, despite initial difficulties raised by heterogeneous ontologies.