Stefan Kopp

A conversational agent as museum guide: design and evaluation of a real-world application

This paper describes an application of the conversational agent Max in a real-world setting. The agent is employed as guide in a public computer museum, where he engages with visitors in natural face-to-face communication, provides them with information about the museum or the exhibition, and conducts natural small talk conversations. The design of the system is described with a focus on how the conversational behavior is achieved. Logfiles from interactions between Max and museum visitors were analyzed for the kinds of dialogue people are willing to have with Max. Results indicate that Max engages people in interactions where they are likely to use human-like communication strategies, suggesting the attribution of sociality to the agent.

Synthesizing multimodal utterances for conversational agents

Conversational agents are supposed to combine speech with non‐verbal modalities for intelligible multimodal utterances. In this paper, we focus on the generation of gesture and speech from XML‐based descriptions of their overt form. An incremental production model is presented that combines the synthesis of synchronized gestural, verbal, and facial behaviors with mechanisms for linking them in fluent utterances with natural co‐articulation and transition effects. In particular, an efficient kinematic approach for animating hand gestures from shape specifications is presented, which provides fine adaptation to temporal constraints that are imposed by cross‐modal synchrony. Copyright

Towards a common framework for multimodal generation: the behavior markup language

This paper describes an international effort to unify a multimodal behavior generation framework for Embodied Conversational Agents (ECAs). We propose a three stage model we call SAIBA where the stages represent intent planning, behavior planning and behavior realization. A Function Markup Language (FML), describing intent without referring to physical behavior, mediates between the first two stages and a Behavior Markup Language (BML) describing desired physical realization, mediates between the last two stages. In this paper we will focus on BML. The hope is that this abstraction and modularization will help ECA researchers pool their resources to build more sophisticated virtual humans.

Simulating the Emotion Dynamics of a Multimodal Conversational Agent

We describe an implemented system for the simulation and visualisation of the emotional state of a multimodal conversational agent called Max. The focus of the presented work lies on modeling a coherent course of emotions over time. The basic idea of the underlying emotion system is the linkage of two interrelated psychological concepts: an emotion axis – representing short-time system states – and an orthogonal mood axis that stands for an undirected, longer lasting system state. A third axis was added to realize a dimension of boredom. To enhance the believability and lifelikeness of Max, the emotion system has been integrated in the agent’s architecture. In result, Max’s facial expression, gesture, speech, and secondary behaviors as well as his cognitive functions are modulated by the emotional system that, in turn, is affected by information arising at various levels within the agent’s architecture.

Towards integrated microplanning of language and iconic gesture for multimodal output

When talking about spatial domains, humans frequently accompany their explanations with iconic gestures to depict what they are referring to. For example, when giving directions, it is common to see people making gestures that indicate the shape of buildings, or outline a route to be taken by the listener, and these gestures are essential to the understanding of the directions. Based on results from an ongoing study on language and gesture in direction-giving, we propose a framework to analyze such gestural images into semantic units (image description features), and to link these units to morphological features (hand shape, trajectory, etc.). This feature-based framework allows us to generate novel iconic gestures for embodied conversational agents, without drawing on a lexicon of canned gestures. We present an integrated microplanner that derives the form of both coordinated natural language and iconic gesture directly from given communicative goals, and serves as input to the speech and gesture realization engine in our NUMACK project.

Guest Editorial: Gesture and speech in interaction: An overview

Gestures and speech interact. They are linked in language production and perception, with their interaction contributing to felicitous communication. The multifaceted nature of these interactions has attracted considerable attention from the speech and gesture community. This article provides an overview of our current understanding of manual and head gesture form and function, of the principle functional interactions between gesture and speech aiding communication, transporting meaning and producing speech. Furthermore, we present an overview of research on temporal speech-gesture synchrony, including the special role of prosody in speech-gesture alignment. In addition, we provide a summary of tools and data available for gesture analysis, and describe speech-gesture interaction models and simulations in technical systems. This overview also serves as an introduction to a Special Issue covering a wide range of articles on these topics. We provide links to the Special Issue throughout this paper.

Social resonance and embodied coordination in face-to-face conversation with artificial interlocutors

Human natural face-to-face communication is characterized by inter-personal coordination. In this paper, phenomena are analyzed that yield coordination of behaviors, beliefs, and attitudes between interaction partners, which can be tied to a concept of establishing social resonance. It is discussed whether these mechanisms can and should be transferred to conversation with artificial interlocutors like ECAs or humanoid robots. It is argued that one major step in this direction is embodied coordination, mutual adaptations that are mediated by flexible modules for the top-down production and bottom-up perception of expressive conversational behavior that ground in and, crucially, coalesce in the same sensorimotor structures. Work on modeling this for ECAs with a focus on coverbal gestures is presented.

Generation and Evaluation of Communicative Robot Gesture

How is communicative gesture behavior in robots perceived by humans? Although gesture is crucial in social interaction, this research question is still largely unexplored in the field of social robotics. Thus, the main objective of the present work is to investigate how gestural machine behaviors can be used to design more natural communication in social robots. The chosen approach is twofold. Firstly, the technical challenges encountered when implementing a speech-gesture generation model on a robotic platform are tackled. We present a framework that enables the humanoid robot to flexibly produce synthetic speech and co-verbal hand and arm gestures at run-time, while not being limited to a predefined repertoire of motor actions. Secondly, the achieved flexibility in robot gesture is exploited in controlled experiments. To gain a deeper understanding of how communicative robot gesture might impact and shape human perception and evaluation of human-robot interaction, we conducted a between-subjects experimental study using the humanoid robot in a joint task scenario. We manipulated the non-verbal behaviors of the robot in three experimental conditions, so that it would refer to objects by utilizing either (1) unimodal (i.e., speech only) utterances, (2) congruent multimodal (i.e., semantically matching speech and gesture) or (3) incongruent multimodal (i.e., semantically non-matching speech and gesture) utterances. Our findings reveal that the robot is evaluated more positively when non-verbal behaviors such as hand and arm gestures are displayed along with speech, even if they do not semantically match the spoken utterance.

Model-based animation of co-verbal gesture

Virtual conversational agents are supposed to combine speech with non-verbal modalities for intelligible and believable utterances. However, the automatic synthesis of co-verbal gestures is still struggling with several problems like naturalness in procedurally generated animations, flexibility in pre-defined movements, and synchronization with speech. In this paper we focus on generating complex multimodal utterances including gesture and speech from XML-based descriptions of their overt form. We describe a coordination model that reproduces coarticulation and transition effects in both modalities. In particular, an efficient kinematic approach to creating gesture animations from shape specifications is presented, which provides fine adaptation to temporal constraints that are imposed by cross-modal synchrony.

MULTIMODAL COMMUNICATION FROM MULTIMODAL THINKING|TOWARDS AN INTEGRATED MODEL OF SPEECH AND GESTURE PRODUCTION

A computational model for the automatic production of combined speech and iconic gesture is presented. The generation of multimodal behavior is grounded in processes of multimodal thinking, in which a propositional representation interacts and interfaces with an imagistic representation of visuo-spatial imagery. An integrated architecture for this is described, in which the planning of content and the planning of form across both modalities proceed in an interactive manner. Results from an empirical study are reported that inform the on-the-spot formation of gestures.