Showing papers by "Ana Paiva published in 2006"

Unscripted narrative for affectively driven characters

Abstract: In this article, we report on the emergent narrative concept aiming at the definition of a narrative theory adapted to the VR medium (whether a game or VR application). The inherent freedom of movement proper to VR - an indisputable element of immersion - collides with the Aristotelian vision of articulated plot events with respect to the given timeline associated with the story in display. This narrative paradox can only be observed in interactive VR applications and it doesn't seem possible to resolve it through the use of existing narrative theories. Interactivity is the novel element that storytellers must address. The authors discuss designing unscripted dramas with affectively driven intelligent autonomous characters based on the development of the FearNot! system for education against bullying

An affectively driven planner for synthetic characters

Abstract: This paper discusses the requirements of planning for believable synthetic characters and examines the relationship between appraisal and planning as components of an affective agent architecture. It discusses an implementation in the synthetic characters of the FearNot! anti-bullying education demonstrator and how far this provides an adequate mechanism for believable behaviour.

Mind the body: filling the gap between minds and bodies in synthetic characters

Abstract: Interactive virtual environments (IVEs) are inhabited by synthetic characters that guide and engage children in a wide variety of activities, like playing games or learning new things. To build those environments, we need believable autonomous synthetic characters that are able to think and act in very dynamic environments. These characters have often able minds that are limited by the actions that the body can do. In one hand, we have minds capable of creating interesting non-linear behaviour; on the other hand, we have bodies that are limited by the number of animations they can perform. This usually leads to a large planning effort to anticipate possible situations and define which animations are necessary. When we aim at non-linear narrative and non-deterministic plots, there is an obvious gap between what minds can think and what bodies can do. We propose smart bodies as way to fill this gap between minds and bodies. A smart body extends the notion of standard body since it is enriched with semantic information and can do things on its own. The mind still decides what the character should do, but the body chooses how it is done. Smart bodies, like standard bodies, have a model and a collection of animations which are provided by a graphics engine. But they also have access to knowledge about other elements in the world like locations, interaction information and particular attributes. At this point, the notions of interaction spot and action trigger come into play. Interaction spots are specific positions around smart bodies or items where other smart bodies can do particular interactions. Action triggers define automatic reactions which are triggered by smart bodies when certain actions or interactions occur. We use both these constructs to create abstract references for physical elements, to act as a resource and pre-condition mechanisms, and to simulate physics using rule-based reactions. Smart bodies use all this information to create high-level actions which are used by the minds. Thus, minds operate at a higher level and do not have to deal with low-level body geometry or physics. Smart bodies were used in FearNot!, an anti-bullying application. In FearNot! children experience virtual stories generated in real-time where they can witness (from a third-person perspective) a series of bullying situations towards a character. Clearly, in such an emergent narrative scenario, minds need to work at a higher-level of abstraction without worrying with bodies and how a particular action is carried out at low-level. Smart bodies provided this abstraction layer. We performed a small study to validate our work in FearNot! with positive results. We believe there may be other applications where smart bodies have much to offer, particularly when using unscripted and non-linear narrative approaches.

Using anticipation to create believable behaviour

Abstract: Although anticipation is an important part of creating believable behaviour, it has had but a secondary role in the field of life-like characters. In this paper, we show how a simple anticipatory mechanism can be used to control the behaviour of a synthetic character implemented as a software agent, without disrupting the user's suspension of disbelief. We describe the emotivector, an anticipatory mechanism coupled with a sensor, that: (1) uses the history of the sensor to anticipate the next sensor state; (2) interprets the mismatch between the prediction and the sensed value, by computing its attention grabbing potential and associating a basic qualitative sensation with the signal; (3) sends its interpretation along with the signal. When a signal from the sensor reaches the processing module of the agent, it carries recommendations such as: "you should seriously take this signal into consideration, as it is much better than we had expected" or "Just forget about this one, it is as bad as we predicted". We delineate several strategies to manage several emotivectors at once and show how one of these strategies (meta-anticipation) transparently introduces the concept of uncertainty. Finally, we describe an experiment in which an emotivector-controlled synthetic character interacts with the user in the context of a word-puzzle game and present the evaluation supporting the adequacy of our approach.

Fighting bullying with the help of autonomous agents in a virtual school environment

Abstract: Using empathic virtual agents for Personal and Social Education is a powerful and immersive way to sensitise students for the problems and dangers related to persistent aggressive behaviour among students, also known as bullying. The work reported here relates to the evaluation of applying such agents in schools in the UK, Portugal, and Germany as well as to consequences that can be drawn from these evaluation results. The Bullying Problem The problem of bullying is well-known to educators and parents across Europe. Among others, the enduring victimisation of one student by one or more other students may cause health problems, depression, truancy, and even suicide in the victim. It has been defined as “repeated action that occurs regularly over time, and usually involves an imbalance in strength, either real or perceived” (Olweus, 1999). Bullying means various types of aggressive behaviour including punching, kicking, hitting (direct physical bullying), teasing and cruel name-calling (direct verbal bullying) and rather indirect actions like social exclusion or deliberate withdrawal from friendship (indirect relational bullying). To fight the serious long-term effects, the EU sponsored project VICTEC (Virtual ICT with Empathic Characters) intended to deliver a software product based on episodic virtual drama to be used in schools with the aim to enhance students’ insight in the destructive nature of bullying and sensitise them for the harmful consequences for the victim. By using a 3D virtual environment for education purpose, students are encouraged to explore the problem of bullying in a save and exiting environment. The basic idea is to encourage empathic processes towards the virtual victims of bullying and hence create sensitivity towards the bullying problem.

Multimodal expression in virtual humans

Abstract: This work proposes a real-time virtual human multimodal expression model. Five modalities explore the affordances of the body: deterministic, non-deterministic, gesticulation, facial, and vocal expression. Deterministic expression is keyframe body animation. Non-deterministic expression is robotics-based procedural body animation. Vocal expression is voice synthesis, through Festival, and parameterization, through SABLE. Facial expression is lip-synch and emotion expression through a parametric muscle-based face model. Inspired by psycholinguistics, gesticulation expression is unconventional, idiosyncratic, and unconscious hand gestures animation described as sequences of Portuguese Sign Language hand shapes, positions and orientations. Inspired by the arts, one modality goes beyond the body to explore the affordances of the environment and express emotions through camera, lights, and music. To control multimodal expression, this work proposes a high-level integrated synchronized markup language—expressive markup language. Finally, three studies, involving a total of 197 subjects, evaluated the model in storytelling contexts and produced promising results. Copyright © 2006 John Wiley & Sons, Ltd.

Making it up as you go along : Improvising stories for pedagogical purposes

Abstract: We consider the issues involved in taking educational role-play into a virtual environment with intelligent graphical characters, who implement a cognitive appraisal system and autonomous action selection. Issues in organizing emergent narratives are discussed with respect to a Story Facilitator as well as the impact on the authoring process.

Making it up as you go along – improvising stories for pedagogical purposes

Abstract: We consider the issues involved in taking educational role-play into a virtual environment with intelligent graphical characters, who implement a cognitive appraisal system and autonomous action selection. Issues in organizing emergent narratives are discussed with respect to a Story Facilitator as well as the impact on the authoring process.

Using theory of mind methods to investigate empathic engagement with synthetic characters

Abstract: This paper is concerned with the simulation of human-likess capabilities in synthetic characters within the domain of Personal and Social Education. Our aim was to achieve socially meaningful and engaging interactions with children in the 8–12 age group to enable an exploration of bullying and coping strategies. We consider the engagement between the interacting partners, focusing particularly on the affective and empathic aspects of this relationship. We have used Theory of Mind methods to enable us to evaluate children's understanding of social scenarios and the thinking of others. The results from this 345 children study highlight that children are able to recognize and interpret affect in synthetic characters and are empathically engaged with the characters in the scenarios.

A story about gesticulation expression

Abstract: Gesticulation is essential for the storytelling experience thus, virtual storytellers should be endowed with gesticulation expression. This work proposes a gesticulation expression model based on psycholinguistics. The model supports: (a) real-time gesticulation animation described as sequences of constraints on static (Portuguese Sign Language hand shapes, orientations and positions) and dynamic (motion profiles) features; (b) multimodal synchronization between gesticulation and speech; (c) automatic reproduction of annotated gesticulation according to GestuRA, a gesture transcription algorithm. To evaluate the model two studies, involving 147 subjects, were conducted. In both cases, the idea consisted of comparing the narration of the Portuguese traditional story “The White Rabbit” by a human storyteller with a version by a virtual storyteller. Results indicate that synthetic gestures fared well when compared to real gestures however, subjects preferred the human storyteller.

Mainstream Games in the Multi-agent Classroom

Abstract: Computer games make learning fun and support learning through doing Edutainment software tries to capitalize on this however, it has failed in reaching the levels of motivation and engagement seen in mainstream games In this context, we have integrated a mainstream first-person shooter game, Counter-Strike, into the curriculum of our Autonomous Agents and Multi-agent Systems course In this paper we describe this integration and a platform to support the creation of Counter-Strike agents In addition, a questionnaire was posed to our students to assess the success of our approach Results show that students found the idea of applying a first-person- shooter game motivating and the integration with the curriculum useful for their education

What voice do we expect from a synthetic character

Abstract: The emerging new applications of synthetic characters, as a way to achieve more natural interactions, puts new demands on the synthetic voices, in order to fulfill the expectations of the user. The work presented in this paper evaluates a synthetic voice used by a synthetic character in a storytelling situation. To allow for a better comparison, a real actor was filmed telling a children’s story. The pitch, duration and energy of the recorded speech were copied to the synthetic speech generated with a FESTIVAL-based LPC-diphone synthesizer. At the same time, the synthetic character was also animated with the gestures, emotions and facial expressions used by the actor. Using different conditions combining the synthetic voice, synthetic character with the real voice, and the real character, the voice was evaluated regarding the comprehension of the storyteller, the expression of emotions, its credibility and the user satisfaction.