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The Non-Player Character: Exploring the believability of NPC presentation and behavior
Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Over the last few decades there has been immense growth in the video game industry, and we have seen great improvements in both graphics and audio. Unfortunately, the development of artificial intelligence (AI) and non-player characters (NPCs) has not proceeded at the same pace. Although there have undoubtedly been improvements, the field as a whole has lagged behind its siblings.

Many of the problems with NPCs stem from the fact that they do not achieve a sufficient level of believability, particularly in the social arena. This is primarily related to the fact that the NPCs do not behave in ways that align with the expectations of the player. This can lead to the player misunderstanding the role and purpose of the NPC, which damages the believability of the game. By extension, this lessens the enjoyment the player can derive from the game. Hence, it is imperative that the design of the NPC be in line with player expectations.

This thesis takes a holistic view of NPCs, encompassing their design, evaluation, and player perceptions. It uses a design science methodology, and primarily uses qualitative and interpretative methods. It will provide a description of the various types of NPCs found in games, what their design elements are, and how they are interpreted by players.

Place, publisher, year, edition, pages
Stockholm: Department of Computer and Systems Sciences, Stockholm University , 2016. , 118 p.
Series
Report Series / Department of Computer & Systems Sciences, ISSN 1101-8526 ; 16-003
National Category
Information Systems
Research subject
Computer and Systems Sciences
Identifiers
URN: urn:nbn:se:su:diva-128079ISBN: 978-91-7649-379-3 (print)OAI: oai:DiVA.org:su-128079DiVA: diva2:912617
Public defence
2016-05-20, Aula NOD, NOD-huset, Borgarfjordsgatan 12, Kista, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript. Paper 6: Manuscript.

 

Available from: 2016-04-27 Created: 2016-03-17 Last updated: 2017-02-24Bibliographically approved
List of papers
1. Analyzing the social dynamics of non-player characters
Open this publication in new window or tab >>Analyzing the social dynamics of non-player characters
2014 (English)In: Frontiers in Gaming Simulation: 44th International Simulation and Gaming Association Conference, ISAGA 2013 and 17th IFIP WG 5.7 Workshop on Experimental Interactive Learning in Industrial Management. Revised Selected Papers / [ed] Sebastiaan A. Meijer, Riitta Smeds, Berlin: Springer, 2014, 173-187 p.Conference paper, Published paper (Refereed)
Abstract [en]

Much of the current research into artificial intelligence (AI) for computer games has been focused on simple actions performed by the characters in games (such as moving between points or shooting at a target, and other simple strategic actions), or on the overarching structure of the game story. However, we claim that these two separate approaches need to be bridged in order to fully realize the potential of enjoyment in computer games. As such, we have explored the middle ground between the individual action and the story – the type of behavior that occurs in a “scene” within the game. To this end we have established a new model for that can be used to discover in what ways a non-player character acts in ways that break the player’s feeling of immersion in the world.

Place, publisher, year, edition, pages
Berlin: Springer, 2014
Series
Lecture Notes in Computer Science, ISSN 0302-9743 ; 8264
National Category
Information Systems, Social aspects
Research subject
Computer and Systems Sciences; Man-Machine-Interaction (MMI)
Identifiers
urn:nbn:se:su:diva-97199 (URN)10.1007/978-3-319-04954-0_21 (DOI)000341131500021 ()978-3-319-04953-3 (ISBN)978-3-319-04954-0 (ISBN)
Conference
44th International Simulation and Gaming Association Conference, ISAGA 2013 and 17th IFIP WG 5.7 Workshop on Experimental Interactive Learning in Industrial Management, Stockholm, Sweden, June 24-28, 2013
Available from: 2013-12-05 Created: 2013-12-05 Last updated: 2017-10-18Bibliographically approved
2. Analyzing the believability of game character behavior using the Game Agent Matrix
Open this publication in new window or tab >>Analyzing the believability of game character behavior using the Game Agent Matrix
2014 (English)In: Proceedings of DiGRA 2013: DeFragging Game Studies, Digital Games Research Association , 2014, 1-11 p.Conference paper, Published paper (Refereed)
Abstract [en]

In recent years there has been significant improvement in the simpler actions performed by characters in computer games – such as navigating the world and attacking enemies and similar actions. In previous work, the ability of NPCs to adapt to changing circumstances was found to be inadequate in many circumstances. In order to validate these findings we have studied a total of 20 games, observing NPC behavior in each of the games in many different situations, ranging from everyday town life to combat. Using the Game Agent Matrix, we found a number of different behavior categories related to the social context of the agent and its behavior within that context indicating a gap between the most convincing behavior was focused around navigating the world, using tools and using language, as well as more complex behavior such as social sanctions and ranking, connected to the narrative of the game. The middle ground, containing behaviors such as dynamic group formation and the ability to perceive the actions of others were generally seen as unconvincing.

Place, publisher, year, edition, pages
Digital Games Research Association, 2014
Keyword
believable behaviour, believable NPCs, evaluation, immersion
National Category
Information Systems
Research subject
Computer and Systems Sciences
Identifiers
urn:nbn:se:su:diva-97198 (URN)
Conference
The 6th Digital Games Research Association (DiGRA) Conference, August 26-29, 2013, Atlanta, GA, USA
Available from: 2013-12-05 Created: 2013-12-05 Last updated: 2016-03-22Bibliographically approved
3. Cues and insinuations: Indicating affordances of non-player characters using visual indicators
Open this publication in new window or tab >>Cues and insinuations: Indicating affordances of non-player characters using visual indicators
2015 (English)In: Proceedings of DiGRA 2015: Diversity of play: Games – Cultures – Identities, Digital Games Research Association , 2015, 1-12 p.Conference paper, Published paper (Refereed)
Abstract [en]

Non-player characters (NPCs) provide an important service in video games in that they provide an active connection to the narrative through their behavior, as if they were actors in a play. In this study, we aim to explore in what ways the visual appearance of an NPC affects how players perceive their role in the game, and what criteria players use to evaluate the role of NPCs based on visual information. This is done by performing a survey of players, where the respondents are asked to determine the role that a number of NPCs had given their visual appearance, and describe how they decided the roles of the NPCs.

Place, publisher, year, edition, pages
Digital Games Research Association, 2015
Keyword
Non-player characters, affordances, visual indicators
National Category
Information Systems
Research subject
Computer and Systems Sciences
Identifiers
urn:nbn:se:su:diva-122803 (URN)
Conference
DIGRA 2015, Lüneburg, Germany, May 14-17, 2015
Available from: 2015-11-11 Created: 2015-11-10 Last updated: 2016-03-22Bibliographically approved
4. Towards an updated typology of non-player character roles
Open this publication in new window or tab >>Towards an updated typology of non-player character roles
2015 (English)In: Proceedings of the IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing / [ed] Piet Kommers, Pedro Isaías, Heredina Fernandez Betancort, International Association for Development of the Information Society , 2015Conference paper, Published paper (Refereed)
Abstract [en]

In video games, non-player characters (NPCs) provide important services in that they facilitate the player's interaction with the game in a way that is in accordance with the expectations set by the narrative. It is, however, still unclear in what ways these NPCs must act, look, and feel in order to fulfill these expectations. In this study we aim to establish a typology of the roles NPCs play in games, building on a previous typology by Bartle (2004) aimed at providing a framework for describing the requirements put on NPCs by these expectations. This was done via an online survey, where respondents were asked to classify NPCs in images from 4 games, and to provide a description of why they classified it as belonging to a certain role. The results of the survey were the analyzed for instances where players expressed confusion about which role an NPC belonged to. These findings were used to update the previous typology. The results from this were later verified by applying the new typology to 10 other games. In the end we identified a number of new roles, as well as modifications to existing roles, which when combined with Bartle’s original typology created a typology applicable to a larger number of genres.

Place, publisher, year, edition, pages
International Association for Development of the Information Society, 2015
Keyword
Non-player characters, roles, affordance, interaction, games, evaluation
National Category
Information Systems
Research subject
Computer and Systems Sciences
Identifiers
urn:nbn:se:su:diva-122893 (URN)978-989-8533-38-8 (ISBN)
Conference
IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing, Las Palmas de Gran Canaria, Spain 22 - 24 July 2015
Available from: 2015-11-11 Created: 2015-11-11 Last updated: 2016-03-22Bibliographically approved
5. A typology of non-player characters
Open this publication in new window or tab >>A typology of non-player characters
2016 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Non-player characters (NPCs) critically impact the experience of the game, and must help uphold the player's feeling of immersion. To avoid negatively impacting the player's sense of immersion, the NPCs must be designed in ways that are in line with the player's expectation on the game, and must fulfill the interaction conventions of games. In this article, we present a typology that provide descriptions of the various types of NPCs found in games, and their design features. This typology was created based on previous work by Bartle (2004) and Warpefelt and Verhagen (2015), which was verified and expanded on using an online survey. The end product can be used to describe NPCs and their design features, primarily for analytical purposes but possibly also as a basis for procedural content generation.

National Category
Information Systems
Research subject
Computer and Systems Sciences
Identifiers
urn:nbn:se:su:diva-128077 (URN)
Conference
First Joint International Conference of DiGRA and FDG
Available from: 2016-03-17 Created: 2016-03-17 Last updated: 2016-03-21Bibliographically approved
6. A model of non-player character believability
Open this publication in new window or tab >>A model of non-player character believability
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this study we aim to describe in what ways non-player characters (NPCs) affect believability. To this end, we have conducted an online survey, where respondents were asked to classify and describe NPCs. Furthermore, we also examined recordings of NPCs in games. These data sources were examined using a model for NPC believability in order to describe the effect on believability by different types of NPCs. Based on this, we were able to construct a model of NPC believability, based on the NPC’s level of complexity and ability to handle a mutable social context. As described by the model, NPCs are currently less capable of handling changing social contexts. They do, however, show promise, and given current emerging technologies it is feasible that new types of more socially capable NPCs will arise within the near future.

National Category
Information Systems
Research subject
Computer and Systems Sciences
Identifiers
urn:nbn:se:su:diva-128078 (URN)
Available from: 2016-03-17 Created: 2016-03-17 Last updated: 2016-03-21Bibliographically approved

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