Karel van den Bosch


Serious games offer an opportunity for the learning of tasks that rely upon communication skills, like legal profession, human resource management, intelligence, sales, and many other professions. The player can practice his communication skills by conducting conversations (e.g. interviews, sales talks, negotiation) with one or more virtual characters. To realize the learning potential of games, the player needs freedom of play to discover the relationships between its actions and their effects on the virtual game partner and the conversation. However, the common approach of scripting tends to produce deterministic conversations, allowing little control to the player.


In this project we used the Belief-Desire-Intentions (BDI) concept for modeling the behavior of the virtual game character. This knowledge-based modeling approach allows greater freedom to the player, and delivers better scalability and re-use of dialogues.
Together with Ranj, a Dutch game studio, the BDI was implemented in a sales training game: the player-trainee is a real-estate salesman; the virtual character is a potential buyer.



Results show that BDI alowed to for designing mixed-initiative dialogues, creating flexible and life-like conversations. Furthermore, the framework enabled us to equip virtual characters with personality traits, and make them act accordingly. Characters could be modeled to behave extravert or introvert; agreeable or non-agreeable; and combinations thereof. A human subjects study showed that naïve players experience the virtual characters in accordance with their assigned personality profile.

The approach developed in this project is effective for creating individualized characters, it is flexible, and it is relatively easy to scale, adapt, and re-use developed behavior models.




Karel van den Bosch
Annerieke Heuvelink
Tijmen Muller
Ivo Swartjes

Project Term



Clips & presentations

Demo van GGR met toelichting (2'03")

(deze demo bevat toelichting in kaders; die worden niet getoond als mensen het spel spelen)

[pdf] van de dia's van de presentatie "Characters with Personality!" (Intelligent Virtual Agents 2012 conference)


Bosch, K. van den (2012). Buyers are Liars, Sellers are Yellers. GATE Magazine (pp58-59). [pdf]

Bosch, K. van den, Brandenburgh, A., Muller, T. J., & Heuvelink, A. (2012). Characters with Personality! In: Intelligent Virtual Agents (pp. 426-439). Held at: Santa Cruz, CA. Heidelberg: Springer. [pdf]

Muller, T. J., Heuvelink, A., Bosch, K. van den, & Swartjes, I. (2012). Glengarry Glen Ross: Using BDI for Sales Game Dialogues. In: The Eighth Annual AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment. Held at: Palo Alto, CA. [pdf]