Semi-Autonomous Avatars in World of Minds A Case Study of AI-based - - PowerPoint PPT Presentation

Semi-Autonomous Avatars in World of Minds

A Case Study of AI-based Game Design

ACE 2008 ACE 2008

Yokohama, Japan Thursday, Dec 4, D1, 9.00

Mirjam Palosaari Eladhari Gotland University, Sweden Michael Mateas University of California, Santa Cruz, USA

Introduction

Round Characters

Characters in MMOs

• Majority of characters in MMORPGs are player

characters/avatars.

• Most character interaction take place between

avatars. avatars.

• NPC’s in MMORPGs mainly give quests, sell

items or give information about the world.

Round and Flat

• A flat character consist of only a

few traits and usually have a single, static aim, transparent to the audience.

• A round character is complex and

capable of contradiction, surprise and change. Round characters have a multitude of contradictory traits.

(Forster, Aspects of the Novel, 1927)

Chatman on Round Characters

“Round characters […] possess a variety of traits, some of them conflicting or even contradictory [...] We remember them as real

• people. They seem strangely familiar. Like

real-life friends and enemies it is hard to real-life friends and enemies it is hard to describe what they are exactly like. “

(Chatman,Story and Discourse, 1978)

In MMORPGs, the player characters ARE real

Round and Flat

• A flat character consist of only a

few traits and usually have a single, static aim, transparent to the audience.

NPCs

• A round character is complex and

capable of contradiction, surprise and change. Round characters have a multitude of contradictory traits.

(Forster, Aspects of the Novel, 1927)

Avatars

Where MMO’s fail

Despite the focus on player-to-player interaction, current MMORPG designs fail to provide explicit designs fail to provide explicit support for helping players to roleplay and fail to incorporate such social interaction and roleplay into the game mechanics themselves.

Our goal

• To develop an AI-based game mechanic that

brings round characters into MMORPGs to support the player in roleplaying through their avatar. avatar.

• Find ways to utilize the richness of the present

human intelligence in virtual game worlds and via, the right triggers, enrich the game experience in terms of characterdriven drama woven into the virtual world through its rulesystem.

Outline and summary

One of the most exciting possibilities in game AI research is for AI to

• pen up new game design possibilities. New AI will suggest new

design possibilities while design will push back on AI requirements. This paper provides:

• A concrete case study of AI-centric game design, specifically

describing how AI can be powerfully and effectively used in an describing how AI can be powerfully and effectively used in an MMORPG design.

• The Mind Module, a technical framework for modeling personality

and emotion for both player and non-player characters.

• The World of Minds (WoM), an MMORPG that employs an AI-based

game mechanic designed around the MM.

• Lessons learned from a paper prototype playtest of the mechanic.

Mind Module

• verview

Mind Module (MM) Overview

• a semi-autonomous agent architecture
• built to be used in a multiplayer environment as a part of the

player's avatar.

• The MM models the avatar's personality as a collection of traits

inspired by the FFM inspired by the FFM

• maintains dynamic emotion state as a function of interactions with
• bjects in the environment and trait values, and summarizes the

avatar's current emotional state as an inner and outer mood

• Spreading Activation Network (SAN)

Deconstruction and reconstruction

• In psychlogy and neuropsychology the

complexity of the human mind is made more comprehensible by deconstruction into subsystems. subsystems.

• As builders of virtual humans we need to

reconstruct agents that can function in way that is believable and useful to the users in the contexts and systems we devise.

Node types

Weighted network of interconnected nodes

Two-dimensional affect plane

• Emotions: brief and focused (ie. directed at an intentional object)

disposition

• Sentiments: permanent and focused disposition
• Mood: brief and global disposition
• Personality: permanent and global disposition

Personality

• Plethora of personality theories;

psychoanalytic, behaviorist, cognitive and biophysiological theories.

• Trait theory pioneered by Allport (1930ies)
• Trait theory pioneered by Allport (1930ies)

where the most prominent personality assessment is called the Five Factor Model.

• (also used by Guoliang, Klesen, Khirsagar, El

Jed, etc)

Five Factor Model

NEO PI-R (also called OCEAN)

• !

Emotions in MM

Emotion Weight to Inner Mood Weight to Outer Mood

Amusement +2 Interest Excitement +1.5 Enjoyment/Joy +2 +2 Relief +1.5 +1.5 Satisfaction +2

13 ”basic emotions”, common to

Satisfaction +2 Surprise +1.5 Confusion

• 1.5

Distress/Anguish

• 2
• 1.5

Fear/Terror

• 2

Anger

• 2

Shame/Humiliation

• 1.5

Sadness

• 2

Guilt

• 1.5

common to primates, as described by Ekman, Tomkins, Nathansson

• 13
• 13

Mood

In everyday sense: An overall state or quality of feeling at a particular time Changes slower than emotions Temporary Temporary Highly contextual Lingers even if the context changes Becomes part of the next context Individual – ”same” type of event result in differents moods for different people.

"

extroverted side of the mood, how the character emotionally is relating to the game world and to

• ther characters.

private, inner mood

Inner and Outer Mood

• The inner mood is the private sense of harmony that can

be present even if the character is in an environment where events lead to a parallel mood of annoyance.

• The nature of the outer mood is social, and as such tied to

emotions that are typically not only directed towards emotions that are typically not only directed towards another entity but also often expressed toward an entity, such as anger or amusement.

• The two scales for the mood nodes open up the possibility
• f more complex states of mind than a single binary axis of

moods that cancel each other out.

"

Sentiments – Emotional attachements

• MM allows several sentiments ie, of different

emotions, to be attached toward an other entity, thus creating a compound set of sentiment.

• emergent sentiments origin from interactions

with other entities in the world, thus creating with other entities in the world, thus creating emotional memories.

• authored sentiment sets have certain pre-set
• combinations. For example ``infatuation" is a

combination of interest/excitement/amusement and joy toward another character.

Player might realize it is a good idea to RUN! RUN!

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• &

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Node types

Weighted network of interconnected nodes

MM Summary

• The MM thus provides the player with

information about the avatars feelings toward

• ther entities in the world.
• Proximity to objects or characters affect the
• Proximity to objects or characters affect the

emotions, and thus the mood of an avatar, functioning as information the player can use to form an agenda for game play.

World of Minds Game Play Game Play

World of Minds Summary

• Prototype mutiplayer game world where the

personalities of the inhabitants are the base for the game mechanics.

• When interacting with other characters, the
• When interacting with other characters, the

action potential depend upon the player character's current mood and personality

Basic Game Play of WoM

Players need to defeat physical manifestations of negative mental states by using

• Spells
• Affective actions
• Affective actions

The spells available to the character depends on personality The affective actions available to the character depends on the current mood.

Spells and mind energy

• Spells cost Mind Energy to use (”mana”)
• Attacks reduce Mind Resistanse (”health”)
• The amount of Mind Energy is tied to Outer
• The amount of Mind Energy is tied to Outer

Mood

• The amount of Mind Resistanse is tied to Inner

Mood

Fluctuations of Energy and Resistanse

Affective actions and Mood

• players can affect each other's moods by using

affective actions (AAs).

• AAs are actively chosen by the players
• the AA ``Comfort" can be used

successfully on targets that have an active emotion node of Sadness, but only if the player's own avatar is not in the area of Furious on the mood matrix.

• If the AA Comfort is used successfully the

values of the emotion nodes Sadness and Anguish of the target are diminished, which in turn affects the mood of the character.

Mood manipulation

• Current mood affects:

– Regeneration of Energy and Mana – The range of availiable current actions Thus, by affecting the mood of a another character the action potential of that character is changed.

Mood, Spells and Resistanse

How a sentiment and/or a manifestaion is born in WoM

Playtest

Playtest Research Questions

The playtest was designed to elicit design feedback from players on three different questions: 1) During gameplay, are players able to "reverse engineer" the MM to build a mental model of how to manipulate emotional state to achieve gameplay goals?

(For any successful game design, players must be able to build a model of the (For any successful game design, players must be able to build a model of the mechanics that allow them to successfully interact with the game.)

2) Understand the player's theory of how traits relate to MM state and gameplay in order to gather new design ideas for how traits might influence emotional state and gameplay. 3) How do the players perceive the relationship between the emotional state maintained by the MM and the game mechanics and interaction options that depend on that state?

Approach

Evaluation of the game design via a paper prototype During the play tests, the test leader walks individual players through a paper simulation of several scenarios. scenarios. Players are asked to think aloud while playing the game; additionally, the test leader stops the game at several points and conducts interviews.

(User-Centered Design, where the user's experience is a main driver for design, Rapid prototype and playtesting)

• Ten players individually went through five

game mastered scenarios where her avatar had a mind, represented by the character sheet. sheet.

For each playtest, the participant:

• Filled in a short (less than ten questions) survey on demographic

data and previous gaming experience.

• Took the IPIP-NEO Personality test and emailed the results to the

test leader.

• Filled in a short survey about their experience taking the

personality test and their opinions about the use of personality

• Filled in a short survey about their experience taking the

personality test and their opinions about the use of personality traits for avatar creation.

• Participated in the playtest, which took between 1 and 1.5 hours.

Each playtest session consisted of playing five scenarios, and answering questions in two interviews, one in the middle, and one at the end of the playtest. Each session was videotaped.

• Filled in two more short surveys, one focused on sentiment objects,

and the other on general impressions of the experience.

Playtest

• During the five scenarios, the player was guided through using the main categories of actions in the

game including :

– affective actions – navigation in a landscape of sentiment objects – mind magic spells.

• Using the character sheet the test leader updated the state of mind of the avatar and NPCs,

showing the player the effect of her actions in the game in terms of fluctuations in emotions, mood, mind energy and mind resistance.

• In order to best capture player's problem-solving processes within the game, and to best

understand potential areas for confusion, the players were given minimal explanations about how and what to do.

• At any point, players could access a ``help system" in order to ask any question.
• The twenty-two interview questions focused on the player's understanding of the relationship

between values in the MM, effects of game actions, relationship between personality and availability of actions such as spells, etc

Data analysis

• We used the video analysis tool Transana to

analyze the 15 hours of video of interviews and play sessions.

• We developed a coding scheme for potentially

relevant phenomena and states of mind; this provided us with the initial framework for searching for patterns and regularities, as advocated by Miles and Huberman

Scenario 1 - Sentiments

The avatar meets the character "Gate Keeper" (GK).

• Via a prewritten dialog script GK gives

information about the world the player has just arrived to.

• The GK searches his bucket to give the player two
• The GK searches his bucket to give the player two

random sentiment objects.

(The player represented by the avatar Mastaya got sentiments of anger toward mittens and amusement toward socks.)

• The GK asks the player to picture an unnerving

scenario where she can choose which of three different objects would be most scary.

(Mastaya picked garden gnomes and got a fear sentiment towards them.)

Scenario 2 - Affective Actions

The avatar meets the character Teresa.

• Teresa says she is too sad to explain what affective actions (AAs)

are, and asks the avatar for a hug.

• A selection of affective actions is presented to the player.
• Teresa and the avatar exchange affective actions until threshold

values for emotions result in the generation of sentiment objects between the characters.

(Mastaya chose to comfort Teresa instead of hugging her. Teresa's distress and sadness decreased, and her mood improved. After a few exchanges of AAs, a threshold value for Mataya's emotion Interest/Excitement was reached and the system generated a sentiment for Mastaya of this emotion toward Teresa.)

Seven of the players chose to ``hug'' Teresa, while three of them started the chain of AA's in the scenario with using ``Comfort". with using ``Comfort". The AA ``comfort" would diminish the emotions of sadness and anguish in the targeted character.

• More AA:s were

revealed as the scenario continued

• Players were asked for

AA:s they would like in such a scenario

• The first meeting with

Teresa resulted in sentiment objects between her and the player’s character. player’s character.

• Type of sentiment

depenent on the exchange of affective actions

Scenario 3 - Facing the Sentiments

• The player needs to guide the avatar through

an environment with sentiment objects in

• rder to successfully accomplish a quest.
• The state of mind of the avatar changes

according to which sentiments are encountered in proximity of the avatar.

(Mastaya navigated the board successfully and spent some time on the sock in order to gain amusement before moving on.)

Scenario 4 - Using Spells (and Affective Actions)

The player finds Teresa in a state of distress as she is attacked by a manifestation of Confusion.

• The player finds a spell, Laser Pen of Clarity, which reduces

confusion and mental resistance in the target.

• The player is introduced to the concepts of mental energy
• The player is introduced to the concepts of mental energy

and resistance through seeing the mind values on Theresa, the Colossus of Confusion and the players' own avatar.

• When the Colossus of Confusion is defeated, a new foe

enters the scene, the Sail of Sorrow.

• When this is defeated, Teresa explains that when an

emotion goes out of bounds a manifestation of that emotion is created.

• The players has been doing another scenario and comes back to

Teresa.

• She needs help she is attacked by a manifestation of confusion.
• Here players act very in ways very different to each other for

manipulating the mood of themseleves and of Teresa

Casts spell: Trumpet irrelevant questions and

• bscure answers

(++ Confusion) Voulnerable to spell: Voulnerable to spell: Laser Pen of Clarity (-- Confusion)

In some of plays of this scenario Teresa, who’s personality makes her prone to depression, got so sad that a manifestation of sorrow spawned

Casts spell: Wet Net of Tears (++ Sadness) Voulnerable to spell: Accommodate sorrow (-- Sadness)

Scenario 5 - Trait based spells

The Gate Keeper gives the avatar two spells that he claims are based on the personality of the avatar. Example:

• Mastaya earns the spell "Interest/Excitement Shower",

based on the fact that her highest factor except based on the fact that her highest factor except Neuroticism is Openness.

• She also learns the "Soothing Hand", which lowers fear in

the target, based on the fact that the highest value of the traits in the neuroticism factor is Anxiety.

• The Gate Keeper tells her that she will be particularly good

at defeating manifestations of fear, the Terror Trolls.

Lessons from Playtest

Effects of Personality

• All players built correct mental models of

at least one of the effects of personality

• n the MM and the game mechanics.
• All players demonstrated enough

Examples:

• Two players thought

that personality affected the amount of mind energy and mind resistance.

• Three players thought

that the effect of AAs

• n themselves and
• thers depended on
• All players demonstrated enough

understanding of the system to be able to act in the world in such a way as to reach an emotional state they found desirable.

• thers depended on

personality.

• One player thought

there were personality- specific effects on mood values, hypothesizing a mapping between traits, emotions and mood.

Effects of Personality Factors

• Strong trend towards building models about
• extraversion. Eight of the ten players theorized

about the factor.

Kita: "So, like, if you are an extrovert you might get interested and excited more easily, but you also might get Eric the Red: "Depending on how extroverted

• Agreeableness discussed by six players
• Conscientiousness discussed only by one

more easily, but you also might get distressed or anguished more easily, so each one kind of ... you know ... had an effect on your emotions." "Depending on how extroverted you are, sadness and guilt would probably move more or less as you are affected by them." Dante: "If you are not conscientious at all [...], other people pick up on that, how [...] are they going to ask you to do anything for them?"

Extraversion and the design risks of FFM

• Exraversion is a commonly described personality factor.
• The GOOD thing with it is that players have an existing

mental model of it. The BAD thing is that it is often a normative model.

• Players expressed worries about how their avatars would

perform in social situations if their level of extraversion is low.

Ancient Greek philosophy, Jung’s typology, etc. Also the factor most commonly studied in tests of applications for synthetic humans and conversational agents

The design goal of WoM is for personality traits to be non normative: we want a game design in which each possible combination of personality traits allows a player to success fully progress in the game. Current design of the Mind DO weight connections between trait and emotion nodes such that it may be more difficult for an introverted avatar to perform certain social

• actions. However, this is balanced by having some mind magic spells only be available

when the avatar is in specific mood ranges.

Personality-based Spells

In the final scenario, each player was given two spells by the Gate Keeper, based on their personality traits. 7 players were very positive to this while 3 players were hesitant. These 3 are all avid

Solemni: "Getting spells from personality

These 3 are all avid players of single player role playing games, where a character’s ability is based on it’s class.

"Getting spells from personality is a different method of choosing how your avatar interacts with the world - like a class. Not having direct control over your class may be a difficult pill to swallow."

Trait system / class system

Since personality-based capabilities (such as mind magic spells) are not organized under classes, but instead rely on relationships between the different traits, the combination space of the possible actions for an individual avatar is larger than in a traditional class-based RPG. class-based RPG. Experienced players of class-based RPGs may need extra support to become comfortable with this system – a clarification of what can be expected can be necessary in future playtest, despite our principle of minimal information.

Emergent Game Play

• The scenarios in the prototype are

purposefully tightly scripted, since a primary purpose of the prototype is to explore the player's understanding of the MM in the context of WoM. context of WoM.

• Desprite this players leveraged the MM-based

game mechanics to discover alternative strategies for completing the scenarios that had not been foreseen by the designers.

Examples of emergent game play

In the fourth scenario, the players is asked to help Teresa battle the Colossus of Confusion (CoC). The

• nly other object in the environment is the Laser Pen of Clarity (LPC), which the player can pick up

to learn the spell of the same name. This spell reduces confusion and mental resistance. As designers, we had assumed that players would use this spell on the CoC to help Teresa.

• However, 70% of the players combined the use of AAs on Teresa with the use of their (only) spell on

the CoC. Players hoped to improve Teresa's emotional state through the AAs, and thus increase her effectiveness at battling the CoC. effectiveness at battling the CoC.

• 30% of the players used their LPC on Teresa, which decreases her confusion and again makes her

more efficient against the CoC.

• 20% percent of the players used AAs instead of the LPC on the CoC, damaging the CoC with a lesser

decrease in their mind energy than using the LPC.

• 20% ran off to the gate keeper and just so happened to learn another spell that they could go back

to the CoC to use.

• Encouraging for this case of AI based game

design:

• The fact that players discovered interesting,

alternative strategies even in very constrained alternative strategies even in very constrained and simple scenarios validates the potential for rich and emergent gameplay in MM-based game mechanics.

Ending summary,

we have described:

• The Mind Module, a semi-autonomous agent architecture.
• An experimental MMORPG, World of Minds, in which the game

mechanics build upon the Mind Module's model of personality and emotion.

• In a case study of AI-based game design, we have shared lessons

learned from a test of a paper prototype.

• The players were able to form and communicate mental models of
• The players were able to form and communicate mental models of

the mind module and game mechanics, validating the design and giv ing valuable feedback for the future development of the project.

• Despite the constrained scenarios presented to test players, they

discovered interesting, alternative strategies, indicating that the \mental physics" of the Mind Module may open up new game design possibilities

Thank You for listening!

Questions?

Mirjam.eladhari@hgo.se, michaelm@cs.ucsc.edu