Achieving Believable Conversation in Games Why It’s Important and a Presentation of Current...

Achieving Believable Achieving Believable Conversation in Games Conversation in Games

Why It’s Important and a Why It’s Important and a Presentation of Current ResearchPresentation of Current Research

USC School of Cinema-Television / USC Game USC School of Cinema-Television / USC Game Innovation LabInnovation Lab

Chris Swain, Co-Director – [email protected] Swain, Co-Director – [email protected]

Jesse Vigil, Researcher – [email protected] Vigil, Researcher – [email protected]

Jessica Rosenblatt, Researcher – [email protected] Rosenblatt, Researcher – [email protected]

OverviewOverview The Challenge (~12 minutes)The Challenge (~12 minutes)

– Creating believable conversation in Creating believable conversation in games – the good, the bad, and the uglygames – the good, the bad, and the ugly

Case Study: The Augmented Case Study: The Augmented Conversation Engine - ACE (~32 Conversation Engine - ACE (~32 minutes)minutes)– Demonstration of ACE in actionDemonstration of ACE in action– Details of ACE System DesignDetails of ACE System Design– Details of ACE Character DesignDetails of ACE Character Design

The Future (~1 minute)The Future (~1 minute) Q&A (~15 minutes)Q&A (~15 minutes)

Achieving Believable Achieving Believable ConversationConversation

The ChallengeThe Challenge– Create a Create a systemsystem that generates robust, realistic that generates robust, realistic

human conversationhuman conversation

The ReasonThe Reason– Conversation is a core human quality and core Conversation is a core human quality and core

aspect of traditional dramatic media (theater, film, aspect of traditional dramatic media (theater, film, TV)TV)

– Without characters that can converse interactive Without characters that can converse interactive media is very limited – e.g. hard to make an media is very limited – e.g. hard to make an emotional connection with a character who can’t emotional connection with a character who can’t talktalk

Conversation Systems Prior Conversation Systems Prior ArtArt

Generally two schools of thought…Generally two schools of thought…1.1. Parser / AI-based systemsParser / AI-based systems

Chatterbots (Eliza, Julia, etc.)Chatterbots (Eliza, Julia, etc.) Starship TitanicStarship Titanic FaçadeFaçade

2.2. Branching Narrative-based systemsBranching Narrative-based systems RPGs like Final Fantasy, Knights of the Old RPGs like Final Fantasy, Knights of the Old

Republic, and Jade EmpireRepublic, and Jade Empire You Don’t Know JackYou Don’t Know Jack

Parser / AI-based Parser / AI-based ConversationConversation

Gives player unlimited choice in Gives player unlimited choice in what to say – player can type in what to say – player can type in anythinganything

Parser / AI system generates text Parser / AI system generates text response using rules-based systemresponse using rules-based system

– Rules based on “rules” of English Rules based on “rules” of English languagelanguage

ELIZA ExampleELIZA Example Player: I feel blue.Player: I feel blue. ELIZA: Do you often feel blue?ELIZA: Do you often feel blue? Player: Yes. My work is stressful.Player: Yes. My work is stressful. ELIZA: Tell me more…ELIZA: Tell me more… Player: I guess I’m a perfectionist.Player: I guess I’m a perfectionist. ELIZA: Do you believe it’s normal to be ELIZA: Do you believe it’s normal to be

a perfectionist?a perfectionist? Player: No, I wish I could be free of it.Player: No, I wish I could be free of it. ELIZA: Why do you want to be free of ELIZA: Why do you want to be free of

it?it?

ELIZA Example 2…ELIZA Example 2… Player: I am doing fine thank you.Player: I am doing fine thank you. ELIZA: Do you think it is normal to be ELIZA: Do you think it is normal to be

doing fine thank me?doing fine thank me? Player: Huh?Player: Huh? ELIZA: Ok, “I are doing fine thank ELIZA: Ok, “I are doing fine thank

you.” Tell me more.you.” Tell me more. Player: I’m outta here.Player: I’m outta here.

Parser / AI-based Parser / AI-based ConversationConversation

ProsPros– Big Possibility Space – feels believable to be Big Possibility Space – feels believable to be

able to say anything you wantable to say anything you want ConsCons

– Generally not believable experience because of Generally not believable experience because of language tie-upslanguage tie-ups

– Verbal choices generally do not affect game Verbal choices generally do not affect game state in a meaningful/discernible way (ie move state in a meaningful/discernible way (ie move towards or away from objective)towards or away from objective)

Branching Narrative-based Branching Narrative-based ConversationConversation

Give player very limited choice of Give player very limited choice of what to say (e.g. choose from a list what to say (e.g. choose from a list of 2-4 options)of 2-4 options)

Each choice comes with a set of Each choice comes with a set of contextually relevant, custom-written contextually relevant, custom-written responsesresponses

Branching Narrative-based Branching Narrative-based ConversationConversation

ProsPros– Always responds with believable dialog Always responds with believable dialog

snippet because all system responses are snippet because all system responses are controlled by writercontrolled by writer

ConsCons– Stiflingly small possibility space. Stiflingly small possibility space.

Conversation experience overall is not Conversation experience overall is not believable because player is on railsbelievable because player is on rails

– Verbal choices generally do not affect Verbal choices generally do not affect game state in a meaningful/discernible game state in a meaningful/discernible way (ie move towards or away from way (ie move towards or away from objective)objective)

Ideal Conversation SystemIdeal Conversation System

1.1. Very broad set of verbal choices Very broad set of verbal choices (feels unlimited)(feels unlimited)

2.2. Verbal choices come with Verbal choices come with contextually relevant responses contextually relevant responses (avoids parser problems)(avoids parser problems)

3.3. Verbal choices are meaningful – Verbal choices are meaningful – move toward or away from objectivemove toward or away from objective

[Demo ELECT and the Augmented [Demo ELECT and the Augmented Conversation Engine here]Conversation Engine here]

At a basic software level, most game characters are the equivalent of hitting a tennis ball against your garage door.

The goal is to make characters converse like people. There are a lot of factors that determine how a person responds to a given stimulus. The job of the A.C.E. is to model that accurately.

A garage door does not play like a human.

And easily. That’s the catch..

Structural DifferencesStructural Differences

• Trees built out of response sets like this advance the story but in a very mechanical way.

• How can we improve on this?

• Approach the problem as a writer or a dramatist would

• What circumstances would give a different result?

• What actions over time might affect this result?

A.C.E conversation flowA.C.E conversation flow

Factors That Influence Factors That Influence Response IResponse I

For the ELECT project, USC collaborated with ICT, beginning by using the concepts of a state machine as framework. To improve on state machine framework and make the process of writing characters easy in order to improve authorability, every dialogue response needed a common but robust structure.

Roll Roll lowlow

Roll Roll low-low-medmed

Roll Roll med-med-highhigh

Roll Roll highhigh

Trust Trust lowlow 11 22 33 44Trust Trust mediumediumm

55 66 77 88

Trust Trust highhigh 99 1010 1111 1212

What do you mean “Roll?”What do you mean “Roll?” For ELECT, a die roll is For ELECT, a die roll is

used to calculate the used to calculate the effectiveness of the effectiveness of the action or dialogue action or dialogue response a player response a player makes.makes.– This is not a random roll. This is not a random roll.

Every action has a large Every action has a large list of potential modifiers list of potential modifiers based on whether or not based on whether or not skills or knowledge skills or knowledge related to the action have related to the action have been learned.been learned. The modified roll adds The modified roll adds

texture, varying which texture, varying which response might be response might be received by one or two received by one or two subtle gradessubtle grades

ModifiersModifiers

Modifiers ensure inaccurate results Modifiers ensure inaccurate results do not occur through luck.do not occur through luck.

The roll is not enough to determine The roll is not enough to determine the response. After determining how the response. After determining how well the action was performed, the well the action was performed, the result is checked against the AI’s result is checked against the AI’s current mood to determine the current mood to determine the response.response.

EXAMPLE: greeting in a foreign languageEXAMPLE: greeting in a foreign language

CATEGORY: RESPECTACTION: Ask about the plant

Low rollLow roll Low-medLow-med Med-highMed-high High rollHigh roll

Low TrustLow Trust Why would I Why would I share the share the secrets of my secrets of my village with an village with an outsider? Get outsider? Get stuffed, why stuffed, why don’t you?don’t you?

What makes What makes you think it’s you think it’s anything but a anything but a plant?plant?

I wish I could I wish I could trust you trust you enough to tell enough to tell you the full you the full story.story.

How do you How do you know about know about that plant? It is that plant? It is a carefully a carefully guarded secret!guarded secret!

Med TrustMed Trust It’s not really It’s not really for outsiders to for outsiders to ask such things.ask such things.

You’ve heard You’ve heard stories of a stories of a curse, then?curse, then?

Bah. Nothing Bah. Nothing but old wives’ but old wives’ tales about a tales about a curse.curse.

I’m impressed I’m impressed with your with your manners, but manners, but don’t think I don’t think I don’t know don’t know what you’re up what you’re up to.to.

High TrustHigh Trust Something Something about how you about how you ask makes me ask makes me suspicious, but suspicious, but I’ve known you I’ve known you to be honest in to be honest in the past so I’ll the past so I’ll tell you.tell you.

My friend, My friend, you’re talking you’re talking about things about things you know you know nothing about.nothing about.

It’s a curse, It’s a curse, plain enough. plain enough. That’s what the That’s what the rumor is at any rumor is at any rate. Keep it to rate. Keep it to yourself.yourself.

You deserve to You deserve to know. Long ago, know. Long ago, a gypsy cursed a gypsy cursed it. Keep the it. Keep the secret safe, and secret safe, and I’ll be grateful.I’ll be grateful.

Factors that Influence Factors that Influence Response IIResponse II

MemoryMemory ContextContext PersonalityPersonality

All of these create situations that commonly occur in real All of these create situations that commonly occur in real conversation that the die roll and dialogue matrix cannot by conversation that the die roll and dialogue matrix cannot by themselves produce believable results for. So additional themselves produce believable results for. So additional layers are needed, like a sieve.layers are needed, like a sieve.

Player Input

Dialogue Matrix

Augmented Conversation CHALLENGE Context-Sensitive

APPROPRIATE?

Memory and FlagsMemory and Flags How do you solve the problem How do you solve the problem

of needing a character to, of needing a character to, through conversation, through conversation, make a make a judgment about the player?judgment about the player?

Every action, every triggered Every action, every triggered special event, and every special event, and every response to a challenge is response to a challenge is assigned a flag, or at least a assigned a flag, or at least a category of flags.category of flags.– This simulates memoryThis simulates memory

The A.C.E. also contains a list The A.C.E. also contains a list of “if-then” special conditions of “if-then” special conditions that are triggered whenever that are triggered whenever combinations of these flags combinations of these flags are true.are true.– This helps model a character’s This helps model a character’s

personality. personality. EX: what combinations would EX: what combinations would

provoke a response in this provoke a response in this SPECIFIC character?SPECIFIC character?

Did Did something something nice.nice.

Flattery.Flattery. Did Did something something rude.rude.

Did not Did not apologize apologize when when confronted.confronted.

Asked an Asked an inappropriainappropriate te question.question.

Took safe Took safe road in a road in a challenge.challenge.

Made a Made a threat.threat.

CapitulateCapitulated when d when challengedchallenged..

Flattery.Flattery.

ChallengesChallenges

Why is it more rewarding to play tennis Why is it more rewarding to play tennis with a person than the garage door?with a person than the garage door?– The person hits the ball back in ways that are The person hits the ball back in ways that are

not as easy to predict with accuracy.not as easy to predict with accuracy. Game characters tend to give answers to Game characters tend to give answers to

questions, but ask few themselves. Fewer questions, but ask few themselves. Fewer still still challengechallenge the player in a way that the player in a way that causes the player to think and make causes the player to think and make meaningful choices.meaningful choices.– EX: the rude hotel staff of EX: the rude hotel staff of Starship TitanicStarship Titanic

A.C.E. Challenge SystemA.C.E. Challenge System

The character becomes much more The character becomes much more believable in conversation if it believable in conversation if it routinely goes on the offensive and routinely goes on the offensive and pursues its own goals.pursues its own goals.– This is the A.C.E. Challenge systemThis is the A.C.E. Challenge system

Challenges can be triggered by changing Challenges can be triggered by changing phases of the conversation, or through phases of the conversation, or through specific player actions.specific player actions.

Combinations and the flag memory system Combinations and the flag memory system ensure that the challenges seem to flow ensure that the challenges seem to flow naturally out of whatever the current topic of naturally out of whatever the current topic of conversation isconversation is

Context-Sensitive PromptsContext-Sensitive Prompts

Game characters lose credibility when they Game characters lose credibility when they ignore circumstances that seem obvious to ignore circumstances that seem obvious to the player.the player.– EX: KOTR II’s “nice” characters that ignore an EX: KOTR II’s “nice” characters that ignore an

insultinsult Solution for ELECT: give the system the Solution for ELECT: give the system the

ability to trigger periods of context-ability to trigger periods of context-sensitivity that allow for alternate dialogue, sensitivity that allow for alternate dialogue, modifiers, or responses.modifiers, or responses.– Example: insulting an ELECT character and the Example: insulting an ELECT character and the

next three turns of playnext three turns of play

Augmented DialogueAugmented Dialogue

A game character can be more believable A game character can be more believable when they can prove to the player they’ve when they can prove to the player they’ve been paying attention.been paying attention.– This works even better when they show they’ve This works even better when they show they’ve

formed an opinion of the player based on this.formed an opinion of the player based on this. EX: noticing a trend in the player’s responsesEX: noticing a trend in the player’s responses EX: pointing out a contradictionEX: pointing out a contradiction

Dialogue that results from these trends Dialogue that results from these trends removes some of the mechanical feel and removes some of the mechanical feel and makes a conversation seem free-flowing and makes a conversation seem free-flowing and natural.natural.– The player cannot predict when the game The player cannot predict when the game

character will interrupt or go on a tangent based character will interrupt or go on a tangent based on what was said.on what was said.

Simplicity of Design/Powerful Simplicity of Design/Powerful ToolsTools

The A.C.E. is designed to be easy to The A.C.E. is designed to be easy to understand and use from a top-level understand and use from a top-level perspective.perspective.– Creating believable characters should, like in Creating believable characters should, like in

literature and drama, be rooted in writing, not literature and drama, be rooted in writing, not coding.coding.

Elegant system design with solid structure and Elegant system design with solid structure and common multi-use tools to make it accessible common multi-use tools to make it accessible and authorable.and authorable.– ELECT’s 11 characters and 20+ conversations were ELECT’s 11 characters and 20+ conversations were

written by 7 writers. Only two had ever programmed written by 7 writers. Only two had ever programmed anything before.anything before.

Crafting a Conversation Crafting a Conversation SpaceSpace

Who is this character? What is his or Who is this character? What is his or her backstory?her backstory?

In what situation will the player In what situation will the player encounter this character?encounter this character?

Routine:Routine: On a regular work day On a regular work day Surprise:Surprise: Just received invitation to Just received invitation to

friend's weddingfriend's wedding Celebration:Celebration: At a birthday party At a birthday party Mourning:Mourning: At a funeral At a funeral Anger:Anger: Bumped off a flight Bumped off a flight Personal significance:Personal significance: Childhood Childhood

school bulldozedschool bulldozed


Abe is a younger man in his mid Abe is a younger man in his mid thirties with an imposing physique, thirties with an imposing physique, something he frequently uses for the something he frequently uses for the purposes of physical intimidation.purposes of physical intimidation.

He is reluctant to change his behavior He is reluctant to change his behavior because he sees himself on high because he sees himself on high moral ground. More than anything, moral ground. More than anything, Abe wants a return to normal for his Abe wants a return to normal for his business.business.

He is well versed in town politics and He is well versed in town politics and feels strongly that the town was feels strongly that the town was better off under the previous mayor.better off under the previous mayor.

Crafting a Conversation Crafting a Conversation SpaceSpace Nancy is at the end of her rope. The Nancy is at the end of her rope. The

collapse of the bridge delayed a lot of collapse of the bridge delayed a lot of the supplies she needs to keep the the supplies she needs to keep the medical clinic running smoothly. medical clinic running smoothly. Many of her doctors are quitting Many of her doctors are quitting because of the risks involved with because of the risks involved with working in the town.working in the town.

Nancy is convinced she's being Nancy is convinced she's being ignored by town officials because ignored by town officials because she's a woman. Even though she she's a woman. Even though she hates doing it, she has now resorted hates doing it, she has now resorted to making threats just to get the to making threats just to get the clinic's needs noticed.clinic's needs noticed.


What will the player want from this What will the player want from this character?character?

What will the character want from the What will the character want from the player?player?

InformationInformationProtectionProtectionResourcesResourcesChange in behaviorChange in behaviorSympathy or friendshipSympathy or friendship


How do we as designers want to allow How do we as designers want to allow the player to interact with the the player to interact with the character?character?

Helpful: Befriend or aidHelpful: Befriend or aid

Harmful: Hurt or insultHarmful: Hurt or insult

Neutral: Discuss or bargainNeutral: Discuss or bargain


What do we want the player to learn What do we want the player to learn from interacting with this character?from interacting with this character?

Objective informationObjective informationPersonal character informationPersonal character informationGame world informationGame world informationExpected behavior, procedures, Expected behavior, procedures, customscustoms

What actions will the player need to What actions will the player need to have available in order to provoke all have available in order to provoke all of the possible character responses of the possible character responses we want?we want?

Weighting Actions with Weighting Actions with VariablesVariables

Evaluate each action available to the Evaluate each action available to the player with respect to player and player with respect to player and character variables tracked by our character variables tracked by our game:game:

PowerPowerAttitudeAttitudeExperienceExperience

Action:Action: Compliment character's status Compliment character's status Roll improved by character's powerRoll improved by character's power Roll improved by character's attitude Roll improved by character's attitude

towards the playertowards the player Roll harmed by character's amount of world Roll harmed by character's amount of world

experienceexperience


Evaluate each action with respect to Evaluate each action with respect to ACE tags:ACE tags:

Event referenceEvent referenceFlatteryFlattery InsultInsult

Action: Compliment character's statusAction: Compliment character's status Did the character recently gain or lose Did the character recently gain or lose

status?status? Has the player complimented the Has the player complimented the

character repeatedly?character repeatedly? Does this character find such Does this character find such

compliments acceptable?compliments acceptable?


Anticipate long-term repercussionsAnticipate long-term repercussions If the player pleases or displeases If the player pleases or displeases this character, what are the this character, what are the consequences with respect to:consequences with respect to:

The player's objectiveThe player's objectiveThis characterThis characterThis character's friendsThis character's friendsThis character's enemiesThis character's enemiesThe game worldThe game world

The FutureThe Future

Would like to see ACE used and Would like to see ACE used and improved on in other ICT projectsimproved on in other ICT projects

Would like to see ACE used in Would like to see ACE used in commercial RPG projectscommercial RPG projects

Questions?Questions?

Achieving Believable Conversation in Games Why It’s Important and a Presentation of Current...

Documents

Transcript of Achieving Believable Conversation in Games Why It’s Important and a Presentation of Current...