Information 3OutlineInformation FlowCybernetic SystemsFeedback LoopsTwo Types of Feedback LoopsAudio exampleFeedback Loops in GamesExampleEffects?Example 2Slide 12Slide 13Multiple LoopsIn GeneralThe Other SenseGame Design IssuesActivityInformation 3Robin BurkeGAM 224Spring 2004OutlineCyberneticsFeedback loopsInformation FlowSystems have objects that interactInformation is a quantity that objects in a system may exchangeWeiner developed cybernetics to explain this type of systemCybernetics is an attempt to unify the study of engineered and natural systemsCybernetic SystemsCybernetics is about controlHow is the behavior of a system controlled?Control implies that there are parameters that should be maintainedExample: temperature•human body•car engineControl implies informationTemperature messages•"too high"•"too low"•"OK"Feedback LoopsBasic loopA cybernetic system needs a sensor that detects its stateThe information detected by the sensor is then compared against the desired valueIf the value is not correct, the system adjusts its statethe sensor detects this new state, etc.The system maintains stability by feeding the information about its state back to the process producing the stateTwo Types of Feedback LoopsNegative Feedback Loop"inhibition"As the state changes, the loop acts to move it in the direction of its previous stateExample•thermostatPositive Feedback Loop"excitation"As the state changes, the loop acts to move it in the direction that it is movingExample•automobile turbocharger•home team advantageAudio exampleFeedback Loops in GamesFrom bookgame statescoring functioncontrollergame mechanical biasExamplegame statestate of a fighting gamescoring functionplayer's healthcontrollernear-KObiasincrease chance of critical (high damage) hit on opponentEffects?Example 2game statestate of the chessboardscoring functionthe number of pieces takencontrollerfor each piece takenbiasadd a pawn to the taker's side in any positionEffects?ExampleMultiple LoopsGames may have multiple feedback loops in operationExamplesracing game•a player who falls behind may be better power-ups•AI racers may adjust their ability to keep pace with playerRPG•killing monsters gives experience points for gaining levels•as a player gains levels, they gain better weapons and greater abilities•more success at killing monsters, etc.•but•game is designed so advanced areas have tougher monsters•levels get farther and farther apartIn GeneralNegative feedback loopsincreases system stabilitymakes the game last longermagnifies late successesPositive feedback loopsdestabilizes the systemmakes the game shortermagnifies early successThe Other SenseWe also use the word "feedback" to meanpraise vs criticism"I got some negative feedback on the proposal, so I'm revising it."This is not the samepsychological sense of feedback•information about the quality of something•good or badcybernetic sense of feedback•a dynamic established by a system's structure that pushes its state in one direction or another•in response to informationGame Design IssuesKnow what feedback is going on in your systemanalyze how game mechanisms combine to produce feedbackFeedback may be undesirablenegative feedback may make a successful player feel punishedpositive feedback may magnify ability differences between playersActivityCrazy Eights1. Destabilize2. RestabilizeMust actually be a loopnot a single event in the