Sensation&Perception

Chapter3

PartIIWilliamG.HuittLastrevised:May2005Sensation&Perception

Chapter1SensationandPerceptionSensationTheprocessthroughwhichthesensespickupvisual,auditory,andothersensorystimuliandtransmitthemtothebrain;sensoryinformationthathasregisteredinthebrainbuthasnotbeeninterpretedPerceptionTheprocessbywhichsensoryinformationisactivelyorganizedandinterpretedbythebrainSensationandPerceptionSensat2PerceptionGestaltprinciplesofperceptualorganizationFigure-groundOrganizationdependsonwhatweseeasfigure(object)andwhatweperceiveaground(context).SimilarityObjectsthathavesimilarcharacteristicsareperceivedasunit.ProximityObjectsclosetogetherinspaceortimeperceivedasbelongingtogether.ContinuityWetendtoperceivefiguresorobjectsasbelongingtogetheriftheyappeartoformacontinuouspattern.ClosureWeperceivefigureswithgapsinthemtobecomplete.PerceptionGestaltprincipleso3PerceptionYoucanseeawhitevaseasfigureagainstablackbackground,ortwoblackfacesinprofileonawhitebackgroundPerceptionYoucanseeawhite4PerceptionPerception5PerceptionPerceptualconstancyThetendencytoperceiveobjectsasmaintainingstableproperties(e.g.,size,shape,brightness,andcolor)despitedifferencesindistance,viewingangle,andlightingSizeconstancyPerceivingobjectsasbeingaboutthesamesizewhentheymovefartherawayShapeconstancyPerceivingobjectsashavingastableorunchangingshaperegardlessofchangesintheretinalimageresultingfromdifferencesinviewinganglePerceptionPerceptualconstancy6PerceptionPerception7PerceptionMonoculardepthcuesDepthcuesthatcanbeperceivedbyonlyoneeyeTypesofcuesInterpositionWhenoneobjectpartlyblocksyourviewofanother,youperceivethepartiallyblockedobjectasfartherawayLinearperspectiveParallellinesthatareknowntobethesamedistanceapartappeartogrowclosertogether,orconverge,astheyrecedeintothedistancePerceptionMonoculardepthcues8PerceptionMonoculardepthcuesTypesofcuesRelativesizeLargerobjectsareperceivedasbeingclosertotheviewer,andsmallerobjectsasbeingfartherawayTexturegradientNearobjectsappeartohavesharplydefinedtextures,whilesimilarobjectsappearprogressivelysmootherandfuzzierastheyrecedeintothedistanceAtmosphericperspectiveObjectsinthedistancehaveabluishtintandappearmoreblurredthanobjectscloseathandPerceptionMonoculardepthcues9PerceptionMonoculardepthcuesTypesofcuesMotionparallaxWhenyourideinamovingvehicleandlookoutthesidewindow,theobjectsyouseeoutsideappeartobemovingintheoppositedirectionObjectsseemtobemovingatdifferentspeeds–thoseclosesttoyouappeartobemovingfasterthanthoseinthedistanceObjectsveryfaraway,suchasthemoonandthesun,appeartomoveinthesamedirectionastheviewerPerceptionMonoculardepthcues10PerceptionJamesGibsonPointedoutthatourperceptionsofmotionappeartobebasedonfundamental,butfrequentlychanging,assumptionsaboutstabilityOurbrainssearchforsomestimulusintheenvironmenttoserveastheassumedreferencepointforstabilityWhenyou’redrivingacar,yousensethecartobeinmotionrelativetotheoutsideenvironmentPerceptionJamesGibson11PerceptionDepthperceptionTheabilitytoseeinthreedimensionsandtoestimatedistanceBinoculardepthcuesDepthcuesthatdependontwoeyesworkingtogetherConvergenceOccurswhentheeyesturninwardtofocusonnearbyobjects–theclosertheobject,thegreatertheconvergenceBinoculardisparity(orretinaldisparity)Differencebetweenthetworetinalimagesformedbytheeyes’slightlydifferentviewsoftheobjectsfocusedonPerceptionDepthperception12PerceptionAmbiguousfiguresCanbeseenindifferentwaystomakedifferentimagesBestknownambiguousfigureis“OldWoman/YoungWoman,”byE.G.BoringPerceptionAmbiguousfigures13Whatdoyousee?Nowwhatdoyousee?Copyright?Allyn&Bacon2005Whatdoyousee?Nowwhatdoyo14PerceptionImpossiblefiguresDonotseemunusualatfirstFiguresthatcannotbebuiltPerceptionImpossiblefigures15PerceptionPerception16PerceptionIllusionAfalseperceptionofactualstimuliinvolvingamisperceptionofsize,shape,ortherelationshipofoneelementtoanotherPerceptionIllusion17PerceptionMüller-LyerIllusionThetwolinesabovearethesamelength,butthediagonalsextendingoutwardfrombothendsofthelowerlinemakeitlooklongerthantheupperlinePerceptionMüller-LyerIllusion18InfluencesonPerceptionBottom-upprocessingInformationprocessinginwhichindividualcomponentsorbitsofdataarecombineduntilacompleteperceptionisformedTop-downprocessingApplicationofpreviousexperienceandconceptualknowledgetorecognizethewholeofaperceptionandthuseasilyidentifythesimplerelementsofthatwholeInfluencesonPerceptionBottom19InfluencesonPerceptionInfluencesonPerception20InfluencesonPerceptionInfluencesonPerception21InfluencesonPerceptionPerceptualsetAnexpectationofwhatwillbeperceived,whichcanaffectwhatactuallyisperceivedDavidRosenhanDavidRosenhanandsomeofhiscolleagueswereadmittedaspatientstovariousmentalhospitalswith“diagnoses”ofschizophreniaOnceinside,theyactednormalbutthestaffmembersonlysawwhattheyexpectedtoseeandnotwhatwasactuallyoccurringTherealpatientswerethefirsttorealizethatthepsychologistswerenotreallymentallyillInfluencesonPerceptionPercep22InfluencesonPerceptionInattentionalblindnessThephenomenoninwhichwemissanobjectinourfieldofvisionbecauseweareattendingtoanotherInfluencesonPerceptionInatte23InfluencesonPerceptionSimonsandhiscolleaguesShowedparticipantsavideotapeofabasketballgameinwhicho