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1、要点：要点：人眼视觉人眼非正常视觉人眼错觉人眼视觉特性人眼视觉感光细胞(photoreceptorcells)：杆状细胞(rod)：单色夜视 锥状细胞(cone)：彩色视觉 红(red)绿(green)蓝(blue)Primary Color 基色Lightenterstheretinaonthesidecontainingtheopticnervesandtravelsthroughallthelayerbeforereachingthereceptors.RetinaThisanimatedcartoonillustrateshowlight(whitedot)enterstheretin
2、aonthesidecontainingtheopticnervesandtravelsthroughalloftheretinallayersbeforefinallybeingabsorbedbythephotopigmentsintheoutersegmentsofthereceptors.Aneuralsignal(yellowdot)isgeneratedinthereceptorswhichthentravelsthroughtheneuronsofthevariousretinallayersandfinallytravelsoutthroughtheopticnerveupto
3、thelateralgeniculatenucleus.HowlightenterstheretinaandistransmittedouttheopticnerveHowlightenterstheretinaandistransmittedouttheopticnerveElectronMicrographofHumanVisualReceptorsElectronMicrographofHumanVisualReceptorsWhenlookingatanobjectthatisfarawaythelensiskindofskinny.Whathappenswhenlookingatan
4、earbyobject?RefractionRefractionWhenlookingatnearbyobjectsthelensgetsfatter,causingtheimageoftheobjecttobefocusedontotheretinainthefovea.Whatwouldhappenifthelensdidnotgetfatter?Bytheway,thetechnicaltermforthischangeinlensshapeisaccommodation.Wefrequentlycallitfocusing.Ifthelenscannotproperlyfocuslig
5、htontheretina,theimagewillfalleitherbehindorinfrontoftheretina.Canyouguesswhatwouldhappenifthelensistoofat?Ifyouguessedthatwhenthelensistoofatthatlightisfocussedinfrontoftheretina,youwereright.Istherearemedyforlensproblemsthatdonotallowlighttobeproperlyfocusedontheretina?Sure.Manypeoplewearcontactle
6、nsestohelpimagelightproperlyontotheretina.Anothersolutionisforapersontowearglasses.Thisplacesalensinfrontoftheeyenotonthecorneaasisthecasewithcontactlenses.Arecentsolutionistousealasertoreshapethecornea.thissolutionispossibleonlyinsomecases.Therearetwokindsofastigmatism:1.lenticularand2.corneal.Asti
7、gmatismoccurswhenthesurfaceofthecorneaorofthelensisnotperfectlysmooth.If,forexample,thereisasmallflatspotonyourcorneatheimageinacertaindirectiononyourretinawillnotbeinperfectfocus.Ifthefigureontherightwasconstructedwithalltheradiallinesofequalsharpnessandcontrastapersonwithoutastigmatismwouldseeallt
8、heseradiallinesasperfectlysharpandwiththesamecontrast.Thediagramontherighthasbeenfudgedtoillustratehowitmightappeartoapersonwithastigmatism.Thisconditioncanbecorrectedwithacornealcontactlensorcylinderlensinapairofspectacles.AstigmatismAstigmatismContactLensesContactLensesAverythinplasticlens,oftenfl
9、exible(softlenses)floatsonalayeroftearsonthecornealsurfaceoftheeye.Theselensescanbeofthepermanentvarietyordisposable.Thepermanentvarietyneedtobeproperlycleanedandcaredfor.ThedisposableareoftenworncontinuouslyandthethrownCornealContactLensCornealContactLensawaywhenremoved.Notehowthebottomedgeofthelen
10、sisagainstthelowereyelid.Ifthewearerlooksdown,thelensispushedupalittle.Thistrickcanbeusedtoprovidebifocalcontactlenses.Theselenseshavedifferentpowersinthecenterthanintheperiphery.Whenthewearerlooksdowntoreadthelensismovedtoanewpositiontofacilitateseeingsharplyatnormalreadingdistances.Ifthereisanirre
11、gularityonthecornea(astigmatism)itisautomaticallycorrectedbythecombinationofthetearlayerandthecontactlens.Acylinderlensisdifferentthanasphericallenswhichiswhatonenormallyseesinspectacles.Althoughacylindricalcomponentmybebuiltintothatwhichappearsspherical.Ascanbeseenintheleftdiagramacylinderlenshaspo
12、weronlyinoneaxis.Intheleftitisthehorizontalaxis.Thislensdoesnotrefractlightintheverticaldirection.CylinderlensCylinderlensSpectralSensitivityCurvesofSpectralSensitivityCurvesofRodsRods&C Co on ne es sWhenyoufirstenteranextremelybrightenvironment,forexample,whenemergingfromadarkmovieshouseintoaverybr
13、ightsunlitareathemancarvingtheduckwouldappearlikethis.Butinlessthanaminutehewillappearasseenbelow.Intheleftphotothecontrastisverylow.Belowthecontrastisnormal.Whenlightadaptedascenemightlooklikethis.DarkAdaptationDarkAdaptationForapproximatelythefirst10minutesinthedark,theconesrequirelesslighttoreach
14、athresholdresponsethandotherods.Thereafter,therodsrequirelesslight.Thepointatwhichtherodsbecomemoresensitiveiscalledtherod-conebreak.DarkAdaptationFunctionDarkAdaptationFunctionp.18The following demonstration isan example of how the worldappears to a person with asevere type of color blindness,deute
15、ranopia.See how you would do in a colorblind world人眼视觉Color vision defects causeColor vision defects cause problems in the real worldproblems in the real world Which meat is the most thoroughly cooked?Which meat is the most thoroughly cooked?Which flask contains a light pink solution?Which flask con
16、tains a light pink solution?Which of the following slides contains a pink cell?Which of the following slides contains a pink cell?Which picture contains a red crayon?Which picture contains a red crayon?The use of color so that color blind people(andeveryone else)can see what you are presenting.Red-g
17、reen color blindness is Red-green color blindness is common-aboutcommon-about4-5%of the population.In 4-5%of the population.In your presentations,your presentations,color should be used with color should be used with care to ensure thatcare to ensure thatyour color blind your color blind colleagues
18、can see.colleagues can see.In its most severe forms,colorblindness is caused by the absence ofone of the cone visual pigments.Shown here,the spectral sensitivitiesof the cone pigments in color normaltrichromats are compared with thoseof a color blind person.Also comparethe spectrum as it appears to
19、a colornormal person with the illustration ofhow it might look to a red-green color blind person.The difficulties with certain colors can be illustrated on acolor wheel.For a severely red-green color blind person thereare only two hues,the ones a color normal person sees as yellow and blue.Intermedi
20、ate colors,the ones seen as blueish-green and magenta,appear gray.Clear graphics are very important and often the source of the most difficulty;here are two examples showing the difference between good and bad use ofcolor.The Trick is to keep brightness differences large and to avoid color combinati
21、ons that do not contrast well.A comparison of the two color wheels shows which color combinations would bedifficult to see.Graphics cause the most problems,but the colors can be economically illustrated as text examples,below.The right-hand column illustrateshow the left hand column might look to a
22、color blind person.Some examples of color combinations that are easily seen by a color blind personare shown below.These are illustrated as text examples but these principles aremost important to keep in mind when preparing drawings,graphs,and figures.cone狗是色盲？点点击击图图片片播播放放视视频频眼见为实？马赫带效应MachbandsBoyn
23、tonIllusionBoyntonIllusionColorInfluencesDistancePerceptionColorInfluencesDistancePerceptionRadiatingLinesRadiatingLinesTaketwopiecesofpaperandplacetheiredgesascloseaspossibletobothsidesofonereddiagonal.Notethattheredsquareinthemiddleisthesameasalltheothersquaresonthatdiagonal.Nowmoveyourpiecesofpap
24、ertoexposemainlytheredsquaresontheotherdiagonal.Onthisdiagonalalltheredsquares,includingthecenterone,areagainthesamecolorred.Becausethecentersquareiscommontobothdiagonalsthisexerciseprovesthatalltheredsquaresinbothdiagonalsareexactlythesameredcolor.Yet,whenthepatternisseenasawhole,thetworeddiagonals
25、appeardifferentfromeachotherColorAssimilationColorAssimilationHermannGridIllusionHermannGridIllusion点击图片点击图片 播放播放FLASHFLASHHering&PogendorfIllusionsHering&PogendorfIllusions点击图片点击图片 播放播放FLASHFLASHWhichlineislonger,theredoneorthegreenone?Usearulertofindout.Youwillprobablybesurprised.Horizontal-Vertic
26、alIllusionHorizontal-VerticalIllusion点击图片点击图片 播放播放FLASHFLASHLookattheupperrightfigure.Thisexperimentworksbetterifyoucloseoneeye.Fixateontheblackdotinthecenterforabout10-15seconds.Paycloseattentiontowhatyousee.Nowdothesamethingwiththeupperleftfigure.Didyounoticeanydifference?Intheaccompanyingexplanat
27、ionItellyouwhatmostpeopleseeandthereasonforit.StabilizationCausesFadingStabilizationCausesFadingThisiscalledaKanizsafigureafterthepersonwhoinventedit.Ifyoulookcarefullyyouwillprobablyseetheedgesoftheentiretriangle,eventhoughthetriangleisdefinedonlybythenotchesinthereddisks.KanizsaIllusionKanizsaIllu
28、sionWhichislonger,theredlineortheblueline?Usearulertofindouttheanswer.Selecttheanswertodoublecheckonyourresult.Mueller-LyerIllusionMueller-LyerIllusion点击图片点击图片 播放播放FLASHFLASHTherounddotsareallexactlythesamecolorgray.Imerelycreatedtheoneontheextremerightandthencopiedittoeachofthedarkerrectangles.Clea
29、rly,thelightnessofthebackgroundeffectsthewayinwhichweperceivethecentergraydot.Thiseffectiscalledsimultaneouscontrast.Again,ascanbeseeninotherdemonstrations,theperceptionofthiskindofdisplayisaresultoflateralinteractions.SimultaneousContrastSimultaneousContrastThecircularareaineachquadrantintheleftfig
30、ureisexactlythesamecolor.Thedifferentappearanceisduetothesurroundandthelateralinteractionsthatoccur.OntherightImerelychangedthebackgroundcolorssothattheyareallidentical.Youcannowseethatthecircularareasare,indeed,identical.Thisphenomenoniscalledsimultaneouscolorcontrast.SimultaneousContrastSimultaneo
31、usContrastNeckerCubeIllusionNeckerCubeIllusionPerspectiveIllusionPerspectiveIllusion点击图片点击图片 播放播放FLASHFLASHWhatdoyouseeinthisdiagram?Inordertofindoutwhatpeopleoftensaytheyseeselectpossibleperceptions.点点击击图图片片播播放放视视频频点点击击图图片片播播放放视视频频点击图片点击图片 播放播放FLASHFLASH更高层次的视觉认知心理文化东方歌舞团的演员在演出西班牙响板舞火之恋。暖色 冷色 麦当劳眩晕
32、的艺术眩晕的艺术一名参观者在澳大利亚悉尼当代艺术博物馆欣赏瑞士艺术家乌戈龙迪诺内创作的一幅作品。龙迪诺内善于利用绘画、视频、雕刻和摄影创造情感和心理环境，并因此而闻名于世。照片中的作品使观赏者无法将视线集中在彩色的圆圈上，许多人感到眩晕，有人甚至感到头昏眼花。红白黑黄绿电影利用了人眼的视觉特性点点击击图图片片播播放放视视频频电影利用了人眼的视觉特性点点击击图图片片播播放放视视频频视觉暂留视觉暂留点点击击图图片片播播放放视视频频快拍慢放点点击击图图片片播播放放视视频频慢拍快放点点击击图图片片播播放放视视频频点点击击图图片片播播放放视视频频TermsPhotoreceptorcells:感光细胞 Rod:杆状细胞Cone:锥状细胞Retina:视网膜Iris:虹膜Fovea:中央凹Visualcortex:视觉皮层