PSYCO104 Lecture Notes - Lecture 7: Dual Process Theory, Alpha Wave, Theta Wave

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PSYCH104–Lecture7–VisionandConsciousness
DarkAdaptation:
● Eyesaremoresensitiveinlowilluminationconditions
o Rodsareactivatedatalowerlightthreshold
o Ex.Optimallightconditionsthenthelightisturnedoff(canstillseewith
limitedvisualinformation),butthevisualinformationwillgradually
improveinthelowconditions
▪ Lessandlesslightneededthelongertheeyesstayinthelowlight
condition(30mintocompletethecycle)
LightAdaptation:
● Whenthevisualreceptorhasadaptedtolowlightconditionandactivatesatalow
intensitylightstimulation
o Conesareactivatedathighlightconditions
o Ex.Stayinginadimroomallday,andthenwalkoutoftheroomtosee
sunlight
▪ Sunlightoverstimulatedyourvisualreceptorssoyoucouldn’t
detectvisualinformationforamoment
● Remainingexposedtothehighlightenvironmentwillallow
thevisualreceptorstobelesssensitiveinquickchanging
environments
● Cycletakesplacealotfasterthandarkadaptation(10
minutes)
ColourVision:
● Humanscandetectmillionsandmillionsofcolours(distinguishsmallchanges
justfromonecolour)
o Wavelengthrelatestothecolour(thetypeofcolourwesee)
o Amplituderelatestothebrightness(value)
o Purityrelatestothesaturation
ColourMixing:
• Basicprocessesofhowcoloursarecreated:SubtractiveandAdditive
o Humancolourperceptionparallelswithadditiveratherthansubtractive
• SubtractiveColourMixing:onesubstancehasanothersubstanceaddedontop
ofit
o Addingmorecolourstothebasesubstancesubtractsmoreandmorelight
waves
▪ Ex.Redpaintwillabsorbtheredlightwavesandreflecttherest
▪ Ex.Yellow,blue,andredpaintwillreflectthecolourblack
becauseallthelightwaveshavebeenabsorbed
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• AdditiveColourMixing:substancesaddtogethertheirpropertiessotherewillbe
adifferentlightwave,aproductoftheirsummationofagivencolour
o Ex.Green+blue+redpaintcreateswhite
TrichromaticTheoryofColourVision:
• Eachconeismoresensitivetoaparticularwavelength
o Threemaincolours:Red,Green,andBlue
▪ Ifcoloursaremixedwithanadditiveprocess,itcanformanyother
colourusingjustthesethreecolours
▪ Signalswillbesenttotheprocessingcenterandcombinedtosee
hybridcolourfromthewavelengths
● Ex.HowTVworks:usesthreebasiccolourstopresent
picturesinfinegrainpixels
ColourBlindness:
• UsuallyDichromatic:canseetwooftheprimarycoloursreadily,butproblems
withathirdcolour
o Red,green,orbluecolourblindness
▪ Thegivencolourpeopleareinsensitiveof,can’tdetectthe
colourationsoflightwaves
● Ex.Can’tdifferentiateredandorange,maybedueto
greeninsensitivity(greencolourblindness)becauseto
detectorange,redandgreenhavetobemixedtogether
OpponentProcessTheoryofColourVision:
• Ifanimageislookedatlongenoughandthestimulusisintenseenoughfromthe
beginningandyousuddenlylookaway,anafterimageremainsforafractionofa
secondorafewseconds
o Ex.Lookingatthesunandthenyouturnawayfromthestimulus,you
mightseepurpledotsinyourvision(complementaryafterimage)
• Threeprimaryvisualreceptorsintheretinaarealongacontinuumalongthe
spectrum
o RedvsGreencolourreceptor(redisseeninhighconditions,andifitisa
lowreceptionthenyou’dseegreen)
o YellowvsBlue(yellowinhighandlowreceptionyouwillseeblue)
o Blackvs.white(willseeblackinhighlyreceptiveconditionsandwhitein
low)
• Threebasicdifferentialchannels
o Malfunctioninthesechannelsonhighlevelactionfortheredvsgreen
colourchannel(willhaveproblemseeingred,shouldnotinterfereseeing
green)
o Differenttypesofdamageleadstodifferencesincolourperception
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▪ Trichromatictheorycouldnotaddressthisproblembecause
peoplecouldstilldetectyelloweventhoughtheycan’tseeredand
green
GraphemeColourSynesthesia:
Individualwillexperienceacertaincolourbyseeingastimulus 
o Ex.SeeingablackletterA,willseeredeventhoughit’snottheredueto
theactivationofasubsetofreceptorsintheretina
CombinationoftheTrichromaticandOpponentProcessTheory:
• Eachtheoryhasproblemsthatitcannotaddress
o Conclusion:Hybridofthetwosystemsactingontheindividuals
▪ Dualprocesstheory
• 3conelikereceptors
o Receptorsactivatealongtheopponentprocesschannels
o Individualscanhavemalfunctionsinanyaspectinthesystem
▪ Canhaveproblemsintheredconereceptor(willcauseyouto
haveproblemidentifyingreds,oranges,andyellows)
▪ Canhaveproblemsinchannels,allprimarycolourswillworkbut
thesubsystemisimpaired
● Ex.Impairmentongreenandredchannel,candetect
yellow,butwillnotbeabletodifferentiatefromgreenand
red
ColourAffectsBehaviour:
Colourcaninfluencetheratingofattractivenessordetermineiftheindividualisa
threat
o Ex.Redunderminesperformance:
▪ GaveindividualsparticularIQtestswiththecolourofthefront
pageoftheexam(red,greenorwhite),foundthatindividualswith
theredfrontpagegenerallyscorelower
● Reasoning:Redhasnegativeconnotationssuchasred
lightsmeanstop,thesightofbloodisredwhichgives
somepeopleanxiety,teachermarkswithredwhenyouget
aquestionwrong
o Ex.RatingsofAttractiveness
▪ Malescameintoalabandwereshownpicturesoffemalestorate
theirattractiveness
● Addeddressestothemodelsafterwards(themodelwas
wearingblueorredclothes)
o Womenthatwerewearingredwerejudgedmore
attractivethanthosewearingbluedresses
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Document Summary

Humans can detect millions and millions of colours (distinguish small changes just from one colour: wavelength relates to the colour (the type of colour we see, amplitude relates to the brightness (value, purity relates to the saturation, basic processes of how colours are created: subtractive and additive, human colour perception parallels with additive rather than subtractive, subtractive colour mixing: one substance has another substance added on top, adding more colours to the base substance subtracts more and more light waves, ex. Three primary visual receptors in the retina are along a continuum along the spectrum: red vs green colour receptor (red is seen in high conditions, and if it is a low reception then you"d see green, yellow vs blue (yellow in high and low reception you will see blue, black vs. white (will see black in highly receptive conditions and white in low)

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