Colour Perception Flashcards
What is perceptual segregation?
Aids in discriminating objects from background
What is crypsis?
Camouflage, concealment, or disruption with respect to the surrounding environment
What is concealing coloration?
Animal has the same colour as its environment
What is disruptive coloration?
Pattern breaks up outline so one individual doesn’t stand out
What is mimesis?
Camouflage or concealment by imitation of another object
What is a disguise?
Animal that looks like another, unimportant object to predator or prey
What is mimicry?
Animal that looks like other distasteful or dangerous animals
What are spectral colours?
Those found in the rainbow
What are the 3 physical dimensions of colour?
Wavelength
Purity
Intensity
What are the 3 psychological dimensions of colour?
Hue
Saturation
Brightness
What is the colour spindle?
Describes all colours we can see
Slice = colour circle
What is the problem with the colour spindle?
Some hues saturate before others
How many colours can we discriminate between?
2 million
What is represented in a language with only two colour terms?
Light and dark
What is represented in a language with 3 colour terms?
Light, warm, and dark
Are warm or cool colours split first?
Warms (red and yellow) are split before grue is split into blue and green
How many basic colour terms are there?
11
What are the basic colour terms?
Black, white, red, green or yellow, blue, brown, orange, pink, purple, grey
What colour is light with a single wavelength at 570 nm?
Yellow
What colour are green (500 nm) and red (650 nm) lights?
Yellow
What are metamers?
Two lights with different wavelength distributions, but appearing identical in colour
must produce identical neural activation
What is an additive colour mixture?
Mix light of different wavelengths
Mixing all colours = white
What is a subtractive colour mixture?
mix paint of different pigments
Mixing all colours = black
What are complementary colours?
Colours on opposite sides of the colour circle which, when added, produce greyish-white
What are primaries?
Three wavelengths that, when mixed in certain proportions, can match any other hue
What do primaries define?
The colour triangle
What does spectral yellow require?
Negative primary
What is trichromatic theory?
Only three different types of receptors are needed, each sensitive to a different wavelength
What is evidence for trichromatic theory?
You can match a given colour by combining the proportions of the 3 primaries together
3 different types of cones were found on the retina
What is the eryhthrolabe cone?
Red-catching, long wavelengths
What is the chlorolabe cone?
Green-catching, medium wavelengths
What is the cyanolabe cone?
Blue-catching, short wavelengths
What is opponent-process theory?
Proposes that basic colours come in opposing pairs
What is the evidence for opponent-process theory?
Afterimage = visual sensation appearing after adapting to a stimulus, produces opposite colour
Simultaneous colour contrast = surrounding an area with a colour changes the appearance of the surrounded area
Habituation = infants get bored of looking at the same thing
Center-surround cells have opposing receptive field regions of bright and dark
What is two-stage theory?
Opponent process obtains a difference function for the associated pair of wavelengths
What is rod monochromacy?
No cones
What is cone monochromacy?
One type of cone only
What is dichromacy?
Two types of cones only
What is protanopia?
Long wavelength cone deficient
Perceives spectrum as blue-yellow
Impaired in ability to distinguish red and green
What is deuteranopia?
Medium wavelength cone deficient
Perceives spectrum as blue-yellow
Impaired ability to distinguish red and green
What is tritanopia?
Short wavelength cone deficient
Perceives spectrum as turquoise-red
Impaired ability to perceive blue and yellow
What is anomalous trichromacy?
Have all types of cones but one is abnormal
Poor at discriminating hues
What is colour constancy?
Perception of an object’s colour remains constant, despite variations in the quality of illumination
What is colour constancy disrupted by?
Chromatic adaptation
Memory colour
What is chromatic adaptation?
Prolonged exposure to a particular wavelength causes cones to be less sensitive to it
What is memory colour?
Characteristic colour of a familiar object may influence colour perception
What is lightness constancy?
Perception of an object’s lightness remains constant, despite changes in illumination
What is the equation for retinal luminance?
Illumination x reflectance
What is the ratio principle?
Percentage of light reflected from an object determines perception of lightness
What is the McCollough effect?
Fatigue of cortical coloured-line detecting cells after looks at vertical black and green stripes for 5 minutes
Afterimages last weeks
What is absolute identification of colour?
It is difficult to identify unidimensional stimuli
Poor performance on colour recognition test
What is relative identification of colour?
The task is easier if a comparison scale is provideed
What is redundant coding of colour?
Coding colours with thing like patterns accommodates those with visual deficiencies
