CH 5 Colour Perception (TERMS) Flashcards
Perception
Interpretation of sensation
Sensation
Raw interrupted sensory information
Subtractive Colour Mixing (2,1)
- Certain wavelengths of light selectively absorbed by the pigments of paint or filters
- Perceived colour reflects combination of wavelengths that were not absorbed
ex. White light makes contact with all the object in a room; white because it is made up of all the colours in a wavelength; certain objects absorb certain wavelengths, the unabsorbed light reflects back to the eyes to be perceived
Additive Colour Mixing (1,2)
Different wavelengths of light add together to form the resultant colour
- red + blue + green = white
- TV = if you go close to tv you will see pixels; primary colours all get projected to your eyes, combination of colours produce different colours
Colour matching
Any 3 wavelengths of light (primaries; RBG) may be mixed in different proportions to produce all possible colours
Trichromatic theory (1,2)
- Colour matching (RBG)
Theory proposes that the eye contains 3 colour receptors each differentially sensitive to the various wavelengths of light
- For any colour, 3 receptors will produce a unique ratio of activity
Opponent-process theory (2,2)
Theory proposed that the eye contains 3 opponent-process receptors: red/green, blue/yellow, and black/white
Unlike the Trichromatic Theory, participants describe various colours using 4 rather than 3 primaries (blue, green, yellow, red):
- Complementary colours: when arranged in the colour circle, opposite colours when mixed in equal proportions yield neutral grey
- Afterimages: blue and yellow, red and green
Rod monochromats
Non-functional cones, poor visual acuity, shades of gray
Protanopia
Defective long, inability to distinguish red and purple
Deuteranopia
Defective medium, insensitive to green
Tritanopia
Defective short, insensitive to blue and yellow
Lateral Geniculate Nuclei (LGN) (1,1)
- “Nut that looks bent at the knee” ; Thalamus
A part of the thalamus that relays visual information from the retina to the brain’s visual cortex
Magnocellular channel (1,1)
- LGN
A visual system pathway that carries information about motion, depth, and luminance
Parvocellular channel (1,1)
- LGN
A visual processing pathway in the brain that handles high-resolution information about colour, form, and texture.
Primary visual cortex
- Receives most visual information
- Forms a retinotopic map with more area dedicated to the fovea
Retinotopic map
A detailed spatial layout in the brain where each tiny area corresponds to a specific location on the retina of the eye
Superior Colliculi
- Midbrain (Older)
-Reflexes and object localization
First level visual association cortex (3)
- Simple
- Adjacent areas of the occipital lobe
- Form, movement, colour analyzed separately
Second level visual association cortex
- Complex
Parietal (magnocellular info) and temporal (parvocellular info) lobes
Receptive Field
Area on the retina that a neuron will respond to
Simple cells
Light or dark bars in a specific orientation
Centre-surround receptive field
Found in the retina; neurons with receptive fields organized into a central area and a surrounding area, where stimulation of the centre excites the cell while stimulation of the surround inhibits it, enhancing contrast and edge detection.
Complex cells
Movement of a light or dark bar in a specific direction
Hypercomplex (End-stopped cells)
Moving lines of a specific length, or moving corners or angles
Bottom-up/Data-driven processing
Analysis and integration of basic features into a perceptual unit (features ⇨object)
Hierarchal Organization
Formation of perceptual units through increasingly complex connections between simple units (feature detectors ⇨ object)
Second level Parietal (1,1)
Where is it?
- Processes Movement and Magnocellular information
Second level temporal
What is it? (1,1)
- Processes colour, form, and parvocellular information
Motion Agnosia
- Caused by damage on the second level parietal lobe
Neurological condition where individuals are unable to consciously perceive motion
Balint’s syndrome
- Caused by damage on the second level parietal lobe
Neurological condition where individuals are unable to consciously identify where things are even if they see the object
Visual agnosia
- Caused by damage on the second level temporal lobe
Unable to identify what objects are (e.g., able to describe clock by it’s characteristics but not label it)
Prosopagnosia
- Caused by damage on the second level temporal lobe
Can’t consciously recognize faces (e.g., if they feel or hear the person, they could recognize them—but if they see them, they won’t)
