10 Questions
What percentage of tracks from photoreceptors in the retina goes into the lateral geniculate nucleus?
90%
What is the primary function of the dorsal stream?
Processing motion information
What is the main function of the superior colliculus?
Guiding eye movements and processing multi-sensory information
What is the result of a lesion in the primary visual cortex?
Loss of vision
What is the name of the phenomenon where individuals with lesions in the primary visual cortex can guess above chance about visual stimuli?
Blindsight
What is the name of the area where multi-sensory integration occurs?
Superior colliculus
What percentage of tracks from photoreceptors in the retina goes into the superior colliculus?
10%
What is the main function of the ventral stream?
Processing color and details
Where do 90% of the tracks from photoreceptors in the retina go?
Lateral geniculate nucleus
What is the name of the area that receives visual information from the lateral geniculate nucleus?
Primary visual cortex
Study Notes
Depth Perception
- Retinal disparity helps dissociate the difference between 2 images, with objects closer having a bigger difference on the back of 2 eyes & larger difference between the 2 eyes compared to those that are larger.
- Big visual angle = closer and smaller, while small visual angle = bigger and further away.
- Convergence = the amount that your eyes have to rotate to have both focus on an object, with eyes getting closer and closer as an object moves closer.
- Horses, zebras, fish, and birds have no overlap between the 2 images of their eyes, resulting in limited depth perception.
Colour Perception
- A frog can't see dead flies unless they move, with retinal ganglion cells responding to 4 different stimuli, including stationary walls, overall dark and light, moving walls, and little moving dots.
- Colour perception allows for facial processing, determining physical attractiveness, and staying away from those who are sick.
- Old world monkey colour blindness rates are low and not changing.
Why People Have Blue Eyes
- Blue eyes are eyes in the absence of melanin, with light scattering into the iris and making it appear blue.
- Green eyes contain a little bit of melanin.
Properties of Colour
- We see colour because when light hits an object, some bounces off into our eye, breaking down the protein that is sensitive to that wavelength.
- Hue, brightness, and saturation are the 3 properties of colour, with hue being the colour, brightness being the amount of light, and saturation being the purity of the wavelength.
- The visible spectrum includes ROYGBIV, with our atmosphere blocking the majority of EM rays.
Photoreceptors
- Transduction is the method by which a physical stimulus becomes a neural signal, with 2 types of photoreceptors in the eye: rods and cones.
- Different opsins are sensitive to different wavelengths, with the perceptual system aiming to create a realistic 3D representation of the world.
The Ecological Approach to Perception
- J.J Gibson's approach emphasizes that perception is not inferential but ecological, with the purpose of perceiving the environment being to successfully interact within it.
- The rate of change of visual information matters, with a retinal image that changes over time.
Cues to Disambiguate Speech
- Context and experience are cues to disambiguate speech, with the phonemic restoration effect demonstrating how our perceptual system makes up missing phonemes.
- Categorical boundaries are developed over time, with our perceptual system lumping similar auditory stimuli into categories.
Learn how our eyes and brain work together to perceive depth and distance. Discover the role of refraction, retinal disparity, and visual angles in creating our sense of 3D vision.
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