Chapter 6 Flashcards
(34 cards)
Why are humans considered highly visual animals?
Humans constantly use vision to sense remote environmental aspects and make decisions.
What type of energy is light?
Light is a form of electromagnetic energy.
What part of the eye does light act on?
Photoreceptors in the retina.
Through which parts does light enter and focus in the eye?
Through the pupil, focused by the cornea and lens onto the retina.
What controls the size of the pupil?
The iris, which expands or contracts with changing light levels.
What is misleading about describing the eye as a camera?
The eye is never static and the brain interprets coded signals rather than viewing images.
What are the two types of photoreceptors?
Rods and cones.
What is the main difference between rods and cones?
Rods are more sensitive to light and used at night; cones are for daytime and color vision.
How many photoreceptors are in the human retina?
Approximately 125 million.
What happens after photoreceptors are activated by light?
They generate electrical potentials which activate retinal ganglion cells, forming the optic nerve.
Where do the optic nerves from both eyes meet?
At the optic chiasm.
What happens at the optic chiasm?
Half the fibers cross to the opposite side, forming the optic tracts.
What is the next major relay after the optic chiasm?
The lateral geniculate nucleus (LGN), which sends signals to the visual cortex.
What is binocularity?
The ability of cortical cells to respond to images from either eye.
What is area V1 known for?
It is the first stage of cortical processing, responding to edges/lines with specific orientations.
What is a receptive field?
The region of retina over which a visual cell responds to a stimulus.
What property does the visual cortex display that allows it to adapt?
Plasticity.
What are M-type ganglion cells?
Large ganglion cells that may be linked to certain types of dyslexia.
What percentage of ganglion cells are M-type?
About 5%.
What is the significance of illusions like the Café Wall or Kanizsa Triangle?
They reveal the brain’s active processing and interpretation of visual input.
What is the Necker cube used to illustrate?
Perceptual reversals and decision-making in vision.
What is binocular rivalry?
When each eye sees different patterns and perception alternates between them.
What is blindsight?
The ability to respond to visual stimuli without conscious awareness, often due to V1 damage.
What is functional blindsight in normal people?
Performing visual tasks (like driving) without consciously focusing on visual input.
