PSY368 Section 2 Practice Questions Flashcards
What percentage of information we get from the world comes through our visual system?
80%
Why is vision considered our most important sense?
We intake a majority of environmental information through vision
What is the function of the eye in terms of processing visual information?
Focusing electromagnetic energy, transducing it into a neuronal signal, then to start processing the signal
How does the placement of eyes differ between prey and predatory animals?
Eyes of prey tend to be on the sides of their head while eyes of predators are usually in the front (binocular vision)
Why do primates have eyes positioned centrally on their head?
The binocular vision helps primates to use tools
Why is the pigment epithelium in the vascular tunic important?
They are heavily pigmented to absorb scattered light (pigment epithelium)
How does the iris affect vision?
determines pupil size
What are photoreceptors and how do they contribute to vision?
photoreceptors are pigmented cells that produce electrical signals when struck by light – photoreceptors intake environmental information making them the first source of visual sensation
What is the difference between rods and cones in terms of their function?
Rods: peripheral vision, dim lighting, achromatic, poor spatial resolution
Cones: central vision, bright lighting, good spatial resolution, color vision
Why does the optic disc create a blind spot in our vision?
There is an absence of photoreceptors at the optic disc
How do horizontal cells and amacrine cells affect the processing of visual information in the retina?
Horizontal cells modulate activity between the photoreceptors and the bipolar cells while amacrine cells modulate activity between the bipolar and the ganglion cells
Where must light pass through to reach the photoreceptors?
The cornea
The lens
The aqueous and vitreous humors
The ganglion, amacrine, bipolar, and horizontal cells
What is the primary function of the eye
To focus light on the retina
Which part of the eye accounts for about 80% of the bending needed to focus light on the retina?
The cornea
What is the difference between light coming from distant objects and light from near objects in terms of how the eye handles it?
Light coming from near objects requires the lens to bend more while objects far away require less bending
Why is the fovea the area of the retina with the best visual acuity?
Few cell bodies are located at the fovea and the fovea contains mainly cones which are specialized for detailed pattern vision
How does visual acuity change with increasing distance from the fovea?
As you move away from the optical axis images at the fovea have increasing lens distortions
What is the visual angle, and how does it relate to object size and perception?
The visual angle is the angle that a
How does the visual angle of an object affect its ability to be resolved at different distances?
A larger visual angle (closer) means a larger image projected on the retina, allowing for better detail perception
What is neuronal convergence and how does it affect visual resolution?
Neuronal convergence describes how many cells project to a smaller number of cells
This affects visual acuity because the more photoreceptors converging on a ganglion cell (e.g. 120:1 in rods), the worse spatial resolution is
Under what lighting conditions do rods and cones operate?
Rods operate under low light and codes operate under bright light
Why is visual acuity better in the fovea compared to the peripheral retina?
Acuity is better in the fovea because the more photoreceptors converging on a ganglion cell, the greater loss of spatial information (the fovea has less cells)
What is the difference between photopic vision and scotopic vision?
Photopic vision - mediated by cones (brighter lights)
Scotopic vision - mediated by rods (dimmer lights)
What is rhodopsin and how does it function?
Pigment coating rod outer segments. As light hits rhodopsin it changes shape (isomerization) causing receptor sites to open and hyperpolarization. This is where visual sensory transduction happens.
What happens during the isomerization of rhodopsin?
Rhodopsin changes shape due to a photo of light hitting rhodopsin and the retinal and scotopsin binding changes
What is the difference between luminance and brightness, and how are they related?
Brightness is the perceptual correlate of luminance - luminance is in the world while brightness is in your head
Describe the process of dark adaptation and how the absolute threshold for light intensity changes over time?
Going from a bright room to a dimly lit room will initially leave you nearly blind, but partial vision occurs after remaining in the dark for a few minutes. The longer you spend in the dark, the more sensitive your eyes become to light leading to a lower absolute threshold
What are the phases of dark adaptation?
First the cones provide us with a fast boost in sensitivity but quickly max out. Then the rods, which are slower, kick in and enable us to see in extremely dim lights
