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89 Cards in this Set
- Front
- Back
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What is the Receptive Field
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Area of the retina that affects firing rate of a ganglion cell.
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What are the three types of ganglion cells?
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M Cells
P Cells K Cells |
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Describe M Cells
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Magnocellular
Large Receptive Field Black and White information Fast processing |
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Describe P Cells
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Parvocellular
Smaller Receptive Fields Color information Slower Processing |
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Describe K Cells
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Koniocellular
Very Small Slow processing Not much is known |
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Describe the LGN
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Lateral Geniculate Nucleus
6 layers |
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6 layers of the Lateral Geniculate Nucleus
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Layer 1: M Cells, Contralateral
Layer 2: M Cells, Ipsilateral Layer 3: P Cells, Ipsilateral Layer 4: P Cells, Contralateral Layer 5: P Cells, Ipsilateral Layer 6: P Cells, Contralateral |
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How much space does the Fovea represent on the Visual Cortex?
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About 10%
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3 Types of cells in the Striate Cortex
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Simple, Complex and End-stopped
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Simple Cells of the Striate Cortex
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process lines of different orientations
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Complex Cells of the Striate Cortex
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process bars of light, but only respond to movement of bars of light in a specific direction.
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End-Stopped Cells of the Striate Cortex
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Corners or boundaries
Moving lines of specific length Moving corners or angles |
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Orientation Columns in the Visual Cortex
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Neurons in a column all respond to the same angle
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Ocular Dominance Column
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Column is the V1 that hold information from one eye
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Hypercolumns of the Visual Cortex
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Columns with information from both eyes
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Blobs in Primary Visual Cortex
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Color information from the Parvocellular and Koniocellular Pathways
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Cortical Blindness
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Damage to the V1 cortex
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Describe the "What" Pathway
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M Ganglion Cells--> Magnocellular layers of the Lateral Geniculate Nucleus--> V1 of Cortex--> Dorsal Stream to the Parietal Lobe
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Describe the "Where" Pathway
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Parvocellular Ganglion Cells--> Parvocellular layers of the Lateral Geniculate Nucleus--> V1 of Cortex--> Ventral Stream to the Temporal Lobe
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Visual Object Agnosia
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Damage to the "What Pathway" and the Inferio-Temporal Area
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Prospagnosia
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Damage to the Fusiform Face Area, in the Temporal Lobe
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What is sensation?
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Awareness due to stimulation of a sense organ
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What is transduction?
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Transforming one form of energy into another. ie. energy from environment (light, pressure, chemicals) into electrical/neural signals.
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What is perception?
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interpretation of sensations, giving them meaning and organization.
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What is the sensation/perception paradox?
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It is easy for us to do but hard for us to understand
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What is Naive Realism?
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The belief that the world is as we see it.
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Who was John Locke?
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(1690)
Experiments with water. Warmth or coolness does not reside in the water itself, but depends on the perceiver's state. Primary and Secondary Qualities. |
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Who was David Hume?
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(1739)
All experiences are subjective and unreliable. |
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What is subjective Idealism?
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George Berkley
The physical world in entirely the product of the mind: Compelling mental fiction |
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What is Sollipsism
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Only your mind exists and all worldly objects are just perceptions of your mind
Matrix |
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What is "bottom-up" processing
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Data Driven
Processing based on how receptors register environmental stimuli |
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What is "top-down" processing?
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Conceptually-based or knowledge based.
Perceivers previous knowledge shapes perception. |
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What is cognition?
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The acquisition, storage, transformation, and use of information
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Is there perception without cognition?
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NO
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What is Psychophysics?
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The study of the relationship between properties of physical stimulus and the psychological reactions to those.
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What is absolute threshold?
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"Absolute Limen"
Change from detecting a stimulus from not detecting a stimulus. Smallest amount of energy needed to detect a stimulus When you detect a stimulus 50% of the time |
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What is the Method of Limits?
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Stimuli of different intensities presented in ascending and descending order.
Observer responds to whether she has perceived the stimulus Cross-over point is the threshold |
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What are common errors with the Method of Limits?
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1. Errors of Habituation: "Aren't sure, so you saw what you have been saying
2. Errors of Anticipation: "Jump the gun" |
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What is the Method of Adjustment?
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Stimulus intensity is adjusted continuously until the observer detects it.
Repeated trials average for the threshold |
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What are common errors with the Method of Adjustment?
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Lots of variability, therefore not reliable.
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What is the Method of Constant Stimuli?
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5-9 Stimuli of different intensities are presented in random order.
Multiple trials are presented Threshold= Intensity that results in detection in 50% of the trials. |
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What is sensitivity?
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Ability to detect minor changes around you.
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How are threshold and sensitivity related?
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Inversely, low threshold = high sensitivity.
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Signal Detection Theory is dependent on two things...
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1. Sensitivity to the Stimulus
2. Decision-making strategy or criterion. |
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When a signal is present and the person detects it...
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HIT
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When a signal is present and the person does not detect it...
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MISS
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When a signal is absent and a person detects a signal...
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FALSE ALARM
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When a signal is absent and a person does not detect it...
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CORRECT REJECTIVITY
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What is the Difference Threshold?
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Smallest difference between two stimuli that a person can detect
50 % of the time |
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What is Webers Law?
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Change of Intensity/Intensity = K
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What is the electromagnetic spectrum?
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Band of energy that includes visible light
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What is hue?
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Color
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What is Brightness?
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Amplitude (height of the wave)
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What is Purity?
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Multiple wavelengths presented together
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Where does the eye sit in the head?
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In the Orbit, surrounded by orbital fat/eyelid.
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What happens during a blink?
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Brain inhibits neural processing (Neural inhibition)
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What is the normal blink rate?
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1/4 second
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What causes blink rate to increase?
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Interest/excitement
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What is the sclera?
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The white part of the eye
Tough/Dense material, keeps pressure in the eye. |
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What is the cornea?
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outermost part of the eye. Fibers are not interwoven and there are no blood vessels.
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What is Aqueous humor?
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Fills the anterior chamber, transports nutrients and oxygen.
Made by the cilliary body. |
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What is an Astigmatism?
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Abnormally shaped cornea, "squished in one direction," causes blurry vision.
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What is the Iris?
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Outer layer is pigment, inner layer is the blood vessels.
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What is the pupil?
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A hold which lets more/less light in through muscle fibers.
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What happens to the pupil as you age?
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Is does not open as much.
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Explain the lens.
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What focuses the visual field.
Never stops growing. The center is the hardest/oldest. Highest protein concentration in the body. |
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What is sclerosis?
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Hardening of the lens.
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What is cataract?
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Hardening/Yellowing of the lens.
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What is vitreous humor?
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The gel-like fluid which fills the eye.
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What is Choroid?
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Behind the retina, nourishes the retina and is heavily pigmented/very dark, absorbs extra light.
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What two structures help focus images on the retina?
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The lens (20%) and the cornea (80%)
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What is accommodation?
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The lens/cornea moving around to better focus objects.
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What is Presbyopia?
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"Old eye" the distance of the near point increases.
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What is the Near Point?
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Point at which our eyes can't accommodate any more
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What is the Macula?
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Where most images are centered, contains mostly cones.
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What is the fovea?
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Center of the macula, all cones.
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What is the Optic Disc?
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Where blood vessels enter/leave the eye. Causes the Blind Spot.
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What are rods?
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photoreceptors
Black and white |
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What are cones?
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photoreceptors
Colors |
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How many rods and cones are there?
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120 million rods, 5 million cones.
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Describe the distribution of photoreceptors on the retina.
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In the fovea, there are only cones.
Most rides are right outside the fovea. There are no rods/cones in the Optic Disk. |
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What is macular degeneration?
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A blind spot in the middle of your vision caused by not enough blood to that part of your eye.
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What is retinitis pigmentosa?
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A deterioration of rods and cones in the periphery, you can only see what your fovea detects.
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What are opsin and retinal?
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Retinal: gets light, changes shape and separates from opsin. This causes the hyperpolarization.
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What is adaptation?
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Changes in sensitivity to a particular light intensity.
Pupil. |
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Explain Dark Adaptation
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About 100,000X more sensitive in the dark after we have adapted.
This happens in two stages: 1. Rapid adaptation of cones 2. Slower adaptation of rods |
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What are horizontal cells?
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Send information from Bipolar cell to Bipolar cell
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What are Amacrine cells?
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Send information from Bipolar cells, Ganglion cells, and other Amacrine cells.
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Explain the convergence of photoreceptors to ganglion cells.
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1,000 photoreceptors --> 1 ganglion cell
In fovea, 1 receptor cell--> 1 ganglion cell Generally, 120 rods--> 1 ganglion, 6 cones--> 1 ganglion. |
