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PY305 Exam 1
Sensation and Perception: Vision
59
Psychology
Undergraduate 3
12/13/2010

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Cards

Term
What are the four categories of the perceptual process?
Definition
Stimulus, Electricity, Experience and Action, Knowledge
Term
What is the difference between an environmental stimulus and an attended stimulus?
Definition
An environmental stimulus is everything around you, while an attended stimulus is what you focus on
Term
3 Stages in Electricity?
Definition
Transduction, Transmission and Processing
Term
Transduction
Definition
changes environmental energy to nerve impulses
Term
Transmission
Definition
occurs when signals from receptors travel to the brain
Term
Processing
Definition
occurs during interactions among neurons in the brain
Term
What is the difference between perception and recognition?
Definition
Perception occurs as a conscious experience, while recognition occurs when an object is placed in a category, giving it meaning
Term
Bottom-up processing
Definition
"data-based processing" ; based on incoming stimuli from the environment
Term
Top-down processing
Definition
"knowledge-based processing" ; based on the perceiver's previous knowledge (regularities help us perceive the world)
Term
5 Basic Properties of Action Potentials:
Definition
1. Show propagated response (signals travel same strength same speed)
2. Remain the same size regardless of stimulus intensity
3. Increase in rate of neurotransmitters released to increase stimulus intensity
4. Have refractory period of 1ms - upper firing rate is 500-800 impulses per second
5. Show spontaneous activity that occurs without stimulation
Term
What is lateral inhibition?
Definition
- Antagonistic neural interaction between adjacent regions of the retina
- Enables the signals that reach retinal ganglion cells to be based on differences in activation b/t nearby photoreceptors
- Plays an integral role in visual perception
Term
Why have eyes that use electromagnetic radiation?
Definition
It's abundant; Also, it travels in straight lines, so it retains the properties of the stimuli better, and it travels fast, it's good for quick info delivery
Term
Why have eyes that use light?
Definition
Light waves actually reach our atmosphere - the waves/particles aren't scattered before; light waves interact with surface molecules of most objects in our atmosphere well - reflects and refracts well
Term
Why have eyes that use light?
Definition
Light waves actually reach our atmosphere - the waves/particles aren't scattered before; light waves interact with surface molecules of most objects in our atmosphere well - reflects and refracts well
Term
Why have eyes that are able to move?
Definition
Eyes that are able to move compensate for ltd head movements
Term
Duplex
Definition
In reference to the retina, consisting of two parts: the rods and cones, which operate under different conditions
Term
Photoreceptors
Definition
light-sensitive receptors in the retina; neurons that capture light and initiate the act of seeing by producing chemical signals
Term
Rods
Definition
photoreceptors specialized for night vision; blunt tip; concentrated around - but not in - the retina; functions best in dimly lit conditions; many receptors for each ganglion cell; poor acuity; excellent sensitivity; slow dark adaptation with low threshold
Term
Cones
Definition
photoreceptors specialized for daylight vision, fine visual acuity, and color; tapered tip; concentrated in the fovea; function best in well lit conditions; few receptors for each ganglion cell; excellent acuity; poor sensitivity; rapid dark adaptation with high threshold
Term
Outer segment
Definition
the part of a photoreceptor that contains the photopigment molecule
Term
Inner segment
Definition
the part of a photoreceptor that lies between the outer segment and the cell nucleus
Term
Synaptic terminal
Definition
the location where axons terminate at the synapse for transmission of information by release of a chemical transmitter
Term
chromophore
Definition
the light-catching part of the visual pigments of the retina
Term
rhodopsin
Definition
the visual pigment found in rods
Term
photoactivation
Definition
occurs when a photon makes its way to the outer segment of a rod where it is absorbed by a molecule of rhodopsin and then transfers its energy to the chromophore portion of the visual pigment molecule; this is an activation by light that initiates a biochemical series of events that results in the closing of channels in the cell membrane that normally allow ions to flow into the rod outer segment
Term
hyperpolarization
Definition
an increase in membrane potential where the inner membrane surface becomes more negative than the outer membrane surface; occurs when the cell membrane channels that were closed during photoactivation alters the balance of the electrical current bt the inside and the outside of the rod outer segment, making the inside of the cell more negatively charged
Term
graded potential
Definition
an electrical potential that can vary continuously in amplitude
Term
fovea
Definition
a small depression at the center of the macula of the retina; densely packed with cones - contains no rods; portion of the retina that produces the highest visual acuity; serves as pt of fixation
Term
Eccentricity
Definition
the distance between the retinal image and the fovea
Term
Fovea: photoreceptor type
Definition
mostly rods
Term
Fovea: bipolar cell type
Definition
midget
Term
Fovea: convergence
Definition
Low
Term
Fovea: Receptive-field size
Definition
small
Term
Fovea: acuity
Definition
high
Term
Fovea: light sensitivity
Definition
Low
Term
Periphery: photoreceptor type
Definition
mostly rods
Term
Periphery: bipolar cell type
Definition
diffuse
Term
Periphery: convergence
Definition
high
Term
Periphery: receptive-field size
Definition
large
Term
Periphery: acuity
Definition
Low
Term
Periphery: light sensitivity
Definition
High
Term
horizontal cells
Definition
specialized retinal cells that contact both photoreceptor and bipolar cells
Term
lateral inhibition
Definition
antagonistic neural interaction bt adjacent regions of the retina
Term
amacrine cells
Definition
retinal cells found in the inner synaptic layer that make synaptic contacts with bipolar cells, ganglion cells, and one another
Term
bipolar cells
Definition
retinal cells that synapse with either rods or cones (not both) and with horizontal cells, and then pass the signals on to ganglion cells
Term
diffuse bipolar cells
Definition
bipolar retinal cells whose processes are spread out to receive input from multiple cones
Term
sensitivity
Definition
1. the ability to perceive via sense organs
2. extreme responsiveness to radiation, esp to light of a specific wavelength
3. the ability to respond to transmitted signals
Term
visual acuity
Definition
a measure of the finest detail that can be resolved by the eyes
Term
midget bipolar cells
Definition
small cone bipolar cells in the central retina that receive input from a single cone
Term
ON bipolar cells
Definition
bipolar cells that respond to an increase in light captured by the cones
Term
OFF bipolar cells
Definition
bipolar cells that respond to a decrease in light captured by the cones
Term
ganglion cells
Definition
retinal cells that receive visual information from photoreceptors via two intermediate neuron types (bipolar cells and amacrine cells) and transmit information to the brain and midbrain
Term
P ganglion cells
Definition
small ganglion cells that receive excitatory input from single midget bipolar cells in the central retina and feed the parvocellular layer of the lateral geniculate nucleus (LGN)
Term
M ganglion cells
Definition
ganglion cells resembling little umbrellas that receive excitatory input from diffuse bipolar cells and feed the magnocellular layer of the lateral geniculate nucleus (LGN)
Term
receptive field
Definition
the region of the retina in which visual stimuli influence a neuron's firing rate
Term
ON-center cell
Definition
a cell that depolarizes in response to an increase in light intensity in its receptive field center
Term
OFF-center cell
Definition
a cell that depolarizes in response to a decrease in light intensity in its receptive field center
Term
filter
Definition
an acoustic, electrical, electronic, or optical device, instrument, computer program, or neuron that allows the passage of some frequencies or digital elements and blocks the passage of others
Term
contrast
Definition
the difference in luminance between an object and the background or between lighter and darker parts of the same object
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