Exam 2 - Vision Flashcards
Hue
determine by wavelength (we see between 380-760), color
Brightness
determined by the intensity of the electromagnetic radiation, intensity/brightness of color
Saturation
determined by the purity of the light wave, purity of color
Orbits
bony pockets that hold the eye
Sclera
white portion of the eye
Conjunctiva
mucous membranes that line the eyelid and hold the eye muscles
Cornea
transparent, where light first enters before entering pupil
Pupil
constricts or dilates to let different amounts of light in, where light enters the eye
Iris
colored portion of the eye, muscle that controls pupils - controlled by the ANS
Lens
change shape to change the distance at which you can see
Accommodation
changes in the thickness of the lens by the ciliary muscles, that focus images or near or distant objects on the retina
The receptive fields of most retinal ganglion cells are roughly:
A) square
B) round
C) rectangular
D) perpendicular
B
Simple cells of the primary visual cortex:
A) have receptive fields with static “on” and “off” areas that are separated by a straight edge.
B) do not have receptive fields.
C) have receptive fields that cannot be divided into static “on” and “off” areas.
D) have two receptive fields.
A
Primary visual cortex is in the:
A) parietal lobe.
B) temporal lobe.
C) occipital lobe.
D) frontal lobe.
C
A.T. is a woman with damage to her dorsal visual stream. She:
A) has little difficulty making accurate movements under visual control.
B) has substantial difficulty making accurate movements under visual control.
C) has substantial difficulty consciously recognizing objects.
D) also has damage to her inferotemporal cortex.
B
With respect to vision, wavelength is to intensity as:
A) vision is to audition.
B) wavelength is to color.
C) color is to brightness.
D) color is to loudness.
C
Light enters the human eye through an opening in the iris called the:
A) cornea.
B) fovea.
C) pupil.
D) retina.
E) sclera.
C
High-acuity vision is mediated by the :
A) optic disk.
B) blind spot.
C). Fovea
D) choroid.
C
The receptive field of a visual neuron is the area of the:
A) striate cortex within which stimulation can activate the neuron.
B) striate cortex within which stimulation can inhibit the neuron.
C) visual field within which the suitable visual stimulus can influence the firing of the
neuron.
D) retina within which stimulation with diffuse light can activate the neuron.
C
Retina
where photoreceptors are located
Optic Chiasm
where the optic nerves meet
Cones, what type of light do they see, where are they found?
- daytime vision
- color
- only found at the fovea
Rods, what type of light are they used for, and where are they located?
- nighttime vision
- dim light
- found on the periphery of the back of the eye
Blind spot, what is completion?
- no receptors where information exits the eye
- where the visual system uses information from cells around the blind spot to fill in the space
Fovea, what photoreceptors are here?
- high acuity area at center of retina
- only cones are here
What are the three retinal layers?
- photoreceptors
- bipolar cells
- ganglion cells
On ganglion cell
light has to fall on the center
Off ganglion cell
light has to fall on the periphery
On/off ganglion cell
light has to shine on both the periphery and center
Trichromatic theory of color vision
- proposes 3 types of receptors, each with a different spectral sensitivity
- one that responds to red, a second to green, and a third to blue
What is the opponent process theory?
- 2 different classes of cells encoding color, and another class encoding brightness
- each encodes two complementary color perceptions
Simple cells
- orientation and location
- sensitive cell in the middle of the visual field
Complex cells
- motion sensitive
- light or dark background, can be seen anywhere in the visual field
Hypercomplex cell
responds to the presence of a line segment with a particular orientation that ends at a particular point within a cell’s receptive field
What is a scotoma?
damage to an area of primary visual cortex that causes loss of eyesight
Dorsal stream, what does it start and end with?
- spatial location
- beings with striate cortex and ends with the posterior parietal cortex
Ventral stream, what does it start and end with?
- perception of form
- begins with the striate cortex and ends with inferior temporal cortex
What is color constancy?
relatively constant appearance of the colors of objects viewed under varying lighting conditions
Visual agnosia, what is it caused by?
deficits in visual perception in the absence of blindness, caused by brain damage
Magnocellular layers
- responsive to movement
- input from rods
Parvocellular layers
- color, detail, and still or slow objects
- input from cones
Protanopia
red cones have green in them
Deuteranopia
green cones have red in them
Tritanopia
lacks blue cones
Primary visual cortex
receives most of its input from the LGN
Secondary visual cortex
receives most of its input from primary visual cortex
Visual association cortex
receives input from secondary visual cortex and other secondary sensory systems
Achromatopsia, what is it caused by?
- inability to discriminate among different hues (can only see grays and blacks)
- caused by damage to the visual association cortex
Inferior temporal cortex
highest level of the ventral stream where recognition of particular objects takes place
Apperceptive visual agnosia
failure to perceive objects (don’t recognize objects visually)
Associative visual agnosia
inability to identify objects that are perceived visually (asked to draw a picture, but when looking at the picture they wont know what it is)
Prosopagnosia
Failure to recognize particular people by the sight of their faces
Fusiform face area, this region is part of what?
region of the extrastriate cortex, involved in perception of faces and other objects
What is the visual pathway?
- retina
- superior colliculi
- lateral geniculate nucleus
- primary visual cortex
- secondary and association areas
Akinetopsia
deficiency in the ability to see movement progress in a normal smooth fashion
Intraparietal sulcus
the end of the dorsal stream of the visual association cortex that is involved in perception of location, visual attention, and control of eye and head movements
