Psy 355 Week 2 Review Paper
PSY 355 Exam #2 Review Sheet
Chapter 3: Spatial Vision: From Spots to Stripes
• contrast- the difference in luminance between an object and the background or between lighter and darker parts of the same object
• contrast acuity – the smallest spatial detail that can be resolved (with smallest amount of contrast)
• visual information processing- info goes from retina (optic disc) to -> down optic nerve -> to optic chiasm where fibers cross to opposite hemispheres of brain -> down optic tract -> to LGN (of thalamus) -> thalamus sends info to visual cortex in occipital lobes of each hemisphere
• visual pathways in the brain – optic nerve- leaves each eye at optic disk; information reaches optic chiasm, where medial fibers cross to …show more content…
opposite hemispheres of brain.
Optic tract- carries info to LGN of the thalamus and also to superior colliculi (motion)
Thalamus- sends info to visual cortex in occipital lobes of each hemisphere – where detailed analysis of scene takes place
• lateral geniculate nucleus (LGN) – 6 distinct layers of cells; where axons of ganglion cells first synapse
2 types of layers: magnocellular (bottom 2 layers – large fast moving objects) parvocellular (top 4 layers – details of stationary objects)
Each LGN has a topographical map of half of the visual field
• magnocellular vs. parvocellular layers- magno-bottom 2 layers of the LGN; cells are physically larger. Para- any of top 4 layers of LGN; cells are physically smaller
• contralateral vs. ipsilateral- contra- referring to the opposite side of the brain
Ipsil- referring to the same side of the brain
• topographical mapping of LGN- the orderly mapping of the world in the LGN and the visual cortex; each LGN layer contains a highly organized map of a complete half of the visual field. Provides us with a neural basis for knowing where things are in space
• striate cortex/primary visual cortex/area V1- “layered” organization; consists of 6 major layers; fibers from LGN project mainly to layer 4; more than 100 times as many cells as LGN- major visual transformation takes place here; 2 important features are topography and magnification; cortical magnification of foveal images
• cortical magnification- the amount of cortical area devoted to a specific region in the visual field
• receptive fields in the cortex- neurons in cortex are selectively responsive to specific elements of a visual scene; individual neuron will respond best when the line or edge is at just the right orientation or angle
• orientation tuning- tendency of neurons in striate cortex to respond optimally to certain orientations, and less to others
• ocular dominance- tendency of neurons in striate cortex to respond more rapidly when a stimulus is presented in one eye; could contribute to behavioral habits such as baseball player choosing to bat left handed
• simple and complex cells- simple- a cortical neuron with clearly defined excitatory and inhibitory regions. Complex- a neuron whose receptive-field characteristics cannot be easily predicted by mapping with spots of light; will respond regardless of where the stripe is presented, as long as it is somewhere within the cell’s receptive field
• feature detection- cells’ response to certain orientations of stimulus (stripe)
• columns and hypercolumns- columns- vertical arrangement of neurons that runs perpendicular to the layers; all neurons in column share specific sensitivity for certain orientation. Hypercol- 1-mm block of striate cortex consisting of a collection of columns; each hypercol. Corresponds to one area of the visual field; evaluates all possible orientations and in which eye a stimuls has been received
• Amblyopia- reduced visual acuity in one eye because of abnormal early visual experience; “lazy eye”
• strabismus- where one eye is turned so that it is receiving a view of the world from an abnormal angle; “crossed eyes”
• anisometropia- where the two eyes have very different refractive errors; (one eye is farsighted and the other not)
Chapter 4: Perceiving and Recognizing Objects
• study of perception- study of how incoming sensory information is organized and interpreted in order to extract some meaning about reality
• visual capture- vision most dominant sense in terms of influence on behavior
• extrastriate cortex- region of cortex bordering the primary visual cortex and containing multiple areas involved in visual processing
• “what” and “where” pathways- where: heads up into parietal lobe; important for processing info relating to the location of objects in space and the actions required to interact with them (moving hands, eyes). What: temporal lobe; locus for the explicit acts of object recognition
• middle vision- stage of visual processing that comes after basic features have been extracted from the image (low level vision) and before the object recognition and scene understanding (high level vision); where sensation meets perceotion
• finding edges- important first step to recognizing object; occlusion provides cues for where edges of objects exist
• illusory contours- contour that is perceived because it is the best guess about what is happening in the world at that location; it seems like a contour is present, even if there is no physical evidence at that location
• Gestalt grouping principles- set of rules describing which elements in an image will appear to group together; Gestalt- “form” – the perceptual whole could be greater than the apparent sum of the parts
• grouping rules- (see part 2)
• grouping rule conflict- grouping rules can be overruled by others; common region can overrule proximity as can connectedness
• figure-ground perception- organization of the visual field into objects that stand out from their surrounding; basic component of visual perception
• principles governing figure-ground perception- surroundedness, size, symmetry, parallelism
• relatability- the degree to which two line segments appear to be part of the same contour
• global superiority effect- the finding that the properties of the whole object take precedence over the properties of parts of the object
Chapter 5: The Perception of Color
• basic principles of color perception- 1) detection – wavelengths must be detected. 2) discrimination – we must be able to tell the difference between one wavelength and another. 3) appearance – we want to assign perceived colors to lights and surfaces in the world and for them not to change dramatically as viewing conditions change
• problem of univariance- an infinite set of different wavelength-intensity combinations can elicit exactly the same response from a single type of photoreceptor; one type of photoreceptor cannot make color discriminations based on wavelength
• subtractive color mixing- (painting); a mixture of pigments; if pigments A and B mix, some of the light shining on the surface will be subtracted by A, and some by B – only the remainder contributes to the perception of color
• additive color mixing – (televisions/computer monitors); a mixture of lights; if light A and light B are both reflected from a surface to the eye, in the perception of color the effects of those 2 lights add together
• rods and color vision- scoptic-refers to dim light levels at or below the level of bright moonlight; rods are sensitive to scoptic light levels; but all rods have same sensitivity to wavelengths of light, making it impossible for them to discriminate colors
• trichromatic theory of color vision- (see part 2)
• opponent process theory of color vision- (see part 2)
• explanation of color (of “negative”) afterimages- an afterimage whose polarity is the opposite of the original stimulus; light stimuli produce dark negative afterimages; colors are complementary; for example, red produces green and yellow produces
blue
• color blindness- most cases involve lack of sensitive red or green cones (lack of blue cones is rare); deuteranope – absence of m-cones; protanope – absence of L-cones; these two are associated with red/green colorblindness which is most common
• various types of color deficiency; color-anomalous – 2 types of cones are so similar that they can’t make discriminations. Cone monochromat- only one cone type – truly color blind. Rod monochromat- no cones of any type – badly colorblinded; badly visually impaired
• color constancy- our tendency to perceive familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object; based on light source assumptions and understanding of context (red tomatoes/apples)
• color vision in animals- depends on species; adaptive; color more helpful in finding food; evolves depending on species’ evolutionary needs
Chapter 6: Space Perception and Binocular Vision
• depth perception- seeing objects in 3 dimensions enables us to estimate distance; highly adaptive; involves reliance on both binocular cues (requiring integrated messages from both eyes) and monocular cues (only one eye is necessary)
• monocular cues for depth: • interposition (occlusion)- if one object partially blocks view of another, we perceive it as closer
• relative size- if we assume 2 objects are similar in size, we see one that casts smaller image on retina as farther away
• relative clarity- far away images are typically less clear; clearer = closer
• relative height- objects higher in our field of vision are viewed as farther away
• relative motion (motion parallax)- while moving, objects between you and point of fixation appear to move in opposite direction; objects beyond fixation appear to move in same direction
• linear perspective- parallel lines appear to converge with distance
• texture gradient- gradual change from coarse, distinct texture, to fine, indistinct texture signals increasing distance
• light and shadow- nearby objects reflect more light to our eyes – dimmer objects are perceived as being farther away; shadows give sense of depth consistent with assumed light source (we typically assume light comes from above)
• familiar size- depth cue based on knowledge of typical size of objects
• aerial perspective- depth cue based on implicit understanding that light gets scattered by atmosphere; distant objects appear fainter, bluer and less distinct
• accommodation- process by which the eye/lens changes its focus; lens gets fatter as you focus on objects near you, and thinner as you focus on objects farther away; more accommodation = closer
• binocular cues for depth: • convergence- neuromuscular cue caused by eyes’ greater inward turn when viewing a near object; eyes turned inward- object is closer; eyes turned outward- object is farther • retinal (binocular) disparity- slight difference between each eye’s view of the world; greater disparity- closer; less disparity – farther away
• stereopsis- the ability to use binocular disparity as a cue to depth
• free fusion- the technique of converging (crossing) or diverging the eyes in order to view a stereogram without a stereoscope
• stereoblindness/strabismus- an inability to make use of binocular disparity as a depth cue; this term is typically used to describe individuals with vision in both eyes
• explanation for autostereograms/random dot stereograms (Magic Eye)- a stereogram made of a large number (thousands) of randomly place dots; random dot stereograms contain no monocular cues to depth; stimuli visible stereoscopically in random dot stereograms are Cyclopean stimuli
• binocular rivalry- competition between the 2 eyes for control of visual perception, which is evident when completely different stimuli are presented to the 2 eyes
• stereoacuity- a measure of the smallest binocular disparity that can generate a sensation of depth
• critical period- period of time during development when the organism is particularly susceptible to developmental change; there are CP’s during develop of binocular vision
• suppression- the inhibition of an unwanted image; occurs frequently in persons with strabismus
• perceptual constancy- perceiving objects as unchanging even as illumination and retinal images change; based on reliance on the context or background in which objects are viewed
• shape constancy- perceiving shapes as unchanging
• size constancy (size-distance relationship)- perceived size is based on size of retinal image and perceived distance; objects tend to get smaller as they get farther away
• Ponzo illusion- top image (person) looks bigger because objects farther away are “supposed” to be smaller; wrong “guess” or shortcut made about the 3D world being presented in the 2D picture
• moon illusion- moon looks larger at horizon than directly overhead
• Muller-Lyer illusion-coverging arrow tips make segment AB appear smaller than it really is
• nature (genetic) vs. nurture (experience) influences on size/distance perception- could be due to experience with corners of rooms and buildings (nurture), but works with other shapes as well (nature)
• distorted room illusion- trapezoidal room makes people/objects look bigger as they travel to opposite sides of room
• brightness constancy- a familiar object will appear the same color/brightness regardless of the amount of or colour of light reflecting from it
Chapter 3: Spatial Vision: From Spots to Stripes
• contrast- the difference in luminance between an object and the background or between lighter and darker parts of the same object
• contrast acuity – the smallest spatial detail that can be resolved (with smallest amount of contrast)
• visual information processing- info goes from retina (optic disc) to -> down optic nerve -> to optic chiasm where fibers cross to opposite hemispheres of brain -> down optic tract -> to LGN (of thalamus) -> thalamus sends info to visual cortex in occipital lobes of each hemisphere
• visual pathways in the brain – optic nerve- leaves each eye at optic disk; information reaches optic chiasm, where medial fibers cross to …show more content…
opposite hemispheres of brain.
Optic tract- carries info to LGN of the thalamus and also to superior colliculi (motion)
Thalamus- sends info to visual cortex in occipital lobes of each hemisphere – where detailed analysis of scene takes place
• lateral geniculate nucleus (LGN) – 6 distinct layers of cells; where axons of ganglion cells first synapse
2 types of layers: magnocellular (bottom 2 layers – large fast moving objects) parvocellular (top 4 layers – details of stationary objects)
Each LGN has a topographical map of half of the visual field
• magnocellular vs. parvocellular layers- magno-bottom 2 layers of the LGN; cells are physically larger. Para- any of top 4 layers of LGN; cells are physically smaller
• contralateral vs. ipsilateral- contra- referring to the opposite side of the brain
Ipsil- referring to the same side of the brain
• topographical mapping of LGN- the orderly mapping of the world in the LGN and the visual cortex; each LGN layer contains a highly organized map of a complete half of the visual field. Provides us with a neural basis for knowing where things are in space
• striate cortex/primary visual cortex/area V1- “layered” organization; consists of 6 major layers; fibers from LGN project mainly to layer 4; more than 100 times as many cells as LGN- major visual transformation takes place here; 2 important features are topography and magnification; cortical magnification of foveal images
• cortical magnification- the amount of cortical area devoted to a specific region in the visual field
• receptive fields in the cortex- neurons in cortex are selectively responsive to specific elements of a visual scene; individual neuron will respond best when the line or edge is at just the right orientation or angle
• orientation tuning- tendency of neurons in striate cortex to respond optimally to certain orientations, and less to others
• ocular dominance- tendency of neurons in striate cortex to respond more rapidly when a stimulus is presented in one eye; could contribute to behavioral habits such as baseball player choosing to bat left handed
• simple and complex cells- simple- a cortical neuron with clearly defined excitatory and inhibitory regions. Complex- a neuron whose receptive-field characteristics cannot be easily predicted by mapping with spots of light; will respond regardless of where the stripe is presented, as long as it is somewhere within the cell’s receptive field
• feature detection- cells’ response to certain orientations of stimulus (stripe)
• columns and hypercolumns- columns- vertical arrangement of neurons that runs perpendicular to the layers; all neurons in column share specific sensitivity for certain orientation. Hypercol- 1-mm block of striate cortex consisting of a collection of columns; each hypercol. Corresponds to one area of the visual field; evaluates all possible orientations and in which eye a stimuls has been received
• Amblyopia- reduced visual acuity in one eye because of abnormal early visual experience; “lazy eye”
• strabismus- where one eye is turned so that it is receiving a view of the world from an abnormal angle; “crossed eyes”
• anisometropia- where the two eyes have very different refractive errors; (one eye is farsighted and the other not)
Chapter 4: Perceiving and Recognizing Objects
• study of perception- study of how incoming sensory information is organized and interpreted in order to extract some meaning about reality
• visual capture- vision most dominant sense in terms of influence on behavior
• extrastriate cortex- region of cortex bordering the primary visual cortex and containing multiple areas involved in visual processing
• “what” and “where” pathways- where: heads up into parietal lobe; important for processing info relating to the location of objects in space and the actions required to interact with them (moving hands, eyes). What: temporal lobe; locus for the explicit acts of object recognition
• middle vision- stage of visual processing that comes after basic features have been extracted from the image (low level vision) and before the object recognition and scene understanding (high level vision); where sensation meets perceotion
• finding edges- important first step to recognizing object; occlusion provides cues for where edges of objects exist
• illusory contours- contour that is perceived because it is the best guess about what is happening in the world at that location; it seems like a contour is present, even if there is no physical evidence at that location
• Gestalt grouping principles- set of rules describing which elements in an image will appear to group together; Gestalt- “form” – the perceptual whole could be greater than the apparent sum of the parts
• grouping rules- (see part 2)
• grouping rule conflict- grouping rules can be overruled by others; common region can overrule proximity as can connectedness
• figure-ground perception- organization of the visual field into objects that stand out from their surrounding; basic component of visual perception
• principles governing figure-ground perception- surroundedness, size, symmetry, parallelism
• relatability- the degree to which two line segments appear to be part of the same contour
• global superiority effect- the finding that the properties of the whole object take precedence over the properties of parts of the object
Chapter 5: The Perception of Color
• basic principles of color perception- 1) detection – wavelengths must be detected. 2) discrimination – we must be able to tell the difference between one wavelength and another. 3) appearance – we want to assign perceived colors to lights and surfaces in the world and for them not to change dramatically as viewing conditions change
• problem of univariance- an infinite set of different wavelength-intensity combinations can elicit exactly the same response from a single type of photoreceptor; one type of photoreceptor cannot make color discriminations based on wavelength
• subtractive color mixing- (painting); a mixture of pigments; if pigments A and B mix, some of the light shining on the surface will be subtracted by A, and some by B – only the remainder contributes to the perception of color
• additive color mixing – (televisions/computer monitors); a mixture of lights; if light A and light B are both reflected from a surface to the eye, in the perception of color the effects of those 2 lights add together
• rods and color vision- scoptic-refers to dim light levels at or below the level of bright moonlight; rods are sensitive to scoptic light levels; but all rods have same sensitivity to wavelengths of light, making it impossible for them to discriminate colors
• trichromatic theory of color vision- (see part 2)
• opponent process theory of color vision- (see part 2)
• explanation of color (of “negative”) afterimages- an afterimage whose polarity is the opposite of the original stimulus; light stimuli produce dark negative afterimages; colors are complementary; for example, red produces green and yellow produces
blue
• color blindness- most cases involve lack of sensitive red or green cones (lack of blue cones is rare); deuteranope – absence of m-cones; protanope – absence of L-cones; these two are associated with red/green colorblindness which is most common
• various types of color deficiency; color-anomalous – 2 types of cones are so similar that they can’t make discriminations. Cone monochromat- only one cone type – truly color blind. Rod monochromat- no cones of any type – badly colorblinded; badly visually impaired
• color constancy- our tendency to perceive familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object; based on light source assumptions and understanding of context (red tomatoes/apples)
• color vision in animals- depends on species; adaptive; color more helpful in finding food; evolves depending on species’ evolutionary needs
Chapter 6: Space Perception and Binocular Vision
• depth perception- seeing objects in 3 dimensions enables us to estimate distance; highly adaptive; involves reliance on both binocular cues (requiring integrated messages from both eyes) and monocular cues (only one eye is necessary)
• monocular cues for depth: • interposition (occlusion)- if one object partially blocks view of another, we perceive it as closer
• relative size- if we assume 2 objects are similar in size, we see one that casts smaller image on retina as farther away
• relative clarity- far away images are typically less clear; clearer = closer
• relative height- objects higher in our field of vision are viewed as farther away
• relative motion (motion parallax)- while moving, objects between you and point of fixation appear to move in opposite direction; objects beyond fixation appear to move in same direction
• linear perspective- parallel lines appear to converge with distance
• texture gradient- gradual change from coarse, distinct texture, to fine, indistinct texture signals increasing distance
• light and shadow- nearby objects reflect more light to our eyes – dimmer objects are perceived as being farther away; shadows give sense of depth consistent with assumed light source (we typically assume light comes from above)
• familiar size- depth cue based on knowledge of typical size of objects
• aerial perspective- depth cue based on implicit understanding that light gets scattered by atmosphere; distant objects appear fainter, bluer and less distinct
• accommodation- process by which the eye/lens changes its focus; lens gets fatter as you focus on objects near you, and thinner as you focus on objects farther away; more accommodation = closer
• binocular cues for depth: • convergence- neuromuscular cue caused by eyes’ greater inward turn when viewing a near object; eyes turned inward- object is closer; eyes turned outward- object is farther • retinal (binocular) disparity- slight difference between each eye’s view of the world; greater disparity- closer; less disparity – farther away
• stereopsis- the ability to use binocular disparity as a cue to depth
• free fusion- the technique of converging (crossing) or diverging the eyes in order to view a stereogram without a stereoscope
• stereoblindness/strabismus- an inability to make use of binocular disparity as a depth cue; this term is typically used to describe individuals with vision in both eyes
• explanation for autostereograms/random dot stereograms (Magic Eye)- a stereogram made of a large number (thousands) of randomly place dots; random dot stereograms contain no monocular cues to depth; stimuli visible stereoscopically in random dot stereograms are Cyclopean stimuli
• binocular rivalry- competition between the 2 eyes for control of visual perception, which is evident when completely different stimuli are presented to the 2 eyes
• stereoacuity- a measure of the smallest binocular disparity that can generate a sensation of depth
• critical period- period of time during development when the organism is particularly susceptible to developmental change; there are CP’s during develop of binocular vision
• suppression- the inhibition of an unwanted image; occurs frequently in persons with strabismus
• perceptual constancy- perceiving objects as unchanging even as illumination and retinal images change; based on reliance on the context or background in which objects are viewed
• shape constancy- perceiving shapes as unchanging
• size constancy (size-distance relationship)- perceived size is based on size of retinal image and perceived distance; objects tend to get smaller as they get farther away
• Ponzo illusion- top image (person) looks bigger because objects farther away are “supposed” to be smaller; wrong “guess” or shortcut made about the 3D world being presented in the 2D picture
• moon illusion- moon looks larger at horizon than directly overhead
• Muller-Lyer illusion-coverging arrow tips make segment AB appear smaller than it really is
• nature (genetic) vs. nurture (experience) influences on size/distance perception- could be due to experience with corners of rooms and buildings (nurture), but works with other shapes as well (nature)
• distorted room illusion- trapezoidal room makes people/objects look bigger as they travel to opposite sides of room
• brightness constancy- a familiar object will appear the same color/brightness regardless of the amount of or colour of light reflecting from it