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type of color blindness caused by the absence of two or three cone types
type of color blindness caused by the absence of one cone type
type of color blindness caused by an abnormality in the pigment of one cone type
increased intensity differnce observed on either side of a dark-light border
inhibition that spreads across a neural network
occurs when two groups with different forms of brain damage show reciprocal abilities
Sensory Deficit Agnosia
occurs when damage to cortex has damaged subject's visual accuity and thus the ability to recognize objects
deficit in which the subject's visual accuity is normal but their shape perception is distorted
deficit in which subject has no distortion in shape perception but still cannot recognize objects
inability to recognize faces
smile that constricts zygomatic and obicularis oculi muscles of the cheek and eye, which produces squinting of eyes and pronounced crow's feet
properties of a 2D image that, in general, do not change as a viewer's perspective of the object changes
Inverse Optics Problem
refers to the fact that any 2D image can be created by an infinite number of 3D environments
as one moves through the environment, nearer stationary objects move faster than further stationary objects
the retinal image on the two eyes is slightly different and this difference provides and absolute depth cue
imaginary arc passing through point of fixation. Objects on horopter fall on corresponding points on the two retinas
area around the horopter in which the retinal images are fused and one object is perceived
What is the function of the collicular pathway?
involved in determining eye movements
Name the three types of cells in found in V1 and what stimuli each responds to
- Simple Cells: respond to bars in particular location and orientation
- Complex Cells: respond to bars in a particular location at particular orientation that are moving
- End-stopped Cells: respond to bars in a particular location at particular orientation and length
What are the three types of columns found in V1?
- Ocular Dominance
What is the function of MT?
appears to respond to motion
What is the function V4?
appears to respond to color, especially different shades of same color
What is the function of IT?
appears to respond to complex patterns
Why do we have color vision?
For finding fruit on trees and judging its ripeness
Describe the procedure and results of color matching experiments
- Procedure: Subjects are shown a light with a pure wavelength. They are provided three lights of different wavelenghts and asked to change the intensities of these lights to match the pure wavelength light.
- Results: 3, and only 3, lights are all that are required to match any pure wavelength light
Explain Young-Helmholtz theory of color perception
proposed that there are three different types of color receptor, each responding maximally to a different wavelength, but having some response to every wavelength
What empirical facts did Hering try to explain with the Opponent Process theory?
- Some color combinations are impossible
- Adapting to one color produces after-images of a different color
Explain Herring's Opponent Process Theory
proposed that there are three different types of color receptors that work in pairs (red-green, yellow-blue, black-white). each receptor is excited by one of the pair and inhibited by the other
How were the two different color theories resolved?
The cones respond as the Young Helmholtz theory predicts while ganlion cells respond as Herring's theory predicts
Name each type and subtype of color blindness and its cause
- Monochromatism: two or three cone types are missing
- Dichromatism: one cone type is missing
- *Protanopia: loss of long wavelength cone
- *Deuteranopia: loss of medium wavelength cone
- *Tritanopia: loss of short wavelength cone
- Anomalous trichromatism: one cone-type has an abnormal pigment
- *Protanomaly: long wavelength cones are abnormally close to medium
- *Deuteranomaly: medium wavelength cones are abnormally close to long
- *Tritanomaly: short wavelength cone have abnormal pigment
How do people with different types of color blindness perform relative to normals in color matching experiments?
- Dichromatism: only need two lights to match pure wavelength light
- Anomolous Trichromatism: need three lights to match pure wavelength, but their results will look wrong to normals
What is the significance of the Berlin & Kay experiments?
People of different cultures probably perceive color the same way
Why is the lateral inhibition that creates Mach Bands important?
helps highlight edges
What four facts about human object recognition must theories account for?
- It is extremely fast
- People can recognize objects they have never seen before
- People can recognize objects that are partially occluded
- People can recognize objects at any size, position, orientation
What are the three types of Object Recognition Theory?
- Template theory: shapes stored in memory as templates, stimulus compared to templates in memory and template with most matches indicates pattern that is present
- problem: input must be normalized, no solution for overcoming depth rotation, unclear how recognition of new objects and partial occlution would work
- Feature theory: objects stored in memory as lists of features, features in stimulus are tallied and comapared to list in memory, object with highest number of matching features indiates pattern present
- problem: make incorrect prediction that scrambled objects should be recognized
- Structural-Description theory: objects stored in memory as collections of features and the relations among the features, features and relations extracted from input and compared to shape descriptions in memory
- problem: unclear which features and relations are necessary
What are the properties of geons?
- Based on non-accidental properties
- Robust to noise
Why is it important that the geons are based on non-accidental properties?
can be recognized from any perspective
What are the steps in the object recognition process according to Recognition by Components (RBC)?
- 1. Edges are extracted from image
- 2. Image edges are parsed into parts and non-accidental properties are determined
- 3. The identity of the geons is determined
- 4. The relations among the geons are determined
- 5. The best match in memory is found
What is one piece of evidence in favor of RBC?
Contour deletion that destroys non-accidental properties is more disruptive to object recognition that contour deletion that preserves non-accidental properties
Explain procedure, results, and significance of Ungerlieder and Mishkin experiments
- Procedure: Ablated cells in Posterior Parietal (PP) for one group of monkeys. Ablated cells in Inferior Temporal (IT) for another group of monkeys. Tested both groups of monkey on tasks of recognizing objects and spatial location.
- Results: Monkeys with PP ablated cells did well on object recognition but could not perform spatial location. Monkeys with IT ablated cells showed reciprocal results.
- Significance: Dorsal (PP) pathway codes location, while Ventral (IT) pathway codes identity
What is the anatomical cause for the three types of agnosia?
- Sensory Deficit Agnosia: damage to V1 (occipital lobe) in both hemishperes
- Apperceptive Agnosia: damage to right temporal or right parietal lobe
- Associative Agnosia: damage to both hemispheres at the occipital-temporal junction
How would RBC explain the three types of agnosia?
- Sensory Deficit Agnosia: Cannot perform step 1; extract edges
- Apperceptive Agnosia: Cannot perform step 2; determine non-accidental properties
- Associative Agnosia: Cannot perform step 4 or 5; identify relations or find best match in memory
What are three pieces of evidence that face recognition and object recognition use two separate processes?
- 1. Different parts of the brain are involved in the two tasks
- 2. Faces are difficult to recognize in photgraphic negatives but objects are not
- 3. Faces are difficult to recognize upside-down but objects are not
What is the best perceptual cue for determining whether someone is lying?
Someone who is lying never give Duchenne smile, while someone who is being honest will give a Duchenne smile about 50% of time
What are the four types of depth cues?
- 1. Oculomotor cues: muscular changes that accompany focusing on an object can be used as absolute depth cue
- 2. Pictorial cues: cues to depth that can be represented in a 2D picture
- 3. Motion produced cues: cues to depth that rely on motion of the observer
- 4. Binocular Disperity: the retinal image on the two eyes is slightly different an dthis difference produces an absolute depth cue
Name the eight pictorial depth cues
- 1. Interposition (overlap): closer objects overlap further objects
- 2. Aerial perspective: outside objects further away appear less sharp and bluer than nearer objects
- 3. Size in the Field of View: in general, nearer items take up more of the visual field than further items.
- 4. Height in the Field of View: objects below the horizon appear higher in the field of view the further away they are. Objects above the horizon appear lower in visual field the further away they are.
- 5. Shading: convex shapes have lighter surfaces on top and darker on the bottom. this pattern is reversed for concave objects
- 6. Texture Gradients: texture elements of a surface become more dense as distance increases
- 7. Linear Perspective: Parallel lines tend to converge as tehy receed into depth
- 8. Familiarity: knowledge of the absolute size of objects can be used to determine how far away they are
What are the two types of motion produced cues?
- 1. Motion Parallax
- 2. Deletion and Accretion: when moving in a direction, not perpendicular to 2 objects, the nearer objedct will cover more of the further object if motion is in one direction and less if motion is in the opposite direction
What does the correspondence of an objects' retinal images tell you about its location?
- Corresponding retinal points: Object is on the horopter
- Outwardly displaced: Object is closer than the horopter
- Inwardly displaced: Objects is further than the horopter
What are the two causes of stereo blindness?
- 1.Infantile Strabismus: the eyes did not have coordinated movement during infancy and thus disperity-tuned cells never developed
- 2. Genetic Disorder
What are the three pieces of evidence suggesting that stereo vision is not as important to normal perception as other depth cues?
- 1. People who are stereo-blind often don't realize it
- 2. At long distances, stereopsis is not useful
- 3. Object recognition is not enhanced by stereopsis
What is stereopsis useful for?
Motor control tasks
What are the two types of oculomotor depth cues?
- 1. Convergence: the more the eyes converge to focus on an object, the closer it is
- 2. Accomadation: the more the lens bulges to focus on an object, the closer it is
Draw neural circuit that produces Mach Bands