sens2

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

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

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

involved in determining eye movements

• 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

• Location
• Orientation
• Ocular Dominance

appears to respond to motion

appears to respond to color, especially different shades of same color

appears to respond to complex patterns

For finding fruit on trees and judging its ripeness

• 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

proposed that there are three different types of color receptor, each responding maximally to a different wavelength, but having some response to every wavelength

• Some color combinations are impossible
• Adapting to one color produces after-images of a different color

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

The cones respond as the Young Helmholtz theory predicts while ganlion cells respond as Herring's theory predicts

• 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

• 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

People of different cultures probably perceive color the same way

helps highlight edges

• 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

• 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

• Based on non-accidental properties
• Robust to noise

can be recognized from any perspective

• 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

Contour deletion that destroys non-accidental properties is more disruptive to object recognition that contour deletion that preserves non-accidental properties

• 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

• 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

• 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

• 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

Someone who is lying never give Duchenne smile, while someone who is being honest will give a Duchenne smile about 50% of time

• 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

• 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

• 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

• Corresponding retinal points: Object is on the horopter
• Outwardly displaced: Object is closer than the horopter
• Inwardly displaced: Objects is further than the horopter

• 1.Infantile Strabismus: the eyes did not have coordinated movement during infancy and thus disperity-tuned cells never developed
• 2. Genetic Disorder

• 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

Motor control tasks

• 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