midterm ch 6 vision psych 110

Grouping

Humans have a tendency to organize stimuli into some coherent groups. We like to categorize things and maintain some organization with most stimuli. For example, we meet a new person, and immediately we group them into gender, height, weight, race, etc. This categorization process is done by "grouping" information into logical categories. Read more: http://www.alleydog.com/glossary/definition.php?term=Grouping#ixzz3qkxTRwMd

convergence

A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object

relative height

A monocular cue for perceiving depth; objects higher in our field of vision are perceived as farther away. Relative Height is a concept used in visual and artistic perspective where distant objects are seen or portrayed as being smaller and higher in relation to items that are closer. This phenomenon can be seen when looking at a landscape and seeing that distant objects - trees, rocks, animals, etc. - that are at a distance appear to be smaller and higher than similar objects that are close up. Artists deliberately simulate this effect by portraying distant objects as being both smaller and higher in the perspective of the scene. Read more: http://www.alleydog.com/glossary/definition.php?term=Relative%20Height#ixzz3qkzva4uE

linear perspective

A monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance. Linear Perspective is an artistic or visual term that refers to the eye's sense of depth and distance perception. This is why two identical items will appear to vary in size with the amount of distance involved and why roads appear to narrow with distance. Read more: http://www.alleydog.com/glossary/definition.php?term=Linear%20Perspective#ixzz3ql1umx6x

hue

A particular shade of a given colour Defining hue can be a bit confusing since we have another name for hue; color. Essentially, hue refers to the aspect of color that is determined by the wavelength of light. So, the way humans see and categorize colors is actually hue (blue, green, etc.). Read more: http://www.alleydog.com/glossary/definition.php?term=Hue#ixzz3qkfAUrf1

Sclera

The sclera is commonly referred to as the "whites" of the eye. This is a smooth, white layer on the outside, but the inside is brown and contains grooves that help the tendons of the eye attach properly. The sclera provides structure and safety for the inner workings of the eye, but is also flexible so that the eye can move to seek out objects as necessary.

Visual cliff

The visual cliff is a test given to infants to see if they have developed depth perception. The way it works is there is a platform that is covered with a cloth that is draped all over the place (on the platform, down to the floor, all over...). Then, a piece of glass or other clear material is placed on top of the platform and extends well off of the platform, creating a sort of bridge. An infant is then placed on the platform, and the infant's mother stands on the other side of the clear bridge. The mother calls for the child who, if it crawls off the platform and onto the clear bridge, it does not yet have depth perception. If it stops when it gets to the edge of the platform, looks down, and either is reluctant to cross or refuses to cross, then the child has depth perception. The reason is that the end of the platform looks like a cliff (the child doesn't yet understand that there is some kind of bridge there) and going off the edge of the platform would have bad consequences. Read more: http://www.alleydog.com/glossary/definition.php?term=Visual%20Cliff#ixzz3ql2J0pOh

optic nerve

the nerve that carries neural impulses from the eye to the brain

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhib- ited by red; others are stimulated by red and inhibited by green.

Trichromatic theory of colour vision

the theory that the retina contains three different color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any colour. Young-Helmholtz

Negative after-images

A sensation of opposing colors that occur after staring at a colored stimulus. For example, if you were to stare at a green sheet of paper for an extended period of time, and then switch your focus to a white sheet of paper, an afterimage would appear on the white page. Negative afterimages are cause by stimulation fatigue from your eyes receptors. Read more: http://www.alleydog.com/glossary/definition.php?term=Negative%20Afterimage#ixzz3qks2q2vD

Ames Room

An Ames room is a room built in a distorted manner that produces differing visual illusions. Named after Adelbert Ames, Jr. an Ames room produces two illusions to observers. The first is that the room appears like a cube from a certain angle (seen by looking through a peephole) although the room is a trapezoid in reality. The second visual illusion is that when an individual or object is moved from one corner to another corner they appear to grow or shrink in size. Ames rooms are used to study optical illusions and differing perceptions in individuals. Read more: http://www.alleydog.com/glossary/definition.php?term=Ames%20Room#ixzz3ql5f0Ids

illusions

An illusion is a distortion of a sensory perception. Each of the human senses can be deceived by illusions, but visual illusions are the most well known. Some illusions are subjective; different people may experience an illusion differently, or not at all. Optical illusions, such the use of Mueller Lyer illusion, exploit assumptions made by the human visual system. Auditory illusions, such as the Shepard Tone, exploit our hearing. Touch illusions exploit the human sense of touch. Autokinetic illusion In psychiatry the term illusion refers to a specific form of sensory distortion. Unlike an hallucination, which is a sensory experience in the absence of a stimulus, an illusion describes a distortion of a perception so it is understood and interpreted differently. For example, hearing voices regardless of the environment would be an hallucination, whereas hearing voices which arise only from the sound of running water (or other auditory source) would be an illusion.

Ponzo Illusion

An illusion of size in which two objects of equal size that are positioned between two converging lines appear to be different in size. Also called the railroad track illusion. The Ponzo illusion was first demonstrated in 1913 by an Italian psychologist named Mario Ponzo. The reason the top horizontal line looks longer is because we interpret the scene using linear perspective.

Ciliary Body

Ciliary body is a ring-shaped tissue which holds and controls the movement of the eye lens, and thus, it helps to control the shape of the lens.

Foreground/Background

Figure-ground organization is a type of perceptual grouping which is a vital necessity for recognizing objects through vision. In Gestalt psychology it is known as identifying a figure from the background. For example, you see words on a printed paper as the "figure" and the white sheet as the "background".[1]

Visual Ambiguities

How does the visual system resolves ambiguities by making different types of assumptions.

intensity

Hue intensity (also known as saturation) is the purity or strength of a color. The intensity of a color is how bright or dull it appears and how close it is to the original color. The highest level of intensity a color can have is how it appears on the color spectrum or on a color wheel. A color that is reduced in intensity or purity is called a tone and is less bright than a color higher in intensity. The hue of red can range from pink to maroon to dark blood red. The highest intensity red is the one represented on the color spectrum. As it reduces in intensity it appears less bright and changes from bright red to a more dull red to pink colors. The lowest intensity of a color is when the hue is barely perceptible and appears to almost be the color grey. the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as deter- mined by the wave's amplitude. Read more: http://www.alleydog.com/glossary/definition.php?term=Hue%20Intensity#ixzz3qkfVO4X8

Depth Cues

Humans are able to see things that are both far and near, and can actually identify where those objects are in space (meaning, they can determine if those objects are close or far away). This sort of depth perception requires both of our eyes, which is referred to as binocular cues (depth cues that requires both of our eyes) Read more: http://www.alleydog.com/glossary/definition.php?term=Binocular%20Cues#ixzz3qkxoO4ng igure-ground the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

Interposition

Interposition occurs in instances where one object overlaps the other, which causes us to perceive depth. Learn more about interposition, depth perception, monocular cues, and more. monocular visual cue in which two objects are in the same line of vision and one patially conceals the other, indicating that the first object concealed is further away

parallel processing

Parallel processing is the ability of the brain to do many things (aka, processes) at once. For example, when a person sees an object, they don't see just one thing, but rather many different aspects that together help the person identify the object as a whole. For example, you may see the colors red, black, and silver. These colors alone may not mean too much, but if you also see shapes such as rectangles, circles, and curved shapes, your brain may perceive all the elements simultaneously, put them together and identify it as a car. Note that motion and depth of the object can also be perceived. These cues processed in the brain tell the person that the red car is headed straight at them so they jump out of the way. Without parallel processing, the brain would have to process each aspect of the car separately in progression. By the time the person identified the car, it would be too late. Read more: http://www.alleydog.com/glossary/definition.php?term=Parallel%20Processing#ixzz3qkl1CkNO

Feature Detectors

The ability to detect certain types of stimuli, like movements, shape, and angles, requires specialized cells in the brain called feature detectors. Without these, it would be difficult, if not impossible, to detect a round object, like a baseball, hurdling toward you at 90 miles per hour. Read more: http://www.alleydog.com/glossary/definition.php?term=Feature%20Detectors#ixzz3qkkd1wor

Aqueous Humor

The aqueous humor is a watery substance that fills the eye. It is split into two chambers. The anterior chamber is located in front of the iris, and the posterior chamber is directly behind it. These layers allow the eye to maintain its shape. This liquid is drained through the Schlemm canal so that any buildup in the eye can be removed. If the patient's aqueous humor is not draining properly, they can develop glaucoma.

Choroid

The choroid lies between the retina and the sclera, which provides blood supply to the eye. Just like any other portion of the body, the blood supply gives nutrition to the various parts of the eye.

Cornea

The cornea is the outer covering of the eye. This dome-shaped layer protects your eye from elements that could cause damage to the inner parts of the eye. There are several layers of the cornea, creating a tough layer that provides additional protection. These layers regenerate very quickly, helping the eye to eliminate damage more easily. The cornea also allows the eye to properly focus on light more effectively. Those who are having trouble focusing their eyes properly can have their corneas surgically reshaped to eliminate this problem.

fovea

The fovea is the central focal point on the retina in the eye around which the cones cluster. In fact, the fovea has only cones around it, which are better for detecting fine detail. So, when trying to really see some fine detail or focus something, people tend to move the image onto the fovea (although they may be unaware that this is what they are doing...they just think they are trying to see something better). Read more: http://www.alleydog.com/glossary/definition.php?term=Fovea#ixzz3qkYTlm8U The fovea, also known as the fovea centralis, is a part of the eye, located in the center of the macula region of the retina. [1] [2] The fovea is responsible for sharp central vision, which is necessary in humans for reading, watching television or movies, driving, and any activity where visual detail is of primary importance.

texture gradients

The gradual diminishing of detail that occurs in surfaces as they recede into the distance, compared with objects in the visual field that are close and seen in fine detail texture gradient relates to the ways in which we perceive depth. Specifically, texture gradient is a monocular cue (meaning it can be seen by either eye alone...don't need both eyes) in which there is a gradual change in appearance of objects from coarse to fine - some objects appear closer because they are coarse and more distinct, but gradually become less and less distinct (and more fine) which makes the objects appear to get further and further away. For example, if you look at a photograph of a crowd of people, the people that were closer to the camera are represented in the picture with more coarse and distinct features. But to make the people who were further away actually appear further away in the photo, they are represented by less distinct and finer features Read more: http://www.alleydog.com/glossary/definition.php?term=Textural%20Gradient#ixzz3ql1FFqTW

cones

The human eye has many different parts that are all needed to help us see, including rods, the optic nerve, and cones. The cones are receptor cells that help us see fine details of things and tend to help us see in situations where there is light or daylight. The majority of cones are in the center of the retina (we have approximately 6 million cones in each eye). When you squint to try to read or see something more clearly, what you are actually doing is focusing the image on this grouping of the cones in order to see the fine details. Cones also help us with color perception. Read more: http://www.alleydog.com/glossary/definition.php?term=Cones#ixzz3qkXlamuV

Iris

The iris is the area of the eye that contains the pigment which gives the eye its color. This area surrounds the pupil, and uses the dilator pupillae muscles to widen or close the pupil. This allows the eye to take in more or less light depending on how bright it is around you. If it is too bright, the iris will shrink the pupil so that they eye can focus more effectively.

Lens

The lens sits directly behind the pupil. This is a clear layer that focuses the light the pupil takes in. It is held in place by the ciliary muscles, which allow the lens to change shape depending on the amount of light that hits it so it can be properly focused.

Retina

The light focuses by the lens will be transmitted onto the retina. This is made of rods and cones arranged in layers, which will transmit light into chemicals and electrical pulses. The retina is located in the back of the eye, and is connected to the optic nerves that will transmit the images the eye sees to the brain so they can be interpreted. The back of the retina, known as the macula, will help interpret the details of the object the eye is working to interpret. The center of the macula, known as the fova will increase the detail of these images to a perceivable point.

Pupil

The pupil appears as a black dot in the middle of the eye. This black area is actually a hole that takes in light so the eye can focus on the objects in front of it.

what are the sense receptors in the eye?

The receptors are arrayed along the back of the interior of each eye, in the tissue called the retina. There are two types of cells that act as photoreceptors in the eye: rods and cones. Rods detect only the presence or absence of light without distinguishing between colors, thus giving black and white vision (as at night). Cones detect colors in the images but are less sensitive, i.e. they require more light to function.

Vitreous Humor

The vitreous humor is the gel located in the back of the eye which helps it hold its shape. This gel takes in nutrients from the ciliary body, aqueous humor and the retinal vessels so the eye can remain healthy. When debris finds its way into the vitreous humor, it causes the eye to perceive "floaters," or spots that move across the vision area that cannot be attributed to objects in the environment.

wavelength

The way we measure sound waves, audio waves, and other types of waves is by their length and their height (amplitude). The length of a wave (or wavelength) refers to the distance between the peak of one wave and the peak of the next wave. When the wave reaches its highest point, we use that as the first measure. Then the wave usually goes down to a low point before it begins to go back up, all the way to a high point again. This second point is the next measure. We then simply use the distance between these points to identify the length of the wave. Read more: http://www.alleydog.com/glossary/definition.php?term=Wavelength#ixzz3qkec5Wcm

rods

There are two types of receptor cells in the human eye; the cones and the rods. The rods are the receptors in the eye which detect movement. Rods are also used in night vision. Read more: http://www.alleydog.com/glossary/definition.php?term=Rods#ixzz3qkY3CFKx

Conjunctiva Glands

These are layers of mucus which help keep the outside of the eye moist. If the eye dries out it can become itchy and painful. It can also become more susceptible to damage or infection. If the conjunctiva glands become infected the patient will develop "pink eye."

Lacrimal Glands

These glands are located on the outer corner of each eye. They produce tears which help moisten the eye when it becomes dry, and flush out particles which irritate the eye. As tears flush out potentially dangerous irritants, it becomes easier to focus properly.

retinal disparity

a binocular cue for perceiving depth; by comparing images from the two eyeballs, the brain computes distance - the greater the disparity (difference) between the two images, the close the object

relative clarity

an MC; because light from distant objects passes through more atmosphere, we perceive hay objects are farther away than sharp, clear objects Relative Brightness is a comparison of the brightness of any two objects. This can be done through a specific mathematical equation or simply looking at them and making a judgment. It is also used as a term to compare binoculars. The higher the relative brightness of the binoculars is, the brighter the image will be because more light is taken in the exit pupil (part of the lens of the binoculars. Read more: http://www.alleydog.com/glossary/definition.php?term=Relative%20Brightness#ixzz3ql0q25Ed

relative size

an MC; if we assume that two objects are similar in size, we perceive the one that casts the smaller retinal image as farther away Relative size is a perceptual clue which allows you to determine how close objects are to an object of known size. Sometimes our perceptions are faulty. Humans use relative size to judge the size of the moon. This is why the moon seems bigger and closer when it is near the horizon than when it is high in the sky. We use buildings, trees and other objects of known size to make judgements about the size and closeness of the moon. When the moon is higher in the sky there are no known objects or frame of references to judge the moon's closeness, and thus, appears smaller and farther away. This is called the lunar illusion. Read more: http://www.alleydog.com/glossary/definition.php?term=Relative%20Size#ixzz3qkzi9is6

gestalt

an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of infor- mation into meaningful wholes. The term Gestalt may be defined as an object, idea, or experience as being more than the sum of its parts. When you put the parts together, you get the whole - in other words, you get the Gestalt. Gestalt is the basis of Gestalt Psychology, which is the study of how people integrate and organize perceptual information (information they perceive - things they see, hear, etc) into meaningful wholes. For example, can you tell what this is?: 8> ) The reason you may be able to recognize a face is because you're able to see an overall form (a face) just by putting a few symbols or shapes together. In other words, you see the Gestalt, not just the symbols. This is incredibly useful but can sometimes lead to problems such as illusions or visual tricks. Read more: http://www.alleydog.com/glossary/definition.php?term=Gestalt#ixzz3qkwhf0eN

Monocular Cues

depth cues, such as interposition and linear perspective, available to either eye alone Monocular cues are pieces of information that are taken in when viewing a scene with one eye. These cues include information on motion, perspective, size, texture, light and shading and elevation of items in the visual field. This information is useful for identifying items within the visual field but does not provide the full depth perception of binocular viewing (which is visual information perceived by using both eyes). Read more: http://www.alleydog.com/glossary/definition.php?term=Types%20Of%20Monocular%20Cues#ixzz3qkytV41H

Binocular

depth cues, such as retinal disparity, that depend on the use of two eyes

In what order does light pass through the different cells of the eye?

ganglion cell bipolar cones lens

relative motion

movement in relation to a frame of reference Relative Motion refers to the motion or speed of any object in respect to a particular point. For example, a ball thrown upward while in a moving object such as a bus, would be traveling the same speed with respect to the bus and would fall again in relation to that speed. If the ball stopped in mid-air instead, the ball would hit the back of the bus before falling to the floor. In this example, the relative motion of the ball was described in respect to the bus. If the driver turned left, the ball would also be moving left even if it was stationary on the floor. If the ball was described in relation to a different point, such as a pedestrian on the sidewalk and the bus was moving at 35 mph, it would be traveling faster than the pedestrian. Read more: http://www.alleydog.com/glossary/definition.php?term=Relative%20Motion#ixzz3ql0HkhBA

Visual Constancies

perceptual principles that allow us to view objects as unchanging in terms of their actual size, brightness, shape and orientation regardless of changes to the image the object casts on the retina. Brightness relative to its surrounding stays the same under changing light conditions. Shape e.g. different angle you look at something. Orientation- if you turn on side you still know the true orientation of shape

photoreceptors

photoreceptors are light-sensitive cells, (rods and cones) that are found in the retina of the eye. They are responsible for transmitting sensations of light and color to form, and transmit to the brain, images of what the eye is seeing, Read more: http://www.alleydog.com/glossary/definition.php?term=Photoreceptors#ixzz3qkWrboNt