perception2.doc

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PERCEPTIONDefinition:

It is a constructive process by which we go beyond the stimuli that are presented tous and attempt to construct a meaningful situation

OR

A process organism interprets and organizes sensation to produce a meaningful

experience of the world

The Gestalt Laws of organization

A series of principles that describes how we organize bits and pieces of information into

meaningful wholes. The principles were set in forth in the early 1900s by a group of Germanpsychologists who studied patterns, or gestalts. They discovered a number of principles that arevalid for vision, some of them are given below

Closure: In this type of principle we most likely fill empty spaces to find what real picture is.

This principle is also applied to the students of learn alphabets

Proximity: The law of proximity

states that the closer objects is to

one another the more likely we are

to mentally group them together.

We perceive group of boxes that

are closet to one another, note that

we do not see the second and third boxes from the left as pair because they are spaced farther

apart


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Simplicity:

This law states that the people intuitively prefer the simplest, most stable of possible

organization.

The law of simplicity states that you will see the illustration as three overlapping disks, becausethat is the simplest interpretation.

Similarity: The law of similarity leads us to link to gather parts of visual field that are similar in

color, lightness, shape, texture, or any other quality

If peoples are exposed to picture given below they will perceive the rows of circles of same color

rather they perceive the columns of circles blue and red colors

One fundamental gestalt principle that remains influential that two objects considered togetherform a whole that is different from the simple combination of objects. In nut shell images are

perceived as pattern or a whole rather than merely sum of distinct.

Feature Analysis: Focusing on the parts of the whole

We perceive a shape, pattern or object through the reaction of specific neurons to the individual

element that make up the stimulus. Features analysis begins with the evidence that individualneurons in the brain are sensitive to specific spatial configuration such as angles, curves, shapes

and edges. The presence of these neurons suggests that any stimulus can be broken down into a

series of components features.fir example: The letter R is a combination of vertical line, a


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diagonal line, and a half circle.

According to the features analysis the brains perceptual processing system initially respond to its

component parts. Psychologist Anne Treisman has a different perspective. She suggests that the

perception of objects is best understood in the terms of a two stage processes (preattentive stage& focused attention stage)

In preattentive stage we focus on physical features of stimulus such as its size, shape, color.

In focused attention stage we pay attention to particular features of an object choosing and

emphasizing features that were initially considered separately

Top-Down processing &Bottom-down processing

Ca- yo- re-d tis en-en-e w-ic- ha- ev-ry ir-d l-tt-r m-ss-ng. If you look at this you will not fell

too much difficulty to read this sentence which says that (Can you read this sentence which hasevery third letter missing). You are able to read because of two simultaneous processes Top-down& Bottom-Down processing

Top-Down processing: perception that is guided by higher level knowledge, experience,

expectation and motivation. You are able to do something because of your experience or anything

else. Top-Down processing is illustrated by the importance of context in determining how weperceive

Example: A B C D E F

10 11 12 13 14

Here id we read above line we read it as English alphabet but if we read line below we read them

as numbers. If you concentrate more on this you will find that B in alphabet and 13 in numbersare same but we gave them different meaning because of their context

Bottom-up processing: perception that consists of progression of recognizing and [processing

information from individual component of stimuli and moving to the perception of whole. Before

understanding any word we must understand the individual letter, if we do not the letter than wecan not know the word

Perceptual Consistency: It is a phenomenon in which physical objects are perceived asunvarying and consistent despite id changes in their appreances or in the physical environment.

Its example can be when you see a person at a great distance from you; you do not perceive thatperson is of normal size and far away. Similarly when we view a skyscraper from far away its

image on our retina is small yet we perceive the building as very large

Depth perception: Translating 2-D to 3-D


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The ability to view the world in three dimensions and perceive distances is known as depth

perception. Different images are formed by our both eyes. The difference in the image seen by

left eye and right eye binocular disparity. You can predict the distances by binocular disparity atlength less than 3 meters

The prediction of distance of far away objects id perceived by the monocular cues that is to obtain

the sense of depth and perception only by one eye. Few of the monocular cues are given below

Motion Perception: It is the change in the position of an object on the retina caused by themovement of your body relative to the object. When you are in a car you see the trees nearer to

moving backwards with greater speed but the trees far away from you seems to move forward

with slower speed

Relative Size: Two objects of same size gives different images on the retina when they are neareror far away from you

Texture Gradient: It provides information about distance because the details of the things that are

far away are less distinct. The mountain away from you will A texture gradient arises whenever

we view a surface from a slant, rather than directly from above

Linear Perspective: Train road appears away from each other when viewed nearer but it appearscloser to each other when viewed from a distance.

Motion perception: As worlds turns

The speed and location of a body is judged by perception of motion. For one thing the movement

of an object across the retina is perceived relative to some stable like a batter perceive the speedand location of ball by relating it to the pitch which is not in motion. When ball comes closer to

us the image on the retina is expanding but we so not perceive that the ball is expanding rather we

perceive is coming nearer. The movement of image across the retina brings about the perceptionof motion. If we perceive we see that expanding stimulus viewed at constant distance then we

would perceive the world as moving every time we move our heads.

Illusion

A visual illusion occurs when your perceptual experience of a stimulus is substantially different

from the actual stimulus you are viewing. To experience another illusion, look at the illustration

entitled Zllner Illusion. What shape do you see? You may see a trapezoid that is wider at thetop, but the actual shape is a square. Such illusions are natural artifacts of the way our visual

systems work. As a result, illusions provide important insights into the functioning of the visualsystem. In addition, visual illusions are fun to experience.


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Subliminal Perception: perception of stimuli about which a person has no awareness. The termsubliminalmeans literally below the threshold. In psychological usage the threshold is the level

at which a person is aware of a stimulus, such as light or sound. For example, a person with

normal hearing can hear any sound from 20 cycles per second at the bottom threshold to 20,000cycles per second at the top. There is some indication, however, that a persons senses can to

some degree receive and transmit stimuli to the brain that are below the threshold and can do so

without that person being aware of it

Extrasensory Perception (ESP): knowledge of external objects or events without the aid of thesenses. Since ancient times, people have wondered about various so-called psychic experiences

that seem to defy scientific explanation. Often these phenomena have been associated withcommunication with the dead. Mediums, which purport to mediate between the living and thedead, were particularly popular in the 19th century. Often mediums deliver utterances while in a

trancelike state, and their followers believe that they can deliver messages from the deceased.

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