BEHAVIOUR AS WE know it our own private experience,and the reported experience of others would be impossible witout some way of knowing about the world around us.IT IS THROUGH OUR SENSES that we know about the worldand some simple experiences called sensation are closely tied to what is happening in the sensory system themselves.COLOUR,BRIGHTNESS,THE PITCH OF THE TONE AND BITTER TASTE are example of sensation.

SENSORY CHANNELS
VISION,HEARING,TASTE,SMELL AND TOUCH are the so-colled five senses but number of human senses is closer to ten then five.IN ADDITION to touch the skin contains separates warmth,cold and pain senses.EACH SENSORY SYSTEM is the kind of channel,consisting of the sensative elements [THE RECEPTOR],nerve fiber leading from this receptor to the brain or spinal code,and the various relay stations and processing areas within the brain.WHEN THE sensory channel is stimulated,we have a sensation that is characteristic of that channel.

IN ORDER FOR US to know about the world around us,physical activity must be changed into activity within the NERVOUS SYSTEM.THE PROCESS of converting physical energy into nervous system activity is called TRANSDUCTION.IT OCCURES at the receptor cell which are specialized for the most efficient conversion of one kind of energy.IN GENERAL, during the transduction process,receptor cell convert physicial energy into an electric VOLTAGE,or potentiol called the RECEPTOR POTENTIAL.IN SOME sensory system the receptior potential itself directly trigger the nerve impulses that travel to the brain and spinal code.

SENSORY PROCESS:VISION

VISION START with the ELECTROMAGNETIC RADITION that object emit or reflect.SO WE can think of it as electric charge moving through space at apprioxmately 300 million meters per seconds.ELECTROMAGENTIC RADITION has wavelike properties.These waves can be measured and classified in terms of the distance from the peak of one wave to the peak of the next.THE ENTIRE range of wavelength is called the ELECTROMAGENTIC SPECTRUM.

STRUCTURE OF THE EYE AND SEEING

LIGHT ENTERS the eye through the PUPIL,travel through the CORENA,THE LENS,AND THE INTERIOR OF THE EYEBALL to strike the rod and con cells of the retina at the back of the EYEBALL.TRANSDUCTION of the physical energy into receptor potential occurs in the rod and con cells.NERVE IMPULSES are then generated in certain other cells of the retina,these impulses travel to the brain along the optic nerve,and their pattern signals a visual event in the enviorment.

THE AMOUNT of light striking the photosensative rodes and cons is automatically adjusted by the REFLEX MECHANISM that regulate the size of the pupil-the opening which admit light to the eye.THE RAYS of light are bent by the corena and lens to bring them to a focus on the retina.most of the LIGHT BENDING IN THE EYE IS DONE BY the corena,and the lens by changing its shape.

THE RETINA AND SEEING

THE WORD RETINA MEANS [network] is a complex sheets of cells and fibers at the back of the eyeball.RODS AND CONS two type of cells are the light sensative elements of the retina where the transduction process beings.THE RODS are CYLINDRICAL in shape,while the cones are rather tapered.IT IS estimated that human eye contain about 120 million rods and about six million cones.THE RODS AND CONES are not spread uniformily over retina.IN THE blind spot there is no rods and no cones therefore no vision is possible.THE BLIND SPOT is the region of the retina where the optic nerve fibers leave and where the blood vessels enters and leave the retina;so it is called the optic disc.CONES are most numerous in a specialized region of the retina which is known as FOVEA, WHICH Contain no rods at all.THE RODS occurs most abundately around the back of the eyeball from the fovea.THE FOVEA meaning ['pit'] is the part of the retina that we use in looking at object we wish to see clearly.

TRANSDUCTION IN VISION

THE RODS and cones contain what are known as PHOTOSENSATIVE PIGMENTS.WHEN electromagentic energy in the visible spectrum-light-strike these pigments,some of the light energy is absorved by the pigments and chemical change is occure which initiate the chain of event involved in seeing.

THE VISUAL PATHWAY IN BRAIN

GANGOLIN CELLS have long fibers that leave the retina throgh the optic disc to make up the optic nerve.THE PATTERN of nerve impulse in these fibers carry information about the light that struck the rods and cones.THE AXON the gangoline cell in the optic nerve reach the lateral geniculate body of the thalamus there they make connection,with the cells of the lateral geniculate body,then fiber from the lateral geniculate cells carry nerve impulses to the primary visual sensory area at the back of the brain.

SOME STIMUL-SENSATION RELATIONSHIP IN VISIONA VISUAL experience can have hue, brightness and form.further the hue may be more or less mixed with white in other words,more or less saturated.SENSATION OF HUE,or colour depend primerly on the wavelength of the light.IF OTHER things are controll we sense a single wavelength,such as might be produced by the prism,as a particuler colour.IF SEVERAL wavelength are mixed together as usually happens hue depend upon the proportion contributed by the component wavelength.IF ALL THE wavelength of the visible spectrum are mixed together,we experienced white light.FOR EVERY hue there is a complementry hue and complementry hue when mixed in the proper portion produce a sensation of the white and gray.

SATURATION
WHEN HUES OF LIGHT ARE mixed the resulting colour is different not only in hue but also in saturation.A COLOUR saturation is the degree to which it is not diluted by the whiteness.FOR EXAMPLE, if we take a wavelength giving rise to an experience of blue and add white light to it,we do not change the hue it is still blue.BUT THE HUE is paler;it is''light blue'' rather then a ''rich blue''.so saturation depend upon the ratio of the energy in the dominion wavelength to the amount of white light.

BRIGHTNESS

ANOTHER MAJOR dimension of the visual experience is brightness.other things being equal the intensity of the physical stimulates is the major determinor of the brightness sensation.THE DIMENSION of brightness extend from black to white and through various shades of gray.

FORM
BASICALLY,visual sensation of form or shape depened upon difference in the amount of energy focused on different parts of retina.

TO BE CONTINUED

LINK
INTRODUCTION TO PSYCHOLOGHY

regards

HEARING IS PROBEBLY second only to vision as a channel through which we can learn about and appricate our world.THROUGH HEARING,we can understand speech-our chief medium for imparting and acquiring knowledge.THROUGH HEARING,too,we receive a great many signals and cues-THE warning automobile horn,THE chime of a clock,THE fire engine siren.

THE PHYSICAL STIMULS FOR HEARING,

WHEN AN OBJECT VIBERATES,the molecule of air around it are pushed together and thus are put under positive pressure.IN TURN,they push against the molecules close to them,and these molecules transmit the pressure to neighbouring molecules.A WAVE OF pressure move through the air in much the same way that ripples mnoves on the water.HOWEVER,SOUND PRESSURE waves travel much faster then do waves of water;at sea level,and at a temparture of 20 centigrade,they travel at about 760 miles per hour,or approaxmately 1,130 feet per second.

MOST OBJECT DO NOT MOve pr viberates,in only one direction when struck.A PLUCKED violin string,for example,viberates back and forth.AS THE string moves in one direction,a positive-pressure wave begins to move through the air.BUT WHEN THE strings swing back to its original position and beyond,a little vaccum,or negative pressure,is created just behind the wave of positive pressure.THE VACCUM moves with the speed of sound,just as the positive-pressure wave does.THE ALTERNATION in air pressure moving in all direction from the source are called sound waves,and such sound waves are the physicial stimuls for every thing we hear.

INTENSITY AND DECIBELS

SOUND PRESSURE CAN vary in intensity,as represented by the heights,or amplitudes,of the waves.INTENSITY REFERS to how great the pressure change in the waves are and degree of intensity are related to the sensation of loudness.THE UNIT used to measure the intensity of sound pressure is the DECIBEL.FOR MOST PRACTIAL PURPOSES,we can regard a decibel scale as simply a set of numbers,like a scale of temparature,and then learn that certain numbers corresspounded to certain sensation of loudness.

FREQUENCY

THE FREQUENCY OF a sound a wave is simply the number of the cycles of pressure change occuring within one second.ONE cycle per second is called a HERTZ[HZ]

COMPLEX WAVEFORMS

MOST OF THE sound we hear in everyday life are the result of complex waves.COMPLEX WAVES can take many forms,but,in general,they are PERODIC,or APERIODIC.this means THEY HAVE that they either have a repittive pattern occuring over and over again or they consists of waves with various amplitude and frequencies occuring irregularly.

STRUCTURE OF THE EAR AND HEARING,

IN ORDER FOR US TO HEAR,our nervous system must be set into motion.PHYSCIAL ENERGY must be converted,or transduced,into electrical activity by the auditory receptors.IT ALL begins with mehnical event in the ear.THE EAR HAS three main parts:THE external ear,which collects the energy;THE middle ear,which transmitt the energy;and THE inner ear,where the transduction of energy into nerve impulses is actually occures.THE PINNA of the external ear collect energy,which travel through a small air-filled duct called the auditory canal to the eardrum.THE EARDRUM IS a thin membrane strected tightly across the inner end of the canal.ALTERNATION IN the pressure of the sound wave move this small membrane back and forth.THE OSCILLATION OF THE EARDRUM,intrun moves three small bones,the OSSICLES ,so that viberation is conducted through the middle ear to the enterance of the COCHLEA,IN THe inner ear.THE BONES of the MIDDL EAR are connected like a series of levers.HENCE ENERGY is transmitted mechanicially and amplification take place through the MIDDLE EAR.

THE INNER EAR sense organs for hearing are contained in a bony structure that is spiraled like a snake and called THE COHLEA meaning[snail shell].THE COHLEA has three fluid-filled canals spirling around together aqnd sepreted from one another by MEMBRANES.AS THE OSSICLES, moves back and forth,one of them,the staps pressure on a membrane called the oval window,which seals off the end of the VESTIBULER CANAL OF THE COCHLEA.THE WAVES in the cochlea reach the organ of the CORTI,which lies on the BASILAR membrane.THE PRESSURE waves in the cochlea canal produce bending movement of the FINE,HAIRLIKE PROCESS on the end of the hair cells of the organ of corti.WHEN THESE hairlike process are bent,receptior potential are initated,thus starting the process by which nerve impulses are generated.THE NERVE IMPULSES initated in the COCHELA,travel into the BRAIN,AND Then along certain nerve fiber within the brain.THESE FIBERS,and the nerve cell,from which they originated,make up what is called the AUDITORY PATHWAY.

SOME STIMUL-SENSATION RELATIONSHIP IN HEARING

WHILE THE FREQUENCY of pressure waves can vary over a wide range,human beings are sensative to only a relatively narrow band of frequenicies.GENERALLY SPEAKING,the audioable range of human being is between 20 and 20,000 hertz.OTHER ANIMALS have different ranges doges,for instance can detect higher frequiencies then human beings.OUR EXPERIENCE OF PITCH[how loud and slow the sound seems]depend largely but not entirely on the frequency of the sound wave:LOW FREQUINCES have low pitches,and HIGHER FREQUENCIES give sensation of higher pitch.

to be continued
link
AN INTRODUCTION TO PSYCHOLOGY

REGARD

__________________
''A man is not finished if he is defeated, he is finished if he quits.''

IT IS THROUGH SMELL,OF COURSE that we detect and experience many events in the chemical world that surrounds us.BUT SMELL MAY also have a special role to play in behaviour.SMELL SEEMS to trigger behaviour and start train of thoughts,SMELL judged as pleasent may set off behaviour,while SMELL JUDGED as unpleasent may arouse avoidance behaviour.

THE RECEPTOR OF SMELL,respond to chemical substances,especially if those substances are volatile.smell receptors are located HIGH UP IN THE NASAL PASSAGES LEADING FROM THE NOSTRIL TO THROAT.they lie in two small pataches:ONE ON THE LEFT,ONE ON THE RIGHT,in the roof of these passages.SINCE THEY ARE a little off the main route of air as it moves through the nose in normal breathing,our sense of smell is relatevly dull when we are breathing normaly and quietly.A SHUDDEN SNIFF or vigiours intake of air however,stir up the air in the nasal pessage and brings more of it to the receptors.

THE SENSTIVITY OF THE smell receptor is impressive,peoples can detect incredibly small amounts of odorus substances.IF WE RECALL ALL of the odors that we encounter in the day,we will realize that they have many shades and qualities.SCIENTIST HAVE raised the question of whether such a multitude of sensations might not result from mixture of relatevly few primary qualities.PERHAP THERE are a few uniqe odors which mixed in different propotion,might account for the various discriminable odors.a number of BASIC ODORS SYSTEM HAVE BEEN PROPOSED.each system serve some particuler purpose.

SENSORY PROCESS TASTE,

THE RECEPTOR FOR TASTE are specialized cell grouped together in little clusters known as TASTE BUDS.MOST OF THESE taste buds are located ON THE TOP AND SIDE OF THE TONGUE,but few of them are located at the back of MOUTH AND THROAT.IF WE LOOK closely our tongue in a mirror we will notice a number of bump on it.THESE bumps are called PAPILLAC,are richly populated with taste buds.TASTE SENSTIVITY IS not nearly so keen as smell senstivity.

PRIMARY TASTE QUALITIES

WE KNOW MORE about the primary taste qualities then we do about the primary odors qualities.SEVERAL LINES of evidence point to four basic taste qualities:SALTY,SOUR,SWEET,AND BITTER.PART OF THE evidance for these qualities is the fact that tounge is not uniformaly senstaive to all stimuls.IF WE try to state what kind of solutions give rise to different qualities,we may see,that suger taste sweet but so do many other chemical compounds such as SACCHARINE,that chemically have little in common with suger.A BITTER taste present a same problem.

SENSORY PROCESS:THE SKIN SENSES

IN ORDER TO ADAPT to enviorment,we need to know what is happening at the surface of our bodies.THE SKIN SENSES give us this information,and skin can be taught as GAINT SKIN ORGAN,that covers the body.FOUR SKIN senses are usually distinguished,PRESSURE OR TOUCH,COLD,WARMTH,AND PAIN.MOST OF what we receive from the skin senses result in such simple sensetion as itching,tingling,feeling of hot and cold,or painful sensation of injury.

THE SKIN IS not uniformaly sensative,it has PUNCHATE SENSTIVITY,meaning that it is sensative at some points and not so sensative at others.IN GENERAL,the spots of greatest senstivity to touch,cold,warmth,and pain stimuls are different.

PRESSURE OR TOUCH

THE SENSATION,a person who is touched lightly on the skin report is called pressure or touch.

COLD AND WARMTH SENSATION,

ARE ELICTED BY CHANGE IN the normal griendent of skin temparature.,that is by change in the difference between the temparature of the skin and the temparature of blood benath it.THE TEMPARATURE of the skin surface is usually about 32 or 34 centigrade,and that of the blood benath is about 37 centigrade.A STIMUL OF 28 to 30 c might be feel as cold or if we increase this griendient,a stimul of 34 c will be feel as warmth.

PAIN

PAIN IS a skin sense but of course,it can be felt from the interior of the body too.this sense has great significance in human life.IT MOTIVATES multitude of behaviours,peoples will do many things to reduce it.MANY DIFFERENT STIMUL produce pain,A NEEDLE PICK,scalding steam,A CUT,a hard blow to the skin,inflammation and swelling,OR STRONG CHEMICAL STIMULATION OF THE SKIN.

LINK
INTRODUCTION TO PSYCHOLOGY

REGARD

__________________
''A man is not finished if he is defeated, he is finished if he quits.''

THE PROCESS OF PRECEPTION stands midway along a continuum from direct sensing to thicking .IN ITS PUREST FORM,sensing does not involve the use of learning based on past experiences.THINKING,at the other end of the continuum,is independent of stimuls from physically present objects.IT CAN BE ACCOMPLISHED,purely through the use of symbols which represents absecent objects and relationship among them.PRECEPTION,use both sensory data from present stimulation and the learning gained from past experiences.IT IS THROUGH PERCEPTION ,that we make sense out of many stimuls impinging on us and maintaqin the experience of continuing,stable,enviorment despite the fact that these stimuls are CONTINUING CHANGING AND SHIFTING.



PRECEPTION IS AN active process.FAR FROM BEING,just a mirror whereby,we become aware of what is ''OUT THERE'',preception is a process whereby sensory cues and relavent past experiences are oragnized to give us the most structured,meaningful pictures possible under the circumstances.THUS PRECEPTION is never just a POINT-FOR-POINT,representation of the stimuls fields but include object,relationship,and point of special focus.OFTEN,IN FACT parts of stimuls fields are ignored,distorted,exaggerated,or change to make a more stable or meaningful whole.PRECEPTION NOT ONLY, structure or interpret incoming stimulation but often fill in missing details.WHEN YOU LOOK at sofa,you cannot see all sides of it and perhaps cannot even see one of the legs;yet you ''see'' the sofa as being solid and whole and you recognize it.PRECEPTION IS very personal thing,IT ENABLES THE PERSON TO KNOW where he stands in relations to the object,condition,and people in his enviorment to act accordingly.



PRECEPTUAL ORGANAZATION


WHEN SEVERAL objects are present in the visual field,we tend to perceived them as organazied into patterns and groupings.SUCH ORGANAZTION was studied intensively in the early part of this century by the GESTAULT PSYCHOLOGHIST.THEY EMPHASIZED that oraganized perceptual experience has properties which cannot be predicted from a simple analysis of the components.IN OTHER WORDS,they said that ''the whole is more then the sum of its parts''.ORAGANAZTION IN perception partially explain our perception of COMPLEX patterns as unitary forms,or objects.WE SEE objects as objects only because grouping process operate in perceptiion.WITOUT THEM,the various objects and patterns we perceive,a face on a television set,a tree, a book,would not hang together as objects.



SOME LAW OF PERCEPTION ORGANAZTION


WHAT ARE some law of perceptual organaztion? ONE oraganizing principle is PROXMITY,OR NEARNESS.for example,we see three pair of VERTICAL LINES instead of six single lines.THE LAW of proxmity says that item which are close together in time and space tend to be perceived as BELONGING together or forming an organized group.ANOTHER principle is SIMLARITY,most peoples see one TRIANGLE,formed by the dots with its apex at the top AND another triangle formed by the rings with its apexat the BOTTOM.THEY PERCEIVE triangles because similer items THE DOTS AND THE RINGS,tend to be oraganized together.


GROUPING accordingly to similarity,however,does not always occurs.THE LAW of good figure says that there is tendancy to oraganize things to make a balanced or symmetrical figures that include all the parts.ANOTHER PRICIPLE is CONTINUATION,the tedency to perceive the line that starts in one way as continuing in the same way.FOR EXAMPLE a line that starts out as a curve is seen as continuing on a smoothly covered course.FINALLY THE law of CLOSURE makes our perceived world ofv form more complete then the SENSORY STIMULATION that is presented.THE LAW OF CLOSURE, refers to perceptual process,that oraganized the perceived world by filling in gaps in stimulations.



PERCEPTION OF DEPTH AND SPACE AND DISTANCE


DEPTH PERCEPTION was the puzzle to scientist and philosophers for hundreds of years.THEY COULD not understand how we could see a three-dimenisal world with only a two-dimensial or flat, retina in each eye.TODAY WE realize that the ability to perceive depth is no more amazing than is any other perceptual accomplishment.WE ARE ABLE to make use of information or cues,in the sensory input to ''GENERATE'' the three-dimensial-world that we see.THUS THE question is what are the cues we use to see depth and perception.PART OF THE answer lies in cues received by each eye,seperatly-the MONOCULAR,''one eye cue'' for depth perception.


MONOCULAR CUE FOR DEPTH PERCEPTION


AS THE NAME SUGGEST,monoculer cues are cues that can operate when only one eye is looking.THESE cues are the one used by the painters to give us a three-dimensial-experience from a flat painting.THE EYE pick up them and we perceived DEPTH.LINEAR PERSPECTIVE,the distance seperating the images of far objects appear to be smaller.IN GENERAL,the more closely we see an object,THE nearer it seems,A DISTANT,mountain appear farther away on a hazy day then it does on aclear day because haze in the atmospher blurs fine day,and we can see only the farther objects.ANOTHER CUE is INTERPOSITION, which occures when one object is visible while another covered by it,the first object is perceived as nearer.SHADOWS OR HIGHLIGHT, in an object is very importan for giving us an impression of depth.



A BONOCULER CUE FOR DEPTH PERCEPTION


AS WE HAVE just sen many of the cues for depth require only one eye.IN FACT,one eyed peoples,under most conditions,have quite acqurate depth perception.MOST OF US,through look at world,from both of our eyes stimiltaneously,and we are thus able to add binocular cues for depth perception to ther monoculer ones.BY FAR THE most important binoculer cue comes from the fact that the two eye the retina,receive slightly different views of the world.THEREFORE this cue is known as RETINAL DESPIRETY.TO UNDERSTAND retinal despirety,cosider the gometary of situation when two eyes see an object.THE FOVEA,in the centre of the retina is much sensative,then is the rest of the retina.WHEN WE look one object,we fix our eyes,point them in the manner of the speaking so that the image of the object fall mostly on each fovea.but if two eyes ARE SEPERATED from each other by about 65 MILLIMITTERS,they get slightly different views of the objects and two objects are not the same.


LINK
INTRODUCTION TO PSYCHOLOGY
PSYCHOLOGY AND LIFE

regard

__________________
''A man is not finished if he is defeated, he is finished if he quits.''

ONE OF THE most important adjustment we made to our physcial enviorment is perceiving the size location and physcial qualities of objects in three-dimensial space.WHEN WE LOOK at the parked mobile,we perceive it three-dimensial object of the special size and shape located in a specific area.IF THE AUTO mobile is moving we judge its speed in terms of its changing relationship to other objects in space.IF WE HEAR,only the sound of is horn,we use perceptual cues to judge the distance and direction from which the auto mobile is coming.ALTHOUGH BINOCULAR IMAGE,is necessary if we are to receive the greatest numbers of posible cues about the space and depth,but we have several cues even with the MONCULAR VISION.THE MUSCLES,responsible for various eyes movementspocess sensory receptor which are stimulated when the musclases contracts.

PEOPLES ARE ABLE to locate the position of sounding objects in space in term of DISTANCE AND DIRECTION.THIS ABILITY to locate the sounds is of considerable adaptive value in modern life.FOR EXAMPLE,IN crossing the busy street,your very life may depend upon your knowing accurately the position from which an unsen automobile is bearing down on you.

PERCEIVING THE DIRECTION OF SOUNDS

OUR ABILITY,to localize sound is due almost entirely to our pocesion of two ear located at different points in space.

1 A SOUND COMING from an object at the left of the head strikes the left ear before the right one,this difference in time can ce very short,but ittells us from which side the sound is coming.

2 SOUNDS WAVES coming from the left stimulate the left ear more strongly then right ear.

we can use these cues to direction only when sound comes from one side or the other,sound directly in front of us connot be distinguished from those above or behind us because stimul reaching the two ear is identical.

TWO CLUES HELP us to determine the sounds,how far away the sorse of the fimilar sound is,THE FARTHER away its sourse or the weaker the sound will be.

TO BE CONTINUED,

LINK
PSYCHOLOGY AND LIFE

regards

__________________
''A man is not finished if he is defeated, he is finished if he quits.''

THE WORLD AS we perceive it is a stable world,and this stability is present early in life.FOR INSTANCE,a man size does not appear to change much as he walked toward us;A DINNER plate does not look like a circle when viewd from one side and an ELIPSE when viewd from another;AND LOCATION of the sound does not appear to change when we move our heads.STABILITY Of perception help us to adapt to the ENVIORMENT.it would be virtually imposible to operate in a world where sounds changed their locations as we moved our heads and objects changed their sizes and when viewd from different positions and distances.IMAGINE,what it would be like if your friend assumed a multitude of sizes and shapes.THE STABILITY of the enviorment as we perceive it is termed as PERCEPTUAL CONSTANCY.


SIZE CONSTANCY

THE size of the representation,or image,of an object on the retina of an eye depend upon the distance of the object from the eye;THE farther away it is,THE smaller the representation.YET WHEN you cross the street to speak to a friend,your perception of the friend`s size does not change much,EVEN through the retinal representation alter greatly in accordance with the geomatry of the situation.CONTRIBUTING TO this constancy is the great deal of additional information you have about the circumstances:YOU KNOW something about the distance of your friend from you ;YOU perceive the changes that took place in other objects as you approched;AND YOU know how large your friend supposed to be,the friend assumed`s size.



THE IMPORTANCE of the distance and background information in maintaining size constancy was shown in a classical experiment by E H HOLWAYIN the 1940.THEY USED ambiguous stimuls disk of light which could have no real assumedsize and they changed the amount of distance and background information available to the subject in the experiment.THEY FOUND that size constancy decreased as the distance and background information available to the subject decreased.IN OTHER WORDS, The subject perceived the size of the disk of light more in accordance with the size of the retinal representation when they lacked information about distance and background.


ONE INTERPRETATION of this result,might be that peoples somehow automatically use information about distance and background to ''CORRECT'' the size of their retinal representation,thus keeping their perception relatively constant.SO OUR KNOWLEDGE of a fimilar object the assumed size can be important factor in size constancy,especially under condition in which other information is not avaialble.


SIZE CONSTANCY AND ILLUSION,


SOME OF THE illusion have ben explained in term of MISPLACED size constancy,FOR INSTANCE,two horizontal bars are the same length,but we perceive the upper one as longer then the lower one.THIS ILLUSION is said to work because the railroad track converging in the distance provides a strong cues for depth.THUS WE receive information that that upper bar is farther away bthen the lower bar.SO IN THE illusion the horizontal bar are the same length but size constancy leads you to MAGNIFY the distant one.

BRIGHTNESS CONSTANCY,


VISUAL OBJECT ALSO appear constant in their degree of WHITNESS, GRAVNESS,OR BLACKNESS, even though the amount of physical energy reflected from them may change enormously.PEOPLES ARE not like PHOTOELECTRIC CELLS, simply registring the amount of the light being reflected from the surface.OUR EXPERIENCE of the brightness stay relatively constant despite great changes in the amount of physcial energy reaching our eyes.FOR EXAMPLE, objects or surface that appear white in a bright light are still perceived as white in dim illumination.SIMILARLY, what look black to us in dim light still look black in intense light.SO WE have brightness constancy in most situitions,when the illumition changes,it change over the whole feild:THE PHYSCIAL energy ratio between an object and its surrounds stay constant.IN OTHER WORDS, the unchanged brightness ratio give constant brightness experience.


EFFECTS OF LEARNING AND MOTIVATION

WE HAVE idea about perpectual process that are much the same for everyone,but we know that peoples differ in the ways they processsensory inputs to give rise to what they experience.TWO PEOPLES may have very different perception of the same television drama.BASED ON PAST experiences or any special trainning we have had,EACH OF us has learned to emphasized some sensory inputs or to ignore other.ELEANOR GIBSON, has defined perpectual learning as ''AN INEREASE in the ability to extract information from the enviorment as a result of experience or practice with the stimulation coming from it.GIBSON GIVES many example that shows how perception can be changed through learning.SHE CITES the competence of many peoples trained in various occuption to make perpectual distinction that untrained peoples cannot make.


DISTINGUISHING THE call of birds is one of her examples, A TRAINED ornithologist can do it,but most of us have great diffculty.IF YOU ARE lucky enough to live where there are plenty of birds,try shutting your eyes, and listening to the birds dawn and dusk.THEY MAKE THE DEFENING RACKET.you may be able to extract some features that enables you identify particular speaches of birds.BUT FOR THE most part, unless you have special tranning the whistless,trilling, and buzzing will blend together so that you may not be able to distinguish the call of the one bird from another or recognize call upon hearing them again.PERPECTUAL learning is needed before you do it.



IN THE LATE 1940 and throgh the 1950,MANY PSYCHOLOGIST turned their attention to the idea that MOTIVES and NEED influence perception.THIS VIEWPOINT was called the''NEW LOOK'' in perception.ALTHOUGH many of the newlook experiments were flawed and some of their ideas were criticized,THE GENERAL IDEA that individual differences in motives and needs affect perception persist,IN OTHER WORDS,we we may attend to and organize sensory input in a way that match our needs.FOR EXAMPLE, the peoples who are thirsty will try to pay attention to those events in the enviormenmt which will staisfy their needs.


link

AN INTRODUCTION TO PSYCHOLOGY BY RICHARD A KING

regard

__________________
''A man is not finished if he is defeated, he is finished if he quits.''