Sensory Processes

1. Sensory Processes ThEcOwgAvecOla

2. ThEcOwgAvecOla • Trouble processing it because the normal shape and boundaries of the words and letters have been rearranged • The eye skips and jumps from one part of the sentence to another; if a word is very common, like “and” or “the,” we take only a glimpse at it as the eye looks at clumps of words all at one time. • The normal method for reading is to focus on the beginning of letters of a sentence and determine what basic shape the rest of the words in the sentence have. • If everything looks familiar, we assume, after a very slight pause, that the words are known, if, as we read on, the sentence doesn’t fit with what comes next, we stop and go back to find out what we missed. • If you actually had to stop and read every letter and word on this page, it would take you more than 20 minutes to read it. • So what is the normal structure of the sentence? TheCowGaveCola.

3. All incoming sensation must be interpreted by the brain. • As a result, quite often we see what we want to see and hear what we want to hear. • So sensation is not merely a physical event – it can be very psychological. • Here is a simple example of making something what it isn’t. Read the following sentence from right to left, once, without stopping. Don’t read it again yet. • “.rat eht saw tacehT”

4. “.rat eht saw tacehT” • Most people read one of two versions. • “The cat saw the rat” • “the cat was the rat” • Both of these are wrong. You made this mistake because if you had read the sentence backward the way it really is written, it wouldn’t have made sense to you. Read it again, this time very carefully, and you will see what we mean.

5. Perception Test • http://www.youtube.com/watch?v=lNGwGGOjifY

6. Vision • Vision dominates the human senses. We always believe what we see first, and only secondarily do we accept information from taste, smell, hearing, or feeling. Light Theory • Visible light that we see is but a small part of the electromagnetic spectrum of energy.

7. Color • Light starts out from the sun as white light; • Color is seen only after the waves of white light hit objects and bounce back to us at different speeds. • There really is no such thing as “color”: we simply give different wavelengths certain names. Color is seen because the eyes have different receptors for different wavelengths. • The key to color is white light waves hitting various objects in the environment and bouncing off at different wavelengths, which in turn hit receptors in our eyes.

8. Process by which we see color • Light passes into the eye through the clear outer covering called the cornea on and through the aqueous humor (liquid) located behind it. • The iris is a colored circular muscle that opens and closes into larger or smaller circles in order to control the amount of light getting into the eye. • Experiment for homework: face a mirror, cover one eye, and turn on the light. Stand so that the light will hit the covered eye when you remove your hand. Remove your hand, and watch how the iris, which had opened because it was dark behind your hand, quickly closes to a very small circle. • When you leave a movie matinee, your irises are wide open to catch the limited light in a darkened theater; as you walk out into the sun, the light seems blinding at first because the irises aren’t able to close fast enough; they let in too much light to too many receptors.

9. Lens • The lens of your eye is very much like a camera lens; it helps you to focus the objects you see onto the back of the eye where there are receptors. • If the lens is not shaped correctly, the image coming in will either overshoot or fall short of the receptors at the back of the eye, and this causes image to blur. • Eyeglasses are designed to change the angle at which the light hits the lens, causing the incoming light waves to land properly on the receptors. • The lens automatically adjusts to whatever object we want to see. • As the muscles controlling the lens make the adjustment, they give the brain information about how much they have moved, and this is one way we learn to judge how far away from us an object is.

10. Pupil • What is the black circle in the middle of your eye? Nothing. The pupil is just an opening that changes size as the iris muscles move to cover and uncover the lens. • Since it is dark inside your eye, the opening of the pupil looks black, but if you flash a light inside, the colors coming back through the pupil can vary across the whole range, depending on how the light is bent and what it hits in there. • The light entering the eye gets to the back of the eyeball and hits the retina. Millions upon millions of receptors are embedded in the retina.

11. Psychological factors can control the iris muscles and thus the size of the pupil. • The pupils of our eyes get smaller if we see something unpleasant; they get larger if we see something we really like. • Since the pupils enlarge if someone likes you a lot, checking out pupils may be a way to make sure. • In History: Years and years ago about the only way most women could survive was to marry someone. If they found a desirable male, they would put a few drops of medicine made from a poisonous plant called belladonna into their eyes, causing the pupils to widen. The women couldn’t see very well until it wore off, but long before science nature knew what wide pupils meant, and the men began to fall in love, not quite knowing why. • This method isn’t foolproof however, because pupils open up all the way when someone is afraid also; because this makes it possible to explore the threat in the environment better.

12. Rods and Cones • Retina is made up of two different kinds of receptors. • A rod (it is shaped like one) • A cone (that’s the shape it has) • Rods are very sensitive to the violet-purple range of wavelengths, but we will only see black and white with them because they have no color chemicals in them. • There are about 100 million rods in the retina, and they are used for night vision because they respond very well to low levels of light. • Since the rods are turning on as it darkens, they are keeping the blue objects visible. The cones are shutting off, so the red objects disappear. • Thus, cones are used for color and daylight vision and respond best to wavelengths in the red range. They shut off at night.

13. A Journey Through the Human Eye: How We See • http://www.youtube.com/watch?v=gvozcv8pS3c

14. Examples of how this is used: • Fire departments take rods and cones very seriously. Fire trucks used to be red. Today only a few are. • Too many accidents occurred in twilight because automobile drivers couldn’t see the red trucks very well. • Most trucks today are a yellowish green, which is right in the middle of the color chart between violet on one end and red on the other. • This compromise coloring provides the best visibility for both day and night.

15. Color Vision This is how color vision works: • all the colors we see are red, blue, green or a mixture of these three. • You can understand the principle of mixture if you take red, blue, and green spotlights and shine them on a white wall. By mixing the lights, you will get every color possible. • Throughout the center part of the retina are millions of cones connected together. • Some receive red, some green and some blue wavelengths. • Depending on the texture of the objects we are viewing, light from each part of the object will bounce back at different wavelengths, and the brain will mix these wavelengths, making the object appear a specific color.

16. Color Defects Color blindness= the inability to see certain colors. • The most common form of this problem is found in those who can see color in only the yellow-blue range and cannot see red or green. The receptors respond to the light wave energy but they don’t see it as “colored”. • About 8 percent of males have this inherited defect and only 0.5 percent of females. Common test = normal vision you will see the number 29 but if you have a red-green deficit, you will see the number 70.

17. Afterimages • All physical systems strive to stay in balance. If we are cold, we shiver to increase circulation; if hot we sweat to cool down. • The same principle applies to the cone network of the eyes. • If you stare at a colored object for a minute or so, the chemicals in the cones for the colors you are seeing will be partially used up as changes in the chemicals cause electrical impulses (signals to the brain). • The chemicals for all the colors you are not seeing are still intact. No message has been sent to the brain for them because you haven’t seen these colors. • As a result, the cone system is not in the balance. If you look away from the object and stare at a white piece of paper, you will see the object in opposite colors. • This afterimage results from the remaining “unused” cones firing so that all the cones can restore themselves to equal chemical levels at the same time. The same process will occur if you stare at a television for a while and then looked at the wall.

18. Try staring at the plus sign on the flag for one minute. Then quickly move your eyes to some white paper and you see the flag appear in red, white and blue.

19. Hearing Theory of Sound • Sound is caused by the movement of air. If there is no air, there can be no way to transmit sound - it is ‘dead silent’ in space because it is a vacuum. • If a book falls and hits the ground, if someone shouts, or a bomb explodes, the air is compressed and rarified in a wave-like manner. This vibration in the air travels outward in all directions like ripples on water. • At this point, it is still vibrating air; there is no sound. It only becomes sound if some of it enters your ears, causes receptor cells to create action potentials, and the sensory neurons carry it to our brain. • Then, we perceive it as sound, i.e., a bang, a voice, or an explosion!

20. Structure of the Ear • The ear is composed of three parts: the outer ear, the middle ear, and the inner ear. Sound is captured by the pinna, transmitted down the auditory canal where it strikes the tympanic membrane (eardrum). The resultant vibrating tympanic membrane moves a series of three bones (the malleus, the incus, and the stapes) on the other side in the middle ear. The middle ear is an air filled area with its air pressure the same as the outside air as the result of the Eustachian tube. • The final of these three bones, the stapes, transfers the vibrations to the membrane of the oval window. The oval window is much smaller than the tympanic membrane and as a result the vibrations are magnified 15-20 times.

22. The vibrations then travel into the fluid filled inner ear causing waves to propagate through a coiled section of the inner ear called the cochlea (sound is further amplified in the fluid canals because sound travels faster through water than the air). • Here, special hair cellsprojecting into the fluid of the inner ear catching the movement of the vibrations. • Movement of the hair cells transfers energy to the organ of corti in the membrane which have special receptor cells that when stimulated cause action potentials to occur across synapses which are then transmitted by neural cells.

23. How Your Ear Works: BBC • http://www.youtube.com/watch?v=r-c5GpoD8wI

24. Cutaneous Senses • Our skin contains three types of cutaneous, or touch, receptors. • Each sends a message to the brain where it is recorded. • The first one records pressure. It can register a pinprick, a bruise, or even an ant crawling up the arm. • The second kind responds only to changes in temperature. • The third kind remains active continuously to record an injury or poison. These last receptors cause the painful feelings we all dread, because they fire for hours and hours after a burn or a major cut.

25. Taste and Smell • Taste buds are located primarily on the tongue. It is believed that there are specific receptor cells that respond to substances that are sweet, bitter, salty, and sour. • It is likely that a combination of action potentials generated from a variety of taste bud receptors gives the sensation of the thousands of different tastes. • It could also be that the frequency at which particular receptors fire signals the brain to different taste sensations. • Smell is determined by receptors in the nasal cavity embedded in a layer of mucus. • Air borne particles dissolve in the mucous, combine with receptor cells triggering electrical signals which are sent to the olfactory bulbs, which generate a “code” that is sent to the brain for interpretation.

26. Smell is the most animal-like of the human senses. • Odors are very hard to define using words, but when an odor is associated with an emotional event, we never forget it. • If we ever happen to smell that odor gain, it will recreate a very strong emotional memory. • Taste and smell perception by the brain is related to one another. We are often aware that the smell of food enhances the taste of it. • These two sensory systems tend to work together.

27. Perception Review from last class = • Perception is the process of assembling sensory information so that we can understand what the incoming energy means. • Perception is always a matter of interpretation and expectation.

28. Perceptual Constancieswhat we must do to the world in order to maintain order and control, to make sense out of our environment. • Size Constancy: the ability to retain the size of an object no matter where it is located. This skill is so important that it appears in an infant only a couple of weeks old. • Experiment to trick the brain = the average CD case is about four inches by 5 inches. In a laboratory, a specially constructed CD case only two inches high is put in front of people. They are asked to judge how far it is from them. They will claim the pack is much farther away than it is because they know its usual size and it appears smaller. Hence, their brains tell them that it must be more distant – things get smaller only with more distance. • Color Constancy: We have the ability to increase or decrease mentally the internal firing of visual receptors equal what the brain tells it the color is. This only works when we already know what color something is. • Example: we recognize that an apple is bright red in the kitchen is still the same colour when we bring it into a darkened room with just the TV on. It hasn’t turned darker. The light being reflected from the apple cannot be the same in the two locations.

29. Brightness Constancy • Find a familiar black object. Look at it indoors, then take it outside on a very bright sunny day. The level of brightness reflected from the object is extremely high outside, yet it looks to be about the same color as it did inside, rather than “bright black”. The brain causes the rods and cones to compensate for the brightness. If the object seems too bright to match our concept of “black”, some of the visual nerve cells shut off. • To see this aspect of perception in action, look at the picture below. We assume the light is hitting the object from the left side. This makes the right side darker, as it would be in real life. But if you cover the “shadow” at the lower right, the picture no longer makes sense in terms of a belief that light is coming from the left. It now looks like an open book, one side of which could be dark regardless of light direction. Further, since a book is printed, note that your visual system makes the “page” look much darker once you cover the shadow.

30. Space Constancy • The most common type of auto accident is the rear-ender. Despite many warnings, people don’t take “not following too closely” to heart – because they don’t understand perception. • We have to keep objects in the environment steady in order to survive. This is called space constancy. But we must allow some motion. • There are two types of motion: self-motion and object-motion. We must choose between allowing ourselves to move in reference to the environment and allowing the environment to move in reference to us. • If we allow both at one time, severe dizziness results. • For example, we can focus on telephone poles as we move along in a car (object motion), or we can focus on ourselves and the inside of the car (self-motion), letting the poles blur. Usually when we drive, we are aware of our movement. When that is the case, we must hold the cards in front of us steady in our minds. As a result, only a major change in the speed of the cards will be noticed. A small change, such as occurs during a normal stop, will not be perceived well. This is why auto manufacturers were forced to put a third brake warning light at eye level starting with 1986 cars.

31. Depth Perception • the ability to see objects “out there” in space. It is built into a baby from a very young age. • http://www.youtube.com/watch?v=p6cqNhHrMJA&feature=related Baby Experiment: • Experimenter was on a picnic one day in the Grand Canyon. She wondered if her baby would crawl over the canyon rim or already “knew better”. • So, in a laboratory, she constructed what is called the visual cliff experiment. This experiment uses a large table with retaining walls of wood on three sides. The fourth side is left open. A piece of heavy, clear Plexiglas covers the table and extends many feet beyond the open edge. • To the baby’s eyes it looks as if anyone going beyond the end of the table will fall into space. Babies from six to 14 months old were placed on the table and enticed by rattles and goodies to leave the table and “fall” over the fake cliff. • But the babies wouldn’t go beyond the edge onto the Plexiglas. This showed that humans have depth perception almost from the beginning.

32. Depth perception requires a number of brain skills. • First, there is binocular disparity. There is a difference between the images received by each of your eyes. Example: Hold your finger steady in front of your eyes; first close one eye, then the other, and notice how the finger shifts. This is the result of each eye seeing a different image. We have to bring these images together in our brains in order to see them correctly. In the process of doing so, we judge and “see” distance and depth. • Another cue to distance is called visual texture. “Texture” refers to how smooth or rough something appears to be – that is, how clear its details are. We can gauge the distance of flowers in the picture below, in each row by how clearly we can see them. Since we can see the individual flowers at the bottom of the picture, we know they are close. As they become more distant, we see much less detail, and they appear “smooth”, blending together, so we know these are “way out there”. Others that we can’t tell apart at all are “way, way out there”.

33. Perceptual Organization • We tend to organize things so that it makes sense. We interpret things the way we think they should be, not in terms of how they actually are.

34. Illusions • Illusionsoccur when we perceive something inaccurately. Most people think of illusions as “mistakes” that we make. That is not really the case. Müller-Lyer illusion

35. Optical Illusions • http://www.switched.com/2008/09/17/top-25-optical-illusions-on-the-web-13/

36. Subliminal Perception • Even though we cannot consciously hear or see the message, it will still be registered at the subconscious level. • It is perception that takes place below our level of conscious awareness. • Example: In the 1950’s, an advertiser very rapidly flashed “EAT POPCORN” on the movie screen at a theater. The advertiser claimed that popcorn sales increased 50 percent.

37. Duke University Subliminal Ad Experiment • http://www.youtube.com/watch?v=3iJWyiaXLLw