I'm not PERFECT but I'm ENOUGH!

I'm not PERFECT but I'm ENOUGH!

Martes, Hulyo 24, 2012

Chapter 4: Sensation & Perception



CHAPTER 4
SENSATION AND PERCEPTION
 
Introduction
To consider how psychologists understand the senses, and more broadly, sensation and perception, we have to first define:


SENSATION
                Sensation is the activation of sense organ using physical energy that processes the receiving of stimulus from the external environment.

PERCEPTION                                                                                                                                     
                These are meaningful sensory experiences that result after the brain combines hundreds of sensations. (Plotnik, et.al, 2008)          Perception is the sorting out, interpretation, analysis and integration of stimuli carried out by the sense organs and brain (Feldman, 2010).

PSYCHOPHYSICS
                This is the study of the relationship between the physical aspects of stimuli and our psychological experience of them (Feldman,2010).

In this chapter, we will discuss six of the major human senses--- vision, hearing, balance (vestibular system), taste, olfaction (smell) and touch.

Your eyes, ears, nose, skin and tongue are complex, miniaturized, living senses that automatically gather information about your environment. These three definitions will help you understand sensation.

Transduction
                It refers to the process in which a sense organ changes, or transforms, physical energy into electrical signals that become neural impulses, which may be sent to the brain for processing
 (Plotnik, et al., 2008).

Adaptation
                Adaptation refers to the decreasing response of the sense organs, the more they are exposed to a continuous level of stimulation (Plotnik, et al., 2008)


THE SCIENCE OF SEEING: Perceptual Properties of Light (White, 2009)
                Light is a complicated phenomenon. When people experience light, they are really aware of its dual nature. There are three aspects to the perception of light: brightness, color, saturation.

A. Brightness
                Brightness is determined by the amplitude of the wave—how high or how low the wave actually is. The higher the wave, the brighter the light appears to be. Low waves are dimmer.

B. Color or Hue
It is determined by the length of the wave. Long wavelengths are found at the red end of the visible spectrum (the portion of the whole spectrum of the light that is visible to the human eye) whereas shorter wavelengths are found at the blue end.

C. Saturation
                It refers to the purity of the color people receive: a highly saturated red, for example, would contain only red wavelengths, whereas, a less saturated red might contain a mixture of wavelengths.
                For example, if the child is using the red paint from a set of poster paints, the paint on the paper will look a pure red, but if the child mixes in some white paint, it will look pink.
                The hue is still red but it will be less of a saturated red because of the presence of white wavelengths. Mixture in black or gray would also lessen the saturation.

THE STRUCTURE OF THE EYE:
Parts of the Eye (Plotnik,et al., 2008/ White, 2009)
                The surface of the eye is covered in a clear membrane called the cornea. It is the rounded, transparent covering over the front of your eye. As the light waves pass through the cornea, its curved surface bends, or focuses the waves into a narrower beam.
                The next visual layer is a clear, watery fluid called the aqueous humor. This fluid is continually replenished and supplies nourishment to the eye.
                The light from the visual image then enters the interior of the eye through a hole, called the pupil in a round muscle called the iris (the colored part of the eye). The iris controls the amount of light entering the eye.
                Behind the iris, suspended by muscles, is another clear structure called the lens. The flexible lens finishes the focusing process begun by the cornea and changes its shape from thick to thin in a process called VISUAL ACCOMODATION, which allows the eye to focus on objects that are close or far away.
                Retina, located at the very back of the eyeball, is a thin film that contains cells that are extremely sensitive to light. These light-sensitive cells, called photoreceptors, begin the process of transduction by absorbing light waves.
                Rods and Cones are the business end of the retina. Rods are receptors of the retina that are sensitive to light, but they are not very useful for color vision. Humans have 120 million rods. Cones are receptors of the retina that we use for color perception. Like the rods, cones are light sensitive.
                However, they require a larger amount of light that the rods do to respond so they operate best in daylight or under high illumination. There are about 6 million cone cells in human eyes
(Santrock, 2005).
                Because rods work well in low levels of light, they are also the cells that allow the eyes to adapt to low light.
                Dark Adaptation occurs as the eye recovers its ability to see when going from a brightly lit state to a dark state.
                Light Adaptation on the other hand is the recovery of the eye’s sensitivity to visual stimuli in light after exposure to darkness.


THE BLIND SPOT
                This is the area in the retina where the axons of the three layers of retinal cells exit the eye to form the optic nerve, insensitive to light. 
                Nerve impulses that are generated in the ganglion cells exit the back of the eye through the optic nerve, which carries impulses toward the brain. The point where the optic nerve exits the eye has no receptors and is called the blind spot. At this point, there are no rods and cones here. You do not notice the blind spot because your eyes are continually moving.

Color Blindness
                It is caused by defective cones in the retina of the eye.

Kinds of Color Blindness:
  1. Monochrome Color Blindness- people either have no cones or have cones that are not working at all.
  2. Red-Green Color Blindness- People with this kind of color blindness, either their red or their green cones are not working. They would see the world in blues, yellow and shades of gray. If blue cones are not working, which is less common, they see reds, greens and shades of gray.  (Ciccarelli, et al., 2009)

THE HEARING SENSE: PERCEPTION OF SOUND
                Although many of us think primarily of the outer ear when we speak of the ear, that structure is only one simple part of the whole. The outer ear acts as reverse megaphone, designed to collect and bring sounds into the different internal portions of the ear.
                The location of outer ears on different sides of the head helps with SOUND LOCALIZATION, the process by which we identify the direction from which a sound is coming.
                Wave patterns in the ear enter each at a slightly different time, and the brain uses as discrepancy as a clue to the sound’s point origin. (Feldman, 2010)

TERMS TO REMEMBER: (Ciccarelli et al., 2009/ Plotnik et al., 2008)

Loudness-It refers to the sounds’ intensity
Pitch- It is the subjective experience of a sound being high or low, which the brain calculates from specific physical stimuli.
Decibel- This is the unit to measure loudness. Our threshold for hearing ranges from 0 decibels, which is absolutely no sound, to 140 decibels, which can produce pain and permanent hearing loss.
Volume- how soft or loud a sound is
Timbre- richness in the tone of the sound
Hertz (Hz)- cycles or waves per sound, a measurement of frequency


THE STRUCTURE AND FUNCTIONS OF THE EAR
A. OUTER EAR
                The outer ear consists of three structures: the external ear, the auditory canal and the tympanic membrane. It consists of PINNA, the outer, visible part of the ear that serves as a kind of concentrator, funneling the sound waves from the outside into the structure of the ear.
The pinna is also the entrance to the AUDITORY CANAL (or ear canal), the short tunnel that runs down to the TYMPANIC MEMBRANE or eardrum. When the sound waves hit the eardrum, they cause three tiny bones in the middle ear to vibrate (Ciccarelli, et al., 2009).
B. MIDDLE EAR
                The middle ear channels the sound through the eardrum, hammer, anvil and stirrup to the inner ear.    
                The middle ear is a tiny bone cavity that is sealed at each end by membranes. It picks up and increases or amplifies vibrations.
                The three tiny bones are collectively called OSSICLES. When the tympanic membrane vibrates, so does the hammer.  In turn, the HAMMER sends vibrations to the attached ANVIL, which further sends the vibrations to the attached STIRRUP. The stirrup makes the connection with the end membrane, the oval window. The three ossicles act like levers that greatly amplify vibrations, which in turn, cause the oval window to vibrate. (Plotnik, et.al. 2008)
C. INNER EAR
                The functions of the inner ear, which includes
the oval window, the cochlea and the basilar membrane, is to transduce sound waves into neural impulses and send them to the brain.
·                     The OVAL WINDOW transmits sound waves to the cochlea.
·                     The COCHLEA, is a tubular fluid-filled structure that is coiled up like a snail. It contains receptors for hearing and its function is transduction—transforming vibrations into nerve impulses that are sent to the brain for processing into auditory information.
·                     The BASILAR MEMBRANE lines the inner wall of the cochlea and runs its entire length. (Santrock, 2005).

 THEORIES OF HEARING
  1. Place Theory (Herman von Helmholtz, 1863)- states that each frequency produces vibrations at a particular spot on the basilar membrane.
                        In this theory, the pitch a person hears depends on        where the hair cells that are stimulated are located in the            Organ of Corti.
  1. Frequency Theory (Ernest Rutherford, 1886)- states that pitch is related to how fast the basilar membrane vibrates.
                        The faster this membrane vibrates, the higher the           pitch; the slower it vibrates, the lower the pitch. (CIccarelli,   et al., 2009)

TYPES OF HEARING IMPAIRMENTS (CIccarelli, et al., 2009)
  1. Conduction Hearing Impairment- means that sound vibrations cannot be passed from eardrum to the cochlea. The caused might be a damaged eardrum or damage to the bones of the middle ear (usually from an infection).
                        In this kind of impairment, hearing aids maybe of             some use in restoring hearing.
  1. Nerve Hearing Impairment- the problem lies either in the inner ear or in the auditory pathways and cortical areas of the brain.
                        Normal aging causes loss of hair cells in the cochlea         and exposure to loud noises which can damage hair cells.                                              TINNITUS refers for an extremely annoying ringing in     one’s     ears, and it can also be caused by infections or loud               noises.


CHEMICAL SENSES: It Tastes Good, It Smells Terrible
A. Gustation
                TASTE BUDS (name for taste receptors) are specialized kinds of neurons found in the mouth that are responsible for the sense of taste or gestation.
                Each taste bud has about 20 receptors that are very similar to the receptor sites on receiving neurons at the synapse.

THE FIVE BASIC TASTES
  1. Sweet
  2. Sour
  3. Salty
  4. Bitter
  5. Umami (glutamate)

Glutamate not only exists in chicken soup, tuna, cheese, etc., but also in human breast milk.

                The five taste sensations work together, along with the sense of smell and the texture, temperature and “heat” of foods, to produce thousands of taste sensations (CIccarelli, et al., 2009).
                  
                   Taste is often called as a CHEMICAL SENSE because it works with the molecules of foods people eat in the same way the neural receptors work with neurotransmitters.


THE SENSE OF SCENTS: OLFACTION
                Olfaction is called a chemical sense because its stimuli are various chemicals that are carriedby the air. The upper part of the nose has a small area that contains receptor cells for olfaction.
                The function of olfactory receptors is transduction, to transform chemical reactions into nerve impulses (Plotnik, et. al., 2008).

OLFACTORY RECEPTOR CELLS
These cells have about a half dozen to dozen little “hairs” that project into the cavity. These hairs are called CILIA. 
Olfactory receptors also have to be replaced as they naturally die off, every 5 to 8 weeks. Unlike the taste buds, there are more than 5 types of olfactory receptors. In fact, there are at least 1,000 of them (CIccarelli, et al., 2009).
THE OLFACTORY BULB
                These are located right on top of the sinus cavity on each side of the brain directly beneath the frontal lobes.
                The olfactory receptors send their neural signals directly up to these bulbs, by passing the entire lower brain and its selective attention filter, the reticular formation.


SOMETHETIC SENSES (“soma”-body/“esthetic”- feeling) 
(CIccarelli, et al., 2009)

A. The Skin Senses: Touch, Pressure and Temperature
                Skin is the body’s largest organ. It receives and transmits information from the outside world to the central nervous system.

Sensory Receptors in the Skin
                There are about half a dozen different receptors in the layers of the skin.
1. Pacinian Corpuscles
                These can be found beneath the skin and respond to pressure only.


2. Free Nerve Endings
                They are located just beneath the uppermost layer of the skin that responds to changes in temperature and to pressure and to pain.
                Types of Pain:
    1. Visceral Pain- The receptors that detect pain (and pressure) in the organs
    2. Somatic Pain- Large nerve fibers that carry pain sensations in the skin, muscles, and tendons. Somatic pain is the body’s warning system that something is being damaged.

GATE-CONTROL THEORY OF PAIN (Melzack ,1960/Wall ,1965) – states that the spinal column contains a neural gate that can be opened (allowing the perception of pain) or closed (blocking the perception of pain).

B. The Kinesthetic Sense
                This is processed by a proprioceptive receptors in skin, joints, muscles and tendons. Kinesthesia comes from the Greek words kenein (to move) and aesthesis (sensation). 
                When you close your eyes and raise your hand above your head, you know where your hand is because the proprioceptors tell you about the changes in pressure within the muscles (CIccarelli, et. al., 2009).

C. The Vestibular Sense (from the Latin word meaning
    “entrance” or “chamber”)
                This is processed by vestibular organs that convey information about movement and body position. There are two kinds of vestibular organs: (1) the otolith organs and the (2) semicircular canals.
1.       Otolith Organs- tiny sacs found above the cochlea. These sacs contain gelatin-like fluid within which tiny crystals are suspended. The head moves and the crystals cause the fluid to vibrate, setting off some tiny hairlike receptors on the inner surface of the sac, telling the person that he or she is moving forward, backward, sideways, up or down.
2.       Semicircular Canals- circular tubes that are filled with fluid and stimulate hairlike receptors when rotated. These are located in the inner ear; contains the sensory receptors that detect head motion.
               
PERCEPTUAL ORGANIZATION
Psychologists distinguish between bottom-up and top-down processing in sensation and perception

A. Bottom-Up Processing
                The sensory receptors register information about the external environment and send it up to the brain for analysis and interpretation. Bottom-up processing is initiated by stimulus input.

B. Top-Down Processing
                It starts out with cognitive processing at the higher levels of the brain. These cognitive processes include knowledge, beliefs and expectations. Thus, top-down processing does not start with the detection of stimulus, as bottom-up processing does.

Absolute Thresholds
                This is the smallest intensity of a stimulus that must be present for it to be detected. Our senses are extremely responsive to stimuli.     For example, our sense of touch is so sensitive that we can feel a bee’s wing falling on our cheeks when it is dropped from a distance of one centimeter (Feldman, 2010).

Differential Thresholds
                It is the smallest level of added (or reduced) stimulation required to sense that a change in stimulation has occurred. Thus, the differential threshold is the minimum change in stimulation required to detect the difference between two stimuli and so it is also called as JUST NOTICEABLE DIFFERENCE (JND).
                The stimulus value that constitutes a just noticeable difference depends on the initial intensity of stimulus. The relationship changes in the original value of a stimulus and the degree to which the stimulus will be noticed forms one of the basic laws of psychophysics: Weber’s Law (with Weber pronounced as “vay-ber”) states that a just noticeabale difference is in a CONSTANT PROPORTION of the intensity of an initial stimulus (Feldman, 2010).

THE CONSTANCIES: SIZE, SHAPE AND BRIGHTNESS
A.  PERCEPTUAL CONSTANCY     (Ciccarelli, et al., 2009)
                Perceptual constancy is a phenomenon in which physical objects are perceived as unvarying and consistent despite changes in their appearance or in the physical environment.
                One good example for this involves the rising moon.  This type of constancy applies not just to size but to shape and color as well (Feldman, 2010).
  1. Size constancy- the tendency to interpret an object as always being the same actual size regardless of its distance.
  2. Shape constancy- The tendency to interpret the shape of an object as being constant, even when its shape changes on the retina.
  3. Brightness constancy- The tendency to perceive the apparent brightness of an object as the same even when the light conditions change.
 THE GESTALT PRINCIPLES
1. Figure-Ground Relationships
                It refers to the tendency to perceive objects or figures as existing on a background.
2. Proximity
                This is the tendency to perceive objects that are close to each other as part of the same grouping.
3. Similarity
                It refers to the tendency to perceive things that look similar as being part of the same group.
4. Closure
                This is the tendency to complete figures that are incomplete.
5. Continuity
                The principle of continuity is easier to see than it is to explain in words. It refers to the tendency to perceive things as simply as possible with a continuous pattern rather than with a complex, broken-up pattern.
6. Contiguity
                This is the tendency to perceive two things that happen close together in time as being related. Usually, the first occurring event is seen as causing the second event.
                There are various cues for perceiving depth in the world. Some require the use of only one eye (MONOCULAR CUES) and some are a result of the slightly different visual patterns that exist when the visual fields of both eyes are used (BINOCULAR CUES) (Ciccarelli, et al., 2009).


A. MONOCULAR CUES
                Monocular cues are often referred to as PICTORIAL DEPTH CUES because artists can use these cues to give illusion of depth to paintings and drawings.

1. Linear Perspective
                This tendency for lines that is actually parallel to seem to converge on each other. It works in picture, as in real life, the converging lines indicate that the “end” of the lines are a great distance away from where the people are as they view them.

2. Relative Size
                This is the perception that occurs when objects that a person expects to be of a certain size appear to be small and are, therefore assumed to be much farther away.

3. Overlap (Interposition)
                The assumption that an object appears to be blocking part of another object is in front of the second object and closer to the viewer.


4. Aerial (atmospheric) perspective
                The haziness that surrounds objects that is farther away from the viewer, causing the distance to be perceived as greater.

5. Texture gradient
                This is the tendency for texture surfaces to appear to become smaller and finer as distance from the viewer increases. This is another trick used by artists to give illusion of depth in painting.

6.  Motion Parallax
                This is the perception of motion of objects in which close objects appear to move more quickly than objects that is farther away.

7. Accommodation
                As a monocular cue, the brain’s use of information about the changing thickness of the lens of the eye in response to looking at objects that are close or far away.


B. BINOCULAR CUES
1. Convergence
                It refers to the rotation of the two eyes in their sockets to focus on a single object. If the object is close, the convergence is pretty great. If the object is far, the convergence is much less.

2. Binocular Disparity
                This is the scientific way of saying that because the eyes are a few inches apart, they don’t see exactly the same image.
                This is also the difference in images between the two eyes, which is greater for objects that are close and smaller for distant objects.

PERCEPTUAL ILLUSIONS: THE DECEPTIONS OF PERCEPTIONS

ILLUSION- this is a perception that does not correspond to reality; visual stimuli that “fool” the eye.

1. Visual Illusions
                These are physical stimuli that consistently produce errors in perception.

A. Muller- Lyer Illusion
                This is the most common type of visual illusion where the eye movements are greater when the arrow tips point inward, making us perceive the line as longer than it is when the arrow tips face outward (Feldman, 2010).

B. The Moon Illusion
                In which the moon in the horizon appears to be much larger than the moon in the sky with no cues for depth surrounding it (Ciccarelli, et al., 2009).
 

THINKING CRITICALLY ABOUT ESP
                Extra Sensory Perception (ESP) is defined as a claim of perception that occurs without the use of normal sensory channels such as sight, hearing, taste, touch or smell.

PARAPSYCHOLOGY
It is the scientific study of ESP, ghosts and all things that do not normally fall into the realm of ordinary psychology (Ciccarelli, et al., 2009).
KINDS OF ESP
1. Telepathy (“distant feeling”)
                This is commonly used to refer to the claimed ability to read another person’s thoughts, or mind reading
2. Clairvoyance (“clear sight”)
                This is the supposed ability to “see” things that are not actually present.
3. Precognition
                This is the supposed ability to know something in advance of its occurrence or to predict future events.
4. Psychokinesis
                This is the ability to affect the physical world purely through thought.
5. Astral Projection
                The astral body leaves the physical.


                These are physical stimuli that consistently produce errors in perception.
  • MULLER- LYER ILLUSION
                The most common type of visual illusion where the eye movements are greater when the arrow tips point inward, making us perceive the line as longer than it is when the arrow tips face outward. (Feldman, 2010)

  • THE MOON ILLUSION
                In which the moon in the horizon appears to be much larger than the moon in the sky with no cues for depth surrounding it. (Ciccarelli, et.al. 2009)

  • ILLUSION OF MOTION (Ciccarelli, et.al. 2009)
                Sometimes people perceive that the object is moving when it is really still.
  1. Auto-kinetic effect
  2. Stroboscopic motion
  3. Phi phenomenon

THINKING CRITICALLY ABOUT ESP
                Extra Sensory Perception (ESP) is defined as a claim of perception that occurs without the use of normal sensory channels such as sight, hearing, taste, touch or smell.

PARAPSYCHOLOGY
It is the scientific study of ESP, ghosts and all things that do not normally fall into the realm of ordinary psychology. (Ciccarelli, et.al. 2009)

KINDS OF ESP
1. Telepathy (“distant feeling”)
                Commonly used to refer to the claimed ability to read another person’s thoughts, or mind reading
2. Clairvoyance (“clear sight”)
                The supposed ability to “see” things that are not actually present
3. Precognition
                The supposed ability to know something in advance of its occurrence or to predict future events
4. Psychokinesis
                This is the ability to affect the physical world purely through thought.
5. Astral Projection
                The astral body leaves the physical.