L5 Ch5A Test Notes

Sensation and Perception

Pg. 149 Sensation is the detection of physical energy emitted of reflected by physical objects. Cells in the sense organs- eyes, ears, tongue, nose, skin and internal body tissues detect stimuli. What would happen without sensation? Sound, color, heat, pain.

Perception- set of processes that organize sensory impulses into meaningful patterns. Perception allows us to produce a two-dimensional image on the back of the eye, but we interpret the world in three dimensions.

Pg. 150 Our Sensational Senses

Not all scientists agree on the number of senses. The body contains 5 sense organs

• Vision (eyes)• Hearing (ears)• Taste (tongue)• Touch (skin)• Smell (nose)

Skin also senses heat, cold, pain. The ear contains receptors that account for balance. All senses evolved to help us survive. What are the benefits of sensing pain? The skeletal muscles account for a sense of bodily movement.

The Riddle of Separate Sensations

Sense receptors- cells located in the sense organs. They convert energy of the stimulus into electrical impulses that travel along nerves to the brain.

Pg. 151 Measuring the Senses

Absolute Threshold: the smallest amount of energy that can be detected by a person. Reliable detection occurs when a person can detect a signal 50% of the time.

Our senses are very sharp. Normal sensory abilities allow you to:

• See a candle flame on a clear night 30 miles away• Hear a ticking watch in a perfectly quiet room 20

feet away• Taste a teaspoon of sugar diluted in 2 gallons of

water• Smell a drop of perfume diffused through a 3

room apartment

Pg. 152 Difference Threshold also called just noticeable difference

Difference Threshold: the smallest difference in stimulation that a person can detect 50% of the time. Noticeable difference depends on the intensity of the first stimuli. The larger a weight is, the greater the change must be before one can notice the difference. Cola drinkers often cannot tell the difference because the two tastes exceed a person’s difference threshold.

Pg. 153 Signal Detection Theory

Signal Detection Theory: Yeasayers-observers, when uncertain, respond “yes” to a given signal. Naysayers- observers, when uncertain, respond “no”, being more cautious and conservative.

Expectations can influence how a person responds to signals. While showering and waiting for an important phone call, you may often think it rang when it did not.

4 kinds of responses are possible to signal:• The person detects a signal that was present

(hit)• Says the signal was there when it was not

(false alarm)• Fails to detect a signal (miss)• Correctly says the signal was absent when it

was not present (correct rejection)

Sensory Adaptation

Sensory Adaptation: senses are designed to respond to change and contrast in our environment. You do not feel your watch sitting on your wrist. Adapting to a gas leak would be a problem. Do we completely adapt to extreme stimuli? Such as pain, smell, heat

Pg. 154 Sensory deprivation: absence of normal levels of sensory stimulation. The human brain requires a minimum amount of sensory stimulation in order to function normally.

Pg. Sensory Overload

Sensory Overload leads to fatigue and mental confusion.“Cocktail party phenomenon”- blocking out unimportant sounds and focusing only on things of interest.. Important sounds such as your name can be detected.

Pg. 155 Selective Attention

Selective Attention: protects us in daily life from being overwhelmed by all the sensory signals

L5 5B Notes

Pg. 156 VisionMore information comes to us through our eyes than any other sense organ.

What We See

• Hue- the visual experience specified by color names. Related to wavelength of light; the shorter waves are violet/blue; the longer waves are orange/red

• Brightness- the visual experience specified by the amount or intensity of light the object emits or reflects, the more light the object reflects the brighter it appears

• Saturation- the visual experience specified by the complexity of light. (vividness or richness of color)

Hue, brightness, and saturation are all psychological dimensions of visual experience

An Eye on the World

Cornea- transparent protectionLens- changes shape becoming more or less curved to focus light. Does not function the same as a camera.

Pg. 157 Iris- lets light in by opening/closing; gives the eye its colorPupil- round opening of the eye, contracts during bright light, opens during dim light

Retina- visual receptors in the back of the eye; extension of the brain. When the lens of the eye focuses light on the retina, the result is an upside-down image.

Rods- 120 to 125 million in the retina, more sensitive to light. Enable us to see in dim light and peripheral visionCones- 7 to 8 million, allows us to see color

Fovea- center of the retina where vision is the sharpest, only contains cones.Dark Adaptation- visual receptors becoming maximally sensitive to dim light. Rods adapt in 20 minutes. Cones adapt quickly in dim light (10 minutes)

Pg. 160 How We See Color

Trichromatic Theory- 3 basic types of cones, each responds to different range of wavelengths which give us the experience of blue, green, red

Total Color Blindness- usually occurs when cones of the retina are absent or malfunctioning. Usually a color deficient person is unable to distinguish red from green, so the world is painted in shades of blue, yellow, brown and gray

Opponent- Process Theory- treats pairs of colors as opposing; (red/green, blue/yellow, black/white) http://www.youtube.com/watch?v=BkjfYxOm1psAfter-image- cells that switch on or off to signal the presence of one color, send the opposite color when the initial signal is removed.

Pg.161 Constructing the Visual World

Pg.162 Gestalt Principles- Study how people organize the world visually into meaningful units and patterns.

• Figure/Ground- we always organize the visual field into figure ground. Figure stands out from the rest of the environment. Ground- background of the figure

• Proximity- things that are near each other tend to be grouped together

• Closure- the brain fills in gaps to perceive complete forms

• Similarity- things that are alike in some way tend to be perceived as belonging together. See example in the book pg.163

• Pg.163 continuity- lines and patterns tend to be perceived as continuing in time and space

• Identify the following Gestalt principles

• Th prchas of a hme s lkely th sngle mst mprtant fnancl dcisn y’ll evr mke.

• 1, 3, 5, __, 9

Proximity and Closure allow us to see the Big Dipper.

Depth and Distance perception

Binocular Cues- depth or distance cues that require the use of 2 eyes. (We infer an object’s location by estimating its distance)Convergence- turning inward of the eyes when they focus on a nearby object.

Retinal Disparity- slight difference between what the left eye and right eye sees.Binocular Cues help us estimate distances up to 50 feet.Monocular cues- depth or distance cues that can be used by one eye alone

Interposition- one object blocks a second object, the 1st object is perceived as being closerLinear perspective- 2 parallel lines appear to come together

Visual Constancies: When seeing is Believing

Perceptual Constancy- perception of objects as stable

• Shape constancy- shape stays constant when our point of view changes

• Location constancy- stationary objects remain in the same place

• Pg. 164 Size Constancy- an object has constant size as its image becomes smaller or larger

• Brightness constancy- an objects brightness stays even though the amount of light the object reflects changes

• Pg. 165 Color constancy- objects maintain its hue despite wavelength of light reaching our eyes may change.

• Perceptual illusion- misleading perception of reality

Pg. 167 Hearing

What We HearThe stimulus for sound is a wave of pressure

• Loudness- dimension of auditory experience related to the intensity of a wave’s pressure (Amplitude). The more energy the higher the wave. Measured in units called decibels. Rock concert decibels create immediate danger.

• Pitch- frequency of sound waves, frequency refers to how rapid the air vibrates, measured in hertz

• Timbre- distinguishes quality of sound. Dimension of auditory experience related to the complexity of a sound wave

An Ear on the World

The ear has an outer, middle, and inner sectionPg. 169 Hearing would still be good without the outer ear.Eardrum- sound wave hits an oval shaped membraneMiddle ear- 3 tiny bones; hammer, anvil, stirrup

Cochlea- actual organ of hearing, snail shaped structure filled with fluid located in the inner earCilia- hair cell (receptor cells)

Basilar membrane- stretches across interior of the cochlea. Pressure causes wavelike motion in the fluid stimulating the cilia which signals the auditory nerve

Pg 170 Constructing the Auditory World

Figure/ground- figure- primary focus of attention; ground- background noise

Distance-loudness used as a cue, louder sounds are perceived as being closer

Direction- use of 2 ears, sound coming into rt. /left ear signals which direction the sound is coming from. Turning your head to locate a sound is an effort to overcome sounds that are directly in front or behind

Pg. 171 Other Senses

Taste: Savory SensationsTaste or Gustation occurs because of chemical stimulation.Papillae- elevations on the tongue containing the taste buds, receptors for taste are found inside the taste buds

4 basic tastes; salty, sour, bitter, and sweet. All 4 basic tastes can be perceived at any spot on the tongue. Center of the tongue contains no taste buds.Pg. 172 The liking for sweets is universal, a part of our evolutionary heritage.

Smell: The Sense of Scents

Sense of smell or olfaction- 10,000 smells, no smell seems to be more basic than any otherSmokers are nearly twice as likely as non-smokers to have trouble detecting common odors.Pg. 173 Smoking 2 packs a day for 10 years, must abstain for 10 years before a sense of smell returns to normal.

Pg. 174 Senses of the Skin

Basic skin sense- touch, warmth, cold, pain, itch, tickle, burningThe Mystery of PainPain occurs from a skin sense and internal sense. Pain may continue after the stimulus producing the pain is removed.

The Gate- Control theory of PainPain must get past a gate in the spinal cord. The brain controls the gate, thoughts and feeling can influence our reaction to pain. Does not explain how phantom pain can occur.

Phantom pain- a person continues to feel pain from an amputated limb or from an organ that has been removed.

Pg.175 The Environment from Within

Kinethesis- tells us where are body parts are located and lets us know when they move. Information is provided by pain, pressure receptors located in our muscles, joints, and tendons. Damage would give a feeling of being a rag doll.Pg.176 Equilibrium- sense of balance, relies on 3 semi-circular canals in the inner ear.

Pg.177 Perceptual Powers: Origins and Influences

Inborn Abilities and Perceptual LessonsVisual Cliff- testing an infant’s perception of depth. An infant is placed on a board and the child’s mother tries to lure the baby across the deep side. Babies as young as 6 months of age refused to crawl out over the “cliff”.

Pg.178 Psychological and Cultural; Influences on Perception

• Needs-When we need something, or want it, we are likely to perceive it.

• Emotions- emotions influence our interpretation of sensory information. Pain is affected; negative emotions can prolong a person’s pain.

• Expectations – perceptual set: tendency to perceive what you expect, helps fill in missing information.

• Beliefs- what we hold true about the world can affect our interpretation, IE: images of Jesus

Pg.180 Puzzles of Perception

Subliminal perception- simple visual stimulus can affect your behavior even when you are unaware that you saw it. The influence of the subliminal stimulus usually disappears within seconds.

Precognition- perception of an event that has not happenedTelepathy- direct communication of a message from one mind to another

Pg 181 Parapsychology- the study of extrasensory perception. ESP studies are poorly designed. Results cannot be duplicated, concluding there is no scientific justification for the existence of Para psychological phenomena.

Pg.183 Psychology in the news revisited

When a large number of people reported UFO sightings, impartial investigators found, people saw ordinary celestial bodies, weather balloons, or rocket launchings.