Basic Concepts of Sensation and Perception

Processing Sensation and Perception

LOQ: What are sensation and perception? What do we mean by bottom-up processing and top-down processing?

Under normal circumstances, sensation and perception blend into one continuous process.

• Bottom-up processing begins at your sensory receptors and works up to higher levels of processing.

  • bottom-up processing enables your sensory systems to detect the lines, angles, and colors that form the flower and leaves

• Top-down processing creates perceptions from this sensory input by drawing on your experience and expectations.

  • top-down processing interprets what your senses detect.

Sensation: the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

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Sensory Receptors: sensory nerve endings that respond to stimuli.

Perception:  the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Bottom-Up Processing: analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.

Top-Down Processing: information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

Transduction

LOQ: What three steps are basic to all our sensory systems?

All of our sense

• receive sensory stimulation, often using specialized receptor cells. transform that stimulation into neural impulses. deliver the neural information to our brain.

• They also convert one form of energy into another

  • This is called transduction

Transduction:  conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret.

Psychophysics: the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

Thresholds

LOQ: How do absolute thresholds and difference thresholds differ?

Absolute Thresholds

Some kinds of stimuli we are really  sensitive

• Gustav Fechner (German philsophist and scientist) studied the edge of our awareness of these faint stimul

  • Called this the absolute threshold

    • Minimum stimulation needed to notice particular light, sound, pressure, taste, or odor 50 percent of the time

Signal detection theory predicts when we will detect weak signals

• depends not only on its strength but also on our experience, expectations, motivation, and alertness.

• Signal detection theorists seek to understand why people respond differently to the same stimuli

  • why the same person’s reactions vary as circumstances change

Stimuli you cannot consciously detect 50 percent of the time are subliminal

• we can evaluate a stimulus even when we are not consciously aware of i

Absolute Threshold:  the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time

Signal Detection Theory: a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness

Subliminal:  below one’s absolute threshold for conscious awareness.

Priming:  the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response

Difference Thresholds

We need absolute thresholds low enough to allow us to detect important sights, sounds, textures, tastes, and smell

• also need to detect small differences among stimuli

• Ex. Parents must detect the sound of their own child’s voice amid other children’s voices

Weber’s Law

• Developed by Ernest Weber in the late 1800s

• For an average person to perceive a difference, two stimuli must differ by a constant minimum percentage

Difference Threshold: the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference (or jnd).

Weber’s Law: the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

Sensory Adaptation

LOQ: What is the function of sensory adaptation?

When constantly exposed to an unchanging stimulus, we become less aware of it because our

nerve cells fire less frequently

• Ex. rolling up your sleeve-you will only feel the differences for a while but not for long

Sensory adaptation reduces our sensitivity

• Allows freedom to focus on informative changes in our environment

• even influences how we perceive emotions.

Sensory Adaptation: diminished sensitivity as a consequence of constant stimulation.

Point to Remember: Our sensory receptors are alert to novelty; bore them with repetition and they free our attention for more important things

Perceptual Set

LOQ: How do our expectations, contexts, motivation, and emotions influence our perceptions?

Through experience, we come to expect certain results

• expectations may give us a perceptual set

• To believe is also to hear.

• Our expectations can also influence our taste perceptions

Our concepts, or schemas, that we form and organize and interpret unfamiliar information develop our perceptual set

Perceptual Set: a mental predisposition to perceive one thing and not another

Context, Motivation, and Emotion

Context

Examples of the power of context:

• When holding a gun, people become more likely to perceive another person as also gun-toting—a phenomenon that has led to the shooting of some unarmed people who were actually holding their phone or wallet

• Imagine hearing a noise interrupted by the words “eel is on the wagon.” Likely, you would actually perceive the first word as wheel. Given “eel is on the orange,” you would more likely hear peel. In each case, the context creates an expectation that, top-down, influences our perception of a previously heard phrase

• Cultural context helps inform our perceptions, so it’s not surprising that people from different cultures view things differently

Motivation

Motives give us energy as we work toward a goal

• can bias our interpretations of neutral stimuli

Examples:

• Desirable objects, such as a water bottle viewed by a thirsty person, seem closer than they really are. This perceptual bias energizes our going for it.

• A to-be-climbed hill can seem steeper when we are carrying a heavy backpack, and a walking destination further away when we are feeling tired. Going on a diet can lighten our biological “backpack” . When heavy people lose weight, hills and stairs no longer seem so steep.

• A softball appears bigger when you’re hitting well, as researchers observed after asking players to choose a circle the size of the ball they had just hit well or poorly. There’s also a reciprocal phenomenon: Seeing a target as bigger—as happens when athletes focus directly on a target—improves performance

Emotions

Emotions can cause our perceptions to change

• Hearing sad music can predispose people to perceive a sad meaning in spoken homophonic words—mourning rather than morning, die rather than dye, pain rather than pane

• A hill seems less steep to people who feel others understand them

• When angry, people more often perceive neutral objects as guns. When made to feel mildly upset by subliminal exposure to a scowling face, people perceive a neutral face as less attractive and likeable

Emotions and motives color our social perceptions

• perceive solitary confinement, sleep deprivation, and cold temperatures as “torture” when experiencing a small dose of such themselves

• Much of what we perceive comes not just from what’s “out there,” but also from what’s behind our eyes and between our ears.

Vision: Sensory and Perceptual Processing

Light Energy and Eye Structures

LOQ: What are the characteristics of the energy that we see as visible light? What structures in the eye help focus that energy?

The Stimulus Input: Light Energy

When you look at a bright red tulip, the stimuli striking your eyes are not particles of the color red

• pulses of electromagnetic energy that your visual system perceives as red

What we see as visible light is but a thin slice of the wide spectrum of electromagnetic energy

• On the spectrum’s one end are the short gamma waves (not bigger than a size of an atom)

• On the other end are the mile-long waves of radio transmission

Light travels in waves

• The shape of those waves influences what we see.

• Wavelength determines hue

• A light wave’s amplitude, or height, determines its intensity

Wavelength:  the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of gamma rays to the long pulses of radio transmission.

Hue: the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.

Intensity: the amount of energy in a light wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the wave’s amplitude (height).

The Eye

Light enters the eye through the cornea

• bends light to help provide focus

• light then passes through the pupil

• the iris, a colored muscle that dilates or constricts in response to light intensity

  • Every iris is so unique that an iris-scanning machine can confirm your identity

  • responds to your cognitive and emotional states

    • constricts when you are about to answer “No” to a question or when you feel disgust

    • when you’re feeling amorous, pupils will dilate to show interest

• After passing through your pupil, light hits the transparent lens in your eye

• lens then focuses the light rays into an image on your retina,

  • the lens changes its curvature and thickness in a process called

  • Accommodation to focus the rays

Retina: the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

Accommodation:  the process by which the eye’s lens changes shape to focus near or far objects on the retina.

Information Processing in the Eye and Brain

LOQ: How do the rods and cones process information, and what is the path information travels from the eye to the brain?

The Eye-to-Brain Pathway

How light enters the brain

• First, you would thread your way through the retina’s sparse outer layer of cell

• Then, reaching the back of your eye, you would encounter the retina’s nearly 130 million buried receptor cells, the rods and cones

  • There, you would see the light energy trigger chemical changes.

    • That chemical reaction would spark neural signals in nearby bipolar cells.

  • could then watch the bipolar cells activate neighboring ganglion cells

  • axons twine together like the strands of a rope to form the optic nerve

• After stopping at the thalamus, the information would fly on to the last destination, the visual cortex

  • in the occipital lobe at the back of your brain

Optic nerve is an information highway from the eye to the brain

• can send nearly 1 million messages at once through its nearly 1 million ganglion fibers

• With it being this fast, this causes blind-spots

  • no receptor cells, where the optic nerve leaves the eye

Rods:  retinal receptors that detect black, white, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond.

Cones:  retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Cones detect fine detail and give rise to color sensations.

Optic Nerve: the nerve that carries neural impulses from the eye to the brain.

Blind Spot: the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there

Color Processing

LOQ: How do we perceive color in the world around us?

About 1 person in 50 is “colorblind.”

• Typically men as it is genetic and carried on the X-Chromosome

• Most people are not actually blind to all colors

  • Lack functioning red- or green-sensitive cones or both of them

  • Some people are completely colorblind and only see in shades of gray

Ewald Hering trichromatic theory leaves some parts of the color vision mystery unsolved.

• formed a hypothesis: Color vision must involve two additional color processes, one responsible for red-versus-green perception, and one for blue-versus-yellow perception

  • This theory was confirmed by later researchers

  • Now called the opponent-process theory

Young-Helmholtz Trichromatic (three-color) Theory: the theory that the retina contains three different types of color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color.

Opponent-Process Theory: the theory that opposing retinal processes (redgreen, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.

Feature Detection

LOQ: Where are feature detectors located, and what do they do?

David Hubel and Torsten Wiesel showed that our visual processing deconstructs visual images and then reassembles them

• received a Nobel Prize for their work on feature detectors

One temporal lobe area by your right ear enables you to perceive faces

• a specialized neural network recognizes them from varied viewpoint

• If stimulated in this fusiform face area, you might spontaneously see faces

• If this face recognition region were damaged, you might recognize other forms and objects, but not familiar face

Feature Detectors: nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

Parallel Processing

LOQ: How does the brain use parallel processing to construct visual perceptions?

To analyze a visual scene, the brain divides it into subdimensions

• motion, form, depth, color

• works on each aspect simultaneously

Recognizing a face has many parts

• your brain integrates information projected by your retinas to several visual cortex areas and compares it with stored information, thus enabling your fusiform face area to recognize the face

Parallel Processing: processing many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions, including vision.

Perceptual Organization

LOQ: How did the Gestalt psychologists understand perceptual organization, and how do figure-ground and grouping principles contribute to our perceptions?

A group of German psychologists noticed that people who are given a cluster of sensations tend to organize them into a gestalt

• Our conscious perception is, at every moment, a seamless scene

• demonstrated many principles we use to organize our sensations into perceptions

• Claimed: Our brain does more than register information about the world

Perception is not just opening a shutter and letting a picture print itself on the brain.

• We filter incoming information and construct perceptions.

Gestalt: an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

Form Perception

Figure and Ground

Figure-ground the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

Grouping

We must organize the figure into a meaningful form

• color, movement, and light-dark contrast is processed immediately along with other basic scene features

• order and form to other stimuli by following certain rules for grouping

• shows how the perceived whole differs from the sum of its parts

Grouping: the perceptual tendency to organize stimuli into coherent groups.

Depth Perception

LOQ: How do we use binocular and monocular cues to see in three dimensions, and how do we perceive motion?

Gibson and Richard Walk designed a series of experiments in their Cornell University laboratory using a visual cliff

• placed 6- to 14-month-old infants on the edge of the “cliff” and had the infants’ mothers coax them to crawl out onto the glass

  • Most infants refused to do so, showing that they could perceive depth.

Depth perception is also partly innate

• biology prepares us to be wary of heights, and exposure increases that fear

Depth Perception: the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance.

Visual Cliff: a laboratory device for testing depth perception in infants and

young animals.

Binocular Cues

People ****who see with two eyes perceive depth thanks partly to binocular cues.

• Used to judge the distance of nearby objects

• One cue is retinal disparity

  • Compares the two images from each eye and your brain can judge how close an object is to you

    • greater the disparity (difference) between the two retinal images, the closer the object

    • Smaller the disparity, the farther the object

Binocular Cue: a depth cue, such as retinal disparity, that depends on the use of two eyes

Retinal Disparity: a binocular cue for perceiving depth. By comparing retinal images from the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

Monocular Cues

We depend on monocular cues to see objects 10-100 meters away

Monocular Cue: a depth cue, such as interposition or linear perspective, available to either eye alone.

Motion Perception

You could perceive the world as having color, form, and depth but that you could not see motion

• You would have trouble driving, writing, eating, and walking.

Normally your brain computes motion based

• partly on its assumption that shrinking objects are retreating (not getting smaller) and enlarging objects are approaching

• We are are imperfect at motion perception

• sometimes tricked into believing what it is not seeing

  • large and small objects move at the same speed, the large objects appear to move more slowly

    • Ex. big plane landing slower than a little plane even if they are going the same speed

Perceives a rapid series of slightly varying images as continuous movement

• phenomenon called the stroboscopic movement

• We construct that motion in our head

• Lighted signs exploit the phi phenomenon

  • Ex. constructing movement in blinking marquees and holiday lights

Phi Phenomenon: an illusion of movement created when two or more adjacent lights blink on and off in quick succession.

Perceptual Constancy

LOQ: How do perceptual constancies help us construct meaningful perceptions?

Recognizing objects without being deceived by changes in their color, brightness, shape, or size

• a top-down process called perceptual constancy

  • we can identify people and things in very short amount of time no matter the viewing angle, distance, or illumination

Perceptual Constancy: perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change.

Color and Bright Constancy

Our experience of color depends on an object’s context

• perception of consistent color we call color constancy

• see color because of our brain’s computations of the light reflected by an object relative to the objects surrounding it

Brightness constancy (also called lightness constancy) similarly depends on context

• We perceive an object as having a constant brightness even as its illumination changes

  • depends on relative luminance—the amount of light an object reflects relative to its surroundings

Shape and Size Consistencies

we perceive the form of familiar objects, such as the door in FIGURE 6.33, as constant even while our retinas receive changing images of them

• This is because of shape consistency

  • perceive an object as having a constant size, even while our distance from it varies

Perceptual Interpretation

Philosophers have debated whether our perceptual abilities should be credited to our nature or our nurture

Experience and Visual Perception

LOQ: What does research on restored vision, sensory restriction, and perceptual adaptation reveal about the effects of experience on perception?

Restored Vision and Sensory Restrictions

William Molyneux wondered whether “a man born blind, and now adult, taught by his touch to distinguish between a cube and a sphere” could, if made to see, visually distinguish the two.

• John Locke’s response to this was, “No”

Researchers have restricted the vision of infant kittens in clinical cases

• After infancy, when their vision was restored

  • could distinguish color and brightness, but not the form of a circle from that of a square

  • Their eyes had not degenerated

  • They remained functionally blind to shape

Perceptual Adaptation

Our perceptual adaptation to changed visual input makes the world seem normal again.

• we constantly adjust to changed sensory input

• early nurture sculpts what nature has provided.

Perceptual Adaptation: the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field.

The Nonvisual Senses

Hearing

Our other senses such as hearing, or audition, help us to adapt and survive

• provides information and enables relationships

• humanizes us

  • people seem more thoughtful, competent, and likable

Audition: the sense or act of hearing.

The Stimulus Input: Sound Waves

LOQ: What are the characteristics of air pressure waves that we hear as sound?

Sound waves vary in shape like light waves

• height, or amplitude, of sound waves determines their perceived loudness

• length, or frequency, determines the pitch (the high or low tone)

  • Long waves have low frequency—and low pitch.

  • Short waves have high frequency—and high pitch.

We measure sounds in decibels

• zero decibels representing the absolute threshold for hearing

• Every 10 decibels correspond to a tenfold increase in sound intensity

• normal conversation (60 decibels) is 10,000 times more intense than a 20-decibel whisper

• prolonged, exposure to sounds above 85 decibels can produce hearing loss

Frequency: the number of complete wavelengths that pass a point in a given time (for example, per second).

Pitch:  a tone’s experienced highness or lowness; depends on frequency.

The Ear

LOQ: How does the ear transform sound energy into neural messages?

Vibrating air trigger nerve impulses that your brain can decode as sounds

• begins when sound waves strike your eardrum causing this tight membrane to vibrate

• middle ear, a piston made of three tiny bones (the hammer, anvil, and stirrup) picks up the vibrations and transmits them to the cochlea

  • a snail-shaped tube in your inner ear.

Incoming vibrations then cause the cochlea’s membrane-covered opening (the oval window) to vibrate

• This motion causes ripples in the basilar membrane, bending the hair cells lining its surface, rather like wheat stalks bending in the wind

• hair cell movements in turn trigger impulses in adjacent nerve cells

  • axons converge to form the auditory nerve.

  • auditory nerve carries the neural messages to your thalamus and then on to the auditory cortex in your brain’s temporal lobe.

Damage to the cochlea’s hair cell receptors or the auditory nerve can cause sensorineural hearing loss (or nerve deafness)

• With auditory nerve damage, people may hear sound but have trouble discerning what someone is saying

  • Usually caused by biological changes linked with heredity and aging, and prolonged exposure to ear-splitting noise or music.

• Occasionally, disease damages hair cell receptors

• cannot be reversed

  • a cochlear implant is currently the only way to restore hearing

Middle Ear: the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window.

Cochlea: a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses.

Inner Ear: the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.

Sensorineural Hearing Loss: hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves; the most common form of hearing loss, also called nerve deafness.

Conduction Hearing Loss: a less common form of hearing loss, caused by damage to the mechanical system that conducts sound waves to the cochlear

Cochlear Implant: a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlear

Perceiving Loudness, Pitch, and Location

LOQ: How do we detect loudness, discriminate pitch, and locate sounds?

Responding to Loud and Soft Sounds

Your brain interprets loudness from the number of activated hair cells.

• If a hair cell loses sensitivity to soft sounds, it may still respond to loud sounds.

• Explains why really loud sounds may seem loud to people with or without normal hearing

Hearing Different Pitches

There are currently a combination of two theories on how we discriminate pitch

• Place theory presumes that we hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane. Thus, the brain determines a sound’s pitch by recognizing the specific place (on the membrane) that is generating the neural signal. Place theory can explain how we hear high-pitched sounds but not low pitched sounds.

• Frequency theory (also called temporal theory) suggests an alternative: The brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve. The whole basilar membrane vibrates with the incoming sound wave, triggering neural impulses to the brain at the same rate as the sound wave. If the sound wave has a frequency of 100 waves per second, then 100 pulses per second travel up the auditory nerve. But frequency theory also has a problem: An individual neuron cannot fire faster than 1000 times per second. How, then, can we sense sounds with frequencies above 1000 waves per second (roughly the upper third of a piano keyboard)? Enter the volley principle: Like soldiers who alternate firing so that some can shoot while others reload, neural cells can alternate firing. By firing in rapid succession, they can achieve a combined frequency above 1000 waves per second.

Place Theory: in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated.

Frequency Theory: in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch. (Also called temporal theory.)

Locating Sounds

Because of the placement of our two ears, we enjoy stereophonic (“three-dimensional”) hearing

• Two ears are better than one

  • Ex. a car to your right honks, your right ear will receive a more intense sound, and it will receive the sound slightly sooner than your left ear

The Other Senses

Humans would be seriously handicapped without our senses of touch, taste, smell, and body position and movement

Touch

LOQ: How do we sense touch?

Touch aids our development

• Ex. Premature human babies gain weight faster and go home sooner whe stimulated by hands

Our “sense of touch” is actually a mix of these four basic and distinct skin senses

• variations of pressure, warmth, cold, and pain

Pain

LOQ: What biological, psychological, and social-cultural influences affect our experience of pain? How do placebos, distraction, and hypnosis help control pain?

Pain is your body’s way of telling you something has gone wrong

• also serves psychological purposes

• provides a contrast that amplifies our experiences of pleasure

• It enhances our self-awareness

Understanding Pain

Pain reflects both bottom-up sensations and top-down cognition

• Pain is a biopsychosocial event

• Viewing pain from the biological, psychological, and social-cultural perspectives can help us better understand it, and also help us cope with it and treat it

Biological Influences

Pain is a physical event produced by your senses

• pain differs from some of your other sensations

• No one type of stimulus triggers pain the way light triggers vision

• sensory receptors called nociceptors

  • detect hurtful temperatures, pressure, or chemicals

  • mostly in your skin, but also in your muscles and organs

• Your experience of pain depends in part on the genes you inherited and on your physical characteristics

Psychologist Ronald Melzack and biologist Patrick Wall proposed the gate-conttrol theory

• Melzack and Wall theorized that when tissue is injured, the small fibers activate and open the gate. The pain signals can then travel to your brain, and you feel pain

  • large-fiber activity (stimulated by massage, electric stimulation, or acupuncture) can close the gate, blocking pain signals

  • g pain signals. Brain-to-spinal-cord messages can also close the gate. Thus, chronic pain can be treated both by “gate-closing” stimulation, such as massage, and by mental activity, such as distraction

Brain can also create pain

• Ex. phantom limb sensations after a limb amputation

• may haunt other senses too

  • People with hearing loss often experience the sound of silence: tinnitus

Gate-Control Theory: the theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. The “gate” is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.

Psychological Influences

Our perception of pain is the attention we focus on it

• We also seem to edit our memories of pain

• often differ from the pain we actually experienced

Social-Cultural Influences

Pain is a product of our attention, our expectations, and also our culture

• We tend to perceive more pain when others seem to be experiencing pain

Controlling Pain

Pain control therapies may include drugs, surgery, acupuncture, electrical stimulation, massage, exercise, hypnosis, relaxation training, meditation, and thought distraction

• we also benefit from our own built-in pain control when in pain

  • brain releases a natural painkiller—endorphins

    • we are distracted from pain and soothed by endorphin release, the pain we experience may be greatly reduced

Placebos

Even placebos can help

• dampening the central nervous system’s attention and responses to painful experiences—mimicking painkilling drugs

Distraction

Drawing attention away from the painful stimulation is an effective way to activate brain pathways that inhibit pain and increase pain tolerance

• Because pain is in the brain, diverting the brain’s attention may bring relief.

Hypnosis

Research suggests, maximize pain relief by combining a placebo with distraction (Buhle et al., 2012) and amplifying their effects with hypnosis

• After a few minutes of this hypnotic induction, you may experience hypnosis.

  • Words will have changed your brain.

Psychologists have proposed two explanations for how hypnosis works:

• Social influence theory contends that hypnosis is a by-product of normal social and mental processes. In this view, hypnotized people, like actors caught up in a role, begin to feel and behave in ways appropriate for “good hypnotic subjects.” They may allow the hypnotist to direct their attention and fantasies away from pain.

• Dissociation theory proposes that hypnosis is a special dual-processing state of dissociation—a split between different levels of consciousness. Dissociation theory seeks to explain why, when no one is watching, previously hypnotized people may carry out posthypnotic suggestions (which are made during hypnosis but carried out after the person is no longer hypnotized). It also offers an explanation for why people hypnotized for pain relief may show brain activity in areas that receive sensory information, but not in areas that normally process pain-related information

• Selective attention may also play a role in hypnotic pain relief

Dissociation:  a split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others.

Posthypnotic Suggestion: a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control undesired symptoms and behaviors.

Hypnosis: a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviors ANSWER: will spontaneously occur.

Taste

LOQ: In what ways are our senses of taste and smell similar, and how do they differ?

Our sense of taste involves several basic sensations

• Taste’s sensations were once thought to be sweet, sour, salty, and bitter

  • A fifth sensation has been found that is the savory, meaty taste of umami

• It is a chemical sense

The Survival Functions of Basic Tastes

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Smell

Experience of smell is called olfaction

• It is a chemical sense

• We smell something when molecules of a substance carried in the air reach a tiny cluster of receptor cells at the top of each nasal cavity

  • 20 million olfactory receptors

  • Instantly alert the brain through their axon fibers.

Olfactory neurons bypass the brain’s sensory control center, the thalamus

• Our ancestors smelled molecules called pheromones, secreted by other members of their species

  • ome pheromones serve as sexual attractants

• A smell’s appeal depends on cultural experiences

• we also have trouble recalling odors by name

  • brain’s circuitry helps explain an odor’s power to evoke feelings and memories

    • Ex. the smell of your grandparents house

Our sense of smell is less acute than our senses of seeing and hearing

Gender and age influence our ability to identify scents

• Women and young adults have the best sense of smell

• Smokers and people with Alzheimer’s disease, Parkinson’s disease, or alcohol use disorder typically have a diminished sense of smell

• sense of smell tends to peak in early adulthood and gradually declines after that

Body Position and Movement

LOQ: How do we sense our body’s position and movement?

Without kinesthesia, we wouldn’t be able to take a step forward

• This act takes around 200 muscles as well as your brain to conduct the act

Vision interacts with kinesthesia

• Standing with your right heel in front of your left toes is relativly easy

• Closing your eyes and doing it agian is typically harder you you might wobble

Vestibular sense monitors your head’s and body’s position and movement

• this sense of equilibrium are two structures in your inner ear

  • first, your fluid-filled semicircular canals

  • second structure is the pair of calcium crystal-filled vestibular sacs

• second structure is the pair of calcium crystal-filled vestibular sacs

  • These send nerve signals to the back of your brain to help maintain your balance

Kinesthesia: the system for sensing the position and movement of individual body parts.

Vestibular Sense: the sense of body movement and position, including the sense of balance.

Sensory Interaction

LOQ: How does sensory interaction influence our perceptions, and what is embodied cognition?

All our senses interact with one another and our brain blends their inputs to interpret the world

• This is sensory interaction

  • One sense can influence another

    • Ex. Smell is a big part of taste. If you cant smell something, it will be hard for you to taste it

  • If the interactions disagree they blend the experiences together

    • Ex. our eyes see a speaker form one sound but our ears hear another sound

Our perceptions have two main parts

• Our bottom-up sensations

• Our top-down cognitions

• Ex. expectations, attitudes, thoughts, and memories

The brain circuits processing our physical sensations sometimes interact with brain circuits responsible for cognition

• This is embodied cognition. Ex:

• Physical warmth may promote social warmth. After holding a warm drink rather than a cold one, people were more likely to rate someone more warmly, feel closer to them, and behave more generously

• Social exclusion can literally feel cold. After being given the cold shoulder by others, people judged the room to be colder than did those who had been treated warmly

• Judgments of others may also mimic body sensations. Sitting at a wobbly desk and chair makes others’ relationships, or even one’s own romantic relationship, seem less stable

Our brain blends inputs from multiple channels

• This causes some people to have synesthesia

  • This is when the brain circuits for two or more senses become joined

  • Ex: hearing a color

Sensory Interaction: the principle that one sense may influence another, as when the smell of food influences its taste

Embodied Cognition:  the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments.

ESP—Perception Without Sensation?

LOQ: What are the claims of ESP, and what have most research psychologists concluded after putting these claims to the test?

Extrasensory Perception (ESP)

• claims that perception can occur apart from sensory input

  • Ex. reading minds, seeing through walls, or foretelling the future

The most testable and, for this discussion, most relevant ESP claims are

• telepathy: mind-to-mind communication.

• clairvoyance: perceiving remote events, such as a house on fire in another state.

• precognition: perceiving future events, such as an unexpected death in the next month.

Most research psychologists and scientists have been skeptical that paranormal phenomena exist

• several reputable universities, parapsychology researchers perform scientific experiments

Extrasensory Perception (ESP): the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition. Do you think you might have ESP?

Parapsychology: the study of paranormal phenomena, including ESP and psychokinesis.

Premonitions or Pretensions?

“Leading psychics” reveal meager accuracy

• During the 1990s, the tabloid psychics were all wrong in predicting surprising events

• psychic visions offered to police departments have been no more accurate than guesses made by others

• one estimate says that the chance alone would predict that more than a thousand times per day, someone on Earth will think of another person and then, within the next five minutes, learn of that person’s death

Putting ESP to Experimental Test

Both believers and skeptics agree that what parapsychology needs is a reproducible phenomenon and a theory to explain it.

Daryl Bem has made his research materials available to anyone who wishes to replicate his studies

• His results didn’t show a huge signifigant difference

• Science is doing its work still

  • It has been open to a finding that challenges its own assumptions

  • Through follow-up research, it has assessed the validity of that finding.