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© 2014 John Wiley & Sons, Inc. All rights reserved.

•  Understanding sensaAon •  How we see and hear •  Our other important senses •  Understanding percepAon

Chapter four SensaAon and PercepAon

realworldpsychology


Things You’ll Learn in Chapter 4 Do athletes have a higher pain tolerance than non-‐athletes?

Q1

Can looking at a photograph of a loved one lead you to feel less pain? Q2

How can listening to loud music on headphones damage your hearing?

Q3

Why do premature babies grow faster when they receive skin-‐to-‐skin contact?

Q4

Why do people rate themselves as more athleGc if they compare themselves to the Pope than to a professional basketball player?

Q5

•  While your brain floats in complete silence and darkness, your body is bombarded with sAmuli from outside.

•  Sensing the sAmuli is not enough – our brains must receive, convert and adapt the informaAon into meaningful representaAons of the world

Understanding Sensation

What are some of

these s,muli?


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•  SensaGon = process of detecAng, converAng and transmiPng raw sensory informaAon from the external and internal environments to the brain

•  PercepGon = process of selecAng, organizing, and interpreAng sensory info into meaningful paSerns

Understanding Sensation


UNDERSTANDING SENSATION


1.  Receptor cells in sense organs detect appropriate sAmuli

2.  Convert sAmuli (transducAon) into neural impulses (acAon potenAal)

3.  Transmit message to brain through different routes, allowing brain to differenAate physical sAmuli (coding)

4.  Brain assigns meaningful sensory informaAon

Sensation: the basics


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•  Some brain structures purposely reduce some sensory informaAon they receive

•  What types of things can humans not detect? – Ultraviolet light, microwaves, dog whistle, infrared heat paSerns

•  Field of psychophysics studies link between physical sAmuli and psychological experience

Stimulation Overload?

What if this sensory reduc,on

didn’t occur?


Virtual Field Trip: Biofeedback: Learning to

Understand Your Body

•  Consciously aware of only a narrow range of sAmuli at one Ame

•  Difference Threshold (AKA Weber’s Law of just noAceable differences or JND) = minimal difference in sAmulus strength that is detectable 50% of the Ame (Ernst Weber)

•  Absolute Threshold = minimum sAmulaAon needed to consciously detect sAmulus 50% of the Ame (Gustav Fechner)

What Can We Detect?

How could these be measured?


•  Studies on subliminal percepAon use a tachistoscope to flash images too quickly for conscious percepAon (but slowly enough for the brain to register them)

•  At the movies “eat popcorn”? satanic verses when music is played backward? hidden sexual messages in Disney films?

Subliminal Stimuli

•  Subliminal sAmuli are WEAK and don’t lead to subliminal persuasion

Can subliminal s,muli change your behavior?


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•  Suppose you visit a neighbor’s house with 10 cats. You smell the animals, but the owner doesn’t.

•  Sensory adaptaGon = when a constant sAmulus is presented, the sensory receptors become less sensiAve and fire less frequently

•  Normally, smell and touch experience sensory adaptaAon readily; vision and intense sAmuli do not.

Sensory Adaptation

Why not?

Why? What perspec,ve in psychology might

explain this?


realworldpsychology •  Intense pain olen resists sensory adaptaAon to signal danger

•  Endorphins are the body’s natural painkiller and are released during physical exerAon – Does the experience of playing sports change pain tolerance?

– Or are people with high pain tolerance drawn to athleAcs?


Do athletes have a higher pain tolerance than non-‐athletes?

Q1

•  Gate-‐control theory = experience of pain depends on whether the message gets past the “gatekeeper” in the spinal cord –  Normally, the gate is shut and pain signals are blocked, but when body Assue is damaged, impulses open the gate to allow the message of pain through

– Messages from the brain also control the gate, allowing some to conAnue through the pain (athletes, military, first responders)

What about pain?


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realworldpsychology •  Massaging an injury eases discomfort because pressure on larger-‐diameter neurons interferes with pain signals

•  Endorphins from the brain, distracAon by fear or compeAAon, acAvely listening to music – or looking at a picture – can close the gate and reduce pain and anxiety

•  Focusing on pain amplifies it © 2014 John Wiley & Sons, Inc. All rights reserved.

Can looking at a photograph of a loved one lead you to feel less pain?

Q3

•  Phantom limb pain = when amputee conAnues to feel sensaAons (pain, Ackling) in the missing limb

•  Nerve cells send conflicAng messages to the brain, producing “staAc” that is interpreted as pain

•  ProstheAc limbs and mirror visual therapy can help reduce phantom limb pain

What about pain?


HOW WE SEE AND HEAR


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•  Receptor cells in reAna (rods and cones) convert light waves into messages sent along the opAc nerve

Vision


AnimaGon: How We See and Hear

Tutorial Video:

Seeing and Hearing

•  Visual acuity problems result from small abnormaliAes in the shape of the eye, causing the image not to be in focus at the reAna –  Nearsightedness – image reaches focus in front of the reAna –  Farsightedness – image reaches focus behind the reAna

•  Presbyopia – lenses lose elasAcity with age •  Blind spot – no receptor cells where the opAc nerve exits the

eye •  Rods manage dark adaptaAon – changing from sunny to dark

environment leaves you temporarily blind •  Cones manage light adaptaAon – changing from dark to bright

environment acAvate cones

Vision Problems


•  Outer ear captures sound, three Any bones in middle ear transmit eardrum’s vibraAon to the inner ear where cochlea transforms waves into neural impulses

Hearing


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•  Frequency of sound waves provides informaAon about pitch of sound –  Place theory for hearing = hair cells at different locaAons along the basilar membrane are sAmulated by high-‐pitched sounds

–  Frequency theory for hearing = hair cells vibrate at the same low frequency as the low-‐pitched sounds they detect

•  Loud sounds have higher peaks and lower valleys than sol sounds, measured by decibels

Pitch and Volume


•  ConducAon hearing loss (conducAon deafness) = problems with mechanics of sending sound waves to cochlea. Hearing aids and some surgery help

•  Sensorineural hearing loss (nerve deafness) = damage to hair cells or auditory nerve

Hearing Problems

•  Result of loud noise, disease, and biological changes; damage to receptor cells and auditory nerve is irreversible


How can listening to loud music on headphones damage your hearing?

Q3

Video: Hearing

Screenings

OUR OTHER IMPORTANT SENSES


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•  Smell and taste are “chemical senses” because they use chemoreceptors and are sensiAve to chemical molecules

•  Olfactory receptors in the nose transduce info from odorants (molecules with odor) directly to olfactory bulb at base of frontal lobe, where info is processed and sent to other brain regions

•  OlfacAon is the only sensory system NOT routed through the thalamus

Smell


Video: Smart Nose

Video: Super Smellers

Video: The Nose Knows

•  Purpose of taste is to avoid poisonous foods (which are usually biSer); nonpoisonous foods with good energy are olen sweet

•  Dissolved food parAcles pass over papillae on the tongue and down into taste buds (taste receptors), which transduce info to the brain

•  Taste buds are distributed all over the tongue, NOT in dedicated regions by taste

•  Umami – savory; sensiAvity to glutamate found in meat, broth, MSG

Taste


Mennella, Jagnow & Beauchamp, 2001 •  Group 1: carrot juice 4x week for 3 weeks during pregnancy •  Group 2: carrot juice 4x week for 3 weeks aler baby was born

(breast-‐feeding mothers) •  Group 3: no carrot juice •  Mothers rated babies’ facial reacAons to different foods and

quanAty of carrot-‐flavored cereal baby would eat

•  Babies exposed to carrots in utero or through breast milk liked the taste of carrots beSer

Taste Preferences Shaped in Utero


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•  Skin sense detects pressure, temperature, and pain •  Touch receptors are most concentrated in face and hands (that’s why paper cuts hurt!)

Body Senses – Skin Sense

•  Kangaroo care – skin-‐to-‐skin contact between mother and baby recommended immediately aler birth, especially for low-‐birth-‐weight babies

•  Provides warmth, reduces pain, lowers stress arousal, improves sleep, which leads to growth


Why do premature babies grow faster when they receive skin-‐to-‐skin contact?

Q4

•  VesAbular sense tells the brain how our body (especially head) is oriented in 3-‐dimensional space

•  Hair cells in the semicircular canals of the inner ear and in the vesAbular sacs transduce the posiAon of the head into neural impulses

Body Senses -‐ Vestibular


•  Kinesthesis provides informaAon about body posture, orientaAon and movement of individual body parts

•  KinestheAc receptors in muscles, joints, and tendons tell the brain what is moving, how weight is distributed, where body parts are in relaAon to the whole

Body Senses -‐ Kinesthesis


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UNDERSTANDING PERCEPTION PercepAon = process of selecAng, organizing, and interpreAng incoming sensaAons into useful mental representaAon of the world


•  “Seeing is believing, but seeing isn’t always believing correctly” (Lilienfeld et al, 2010, p. 7)

•  Illusion = false or misleading impression produced by errors in the perceptual process or by actual physical distorAons

•  Illusions are NOT the same as hallucinaAons (false sensory experience WITHOUT external sAmuli) or delusions (false beliefs)

Perception Problems

What does this mean?


AnimaGon: PercepGon

Tutorial Video: A

World Turned Upside-‐Down:

Visual PercepGon

•  Cannot pay aSenAon to all sAmuli •  SelecGve aWenGon = paying aSenAon to important informaAon and filtering the rest

•  Feature detectors = specialized neurons to respond to specific sAmuli, like faces –  Prosopagnosia – inability to idenAfy person by facial features

•  HabituaGon = decrease in responding to repeated sAmulaAon of same sAmuli; more responsive to changes in environment –  Compliments from strangers are more exciAng than from long-‐term partner!

–  The song you HATED on first listen might grow on you!

Selection


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realworldpsychology •  How do adverAsers and poliAcal campaigns use selecAve aSenAon, feature detectors, and habituaAon?

•  Capture aSenAon with intense, novel, moving, contrasAng sAmuli and repeAAon


Virtual Field Trip: 3-‐D Media

•  Gestalt psychologists studied how the brain organizes sensory impressions into a “form” or “whole”

•  Figure-‐Ground: objects are disAnct from the background

Organization: Form Perception


•  Depth PercepAon: ability to perceive 3-‐dimensional space using binocular and monocular cues

Organization: Depth Perception

•  Visual cliff: crawling infants refuse to move to the “deep end”


realworldpsychology

Video: Virtual

Reality and Vision

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•  Perceive the environment as stable, despite changes in object’s size, shape, color and brightness

Organization: Constancies Perception

Why is this important?


•  TrichromaGc theory of color = three “color systems”, each of which is sensiAve to red, green and blue; mixing lights of these three colors yields the full spectrum of colors

•  Opponent-‐process theory = each of the color systems is sensiAve to two opposing colors (ex: either blue or yellow) –  Black-‐and-‐white systems respond to differences in brightness

Organization: Color Perception



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•  Color confusion on specific color spectrums, such as red-‐green or blue-‐yellow

Color-‐DeJicient Vision

Is anyone here “colorblind”? What

is it like?


•  Perceptual set = readiness to perceive sAmuli in a parAcular manner, based on expectaAons

•  We see what we expect to see •  Frame of reference = percepAon is influenced by context

Organization: Interpretation


Why do people rate themselves as more athleGc if they compare themselves to the Pope than to a professional basketball player?

Q5

•  BoWom-‐up processing = raw sensory data “sent up” to the brain for higher level analysis

•  Top-‐down processing = perceptual analysis starts “at the top” with expectaAons and knowledge driving the process of percepAon

•  You learn to read from boSom-‐up processing of leSers and words

•  Now, your aiblity to raed uisng top-‐dwon prcessoing mkes it psosible to unedrstnad this sntenece desipte its mnay mssiplllengis

Processing


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•  Extrasensory PercepGon (ESP) = “psychic” perceptual abiliAes that supposedly go beyond the known senses –  Telepathy, clairvoyance, precogniAon

•  Research in ESP don’t withstand scruAny, failure to replicate by rival research labs

•  Why do some believe in ESP? – MoAvaAon and interests influence our percepAons, creaAng selecAve percepAon

–  Strong emoAons about the subject mask faulty reasoning

Sixth Sense?



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