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© 2014 John Wiley & Sons, Inc. All rights reserved. Understanding sensation How we see and hear Our other important senses Understanding perception Chapter.

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Presentation on theme: "© 2014 John Wiley & Sons, Inc. All rights reserved. Understanding sensation How we see and hear Our other important senses Understanding perception Chapter."— Presentation transcript:

1 © 2014 John Wiley & Sons, Inc. All rights reserved. Understanding sensation How we see and hear Our other important senses Understanding perception Chapter four Sensation and Perception

2 realworldpsychology © 2014 John Wiley & Sons, Inc. All rights reserved. Things You’ll Learn in Chapter 4 Do athletes have a higher pain tolerance than non-athletes? Q1Q1 Can looking at a photograph of a loved one lead you to feel less pain? Q2Q2 How can listening to loud music on headphones damage your hearing? Q3Q3 Why do premature babies grow faster when they receive skin-to-skin contact? Q4Q4 Why do people rate themselves as more athletic if they compare themselves to the Pope than to a professional basketball player? Q5Q5

3 While your brain floats in complete silence and darkness, your body is bombarded with stimuli from outside. Sensing the stimuli is not enough – our brains must receive, convert and adapt the information into meaningful representations of the world Understanding Sensation What are some of these stimuli? © 2014 John Wiley & Sons, Inc. All rights reserved.

4 Sensation = process of detecting, converting and transmitting raw sensory information from the external and internal environments to the brain Perception = process of selecting, organizing, and interpreting sensory info into meaningful patterns Understanding Sensation © 2014 John Wiley & Sons, Inc. All rights reserved.

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

6 1.Receptor cells in sense organs detect appropriate stimuli 2.Convert stimuli (transduction) into neural impulses (action potential) 3.Transmit message to brain through different routes, allowing brain to differentiate physical stimuli (coding) 4.Brain assigns meaningful sensory information Sensation: the basics © 2014 John Wiley & Sons, Inc. All rights reserved.

7 Some brain structures purposely reduce some sensory information they receive What types of things can humans not detect? – Ultraviolet light, microwaves, dog whistle, infrared heat patterns Field of psychophysics studies link between physical stimuli and psychological experience Stimulation Overload? What if this sensory reduction didn’t occur? © 2014 John Wiley & Sons, Inc. All rights reserved.

8 Consciously aware of only a narrow range of stimuli at one time Difference Threshold (AKA Weber’s Law of just noticeable differences or JND) = minimal difference in stimulus strength that is detectable 50% of the time (Ernst Weber) Absolute Threshold = minimum stimulation needed to consciously detect stimulus 50% of the time (Gustav Fechner) What Can We Detect? How could these be measured? © 2014 John Wiley & Sons, Inc. All rights reserved.

9 Studies on subliminal perception use a tachistoscope to flash images too quickly for conscious perception (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 stimuli are WEAK and don’t lead to subliminal persuasion Can subliminal stimuli change your behavior? © 2014 John Wiley & Sons, Inc. All rights reserved.

10 Suppose you visit a neighbor’s house with 10 cats. You smell the animals, but the owner doesn’t. Sensory adaptation = when a constant stimulus is presented, the sensory receptors become less sensitive and fire less frequently Normally, smell and touch experience sensory adaptation readily; vision and intense stimuli do not. Sensory Adaptation Why not? Why? What perspective in psychology might explain this? © 2014 John Wiley & Sons, Inc. All rights reserved.

11 realworldpsychology Intense pain often resists sensory adaptation to signal danger Endorphins are the body’s natural painkiller and are released during physical exertion – Does the experience of playing sports change pain tolerance? – Or are people with high pain tolerance drawn to athletics? © 2014 John Wiley & Sons, Inc. All rights reserved. Do athletes have a higher pain tolerance than non-athletes? Q1Q1

12 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 tissue is damaged, impulses open the gate to allow the message of pain through – Messages from the brain also control the gate, allowing some to continue through the pain (athletes, military, first responders) What about pain? © 2014 John Wiley & Sons, Inc. All rights reserved.

13 realworldpsychology Massaging an injury eases discomfort because pressure on larger-diameter neurons interferes with pain signals Endorphins from the brain, distraction by fear or competition, actively 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? Q3Q3

14 Phantom limb pain = when amputee continues to feel sensations (pain, tickling) in the missing limb Nerve cells send conflicting messages to the brain, producing “static” that is interpreted as pain Prosthetic limbs and mirror visual therapy can help reduce phantom limb pain What about pain? © 2014 John Wiley & Sons, Inc. All rights reserved.

15 HOW WE SEE AND HEAR © 2014 John Wiley & Sons, Inc. All rights reserved.

16 Receptor cells in retina (rods and cones) convert light waves into messages sent along the optic nerve Vision © 2014 John Wiley & Sons, Inc. All rights reserved.

17 Visual acuity problems result from small abnormalities in the shape of the eye, causing the image not to be in focus at the retina – Nearsightedness – image reaches focus in front of the retina – Farsightedness – image reaches focus behind the retina Presbyopia – lenses lose elasticity with age Blind spot – no receptor cells where the optic nerve exits the eye Rods manage dark adaptation – changing from sunny to dark environment leaves you temporarily blind Cones manage light adaptation – changing from dark to bright environment activate cones Vision Problems © 2014 John Wiley & Sons, Inc. All rights reserved.

18 Outer ear captures sound, three tiny bones in middle ear transmit eardrum’s vibration to the inner ear where cochlea transforms waves into neural impulses Hearing © 2014 John Wiley & Sons, Inc. All rights reserved.

19 Frequency of sound waves provides information about pitch of sound – Place theory for hearing = hair cells at different locations along the basilar membrane are stimulated 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 soft sounds, measured by decibels Pitch and Volume © 2014 John Wiley & Sons, Inc. All rights reserved.

20 Conduction hearing loss (conduction 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 © 2014 John Wiley & Sons, Inc. All rights reserved. How can listening to loud music on headphones damage your hearing? Q3Q3

21 OUR OTHER IMPORTANT SENSES © 2014 John Wiley & Sons, Inc. All rights reserved.

22 Smell and taste are “chemical senses” because they use chemoreceptors and are sensitive 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 Olfaction is the only sensory system NOT routed through the thalamus Smell © 2014 John Wiley & Sons, Inc. All rights reserved.

23 Purpose of taste is to avoid poisonous foods (which are usually bitter); nonpoisonous foods with good energy are often sweet Dissolved food particles 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; sensitivity to glutamate found in meat, broth, MSG Taste © 2014 John Wiley & Sons, Inc. All rights reserved.

24 Mennella, Jagnow & Beauchamp, 2001 Group 1: carrot juice 4x week for 3 weeks during pregnancy Group 2: carrot juice 4x week for 3 weeks after baby was born (breast-feeding mothers) Group 3: no carrot juice Mothers rated babies’ facial reactions to different foods and quantity of carrot-flavored cereal baby would eat Babies exposed to carrots in utero or through breast milk liked the taste of carrots better Taste Preferences Shaped in Utero © 2014 John Wiley & Sons, Inc. All rights reserved.

25 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 after birth, especially for low-birth-weight babies Provides warmth, reduces pain, lowers stress arousal, improves sleep, which leads to growth © 2014 John Wiley & Sons, Inc. All rights reserved. Why do premature babies grow faster when they receive skin-to-skin contact? Q4Q4

26 Vestibular 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 vestibular sacs transduce the position of the head into neural impulses Body Senses - Vestibular © 2014 John Wiley & Sons, Inc. All rights reserved.

27 Kinesthesis provides information about body posture, orientation and movement of individual body parts Kinesthetic receptors in muscles, joints, and tendons tell the brain what is moving, how weight is distributed, where body parts are in relation to the whole Body Senses - Kinesthesis © 2014 John Wiley & Sons, Inc. All rights reserved.

28 UNDERSTANDING PERCEPTION Perception = process of selecting, organizing, and interpreting incoming sensations into useful mental representation of the world © 2014 John Wiley & Sons, Inc. All rights reserved.

29 “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 distortions Illusions are NOT the same as hallucinations (false sensory experience WITHOUT external stimuli) or delusions (false beliefs) Perception Problems What does this mean? © 2014 John Wiley & Sons, Inc. All rights reserved.

30 Cannot pay attention to all stimuli Selective attention = paying attention to important information and filtering the rest Feature detectors = specialized neurons to respond to specific stimuli, like faces – Prosopagnosia – inability to identify person by facial features Habituation = decrease in responding to repeated stimulation of same stimuli; more responsive to changes in environment – Compliments from strangers are more exciting than from long- term partner! – The song you HATED on first listen might grow on you! Selection © 2014 John Wiley & Sons, Inc. All rights reserved.

31 realworldpsychology How do advertisers and political campaigns use selective attention, feature detectors, and habituation? Capture attention with intense, novel, moving, contrasting stimuli and repetition © 2014 John Wiley & Sons, Inc. All rights reserved.

32 Gestalt psychologists studied how the brain organizes sensory impressions into a “form” or “whole” Figure-Ground: objects are distinct from the background Organization: Form Perception © 2014 John Wiley & Sons, Inc. All rights reserved.

33 Depth Perception: 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” © 2014 John Wiley & Sons, Inc. All rights reserved. realworldpsychology

34 Perceive the environment as stable, despite changes in object’s size, shape, color and brightness Organization: Constancies Perception Why is this important? © 2014 John Wiley & Sons, Inc. All rights reserved.

35 Trichromatic theory of color = three “color systems”, each of which is sensitive 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 sensitive to two opposing colors (ex: either blue or yellow) – Black-and-white systems respond to differences in brightness Organization: Color Perception © 2014 John Wiley & Sons, Inc. All rights reserved.

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37 Color confusion on specific color spectrums, such as red-green or blue-yellow Color-Deficient Vision Is anyone here “colorblind”? What is it like? © 2014 John Wiley & Sons, Inc. All rights reserved.

38 Perceptual set = readiness to perceive stimuli in a particular manner, based on expectations We see what we expect to see Frame of reference = perception is influenced by context Organization: Interpretation © 2014 John Wiley & Sons, Inc. All rights reserved. Why do people rate themselves as more athletic if they compare themselves to the Pope than to a professional basketball player? Q5Q5

39 Bottom-up processing = raw sensory data “sent up” to the brain for higher level analysis Top-down processing = perceptual analysis starts “at the top” with expectations and knowledge driving the process of perception You learn to read from bottom-up processing of letters and words Now, your aiblity to raed uisng top-dwon prcessoing mkes it psosible to unedrstnad this sntenece desipte its mnay mssiplllengis Processing © 2014 John Wiley & Sons, Inc. All rights reserved.

40 Extrasensory Perception (ESP) = “psychic” perceptual abilities that supposedly go beyond the known senses – Telepathy, clairvoyance, precognition Research in ESP don’t withstand scrutiny, failure to replicate by rival research labs Why do some believe in ESP? – Motivation and interests influence our perceptions, creating selective perception – Strong emotions about the subject mask faulty reasoning Sixth Sense? © 2014 John Wiley & Sons, Inc. All rights reserved.

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