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AP Psychology Sensation and Perception

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1 AP Psychology Sensation and Perception
Alice F. Short Hilliard Davidson High School Unit 3, Chapter 4

2 Sensation and Perception
sensation – the process of receiving stimulus energies from the external environment and transforming those energies into neural energy Relate to sensitive – 1.having the power of sensation, 2. responsive to or aware of feelings, moods, reactions, etc., 3. easily irritated; delicate: sensitive skin, 4. affected by external conditions or stimuli perception – the process of organizing and interpreting sensory information so that it has meaning Relate to perceptive - having or showing keenness of insight, understanding, or intuition:

3 Sensation and Perception
sensory receptors  thalamus  specific parts of the cerebral cortex sensation and perception = unified information-processing system

4 Bottom-up vs. Top-down Processing
bottom-up processing – the operation in sensation and perception in which sensory receptors register information about the external environment and send it up to the brain for interpretation (part to whole) song for first time top-down processing – the operation in sensation and perception, launched by cognitive processing at the brain’s higher levels, that allows the organisms to sense what is happening and to apply that framework to information from the world (whole to part) favorite song

5 What do you see?

6 Predator vs. Prey

7 Categories of Sense Organs and Sensory Receptors
sensory receptors – specialized cells that detect stimulus information and transmit it to sensory (afferent) nerves and the brain photoreception – detection of light perceived as sight mechanoreception –detection of pressure vibration, and movement perceived as touch, hearing and equilibrium chemoreception – detection of chemical stimuli perceived and smell and taste

8 Sensory Receptors Name the category for each (photoreception, mechanoreception, or chemoreception)

9 Festive Disease for the Senses
synaesthesia – an experience in which one sense (say, sight) induces an experience in another sense (say, hearing) Possible Outcomes: see music, taste color (seen in Criminal Minds, Season 8 “Magnificent Light”)

10 Another Festive Disease for the Senses
phantom limb pain –pain / felt movement of lost limb Mirror therapy

11 Thalamus thalamus = relay station for brain (nearly all sensory information pass though the thalamus) brain = complex (multiple pathways)

12 Absolute Sensory Thresholds
The foolish definition of absolute threshold – the minimum amount of stimulus energy that person can detect (50 percent of the time)

13 Noise noise – term given to irrelevant and competing stimuli—not just sounds but any distracting stimuli for our senses

14 Difference Threshold (a.k.a. Just Noticeable Difference)
difference threshold – the degree of difference that must exist between two stimuli before the difference is detected Weber’s law – the principle that two stimuli must differ by constant minimum percentage (rather than a constant amount) to be perceived as different

15 Subliminal Perception
subliminal perception – the detection of information below the level of consciousness Challenges the usefulness of the idea of thresholds Read and discuss p. 103, Psychological Inquiry: “Subliminal Perception: Working Up a Thirst”

16 Signal Detection Theory
signal detection theory –a theory of perception that focuses on decision making about stimuli in the presence of uncertainty individual variations How are you feeling? contextual variations What is the urgency of the situation?

17 Signal Detection Theory
information acquisition – the information you can assess criterion – the basis for making a judgement from available information

18 Signal detection theory

19 Perceiving Visual Stimuli
attention perceptual set

20 Perceiving Sensory Stimuli: Attention
attention – the process of focusing awareness on a narrowed aspect of the environment selective attention – the process of focusing on a specific aspect of experience while ignoring others cocktail party effect (hearing specific voice) Stroop effect – the way that automatically reading a color name can make it difficult to name the color in which the word is printed

21 Stroop Effect Stroop effect – the way that automatically reading a color name can make it difficult to name the color in which the word is printed (p. 105) failure of selective attention

22 Attention shiftable novel stimuli size, color, movement
Monitoring many things at once novel stimuli Novel Different Unusual size, color, movement emotional stimuli (specific words, etc.) emotion-induced blindness – when we encounter an emotionally charged stimulus, we often fail to recognize a stimulus that is presented immediately after inattentional blindness – failure to detect unexpected events when our attention is engaged by tasks counting basketball passes and gorilla costume (p. 106)

23 Perceiving Visual Stimuli: Perceptual Set
perceptual set – a predisposition or readiness to perceive something in a particular way children can be for accurate without solidified perceptual sets

24 Sensory Adaption sensory adaption – a change in the responsiveness of the sensory stem based on the average level of surrounding stimulation takes time blind right after you turn off lights freezing when first in pool

25 The Visual System The Visual Stimulus and the Eye
Visual Processing in the Brain Color Vision Perceiving Shape, Depth, Motion and Constancy

26 Light Light – a form of electromagnetic energy that can be described in terms of wavelengths. Travels though space in waves Visible from 400 to 700 nanometers Determines hue or color Wavelength – the distance from the peak of one wave to the peak of the next Amplitude – the height of the waves determines the brightness of the stimulus Purity – whether all the waves are the same or different Affects perceived saturation


28 The Structure of the Eye (p. 111-112)
Sclera Rods Optic chiasm Iris Cones Visual cortex Pupil Fovea cornea Bipolar cells Lens Ganglion cells Curvature Optic nerve Retina Blind spot

29 The Structure of the Eye (camera) (p. 111-112)
sclera - the white, outer part of the eye that helps to maintain the shape of the eye and to protect it from injury iris – the colored part of the eye pupil – the opening in the center of the iris; appears black cornea – clear membrane just in front of the eye Bends light falling on the surface of the eye just enough to focus it at the back (brings image into focus) lens – a transparent and somewhat flexible disk-shaped structure filled with a gelatin-like material Curvature – allows eye to focus on things up close (more curved) or far away (flatter) Ability to curve decreases with age (thus stylish reading glasses)


31 The Structure of the Eye (film)
retina – the multilayered light-sensitive surface in the eye that records electromagnetic energy and converts it to neural impulses for processing in the brain (primary mechanism for sight) rods – the receptor cells in the retina that are sensitive to light bun not only very useful for color vision Found almost everywhere on the retina except the fovea Gives ability to detect fainter spots of light on the peripheral cones – the receptor cells in the retina that allow for color perception fovea – a tiny area in the center of the retina at which vision is at its best contains only cones explains difficulty of reading out of corner of eye

32 Structure of the Eye (p. 112 of textbook)

33 Structure of the Eye: Retina

34 The Structure of the Eye
retina  bipolar cells  ganglion cells (axons = optic nerve bipolar cells – ganglion cells – optic nerve – the structure at the back of the eye, made up of axons of the ganglion cells, that carries visual information for further processing blind spot – the place on the retina where the optic nerve leaves the eye on its way to the brain cannot see anything that reaches only this part of the retina brain uses top-down processing to to “fill in the gaps”

35 The Visual Processing in the Brain
eyes = beginning of visual perception brain = sent neural impulses for analysis and integration optic chiasm – point in brain where the optic nerve fibers divide, and approximately half of the nerve fibers cross over the midline of the brain

36 Visual Processing (p. 114) visual information originating in the right halves of the two retinas (from the left visual field) is transmitted to the right side of the occipital lobe in cerebral cortex; left half of retinas (right visual field) to left occipital lobe

37 The Visual Cortex visual cortex – most visual information is sent here before moving to other visual areas for further analysis located in occipital lobe is the part of cerebral cortex involved in vision feature detectors – neurons in the brain’s visual system that respond to particular features of a stimulus

38 The Visual Cortex: David Hubel and Torsten Wiesel (1963)
won Nobel Prize for research on feature detectors (in cats) recorded activity of a single neuron in a cat while it looked at patterns that varied in size, shape, color , and movement found that the visual cortex has neurons that are individually sensitive to different types of lines and angles Noted that when deprived of certain types of visual stimulation early one, kittens lost the ability to perceive these patterns Suggests there might be a critical period in visual development and that the brain requires stimulation it its efforts to delegate its resources to different perceptual tasks brain “learns” to perceive through experience.

39 Perceiving Shape, Depth, Motion and Constancy
contour – a location at which a sudden change of brightness occurs figure-ground relationship – the principle by which we organize the perceptual field into stimuli that stand out (figure) and those that are left over (ground) Example: text (figure) on a page (ground)

40 Figure-Ground Relationship

41 Gestalt Principles gestalt psychology – a school of thought interested in how people naturally organize their perceptions according to certain patterns main principle: the whole is different from the sum of its parts -- computer screen image (sum) pixels (parts) closure proximity similarity continuity law of Pragnanz “AP Psych – Gestalt Principles”

42 Gestalt Principles: Closure
closure: disconnected or incomplete figures  fill in the spaces and see them as complete figures

43 Gestalt Principles: Proximity
proximity: object near each other  see them as a unit (4 columns; not 16 squares)

44 Gestalt Principles: Similarity
similarity: objects that are similar  seen as a unit (columns of circles and squares; rows of circle and squares)

45 Depth Perception depth perception – the ability to perceive objects three-dimensionally (binocular and monocular cues) binocular cues – depth cues that depend on the combination of the images in the left and right eyes and on the way to the two eye work together convergence - Binocular cue to depth and distance in which the muscle movements in our two eyes provide information about how deep and/or far away something is up close  eyes almost crossing disparity – difference between the images in the two eyes to determine the depth or distance of the object image “jumps” between eyes

46 Depth Perception p. 118 monocular cues – powerful depth cues available from the image in one eye, either the right or the left familiar size height in the field of view linear perspective and relative size overlap shading texture gradient Read p Be prepared to apply terms to image on next slide.

47 Monocular Cues: Shading, Texture Gradient
Note: Instructors should feel free to replace this figure with any picture or pictures illustrating the various monocular cues of depth perception © 2011 The McGraw-Hill Companies, Inc.

48 Monocular Cues: Linear Perspective, Height in Field
Note: Instructors should feel free to replace this figure with any picture or pictures illustrating the various monocular cues of depth perception. © 2011 The McGraw-Hill Companies, Inc.

49 Motion Perception p. 119 Neurons that are specialized to detect motion
Feedback form our body tells us whether we are moving or whether some one or some object is moving The environment we see is rich with cues that give us information about movement apparent movement – the perception that a stationary object is moving

50 Perceptual Constancy perceptual constancy – the recognition that objects are constant and unchanging even though sensory input about them is changing (size, shape, color)  demonstrates that we interpret sensation size constancy shape constancy (door example) color constancy

51 Visual Perception: Motion
© 2011 The McGraw-Hill Companies, Inc.

52 Auditory System The Nature of Sound and How We Experience It
Structures and Functions of the Ear Outer ear Middle ear Inner ear Theories of Hearing Auditory Processing in the Brain Localizing Sound

53 The Nature of Sound and How We Experience It
sound waves – vibration in the air that are processed by the auditory (hearing) system frequency – the number of cycles (full wavelengths) that pass through a point in a given time interval pitch – the perceptual interpretation of the frequency of a sound complex sounds – sounds with numerous frequencies of sound blending together timbre – the tone saturation, or the perceptual quality, of a sound Perceptual difference b/w different instruments playing the same note amplitude – the amount of pressure the sound wave produces relative to a standard, typically 0 decibels--measured in decibels (dB) loudness – the perception of the sound waves amplitude

54 Frequency low frequency = low pitch high frequency = high pitch
distinguish b/w adult and child

55 Amplitude

56 Decibels Source Exposure Danger 180 Space shuttle launch Hearing loss certain within 150 feet of launch pad 140 Jet aircraft motor Any exposure dangerous 120 Sandblaster, thunderclap Immediate danger 100 Heavy auto traffic, lawn mower 2 hours 60 Normal conversation No danger 40 Quiet office 30 Quiet library 20 Soft whisper Minimal detectable sound

57 Volume

58 Complex Sounds: Timbre

59 Structures and Functions of the Ear
outer ear – the outermost part of the ear, consisting of the pinna and the external auditory canal middle ear – the part of the ear that channels sound through the eardrum, hammer, anvil, and stirrup to the inner ear inner ear – the part of the ear that includes the oval window, cochlea, and basilar membrane

60 © 2011 The McGraw-Hill Companies, Inc.
Structure of the Ear IM: Structures and Functions of the Ear Activity © 2011 The McGraw-Hill Companies, Inc.

61 Outer Ear pinna (plural, pinnae) – the outer, visible part of ear
collections sounds and channels them into the interior of the ear moveable in some animals (localization) external auditory canal

62 Middle Ear eardrum (tympanic membrane) – separates the outer ear from the middle ear vibrates in response to sound hammer  anvil  stirrup – intricately connected chain of the three smallest bones in body transmit sound waves to the fluid-filled inner ear (at oval window) by vibrating can amplify sounds or decrease intensity to protect inner ear (muscles)

63 Inner Ear inner ear – converts sound waves into neural impulses to send to brain oval window – transmits sound waves to the cochlea (received from stirrup) cochlea – tubular, fluid-filled structure, coiled basilar membrane – lines the inner wall of the cochlea and runs its entire length tells about frequency, pitch, complexity of sound hair cells – ear’s sensory receptors (cilia sprout at top of hair cells) – delicate  damage can lead to deafness or difficulty hearing tectorial membrane – jellylike flap above hair cells generates impulses that the brain interprets as sound

64 Cochlear Implant cochlear implant – a small electronic device that is surgically implanted in the ear and head allows deaf or hard-of-hearing individuals to detect sound more effective the younger implanted DISUCSSION: Read Critical Controversy: “Are Cochlear Implants a “Cure for Deafness” (p. 124) answer “What do you think?” questions have thoughts 

65 Theories of Hearing place theory – theory on how the inner ear registers the frequency of sound, stating that each frequency produces vibrations at a particular spot on the basilar membrane (better at explaining sounds below 1,000 firing per second) high pitch tone – narrow area of basilar membrane at the base of cochlear explained well by theory low pitch tone – wide end of cochlea explained poorly by theory frequency theory – theory on how the inner ear registers he frequency of sound stating that the perception of a sound’s frequency depends on how often the auditory nerve fires volley principle – modification of frequency theory stating that a cluster of nerve cells can fire neural impulses in rapid succession, producing a volley of impulses combination of theories need for sounds above 1,000 times per second

66 Auditory Processing in the Brain
auditory nerve – the nerve structure that receives information about sound from the hair cells of the inner ear and carries these neural impulses to the brain’s auditory areas (extends from the cochlea to brain stem) left ear  right side of brain right ear  rights side of brain temporal lobe

67 Localizing Sound basilar membrane – tells about frequency, pitch, complexity of sound NOTHING to do with location Localization: sound shadow – caused by the listener’s head, which forms a barrier that reduces the sound’s intensity timing intensity

68 The Other Senses The Skin Senses The Chemical Senses
Touch Temperature Pain The Chemical Senses Taste Smell The Kinesthetic and Vestibular Senses

69 The Skin Senses skin – largest sensory system
cutaneous senses (3 types of receptors): touch (mechanical energy / pressure against skin) temperature thermoreceptors – sensory nerve endings under the skin that respond to changes in temperature at or near the skin and provide input to keep the body’s temperature at 98.6 degrees Fahrenheit (heat = dominant) pain (adaptive for survival; intense stimulation of any sense produces pain) prostaglandin – stimulate receptors that cause the experience of pain (many painkiller reduce production) fast pathway  thalamus (fast response required) slow pathway  detour in limbic system (tells you to “slow down” your lifestyle – “nagging pain”)

70 Pain pain (adaptive for survival; intense stimulation of any sense produces pain) prostaglandin – stimulate receptors that cause the experience of pain (many painkiller reduce production) fast pathway  thalamus (fast response required) slow pathway  detour in limbic system (tells you to “slow down” your lifestyle – “nagging pain”) endorphins – neurotransmitters (slow pathway) factors: motivation, expectation, decision factors women experience more pain

71 Chemical Senses taste (sweet, sour, bitter, salty) + umami or yummy or savory (L-glutamate) papillae – round bumps above the tongue's surface that contain the taste buds, the receptors for taste (replaced every two weeks) 10,000 taste buds (younger) 5,000 taste buds (older) smell olfactory epithelium – the lining of the roof of the nasal cavity, containing a sheet of receptor cells for smell unique: neurons replace themselves after injury; don’t pass through thalamus  temporal lobes  various brain regions (including limbic system – linked to emotion and memory (LOVE!) dogs – 100 times lower levels

72 The Kinesthetic and Vestibular Senses
kinesthetic (MOP) – movement, orientation, posture not in specific organ; embedded in muscle fibers and joints same pathways to brain as touch vestibular (MB) – movement, balance (begins in auditory nerve, which contains both cochlear nerve and vestibular nerve for balance and movement) connects to medulla (most), directly to cerebellum, temporal cortex, or other places (not fully charted) vision used in addition (when everything in visual field is moving… generally WE are moving proprioceptive feedback – information about the position of our limbs and body parts in relation to other body parts semicircular canals of inner ear – three fluid-filled circular tubes that lie in the three plans of the body right-left front-back up-down

73 Sensation, Perception, and Health and Wellness
Take care of yourself! You don’t regenerate.


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