Sensation & Perception Copyright © Allyn and Bacon 2007 This multimedia product and its contents are protected under copyright law. The following are prohibited by law: Any public performance or display, including transmission of any image over a network; Preparation of any derivative work, including the extraction, in whole or in part, of any images Any rental, lease or lending of the program. ISBN:

The story of Jonathan Copyright © Allyn and Bacon 2006 IT’S ALL IN YOUR HEAD!!!!!!!! Color is “perception”

ELECTROMAGNETIC SPECTRUM Copyright © Allyn and Bacon 2006

Sensation and Perception Sensation – Transformation of physical info from the senses into electrical (nerve) impulses Perception – A process that makes sensory patterns meaningful and more elaborate-how the brain interprets this info. Copyright © Allyn and Bacon 2006

I. How Does Stimulation Become Sensation? Copyright © Allyn and Bacon 2006 The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural impulses-it’s different for everyone-my green isn’t exactly your green!

A. Transduction Transduction – Transformation of one form of energy into another – especially the transformation of stimulus information into nerve impulses Receptors – Specialized neurons that are activated by stimulation and transduce (convert) it into a nerve impulse Copyright © Allyn and Bacon 2006

Transduction Sensory pathway – Bundles of neurons that carry information from the sense organs to the brain Copyright © Allyn and Bacon 2006

Sensory Adaptation Sensory adaptation – Loss of responsiveness in receptor cells after stimulation has remained unchanged for a while Copyright © Allyn and Bacon 2006

Thresholds Absolute threshold – Amount of stimulation necessary for a stimulus to be detected Difference threshold – Smallest amount by which a stimulus can be changed and the difference be detected (also called just noticeable difference – JND) Copyright © Allyn and Bacon 2006

Subliminal?? Anything below the absolute threshold Copyright © Allyn and Bacon 2006 LINK

Subliminal Persuasion What is it? Studies have found that subliminal words flashed briefly on a screen can “prime” a person’s later responses No controlled research has ever shown that subliminal messages delivered to a mass audience can influence people’s buying habits Copyright © Allyn and Bacon 2006

Vision: A single candle flame from 30 miles on a dark, clear night Hearing: The tick of a watch from 20 feet in total quiet Smell: 1 drop of perfume in a 6-room apartment Taste: 1 teaspoon sugar in 2 gallons of water Touch: The wing of a bee on your cheek, dropped from 1 cm Copyright © Allyn and Bacon 2006

Thresholds Weber’s law – The JND is always large when the stimulus intensity is high, and small when the stimulus intensity is low -You are more likely to notice a 5 degree increase in air temperature from 72-77, than you are from Examples from other senses? Copyright © Allyn and Bacon 2006

Signal Detection Theory Signal detection theory – Perceptual judgment as combination of sensation and decision-making processes Copyright © Allyn and Bacon 2006 Stimulus event Neural activity Comparison with personal standard Action (or no action) In other words, you compare info received from the physical world w/ what’s already in your head!

Signal Detection allows the mind to work quickly. Feature extraction is an example of this. Copyright © Allyn and Bacon 2006

Volunteer? Pictionary is a great example of signal detection theory and feature extraction Copyright © Allyn and Bacon 2006

What color is the opposite of black? Copyright © Allyn and Bacon 2006 Old McDonald had a what? What do cows drink?

How Are the Senses Alike? How Are They Different? Copyright © Allyn and Bacon 2006 The senses all operate in much the same way, but each extracts different information and sends it to its own specialized processing region in the brain

The Anatomy of Visual Sensation Copyright © Allyn and Bacon 2006 Fovea – Area of sharpest vision in the retina Retina – Light-sensitive layer at the back of the eyeball Photoreceptors – Light-sensitive cells in the retina that convert light energy to neural impulses Rods – Sensitive to dim light but not colors Cones – Sensitive to colors but not dim light

The Anatomy of Visual Sensation Visual cortex – Part of the brain – the occipital cortex – where visual sensations are processed Copyright © Allyn and Bacon 2006 Color – Psychological sensation derived from the wavelength of visible light – color, itself, is not a property of the external world

Neural Pathways in the Human Visual System Copyright © Allyn and Bacon 2006

Transduction of Light in the Retina Copyright © Allyn and Bacon 2006

Blind Spot Close your right eye and look at the cross w/ yo left eye. Copyright © Allyn and Bacon 2006

Sausage finger effect. Copyright © Allyn and Bacon 2006

VISION

Afterimages Afterimages – Sensations that linger after the stimulus is removed In the following slide, fix your eyes on the dot in the center of the flag Copyright © Allyn and Bacon 2006

Negative afterimages are caused when the eyes lose sensitivity from over stimulation. Normally the eye deals with this problem by rapidly moving the eye small amounts, The motion later being "filtered out" so it is not noticeable. However if the color image is large enough that the small movements are not enough to change the color under one area of the retina, those cones will eventually tire or adapt and stop responding. When the eyes are then diverted to a blank space, the adapted photoreceptors send out little signal and those colors remain muted. However, the surrounding cones that were not being excited by that color are still "fresh", and send out a strong signal. The signal is exactly the same as if looking at the opposite color, which is how the brain interprets it.

Theories of Color Vision - The Opponent Process Theory –red - green when red is active green is inhibited and vice versa –blue - yellow when blue is active yellow is inhibited and vice versa –color after images perception of color that is not really present; occurs after viewing the opposite or complimentary color

How the Visual System Creates Color Color blindness – Vision disorder that prevents an individual from discriminating certain colors Copyright © Allyn and Bacon 2006 Brightness – Sensation caused by the intensity of light waves

How the Visual System Creates Brightness Copyright © Allyn and Bacon 2006 Wavelength Color Intensity (amplitude) Brightness

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Color Blindness Copyright © Allyn and Bacon 2006

What numbers do you see revealed in the patterns of dots below? Copyright © Allyn and Bacon 2006 about percent (depending on whose figures you want to believe) of the white, male population and a tiny fraction of the female population

Copyright © Allyn and Bacon 2006

Color blindness is a result of certain cones misinterpreting the wavelengths that correspond to their respective colors. Red, green and blue colors have corresponding wavelengths. If the green cones, for example, only respond to slightly longer wavelengths, green will be interpreted by the brain as red. Copyright © Allyn and Bacon 2006

Hearing: If a Tree Falls in the Forest... The Physics of Sound Frequency – Number of cycles completed by a wave in a given amount of time Copyright © Allyn and Bacon 2006 Low Frequency High Frequency

Hearing: If a Tree Falls in the Forest... The Physics of Sound Copyright © Allyn and Bacon 2006 High Amplitude Low Amplitude Amplitude – Physical strength of a wave

How Sound Waves Become Auditory Sensations Copyright © Allyn and Bacon 2006 Tympanic membrane – The eardrum

How Sound Waves Become Auditory Sensations Copyright © Allyn and Bacon 2006 Cochlea – Where sound waves are transduced

How Sound Waves Become Auditory Sensations Copyright © Allyn and Bacon 2006 Basilar membrane – Thin strip of tissue sensitive to vibrations Cochlea

How Sound Waves Become Auditory Sensations Copyright © Allyn and Bacon 2006 Auditory nerve – Neural pathway connecting the ear and the brain

How Sound Waves Become Auditory Sensations Auditory cortex – Portion of the temporal lobe that processes sounds Copyright © Allyn and Bacon 2006

The Psychology of Pitch, Loudness, and Timbre Pitch – Sensory characteristic of sound produced by the frequency of the sound wave Loudness – Sensory characteristic of sound produced by the amplitude (intensity) of the sound wave Timbre – Quality of a sound wave that derives from the wave’s complexity Copyright © Allyn and Bacon 2006

Deafness Conduction deafness – An inability to hear resulting from damage to structures of the middle or inner ear Nerve deafness – An inability to hear, linked to a deficit in the body’s ability to transmit impulses from the cochlea to the brain, usually involving the auditory nerve or higher auditory processing centers Copyright © Allyn and Bacon 2006

Position and Movement Vestibular sense – Sense of body orientation with respect to gravity Kinesthetic sense – Sense of body position and movement of body parts relative to each other Copyright © Allyn and Bacon 2006

smell How are taste and smell related? Copyright © Allyn and Bacon 2006

Smell Olfaction – Sense of smell Olfactory bulbs – Brain sites of olfactory processing Pheromones – Chemical signals released by organisms to communicate with other members of the species Copyright © Allyn and Bacon 2006

Smell

Taste Gustation – The sense of taste Copyright © Allyn and Bacon 2006 Taste buds – Receptors for taste (primarily on the upper side of the tongue)

Bottom-Up and Top-Down Processing Bottom-up processing – Analysis that emphasizes characteristics of the stimulus, rather than internal concepts Top-down processing – Emphasizes perceiver's expectations, memories, and other cognitive factors Copyright © Allyn and Bacon 2006

Pain Placebos – Substances that appear to be drugs but are not Placebo effect – A response to a placebo caused by subjects’ belief that they are taking real drugs Pain is in the brain!! Copyright © Allyn and Bacon 2006

start

The Skin Senses Info the skins sends the brain: 1. Temperature 2. Texture 3. Pressure -Extremes and tissue damage send “pain” messages to brain-brain’s way of protecting the body- “Don’t do that ya dope!” Copyright © Allyn and Bacon 2006

What is the Relationship Between Perception and Sensation? Percept – Meaningful product of a perception -What you perceive to be, not what is. -Example of Phantom Limb Pain. Copyright © Allyn and Bacon 2006

Factors influencing pain perception Copyright © Allyn and Bacon 2006

62 Biopsychosocial Influences on pain BiologicalPsychologicalSocial-Cultural

1. Location Copyright © Allyn and Bacon 2006

AGE

GENDER

FATIGUE

MEMORY/EXPECTATIONS

FOCUS

69 Gate-Control Theory Melzak and Wall (1965, 1983) proposed that our spinal cord contains neurological “gates” that either block pain or allow it to be sensed. Gary Comer/ PhototakeUSA.com

70 Pain Control Pain can be controlled by a number of therapies including, drugs, surgery, acupuncture, exercise, hypnosis, and even thought distraction. Todd Richards and Aric Vills, U.W. ©Hunter Hoffman,

Cultural Influences on Perception Copyright © Allyn and Bacon 2006 B A Which box is bigger, A or B?

What is the Relationship Between Perception and Sensation? Copyright © Allyn and Bacon 2006 Perception brings meaning to sensation, so perception produces an interpretation of the external world, not a perfect representation of it

Perceptual Constancies Perceptual constancy – Ability to recognize the same object under different conditions, such as changes in illumination, distance, or location -A shortcut the brain uses so it doesn’t have to reprocess information. Copyright © Allyn and Bacon 2006

Perceptual Constancy Copyright © Allyn and Bacon 2006 Without this process, it would take a very long time to figure out that there is an apple in each picture.

Perception physical sensation interpreted in the light of experience Copyright © Allyn and Bacon 2006

Perceptual Ambiguity and Distortion- The Gestalt Psychologists Illusions – Demonstrably incorrect experience of a stimulus pattern, shared by others in the same perceptual environment Ambiguous figures – Images that are capable of more than one interpretation Copyright © Allyn and Bacon 2006

The Machinery of Perceptual Processing Feature detectors – Cells in the cortex that specialize in extracting certain features of a stimulus Binding problem – A major unsolved mystery in cognitive psychology, concerning the physical processes used by the brain to combine many aspects of sensation to a single percept- Copyright © Allyn and Bacon 2006

Gestalt Theory Pragnanz German for conciseness: which says that we tend to order our experience in a manner that is regular, orderly, symmetric, and simple. Copyright © Allyn and Bacon 2006

Gestalt=Holistic

The Gestalt Approach Gestalt psychology – View that much of perception is shaped by innate factors built into the brain Figure – Part of a pattern that commands attention Ground – Part of a pattern that does not command attention; the background Copyright © Allyn and Bacon 2006

The Gestalt Laws of Perceptual Grouping Copyright © Allyn and Bacon 2006 Similarity Proximity Continuity Common fate Closure Symmetry Meaningfullness/Familiarity

Gestalt principles of Perceptual Organization Closure

Gestalt principles of Perceptual Organization Similarity

Gestalt principles of Perceptual Organization Proximity

symmetry Copyright © Allyn and Bacon 2006

Gestalt principles of Perceptual Organization Good continuation what most people would see not this

Common fate

Meaningfulness/familiarity Copyright © Allyn and Bacon 2006

Perceptual Illusions Copyright © Allyn and Bacon 2006 Do you see or ? Necker cube from ch. 1.

Law of Prägnanz Copyright © Allyn and Bacon 2006 A BIRD IN THE THE HAND

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