Published on January 14, 2008
Prologue to Chapter 4: Prologue to Chapter 4 Human life would be very different without the ability to sense and perceive external stimuli Imagine your world without the ability to see, hear, smell, touch, and feel Psychologists are interested in sensation and perception as inputs to and outputs from the brain Sensation: Receiving messages about the world: Sensation: Receiving messages about the world Sense organs operate through sensory receptor cells that receive external forms of energy and translate these external forms into neural impulses that can be transmitted to the brain There are five types of sense organs which we will examine in this chapter Sensation: Receiving messages: Sensation: Receiving messages Stimuli: What messages can be received? Anything capable of exciting a sensory receptor cell can be defined as a “stimulus” Examples include: sound, light, heat, cold, odor, color, touch, and pressure Sensation: Receiving messages: Sensation: Receiving messages Transduction: Translating messages into the brain’s language Sense orgrans transduce sensory energy into neural (bioelectrical) energy Converting one type of energy into another type is the process of transduction Your brain only deals with bioelectrical impulses so transduction must occur; what cannot be transduced cannot be a stimulus Sensation: Receiving messages: Sensation: Receiving messages Sensory limits: How strong must the message (signal) be for it to be detected by the sensory receptor? Absolute thresholds Difference thresholds Sensory adaptation and habituation Study of these sensory limits and phenomena is called “Psychophysics” Investigating sensory input devices: Investigating sensory input devices We will now take a closer look at each of the five sensory input devices We will look at the eye, the ear, skin senses, olfaction, and taste Vision: Your human camera: Vision: Your human camera Light: What is it? light is constructed of wave/particles packets of energy called photons visible light is only a tiny part of the much broader electromagnetic spectrum light is measured by its intensity and its frequency the visible spectra ranges 390 to 710 nanometers/sec. ossilation Vision: Your human camera: Vision: Your human camera The eye: How does it work? The transduction of light wave/particles into neural energy is carried out by the receptor cells in the retina of the eye The retina has 2 general types of cells that engage in transduction rods (for transducing black/white light) cones (for transducing colored light) Vision: Your human camera: Vision: Your human camera Parts of the eye include: cornea, lens, pupil, iris, fovea vitreous humor, aqueous humor the optic nerve, blind spot Here is a picture of the eye Vision: Your human camera: Vision: Your human camera Dark and light adaptation How does the eye adjust to seeing in the dark? How does the eye see in low-light conditions? How does the eye adjust to bright-light conditions? Rods and cones Vision: Your human camera: Vision: Your human camera Color Vision: What is it and how does it work? Color is the conscious experience that results from the processing of light energy of differing frequencies by the eye and the brain There are two theories as to why we can see color yet, in truth, no one knows precisely why we see in color Vision: Your human camera: Vision: Your human camera Theories of color vision The “Trichromatic Theory” 3 cone types: red, green, and blue cones similar to the RGB setup on your color TV red cones detect red, blue detect blue, etc. problems exist in this theory however because there is no known mechanism in the brain for blending the three colors into the rich hue of color that we can see Vision: Your human camera: Vision: Your human camera Theories of color vision The “Opponent-process Theory” 3 cones types (similar to trichromatic theory) but each of the three have opponent processes (unlike trichromatic theory) Red-green cones, blue-yellow cones, and black-white cones After-images and inversions of color, e.g., sunset after-images, attest to the probability that the opponent-process theory is correct Hearing: Sensing sound waves: Hearing: Sensing sound waves We will now examine hearing and the ear Sound: What is it? hearing is the sense that detects vibratory changes in the air called sound waves sound waves are changes in air pressure throwing a rock into a still lake will give you a picture of sound waves as they would look if they were visible to the eye Hearing: Sensing sound waves: Hearing: Sensing sound waves Sound: What is it? Sound waves are measured by their frequency and amplitude frequency: pitch/note amplitude: loudness/decibels Hearing: Sensing sound waves: Hearing: Sensing sound waves The Ear: How does it work? Outer ear: external part that helps to collect sound waves Middle ear: where sound waves are transduced into mechanical energy Inner ear: where mechanical energy is transduced into neural energy/biolelectrical impulses Here is a picture of the ear The Middle and Inner Ear: The Middle and Inner Ear Body Senses: Messages from myself about myself: Body Senses: Messages from myself about myself Orientation and movement senses Vestibular organs located in the inner ear, there are movement detectors and orientation detectors semi-circular canals provide orientation detection or rotary movement detection processes involved in detection of movement in vestibular organs Body Senses: Body Senses Kinesthetic senses located in the muscles, joints, and skin, they provide information about your movement in space, posture, and orientation in space Body Senses: Body Senses Skin Senses located in the epidermis and dermis of the skin; also some in the superficial fascia of the skin pressure sensors temperature sensors relative heat-change sensors relative cold-change sensors Body Senses: Body Senses Skin Senses Pain sensors pain is a complex sensation that involves more than the simple transmission of pain messages to the brain pain sensors are located in the epidermis (called free nerve endings) Phantom limbs the “phantom limb experience” reveals that the brain also influences “sensation” Chemical Senses: The flavors and aromas of life: Chemical Senses: The flavors and aromas of life Taste: What is it? chemical “lock/key” sensation 10,000 taste buds on the tongue the “taste bud” the tongue’s map to taste: sweet, sour, bitter, and salty tastes here is a picture of the tongue Chemical Senses: Chemical Senses Smell/Olfaction: What is it? Stereo-chemical theory of smell Similar to taste sense (lock/key) Receptor cells for smell located at the top of the nasal cavity in the olfactory epithelium Here is a picture of the nasal cavity area Perception: Interpreting sensory messages: Perception: Interpreting sensory messages Visual perception Perceptual organization: why we see things the way we do Gestalt principles of perceptual organization include: proximity, figure-ground, continuity, similarity, and closure In the following slides, I’ll show you examples of each Gestalt organizational rule Perception: Perception Gestalt rule of proximity AAAA BBBB CCCC DDD D Perception: Perception Gestalt rule of figure-ground Perception: Perception Gestalt rule of continuity What color is next and why? Perception: Perception Gestal rule of similarity Perception: Perception The Gestalt rule of closure “The itsy-bitsy spider went up the garden spout… down came the rain and…” What’s next? Why did you say “washed the spider out”? “Shave and a hair cut: two bits” Perception: Perception Perceptual constancy: we perceive objects as being unchanged although the raw sensory data changes size constancy: a car does not grow when it comes toward us; we perceive it is getting closer shape constancy: a pencil is still a pencil even though we see it from many different angles Perception: Perception Depth perception depth perception permits our two-dimensional retinas to perceive a three dimensional world binocular depth cues include: convergence and incongruities in pictures between eyes monocular depth cues include: haziness, darkness, interposition, and motion parallax Perception: Perception Visual Illusions Illusions provide evidence that what we think we “see” is not the same as the visual information entering the eye there are a number of different visual illusions, e.g., the Mueller-Lyre Illusion the “top hat illusion” Perception: Perception The Mueller-Lyre Illusion Which figure has the longest central line? Perception: Perception The “Top Hat Illusion” Is the hat taller or wider? Slide42: Faces or goblet illusion? Figure vs Ground Slide43: Hole or Hill? Slide44: Notice the Intersection of the Boxes: Darker? Slide45: Herringbone Illusion Slide46: The Impossible Bolt Slide47: Impossible Crank Slide48: Impossible Stack Slide49: Impossible Triangle Slide50: Duck or Rabbit? Slide51: Opponent Process American Flag Slide52: Size -Weight Illusion Slide53: Eternal Stairway Illusion Perception: Perception Individual and cultural influences on perception characteristics of the perceiver can influence what is perceived individual differences and cultural differences do affect perception using “projective tests” as a means of assessing the perceiver’s personality/cultural experience Application of psychology: Perception, illusion, and art: Application of psychology: Perception, illusion, and art Art (a two-dimensional surface) uses many monocular depth cues to convey a 3-dimensional picture Media advertising is totally directed toward the goal of influencing your perception about products Vance Packard’s book “Hidden Persuaders” Application of psychology: Application of psychology Subliminal perception and its relationship to emotion studies of subliminal perception have shown that its use can affect the perceiver’s emotions without their awareness all propaganda is designed to affect your emotions using subliminal perceptual techniques Questions?: Questions? Do you have any questions about Chapter 4? Test #1 will cover information presented in lecture, the book, and study guide over these four chapters. How to prepare for my tests?: How to prepare for my tests? You must read the book! read the chapters at least twice and take good notes quiz yourself with another student to see how much you’ve retained You can use the studyguide for extra credit Be sure to bring a #2 pencil to tests! How to prepare for my tests: How to prepare for my tests Any questions about testing?