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Sensation – An early stage of perception in which neurons in a receptor create an internal pattern of nerve impulses that represent the conditions that stimulated it – either inside or outside the body Perception – A process that makes sensory patterns meaningful and more elaborate 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
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
The principle that the jnd for any given sense is a constant fraction or proportion of the stimulation being judged. © Prentice Hall, 1999
Weber’s law – The JND is always large when the stimulus intensity is high, and small when the stimulus intensity is low Fechner’s law – S = k log R S = sensation R = stimulus k = constant that differs for each sensory modality Copyright © Allyn and Bacon 2006
Vision: a candle flame seen from 30 miles on a clear, dark night Hearing: the tick of a watch from 20 feet in very quiet conditions Smell: 1 drop of perfume diffused throughout a three-room apartment © Prentice Hall, 1999
Taste:.0356 ounce of table salt in 529 quarts of water Touch: a bee wing falling on your cheek from a height of 1 centimeter © Prentice Hall, 1999
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
Sensory pathway – Bundles of neurons that carry information from the sense organs to the brain Copyright © Allyn and Bacon 2006
definition: below threshold We can process some information from stimuli too weak to recognize. effect of subliminal stimulation: a subtle, fleeting effect on thinking © Prentice Hall, 1999
No. The goal of using subliminal advertising is to increase the likelihood that you will buy a particular product. Research has repeatedly demonstrated that subliminal advertising cannot change an individual’s behavior. © Prentice Hall, 1999
Sensory adaptation – Loss of responsiveness in receptor cells after stimulation has remained unchanged for a while Copyright © Allyn and Bacon 2006
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)
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
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wavelength amplitude
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Rods C Rods C Receptors: rods and cones 120 million120 million peripheryperiphery sensitivitysensitivity night visionnight vision 8 million8 million centralcentral clarityclarity color visioncolor vision onesonesonesones
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light photo- receptors bipolar cells ganglion cells LGN visual cortex
dark adaptation: increased sensitivity of rods and cones in darkness e.g., entering a darkened room light adaptation: decreased sensitivity of rods and cones in bright light e.g., waking up at night and turning on a bright light © Prentice Hall, 1999
hue: subjective experience of “color” saturation (purity): vividness or richness of a hue brightness: intensity of the light © Prentice Hall, 1999
additive color mixing: mixing lights of differing wavelengths subtractive color mixing: mixing pigments © Prentice Hall, 1999
Trichromatic theory Opponent-process theory © Prentice Hall, 1999
There are three types of cones: red, green, and blue. The colors we see are the result of a combination of the differing amount of light absorbed by the three types of cones. © Prentice Hall, 1999
This theory only explains the way the cones transduct color. The trichromatic theory provides an explanation for some types of colorblindness. © Prentice Hall, 1999
monochromats: people who are totally colorblind dichromats: people who are blind to either red-green or yellow-blue © Prentice Hall, 1999
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black color-sensitive ganglion cells are arranged in opposing cells: red-green, yellow- blue, black-white (brightness) © Prentice Hall, 1999
The activation of one cone (at retinal level) inhibits another cone. This theory explains color vision at the level of the ganglion cells. © Prentice Hall, 1999
Opponent-process theory may explain color afterimages: continual viewing of red weakens the ability to inhibit green; remove red and you see green © Prentice Hall, 1999
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frequency: the number of cycles per second in a wave — primary determinant of pitch amplitude: the magnitude (height) of a wave — primary determinant of loudness © Prentice Hall, 1999
pitch: the frequency of sound vibrations, resulting in a higher/lower tone overtones: tones that result from sound waves that are multiples of the basic tone timbre: the “texture” of sound © Prentice Hall, 1999
hertz (Hz): cycles per second; used to measure pitch decibel: unit of measurement for the loudness of sounds © Prentice Hall, 1999
eardrum middle ear oval window cochlear organ of Corti
© Prentice Hall, 1999 organ of Corti cochlear nerve medulla inferior colliculus medial geniculate nucleus auditory cortex
place theory frequency theory © Prentice Hall, 1999
vibration of the basilar membrane (B.M.) at different places results in different pitches/frequencies near the oval window (where B.M. is thinner)--higher frequencies; lower frequencies occur farther from oval window © Prentice Hall, 1999
The speed of vibration determines pitch: The faster the vibration, the higher the pitch. © Prentice Hall, 1999
auditory neurons fire in sequence: first one, then another, then perhaps a third, and finally the first one is able to fire again © Prentice Hall, 1999
conductive hearing loss: vibrations are not transmitted effectively from the eardrum to the oval window due to a stiffening of the connections between the middle ear bones tinnitus: constantly hearing a steady, high-pitched hum © Prentice Hall, 1999
Odorant binding protein (OBP) makes the detection of odors possible. A nasal gland coats airborne molecules with OBP to facilitate detection by the receptors in the olfactory epithelium. © Prentice Hall, 1999
receptor cells olfactory bulb amygdala thalamus hypo- thalamus temporal lobe
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Women have a better sense of smell than men. The ability to smell diminishes with age. Smell acuity is greatest during early adulthood (ages 20-40). © Prentice Hall, 1999
Pheromones are chemicals produced by an animal that affects the behavior of another animal through scent. Receptors in the vomeronasal organ detect pheromones. © Prentice Hall, 1999
Yes, humans can detect pheromones, but detection typically does not alter behavior. Menstrual synchronicity may be the one exception. © Prentice Hall, 1999
Taste buds are the structures on the tongue that contain taste receptor cells. An adult has about 10,000 taste buds. Taste receptors die and are replaced every 7 days. The number of taste buds decrease with age. © Prentice Hall, 1999
taste buds medulla thalamus primary somatosensory cortex anterior- insular cortex
provides specific information about muscle movement, changes in posture, and strain on muscles and joints receptors: stretch receptors and Golgi tendon organs (provide information about stretching and contraction of individual muscles) © Prentice Hall, 1999
The sense of equilibrium and awareness of body position in space. 2 types of vestibular senses: — body rotation — gravitation and movement © Prentice Hall, 1999
relays messages about the speed and direction of body rotation stimulus: movement of the head receptors: hair cells in the semicircular canals © Prentice Hall, 1999
provides information about gravitation and movement forward and backward, up and down stimulus: movement of body and/or gravity receptors: hair cells in the vestibular sacs © Prentice Hall, 1999
Receptors in the skin provide information about: — touch — temperature — pain © Prentice Hall, 1999
A chemical sense in which certain chemicals are released when injury (tissue damage) occurs. These chemicals activate pain receptors. © Prentice Hall, 1999
A “gate” in the spinal cord either opens to permit pain signals traveling up small nerve fibers to reach the brain or closes to prevent their passage. © Prentice Hall, 1999
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
Optic nerve – Bundle of neurons that carries visual information from the retina to the brain Copyright © Allyn and Bacon 2006 Blind spot – Point where the optic nerve exits the eye and where there are no photoreceptors
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
Copyright © Allyn and Bacon 2006
Electromagnetic spectrum – Entire range of electromagnetic energy, including radio waves, X-rays, microwaves, and visible light Visible spectrum – Tiny part of the electromagnetic spectrum to which our eyes are sensitive Copyright © Allyn and Bacon 2006
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
Copyright © Allyn and Bacon 2006 Wavelength Color Intensity (amplitude) Brightness
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
The Physics of Sound Copyright © Allyn and Bacon 2006 High Amplitude Low Amplitude Amplitude – Physical strength of a wave
Copyright © Allyn and Bacon 2006 Tympanic membrane – The eardrum
Copyright © Allyn and Bacon 2006 Cochlea – Where sound waves are transduced
Copyright © Allyn and Bacon 2006 Basilar membrane – Thin strip of tissue sensitive to vibrations Cochlea
Copyright © Allyn and Bacon 2006 Auditory nerve – Neural pathway connecting the ear and the brain
Auditory cortex – Portion of the temporal lobe that processes sounds Copyright © Allyn and Bacon 2006
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
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
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
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
Gustation – The sense of taste Copyright © Allyn and Bacon 2006 Taste buds – Receptors for taste (primarily on the upper side of the tongue)
Touch Warmth Cold Copyright © Allyn and Bacon 2006
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 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
Percept – Meaningful product of a perception Copyright © Allyn and Bacon 2006
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
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
Perceptual constancy – Ability to recognize the same object under different conditions, such as changes in illumination, distance, or location Copyright © Allyn and Bacon 2006
© Prentice Hall, 1999 shape constancy: a tendency to see an object as the same shape no matter what angle it is viewed from.
© Prentice Hall, 1999 figure: entity perceived to stand apart from the background ground: background against which a figure appears
© Prentice Hall, 1999 Monocular distance cue in which one object, by partially blocking another, is perceived as being closer.
© Prentice Hall, 1999 The higher on the horizontal plane an object is, the farther away it appears.
© Prentice Hall, 1999 Two parallel lines appear to converge at the horizon.
© Prentice Hall, 1999 Objects seen at greater distances appear to be smoother and less textured.
© Prentice Hall, 1999 Shadows often appear on the parts of objects that are more distant.
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
Do you see or ?
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The Herman Grid Do you see small gray squares between the black squares?
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Learning-based inference – View that perception is primarily shaped by learning, rather than innate factors Perceptual set – Readiness to detect a particular stimulus in a given context Copyright © Allyn and Bacon 2006
B A Which box is bigger, A or B?
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
Subjective contours – Boundaries that are perceived but do not appear in the stimulus pattern Copyright © Allyn and Bacon 2006 Closure – Tendency to fill in gaps in figures and see incomplete figures as complete
Copyright © Allyn and Bacon 2006 Similarity Proximity Continuity Common fate Prägnanz
Copyright © Allyn and Bacon 2006 A BIRD IN THE THE HAND
Copyright © Allyn and Bacon 2007
Copyright © Allyn and Bacon 2006