Psych Chapter 5
Psych Chapter 5 Psych 2010
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This 9 page Class Notes was uploaded by Emily Brady on Friday September 30, 2016. The Class Notes belongs to Psych 2010 at Auburn University taught by Jerry Murphy in Fall 2016. Since its upload, it has received 9 views. For similar materials see Introduction to Psychology in Psychology (PSYC) at Auburn University.
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Date Created: 09/30/16
Psych Chapter 5 Sensation and Perception Sensation: the detection of the physical stimuli and the transmission of that information to the brain o Involves no interpretation of what we are experiencing Perception: the brains further processing, organization, and interpretation of sensory information o Results in our conscious experience of the world NOTE: Sensation is detection; perception is construction of useful and meaningful information about a particular information EXAMPLE: getting squirted in the face with grapefruit juice you associate the sensations (strong smell, moist feeling, and sharp taste) with the perception of grapefruit juice Bottom up processing: perception based on the physical features of the stimulus o As each sensory aspect of a stimulus is processed, the aspects build up into perception of that stimulus o Based off of data Top down processing: how knowledge, expectations, or past experiences shape the interpretation of sensory information o Context affects perception o What we see (higher level) influences what we perceive (lower level) Transduction: The process by which sensory stimuli are converted to signals the brain can interpret o Involves sensory receptors Absolute Threshold: the minimum intensity of stimulation that must occur before you experience a sensation Difference Threshold: the minimum amount of change required for a person to detect a difference between two stimuli o Just noticeable difference Signal Detection Theory: (SDT) A theory of perception based on the idea that the detection of a stimulus requires a judgment – it is not an all or nothing process o Involves 4 outcomes: Hit: signal is presented and the participant detects it Miss: participant fails to detect the signal False alarm: participant detects signal that was not presented Correct rejection: signal is not presented and participant does not detect it Response bias: participant’s tendency to report detecting the signal in an ambiguous trial Sensory adaption: is a decrease in sensitivity to a constant level of stimulation SUMMING UP: The brain integrates diverse neural inputs to produce stable representations Sensory adaption occurs when sensory receptors stop responding to unchanging stimuli 5.2 How are We Able to See? Retina: the thin inner surface of the back of the eyeball; it contains the sensory receptors that transduce light into neural signals o Two types of receptor cells: Rods and Cones Rods: retinal cells that respond to low levels of light and result in black and white perception o Responsible at extremely low levels of light and are responsible primarily for night vision Cones: Retinal cells that respond to higher levels of light and result in color perception o Responsible for vision under brighter conditions and for seeing both color and detail Fovea: The center of the retina, where cones are densely packed o Cones are spread throughout the remainder of the retina (except in the blind spot) they become increasingly scarce near the outside edge o Rods are concentrated at the retina’s edges NONE ARE IN THE FOVEA NOTE: Rods and cones do NOT fire action potentials like other neurons Optic chiasm: half of the axons in the optic nerves cross o The axons that cross are the ones that start from the portion of the retina nearest the nose o This arrangement causes all information from the left side of visual space WHAT and WHERE Pathways: Ventral stream (lower): appears to be specialized for the perception and recognition of objects o Determining colors and shapes Dorsal stream (upper): specialized for spatial perception o Determining where an object is and relating it to other objects in a scene The Color of Light is Determined by Its Wavelength: Shorter waves: range from blue to violet Medium length waves: waves range from yellow to green Longer waves: range from red to orange Trichromatic Theory: Color vision results from activity in three different types of cones o cone sensitive to short wavelengths (blueviolet light) S o cone sensitive to medium wavelengths (yellowgreen light) M o cone sensitive to long wavelengths (redorange light) L Opponent process theory: According to this theory, red and green are opponent colors as are blue and yellow Hue: consists of the distinctive characteristics that place a particular color in the spectrum o Example: the color’s greenness or orangeness Saturation: the purity of color o Varies according to the mixture of wavelengths in a stimulus Brightness: the color’s perceived intensity o Determined chiefly by the total amount of light reaching the eye o Example: think of the difference between, say, a navy blue and a pale blue of the same shade Lightness: determined by the brightness of the stimulus relative to its surroundings Proximity: the closer two figures are to each other, the more likely we are to group them and see them as part of the same object Similarity: We tend to group figures according to how closely they resemble each other, whether in shape, color, or orientation Continuity: We tend to group together edges or contours that have the same orientation, known as “good continuation” to Gestalt psychologists. Binocular depth cues: Cues of depth perception that arise from the fact that people have two eyes Monocular depth cues: Cues of depth perception that are available to each eye alone Binocular Depth Perception: Binocular disparity: A depth cue; because of the distance between the two eyes, each eye receives a slightly different retinal image Convergence: A cue of binocular depth perception; when a person views a nearby object, the eye muscles turn the eye inward Occlusion: A near object blocks an object that is farther away Relative size: Far off objects project a smaller retinal image than close objects do, if the far off and close objects are the same physical size Familiar size: Because we know how large familiar objects are, we can tell how far away they are by the size of their retinal images Linear Perspective: Seemingly parallel lines appear to converge in the distance Texture gradient: As a uniformly textured surface recedes, its textures continuously becomes denser Position relative to horizon: All else being equal, objects below the horizon that appear higher in the visual field are perceived as being farther away. Objects above the horizon that appear lower in the visual field are perceived as being farther away Object Constancy: Correctly perceiving objects as constant in their shape, size, color, and lightness, despite raw sensory data that could mislead perception o Size constancy: Need to know how far away the object is from us o Shape constancy: Need to know what angle or angles we are seeing the object from o Color constancy: Need to compare the wavelengths of light reflected from the object with those reflected from its background o Lightness constancy: Need to know how much light is being reflected from the object and from its background SUMMING UP: Vision is our most important sense because it provides the most information about the world Visual transduction occurs when light enters the eye and activates the photoreceptors (rods and cones) 5.3 How Are We Able to Hear? Audition: Hearing; the sense of sound perception Sound Wave: A pattern of changes in air pressure during a period of time; it produces the precept of a sound o Amplitude: determines its loudness o Frequency: determines its pitch (measured in hertz) Eardrum: A thin membrane that marks the beginning of the middle ear; sound waves cause it to vibrate Vestibular sense: Perception of balance determined by receptors in the inner ear Temporal coding: A mechanism for encoding low frequency auditory stimuli in which the firing rates of cochlear hair cells match the frequency of the sound wave Place coding: A mechanism for encoding high frequency auditory stimuli in which the frequency of the sound wave is encoded by the location of the hair cells along the basilar membrane 5.4 How are We Able to Taste? Gustation: the sense of taste Taste buds: sensory organs in the mouth that contain the receptors for taste SUMMING UP: Every taste experience is composed of a mixture of five basic qualities; o Sweet, sour, salty, bitter, umami (savory) People lose more than half of their taste buds by age 20 Supertasters and children can be picky eaters due to the intense nature of their taste experiences Cultural factors influence taste perception. Foods consumed by breastfeeding mothers influence taste preference in their offspring 5.5 How Are We Able to Smell? Olfaction: The sense of smell Olfactory epithelium: A thin layer of tissue, within the nasal cavity, that contains the receptors for smell Olfactory bulb: The brain center for smell, located below the frontal lobes SUMMING UP: Odorants are chemical particles, outside the body, that can be detected by smell receptors Smell receptors are located in the olfactory epithelium, in the lining of the nose and nasal cavity Of all the senses, olfaction has the most direct route to the brain. Smell is the only sense not processed via the thalamus Smell receptors send signals to the olfactory bulb, just below the frontal lobes, for processing Humans can discriminate between thousands of odors but have difficulty naming what they smell Pheromones activate smell receptors but are not identified as odors. Pheromones motivate mating behaviors in nonhuman animals and may affect humans similarly 5.6 How Are We Able to Feel Touch and Pain? Haptic sense: The sense of touch Kinesthetic touch: Perception of the positions in the space and the movements of our bodies and our limbs SUMMING UP: Tactile stimulation gives rise to the sense of touch Haptic receptors process information about temperature and pressure Haptic receptors send signals to the thalamus, which projects to the primary somatosensory cortex (in the parietal lobe) Pain receptors are located all over the body, but most pain is signaled by haptic receptors in the skin Fast, myelinated fibers process information about sharp sudden pain. Slow, non myelinated fibers process chronic dull pain According to the gate control theory, pain perception involves both a painful stimulus and spinal cord processing of the signal Ways to decrease pain include activating touch or other senses, mental distraction, and thinking pleasant thoughts
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