PSY201H - Chapter 4 Sensation
PSY201H - Chapter 4 Sensation PSY 201H
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This 4 page Class Notes was uploaded by Brandon Harvey on Sunday October 16, 2016. The Class Notes belongs to PSY 201H at Marshall University taught by Dr. Fugett in Fall 2016. Since its upload, it has received 3 views. For similar materials see General Psychology Honors in Psychology at Marshall University.
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Date Created: 10/16/16
Chapter 4: Sensation Sensation o Physical process o At lease 6 o Stimulation of our sense organs by energy/chemical from the outer world o Transforms physical stimuli to a pattern of actions potentials called transduction o It is a process of receiving information, not making sense of it Hear many voices at party, but don’t try and understand what is being said Perception o Psychological process o Act of organizing and interpreting sensory signals (action potentials received from sense organs) o Uses previous experiences to interpret new stimuli Basic Sensory Process o Sensory adaptation Ensures that we notice changes in stimulation more than stimulation itself Process by which our sensitivity diminishes when an object constantly stimulates our senses Repeating “mom” constantly because she doesn’t respond Allows us to readily detect changes in stimulation o Transduction Conversion of physical into neural information Basic process of sensation Principles of Perception o Absolute threshold: lowest intensity level of a stimulus we can detect half of the time not constant o Signal detection theory: viewpoint that both stimulus intensity and decision-making processes are involved in the detection of a stimulus o Difference threshold: smallest amount of change between two stimuli that a person can detect half of the time; just noticeable differences o Weber’s Law: the size of the JND is a constant fraction of the intensity of the stimulus o Perceptual set: effect of frame of mind on perception Sensing Visual Stimuli o Reina o Bend light, converts light E to neural E, and sends that information to the brain for processing o Vision and the Eye cornea, pupil, iris, lens accommodation: muscles around the lens alter its shape to adjust to viewing objects at different distances and to allow the lens to focus light on the retina. Retina Photoreceptors o Rods Dark adaptation o Black and white Movement, light/dark, peripheral o Cones Color Color in bright light On Fovea o Fine focus Greatest clarity visual acuity: ability to fine focus Vision and Brain o Optic nerve o Optic nerve: transmits signal from eyes to brain o Ganglion cells o Blind spot o Blind spot: location on retina with no receptor cells; point at which optic nerve exists o Optic chiasm o Optic chiasm: area of the brain where visual stimuli cross hemispheres o Lateral geniculate nucleus o o How well people see Normal: lens projects image to hit just on retina Nearsighted (myopic): image focuses slightly before retina See close object clear Minus lens for correction Farsighted (hyperopic): image focuses behind retina See far object clear Positive lens for correction Age-related farsightedness (presbyopia): lens more flexible, image behind retina o Visual Pathway Input from right field sensed by left side of retina in each eye (the same happens for the left field sensed by the right side of the retina in each eye) Travels along optic nerve to optic chiasm then to thalamus (lateral geniculate nucleus) Nerve fibers transmit visual information from the thalamus to the visual cortex of the occipital lobes Vision and Specific Neurons o Individual neurons fire only because of very specific visual information o Feature detectors: analyze the retinal image and respond to specific aspect of shapes, such as angles and movements Simple – very specific; bar of light oriented at a particular angle Complex – receive input from simple cells and are sensitive to movement of image Hypercomplex – receive inputs from complex cells so they fire in response to patterns of lines; integrate pieces into whole Perceiving Visual Stimuli o Perceiving motion Movement detector neurons Impression of speed Background detail Smaller size of object Apparent motion o Depth perception Discriminating what is near and what is far Binocular depth cues Binocular disparity o Disparity between left and right eye o Judge distance by comparing what is noticed by left eye and what is notice by right eye Monocular depth cures Linear perspective o Parallel lines converge to a point on the horizon Texture gradient o You can see things closer to you better Atmospheric perspective o Things get fuzzy/hazy far away o Heat off road Interposition o Partial blocking of objects farther away by objects closer to viewer that overlap the thing farther away o Perceptual constancy Size o Ames Brains ability to preserve perception of such objects in spite of the changes in retinal image Ames Shape o Bottom-up processing Building a perceptual experience from smaller pieces o Top-down processing Regard of the whole guides perception of smaller elemental features o Perception of color Trichromatic color theory Afterimages are not explained by this theory Opponent process theory Links together the cone colors into three opposite color pairs, so that activation of one in each pair inhibits activity in the other: o Blue/yellow o Red/green o Black/white Trichromatic and opponent process theories work together to explain our color perception o Our red, green and blue cones respond in proportion to the amount of red, green, and blue is the mixture of light that strikes our retina. Red, green, blue light makes white light o Deficiencies in color vision Color dot plate test True colorblindness is very rare Often involves color specific deficits Results from inherited pigment deficiency in the photoreceptors Organizing Visual Information: Gestalt Laws of Grouping o Gestalt – “form,” “pattern,” or “shape” Laws of grouping Similarity Continuity Proximity Closure o Sum = whole of its parts Figure/ground
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