SENSATION and PERCEPTION- Chapter 3 Invisible processes that are constantly working to interact with the world. Sight The Perceptual Process ● Environmental stimulus- light waves ● Attended stimulus (the part of the stimuli we’re paying attention to) ● Stimulus on the receptors ● Transduction- sensory neurons convert sensory stimulation into neural impulses ○ order that light passes through the eye: cornea, lens, retina, optic nerve ○ photoreceptors- rods (shape) and cones (color and detail) ● Processing (knowledge)- feature detectors- neurons that fire depending on small, miniscule details about the stimulus ● Perception (knowledge)- information a person brings to a situation; plays an important role in perception and recognition ● Recognition ● Action ● Entire process repeats Perceiving Color ● Functionalist viewpoint ○ perspective emphasised by Charles Darwin ● color is produced by wavelengths of light that reflect off of (or pass through) an object. ○ this occurs in the visible light of the EM spectrum ● every surface has a reflectance curve ● flat reflectance curves are associated with achromatic colors (white, gray, black) ○ all wavelengths of light are reflected equally ● selective reflection associated with chromatic colors ○ some wavelengths are reflected, while others are absorbed ● colors are created by our perceptual system ○ proposed by Isaac Newton ○ the colors that are absorbed are the ones we cannot see. The colors that are reflected are the ones we can see ■ example: blue (shorter wavelength) is absorbed, and green and red (longer wavelengths) are reflected, revealing a color in the middle of the spectrum, yellow ■ DO NOT THINK ABOUT MIXING PAINTS! ○ achromatic- white, grey, black; is the reflection of all colors ○ chromatic- rainbow colors; only some colors are reflected ○ we must have at least three types of cones to see color ■ short cones (blue) ■ medium cones (green) ■ long cones (red) ○ there are three types of opponent processes
■ blue-yellow ■ red-green ■ black-white ■ when looking at a specific color for too long, those cones become fatigued and the opposite color cones take over ○ Cone-based deficiencies ■ monochromat ● no cones (or only one type of cone) ■ dichromat ● 2 types of cones (different variations) ● red-green color deficiency (more common): more prevalent in males because it’s linked to the X-chromosome. Will appear in girls if the trait is on both X-chromosomes ● blue-yellow color deficiency (rare): males and females equally ○ Cortical deficiencies ■ cerebral achromatopsia- when the part of the brain that translates wavelengths is damaged Perceptual Organization ● Wundt’s structuralism ● Gestalt psychologists ○ structuralism does not equal the sum of the parts, it cannot explain perception ● Perceptual Principles ○ similarity- similar things are grouped together ○ continuity- lines are seen as continues even when interrupted ○
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- Classical Conditioning