Sensation - Kristin Pauker PDF

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Kristin Pauker...

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Sensation: The process by which sense organs respond to external stimuli and transmit their responses to the brain. Perception: The additional processing of sensory signals by the brain to form internal representations of stimuli. Illusions ❖ When perception does not accurately present the world Psychophysics ❖ Study of the relationship between physical events and the corresponding experience of those events ❖ Absolute threshold: is the level of intensity at which participants (correctly) detect a stimulus on 50 percent of the trials in which it is presented. Thresholds ❖ Just-noticeable difference (JND) = minimal stimulus change needed to detect a difference Sensory Adaptation ❖ Constant stimulation decreases the number of sensory messages sent to the brain, which causes decreased sensation ❖ Examples: ➢ When you first get into the ocean… it’s cold! ➢ When you go to hot yoga and the person next to you has BO. Vision ❖ Light falls on receptors in the eye ➢ Light = physical stimulus in vision ■ Wavelength of light determines color Structures of the Eye ❖ Transduction = physical energy converted to neural impulses Photoreceptors (In Retina) ❖ Rods (~120 million) ➢ Light sensitive, sees shades of gray ➢ Periphery & night vision ➢ Not in fovea, fuzzy vision ❖ Cones (~6 million) ➢ Central & color vision ➢ Very acute ➢ Denser near fovea Color Vision ❖ Trichromatic theory = 3 different color sensors ❖ Opponent process theory = ganglion cells (retinal neurons) work in opposing pairs (R/G, B/Y)

❖ Afterimage Perception in the eye ❖ Proximity ➢ Figures near each other get grouped togeher ❖ Continuity ➢ Perceive smooth, continuous lines, rather than discontinuous ones ❖ Closure ➢ Complete figures even when gaps exist ❖ Illusory Contours ➢ Perceive contours, even when they don’t exist Perceptual Constancies ❖ Size constancy Knowing the Distance ➢ Visual cues ➢ Static cues ■ Binocular cues ● Binocular Disparity ◆ Brain compares the images provided by each eye, and determines the difference between the two images. ● Convergence ◆ The brain notes the extent to which our eyes turn inward when we focus. ■ Monocular cues ● Linear Perspective ● Texture Gradient ◆ Gradual change to a finer texture = more distant ● Occlusion ◆ If an object is covered by another, that object is further away ● Position relative to the horizon ◆ Objects higher in field of vision = further away ● Relative size ◆ Smaller objects are perceived as more distant ■ Motion cues ■ Works well with both eyes ❖ Convergence ❖ Prosopagnosia = face blindness...