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Sensation and Perception. Sensation vs. perception. Watch carefully and count the number of passes thrown by the people in white shirts. Neisser’s study Selective attention (we sense, but what do we perceive?). Sensation vs. perception. Bottom-up vs. top down processing.
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Sensation vs. perception • Watch carefully and count the number of passes thrown by the people in white shirts. • Neisser’s study • Selective attention (we sense, but what do we perceive?)
Bottom-up vs. top down processing What does this picture show? Random dots??? Still can’t see it? Here’s some help.
Bottom-up vs. top down processing “The Forest Has Eyes”
Introduction to sensation and perception, Zimbardo style • Video: Discovering Psychology #7
Sensation - psychophysics • Absolute threshold • Signal detection theory
Psychophysics - JND • Difference threshold (JND – just noticeable difference) • Weber’s Law (JND increases in proportion to size of stimulus) • light intensity - 8% • weight - 2% • tone frequency - 0.3%
Sensory adaptation • Sensory adaptation – diminishing sensitivity to stimuli • Example: Motion blindnessand a second example
Sensation – subliminal messages • Video – The Mind #9 • Blindsight – Milner (the zombie within)
Vision Acuitysharpness of vision Normal focus Farsightedness Nearsightedness
Vision Blind spot
Receptors in the Human Eye Cones Rods Number 6 million 120 million Location in retina Center Periphery Sensitivity in dim light Low High Color sensitive? Yes No Vision - receptors
Visual Information Processing • Feature detectors - #8
Visual Information Processing Can a computer help a blind person see again? Cybersenses Parallel Processing The Brain #9. Visual Information Processing: Perception
Color vision: • Wavelength (hue) • amplitude (intensity)
Visual information processing color vision • Trichromatic (three color) Theory • Young and Helmholtz – red, green, blue receptors • Opponent-Process Theory • Certain receptors are excited by blue, inhibited by yellow (explains afterimages) • Others excited by green, inhibited by red • Can’t see bluish-yellow or reddish-green
Audition - hearing • Decibels • Amplitude = loudness • Frequency = pitch • Sound localization Lower pitch Higher pitch
Audition (hearing) • Place theory (high-beginning, low-end) • Frequency theory • Volley principle • Conduction hearing loss • Sensorineural hearing loss • Sensory compensation
New frontiers • Cybersenses
Touch Pressure Cold Warmth Living without touch (proprioception)
Pain • Gate-control theory • Nociceptors • Phantom limb pain • Video #20 • Pain pathways • Treatment helps prevent pathways from forming
Gustatory sense (chemical sense) + umami
Sensory Interaction Synaesthesia McGurk effect
Olfactory sense • In contrast to vision (basically 4 types of receptors), smell has about 1,000 different receptors. • Message does NOT go to thalamus. • Pheromones
Body position and movement • Kinesthesis • Vestibular sense
You should see a man's face and also a word...Hint: Try tilting your head to the right, the word begins with 'L'