OUTLINE Modules 10 11 12 13 SENSATION 1 Sensation vs Perception 2 Psychophysics 3 Vision 4 Audition NOTE Read about Touch Taste Smell Balance PERCEPTION 2 Organization and Interpretation Some Perceptual Illusions Gestalt Psychology Constancy in Perception Perceptual Set Depth Perception Perceptual Adaptation Extra Sensory Perception Experiencing events 2 Stages Stage 1 SENSATION the processes of converting the physical world into a mental representation transduction and relaying that info to the brain conduction transduction EX variations of light experience of color Variations of air pressure experience of sound Stage 2 PERCEPTION the processes of selection organization and interpretation of these mental representations EX We can recognize the color green We can distinguish Bach from Bruno Mars PSYCHOPHYSICS What is it The study of the relationship between physical characteristics of stimuli energy and our psychological experience of them EX Light brightness Sound volume Pressure weight Taste sweetness Key concepts Absolute Thresholds Smallest magnitude of a stimulus that can be reliably discriminated from NO stimulus at least 50 of the time Difference Threshold Minimum difference between two stimuli that a person can detect at least 50 of the time o Just noticeable difference PSYCHOPHYSICS Signal Detection Theory Predicts how and when we will detect the presence of a stimulus amidst background stimulation Complex decision mechanisms are involved to determine if a stimulus exists Based on both Stimulus strength Our experiences expectations motivation level of fatigue o Sounds in my house Point Absolute thresholds and Just noticeable differences are not fixed Our sensitivity to a stimulus varies based on experiences Factors that affect Absolute and Difference Thresholds 1 chance variation noise in the system influences sensitivity rubbing your eyelid changes the light light is not actually changing just noise in the system 2 stimulus intensity Weber s Law the greater the intensity of a stimulus the larger the difference must be to detect a difference They must differ by a constant proportion holding a 100lb weight compared to a 101lb weight you cannot tell the difference 3 Sensory Adaptation our sensitivity to an unchanging stimulus diminishes getting into a hot tub is difficult at first but then you get used to the heat VISION Q How do we turn light energy physical stimulus into vision psychological experience 2 aspects of light energy are crucial Wavelength The distance between peaks of the light wave Corresponds to our sensation of color R O Y G B I V Short wavelength violets and blues Long wavelength reds and oranges Amplitude The intensity of the light wave Corresponds to our sensation of brightness Small amplitude dull color Great amplitude bright color Structure of the EYE read text 1 Rods cells in the periphery of the retina sensitive to light 2 Cones cells in the center of the retina Fovea sensitive to focus and color perception VISION Two Major Theories of Color Vision 1 Trichromatic theory Young Hemholtz Creation of colors Any color can be created by combining the red green and blue light in varying combinations In our eyes we have 3 kinds of cones Cone 1 maximally sensitive to blue Cone 2 maximally sensitive to green Cone 3 maximally sensitive to red Experience of colors Our experience of colors results from mixing different levels of response from these 3 cone types Note Additive light vs subtractive paint color mixing Colorblindness VISION Two Major Theories of Color Vision 2 Opponent process theory opposing retinal processes enable color vision neural impulses are antagonistic a stimulus that elicits a response from the red depresses and response of green antagonistic neural impulses ON Red Blue vs vs OFF Green Yellow White vs Black Explains Color After Images AUDITION HEARING Q How do we turn variations in air pressure physical stimulus into our sense of hearing psychological experience Two aspects are crucial 1 Frequency The number of complete cycles per unit time Hertz cycles per second Corresponds to our psychological sensation of pitch 2 Amplitude The intensity of the wave Corresponds to our psychological sensation of volume Structure of the Ear read text AUDITION HEARING Perceiving Pitch Volume Location Perceiving Pitch highs vs low sounds 1 Place theory different pitches produce responses on different places on the basilar membrane Works well with high pitched sounds 2 Frequency theory different pitches cause the basilar membrane itself to vibrate at different frequencies Works well with low pitched sounds Perceiving volume loud vs soft sounds Not movement of Basilar Membrane but number of stimulated hair cells Perceiving Location where is that sound coming from Why do we have 2 ears Left vs right Up vs down Front vs behind What s up with your own voice Air coming out of your mouth bone conduction When you hear others talk you hear sound waves from the air coming in to your ears You hear your own voice from the sound waves in the air to your ears AS WELL AS sound waves from inside your head via bone conduction PERCEPTION What is it Def the process by which we select organize and interpret these mental representations EX We can recognize the color red We can distinguish Bach from Britney Spears Perception ORGANIZATION INTERPRETATION Most Important Point of the day There is NOT a 1 1 correspondence between our perceptual representation of the world and the physical reality of the world Why Because physical information is ambiguous EX seeing your roommate across the pond you know she s 5 10 but she looks very small across the pond EX What s the matter honey Nothing We do this with all sorts of physical world information We take the available info and interpret it based on what we know about our world PERCEPTION Perceptual Illusions What is an illusion Case where the rules that we use to interpret the world which are usually true are not true and lead us to misinterpretation Examples of Visual Illusions 1 Vertical vs Horizontal lines vertical lines appear longer than horizontal lines 2 Context effects we use the context to figure out which interpretation to go with 3 Experience effects the world Muller Lyer Two lines look different to people who grow up with right angled buildings look the same to people who grow up with circular buildings Why so many visual illusions Visual capture vision dominates EX stare at phone when listening to voicemail on speaker
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