A.P. Psychology Sensation & Perception

Modules 11, 15 & 16A.P. Psychology: Sensation & Perception

Sensation What is it?Bottom-Up Processinganalysis that begins with the sense receptors and works up to the brains integration of sensory informationTop-Down Processinginformation processing guided by higher-level mental processesas when we construct perceptions drawing on our experience and expectationsSensationPsychophysicsstudy of the relationship between physical characteristics of stimuli and our psychological experience of themLight- brightnessSound- volumePressure- weightTaste- sweetnessSensation: Basic PrinciplesAbsolute Threshold minimum stimulation needed to detect a particular stimulus 50% of the timeDifference Thresholdminimum difference between two stimuli required for detection 50% of the timejust noticeable difference (JND)Signal Detection Theorypredicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)assumes that there is no single absolute thresholdSubliminalBelow absolute threshold for conscious awarenessSensation: ThresholdsWebers Lawto be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)light intensity- 8%weight- 2%tone frequency- 0.3%Sensation: ThresholdsSensory Adaptationdiminished sensitivity as a consequence of constant stimulationSelective Attentionfocusing of conscious awareness on a particular stimulusSensation: ThresholdsAwareness testSelective AttentionCocktail Party Effect

Perception What is it?8

Change Blindness9

Perceptual Illusions10

Perceptual Illusions11

Perceptual Illusions12Visual Capturetendency for vision to dominate the other sensesGestaltan organized wholetendency to integrate pieces of information into meaningful wholes

Perceptual Organization13Figure and Groundorganization of the visual field into objects (figures) that stand out from their surroundings (ground)

Perceptual Organization14Groupingthe perceptual tendency to organize stimuli into coherent groupsGrouping Principlesproximity--group nearby figures togethersimilarity--group figures that are similarcontinuity--perceive continuous patternsclosure--fill in gapsconnectedness--spots, lines, and areas are seen as unit when connectedPerceptual Organization15

Perceptual Organization: Grouping Principles16estt groupng principles are at work here.

Perceptual Organization: Closure17

Perceptual Organization: Gestalt Principles18Depth Perceptionability to see objects in three dimensionsallows us to judge distanceBinocular cuesretinal disparityimages from the two eyes differ closer the object, the larger the disparityconvergenceneuromuscular cuetwo eyes move inward for near objectsPerceptual Organization: Depth Perception19Visual Cliff

Depth Perception20Monocular Cuesrelative sizesmaller image is more distantinterpositioncloser object blocks distant objectrelative clarityhazy object seen as more distanttexture coarse --> closefine --> distantDepth Perception21

InterpositionDepth Perception22Monocular Cues (cont.)relative heighthigher objects seen as more distantrelative motioncloser objects seem to move fasterlinear perspectiveparallel lines converge with distancerelative brightnesscloser objects appear brighterDepth Perception23

Perspective TechniquesDepth Perception24Illusory Depth

Depth Perception25Perceptual Constancyperceiving objects as unchanging even as illumination and retinal image changecolorshape size

Perceptual Constancy26Kittens raised without exposure to horizontal lines later had difficulty perceiving horizontal bars

Sensory Restriction: Blakemore & Cooper, 197027Perceptual Adaptation(vision) ability to adjust to an artificially displaced visual fieldprism glassesPerceptual Seta mental predisposition to perceive one thing and not anotherPerceptual Interpretation28What you see in thecenter is influenced by perceptual set

Perceptual Set: Schemas29Human Factors Psychologyexplores how people and machines interactexplores how machine and physical environments can be adapted to human behaviors

Perception & the Human Factor30Extrasensory Perceptioncontroversial claim that perception can occur apart from sensory inputtelepathyclairvoyanceprecognitionParapsychologythe study of paranormal phenomenaESPpsychokinesisIs there Extrasensory Perception?31