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PERCEPTION. Def: the mental process of organizing sensory input into meaningful patterns. psychophysics. Ernst Weber The study of the relationship btwn stimuli and our responses to them. Just noticeable difference (difference threshold).
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PERCEPTION Def: the mental process of organizing sensory input into meaningful patterns
psychophysics • Ernst Weber • The study of the relationship btwn stimuli and our responses to them
Just noticeable difference (difference threshold) • Smallest amt 2 stimuli have to differ for us to tell them apart • Weber’s Law: the amt of change needed to produce a constant JND is a constant proportion of the original stimulus intensity
Absolute thresholds • Lowest levels of awareness of faint stimuli with no competing stimuli present • Must be detected 50% of the time
Subliminal perception • Perception of a stimulus below the threshold for conscious recognition • No evidence to support that it affects our behavior
Signal (or stimulus) detection theory • Detection of a stimulus depends partly on experience, expectations, motivation, and alertness • How we separate the stimulus (signal) from background stimuli (noise)
Top-down processing • Processing info guided by our thoughts or higher-level mental processes • Move from the general to the specific • Deductive Reasoning: logical thinking that begins with a general idea, then develops specific evidence to support or refute it
Bottom-up processing (feature analysis) • Starts with noticing individual elements, then appreciate the whole picture • Inductive Reasoning • Begins with sensory inputs
Feature detectors • Neurons in visual association cortex that focus specifically on edges, lines, angles, curves, and movement • We build an image from simple stimuli and combine them into complex formats
attention • The brain can focus only on one thing at a time • Multitasking is divided attention
Focused or selective attention • Homing in on one particular stimulus • Cocktail Party Effect—hearing name in a crowded party • Stroop Effect
Selective inattention • Screening out unwanted stimuli b/c it causes anxiety or feels threatening or b/c it is thought to be of no importance • “You hear what you want to hear”
Inattentional blindness • Our focus is directed at one stimulus, leaving us blind to other stimuli
Change Blindness • Inability to see changes in our environment when our attention is directed elsewhere
Perceptual adaptation • Ability to adapt to an environment and filter out distractions • Sensory adaptation and habituation
Gestalt psychology • Study of the brain’s tendency to integrate pieces of information into meaningful wholes
Figure-ground • Figure—what is focused on • Ground—blurry background; what is ignored • Ambiguous figures
grouping • Tendency to organize stimuli into groups • 5 types of grouping patterns: • Proximity • Similarity • Continuity • Closure • Connectedness
Depth perception Def: the ability to see the world in 3 dimensions and to know proximity of an object
Binocular cues • Retinal Disparity: difference btwn the images the eyes perceive; due to different angles • Convergence: eyes moving inward when focusing on an object
Monocular cues • Linear Perspective • Interposition (occlusion): overlapping • Relative Size: far away objects look small • Relative Height: objects higher in vision seem farther away • Relative Clarity • Light and Shadow: dimmer objects are farther • Texture Gradient: degree of detail increases for closer objects • Motion Parallax: closer objects appear to move faster
MOTION perception • Phi Phenomenon: movement of a series of pictures at a rate that suggests motion • Relative Motion: when we move, objects fixed in one place appear to move with us
Perceptual constancy Def: ability and need to perceive objects as unchanging even as changes may occur in distance, point of view, and illumination
Color constancy • Perception that color of an object remains the same even if lighting changes
Size constancy • Tendency to perceive objects as the same apparent size regardless of distance from us
Shape constancy • When our viewing angle changes or an object rotates and we still perceive the object as staying the same shape
Lightness constancy • Perception of whiteness, blackness, or grayness of objects remains constant now matter how much illumination has changed
Optical illusion • There are many but only 3 you need to be aware of… • Müller-Lyer Illusion • Ponzo Illusion • Moon Illusion
Perceptual set Top-down processing; refers to our disposition to perceive one aspect of a thing and not another
Influences on perceptual sets • Schemas: mental filters or maps that organize our information about the world • Context • Culture
parapsychology • Fake psychology (pseudopsychology) • Falsely claims the legitimacy of extrasensory perception (ESP): perception w/o sensory input • Telepathy, clairvoyance, precognition, psychokinesis • Research indicates that ESP is not possible