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PERCEPTION

Dive into the fascinating world of perception, from the basics of psychophysics to complex processes like top-down and bottom-up processing. Understand how our brains organize sensory inputs, perceive depth, motion, and constancy, and navigate through attentional mechanisms. Explore Gestalt psychology and the influences on perceptual sets with key illusions and parapsychology insights.

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PERCEPTION

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  1. PERCEPTION Def: the mental process of organizing sensory input into meaningful patterns

  2. psychophysics • Ernst Weber • The study of the relationship btwn stimuli and our responses to them

  3. 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

  4. Absolute thresholds • Lowest levels of awareness of faint stimuli with no competing stimuli present • Must be detected 50% of the time

  5. Subliminal perception • Perception of a stimulus below the threshold for conscious recognition • No evidence to support that it affects our behavior

  6. 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)

  7. Processing incoming information

  8. 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

  9. Bottom-up processing (feature analysis) • Starts with noticing individual elements, then appreciate the whole picture • Inductive Reasoning • Begins with sensory inputs

  10. 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

  11. attention • The brain can focus only on one thing at a time • Multitasking is divided attention

  12. Focused or selective attention • Homing in on one particular stimulus • Cocktail Party Effect—hearing name in a crowded party • Stroop Effect

  13. 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”

  14. Inattentional blindness • Our focus is directed at one stimulus, leaving us blind to other stimuli

  15. Change Blindness • Inability to see changes in our environment when our attention is directed elsewhere

  16. Perceptual adaptation • Ability to adapt to an environment and filter out distractions • Sensory adaptation and habituation

  17. Perceptual organization

  18. Gestalt psychology • Study of the brain’s tendency to integrate pieces of information into meaningful wholes

  19. Figure-ground • Figure—what is focused on • Ground—blurry background; what is ignored • Ambiguous figures

  20. grouping • Tendency to organize stimuli into groups • 5 types of grouping patterns: • Proximity • Similarity • Continuity • Closure • Connectedness

  21. Depth perception Def: the ability to see the world in 3 dimensions and to know proximity of an object

  22. Binocular cues • Retinal Disparity: difference btwn the images the eyes perceive; due to different angles • Convergence: eyes moving inward when focusing on an object

  23. 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

  24. 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

  25. Perceptual constancy Def: ability and need to perceive objects as unchanging even as changes may occur in distance, point of view, and illumination

  26. Color constancy • Perception that color of an object remains the same even if lighting changes

  27. Size constancy • Tendency to perceive objects as the same apparent size regardless of distance from us

  28. Shape constancy • When our viewing angle changes or an object rotates and we still perceive the object as staying the same shape

  29. Lightness constancy • Perception of whiteness, blackness, or grayness of objects remains constant now matter how much illumination has changed

  30. Optical illusion • There are many but only 3 you need to be aware of… • Müller-Lyer Illusion • Ponzo Illusion • Moon Illusion

  31. Perceptual set Top-down processing; refers to our disposition to perceive one aspect of a thing and not another

  32. Influences on perceptual sets • Schemas: mental filters or maps that organize our information about the world • Context • Culture

  33. 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

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