Perceptual organization

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Perceptual organization

• How do we form meaningful perceptions from
  sensory information?

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Gestalt psychology

• Branch of cognitive psychology
• Organization of many sensations into perceptions
  of wholes
• Gestalt whole or form
• Based on experience and expectations
• Perceived whole is not always the same as its
  parts!

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Form perception

• Simplification into easily interpretable wholes
• Figure-ground

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Form perception

• Grouping principles
• Proximity
• Similarity
• Continuity
• Connectedness
• Closure

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Depth perception

• Distance is perceived with vision and hearing
• Visual depth perception
• Binocular cues
• Monocular cues

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Binocular depth cues

• Retinal disparity
• Strongest visual depth cue

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Monocular depth cues

• Light and shadow
• Relative size and position
• Relative height/vertical position
• Linear perspective

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Auditory location cues

• Intensity and pitch
• Arrival times at each ear
• Clarity

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Perceptual constancy

• Cognitive functions that maintain the features of
  an object, despite changing illumination, color,
  size, or shape
• Based on comparisons between the figure and ground

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Color and lightness constancy

• Consistent color and light intensity, despite
  changes in illumination

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Shape and size constancy

• Familiar objects are perceived as unchanging
  despite changes in retinal images.

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Perceptual interpretation

• Making sense of the perceptions produced by the
  cortex
• Genetics
• Experience
• Critical periods
• Plasticity and adaptation

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Perceptual set

• Psychological predisposition to perceive stimuli
  in a particular way
• Shaped by learned assumptions and beliefs
• Affects how we interpret sensory stimuli
• Examples

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Other sensory modalities
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Hearing

• Stimulus - sound waves
• Frequency
• Amplitude

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The ear
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Auditory stimuli

• Bending of hair cells in the cochlea transduces
  vibrations into neural signals

• Auditory nerve
• Primary auditory cortex
• Auditory association cortex

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Touch

• Stimulus - pressure, pain, warmth, cold
• Receptors
• Other sensations
• Stimuli organized in primary somatosensory cortex
• Perceptions created in somatosensory association
  cortex

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Pain

• Critical alert system
• Subjective
• Physiology
• Prior experiences
• Attention
• Context
• Culture

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Pain

• Gate-control theory
• Pain control/management

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Taste

• Stimulus - chemical molecules that impart the
  sensations of sweet, sour, salty, bitter and
  umami
• Tastebuds contain taste and touch receptors

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Taste perception

• Flavor
• Based on taste, olfactory, and touch stimuli
• Begins in brainstem
• Completed in the limbic system

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Taste preferences

• Genetic predisposition
• Biological predisposition
• Learned responses

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Smell

• Stimulus - chemical molecules
• Receptors in olfactory epithelium
• Axons project directly to the olfactory bulb of
  the brain
• Perception begins in
• the olfactory bulb,
• completed in the
• limbic system

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Kinesthesis vestibular sense

• Kinesthesis - sense of body position and movement
• Vestibular sense - sense of head postion and
  movement
• Stimulus - gravity and movement
• Receptors found in muscles (body) and inner ear
  (head)

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Kinesthesis vestibular sense

• Sensory signals about position and movement are
  organized in the medulla and cerebellum
• Perception occurs throughout the brain
• Brain stem
• Temporal cortex