Transcript Sensation and Perception

Perceptual organization
• How do we form meaningful
perceptions from sensory
information?
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!
Form perception
• Simplification into easily interpretable
wholes
• Figure-ground
Form perception
• Grouping
principles
– Proximity
– Similarity
– Continuity
– Connectedness
– Closure
Depth perception
• Distance is perceived with vision and
hearing
• Visual depth perception
– Binocular cues
– Monocular cues
Binocular depth cues
• Retinal disparity
– Strongest visual depth cue
Monocular depth cues
• Light and shadow
• Relative size and
position
• Relative
height/vertical
position
• Linear
perspective
Auditory location cues
• Intensity and pitch
• Arrival times at each ear
• Clarity
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
Color and lightness constancy
• Consistent color and light intensity,
despite changes in illumination
Shape and size constancy
• Familiar objects are perceived as
unchanging despite changes in retinal
images.
Perceptual interpretation
• Making sense of the perceptions produced
by the cortex
– Genetics
– Experience
• Critical periods
• Plasticity and adaptation
Perceptual set
• Psychological predisposition to perceive
stimuli in a particular way
– Shaped by learned assumptions and beliefs
– Affects how we interpret sensory stimuli
• Examples
Other sensory modalities
Hearing
• Stimulus - sound waves
– Frequency
– Amplitude
The ear
Auditory stimuli
• Bending of hair cells in the cochlea
transduces vibrations into neural signals
• Auditory nerve
• Primary
auditory cortex
• Auditory
association
cortex
Touch
• Stimulus - pressure, pain, warmth, cold
– Receptors
– Other sensations
• Stimuli organized in primary
somatosensory cortex
• Perceptions created in somatosensory
association cortex
Pain
• Critical alert system
• Subjective
– Physiology
– Prior experiences
– Attention
– Context
– Culture
Pain
• Gate-control theory
• Pain control/management
Taste
• Stimulus - chemical molecules that
impart the sensations of sweet,
sour, salty, bitter and umami
Sweet
Sour
Salty
Bitter
Umami
• Tastebuds contain taste and touch
receptors
Taste perception
• Flavor
– Based on taste, olfactory, and touch stimuli
• Begins in brainstem
• Completed in the limbic system
Taste preferences
• Genetic predisposition
• Biological predisposition
• Learned responses
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
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)
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