Transcript Sensation and perception

Sensation and
perception
Definitions
Sensation
The detection of physical energy emitted or reflected by
physical objects.
Occurs when energy in the external environment or the
body stimulates receptors in the sense organs.
Perception
The process by which the brain organizes and interprets
sensory information.
Our Senses
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Vision
Hearing
Taste
Smell
Touch
Specific nerve energies
Different sensory modalities exist
because signals received by the sense
organs stimulate different nerve
pathways leading to different areas of
the brain.
Synesthesia
A condition in which stimulation of one sense also
evokes another.
Absolute threshold
The smallest quantity of physical energy that can be reliably detected
Vision
A single candle flame from 30 miles on a clear night
Hearing
The tick of a watch from 20 feet in total quiet
Smell
One drop of perfume in a 6-room apartment
Touch
The wing of a bee on the cheek, dropped from 1 cm
Taste
One teaspoon of sugar in 2 gallons of water
Difference threshold
The smallest difference in stimulation
that can be reliably detected by an
observer when two stimuli are
compared.
Also called the Just Noticeable
Difference (JND).
Sensory adaptation and
deprivation
Adaptation
The reduction or disappearance of sensory
responsiveness when stimulation is unchanging
or repetitious.
Prevents us from having to respond continuously
to unimportant information.
Deprivation
The absence of normal levels of sensory
stimulation.
Sensory overload
Over-stimulation of the senses.
Can use selective attention to reduce
sensory overload.
Selective attention: the focusing of
attention on selected aspects of the
environment and the blocking out of
others.
What we see
Hue
Visual experience specified by color names and related to
the wavelength of light.
Brightness
Visual experience related to the amount of light emitted
from or reflected by an object.
Saturation
Visual experience related to the complexity of light waves.
Trichromatic theory
Young (1802) and von Helmholtz
(1852) both proposed that the eye
detects 3 primary colors.
Red, blue, and green
All other colors derived by
combination.
Ambiguous Figure
• Also known as ambiguous illusions are
pictures or objects that elicit a perceptual
'switch' between the alternative
interpretations.
– The brain can interpret the
ambiguous cues in two different
ways.
Distorting Illusions
• Characterized by distortions of size,
length, or curvature.
Visual constancies
The accurate perception of objects as
stable or unchanged despite changes
in the sensory patterns they produce
Color in context
The way you perceive a color depends on
the color surrounds.
What we Hear
Loudness
The dimension of auditory experience related to the
intensity of a pressure wave.
Pitch
The dimension of auditory experience related to the
frequency of a pressure wave.
Timbre
The dimension of auditory experience related to the
complexity of a pressure wave.
What we Taste
Five basic tastes
Salty, sour, bitter, sweet, and umami
• Umami is one of the five basic tastes sensed by specialized
receptor cells present on the human
• Umami is a Japanese word meaning savory, a "deliciousness" factor
deriving specifically from detection of the natural amino acid,
glutamic acid, or glutamates common in meats, cheese, broth, and
other protein-heavy foods.
• Glutamate appears in foods and food ingredients such as
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soy sauce
fish sauce
parmesan
anchovies
monosodium glutamate (MSG)
Different people have
different tastes based on
Genetics
Culture
Learning
Food attractiveness
What we Smell
Airborne chemical molecules enter
the nose and circulate through the
nasal cavity.
Vapors can also enter through the mouth and pass
into nasal cavity.
Receptors on the roof of the nasal
cavity detect these molecules.
Somatosensory System
• Widespread and diverse sensory system
– touch
– temperature
– pain
– kinesthesia (body position and movement)
– equilibrioception (balance)