Download Sensation-AP-2016

HOW MUCH OF OUR EXPERIENCE OF THE WORLD
IS REAL? AND HOW MUCH IS OUR
INTERPRETATION BASED ON EXPERIENCE?
SENSATION & PERCEPTION (PSYCHOPHYSICS)
TWO PROCESSES THAT WORK
TOGETHER
Sensation
Perception
The process of
attending to and taking
stimuli from the
environment.
 the environment can
be our own bodies.
“Bottom-up”
processing.
The process of
interpretation and
organization of sensory
information.
May be as much as
90% stored
knowledge/memory.
“Top-down”
processing.
TOP-DOWN PROCESSING
Information processing guided by higher-level
mental processes as we construct perceptions,
drawing on our experience and expectations.
THE CHT
http://www.psywww.com/intropsych/ch07_cognition/top-down_and_bottom-up_processing.html
BOTTOM-UP PROCESSING
Analysis of the stimulus begins with the sense
receptors and works up to the level of the brain
and mind.
Letter “A” is really a black blotch broken down into
features by the brain that we perceive as an “A.”
MAKING SENSE OF COMPLEXITY
Our sensory and perceptual processes
work together to help us sort out
complex images.
Need a volunteer
OUR SENSES….
• Vision
• Hearing
• Taste
• Touch (pain, temperature & proprioception)
• Smell
• Vestibular (body balance/equilibrium)
• Kinesthetic (position/movement)
THRESHOLDS
MEASURING SENSATION
• Absolute threshold= the minimum amount of
a stimulus you can detect (50% of the time)
• Just noticeable difference (JND)=the
amount of change in stimuli (increase or
decrease) before it becomes noticeably
different. It is the smallest amount of
difference detected 50% of the time.
• Weber’s Law= The amount of change
needed to produce JND is in proportion to
the original stimulus’s intensity.
DETECTING STIMULI CAN BE
CHALLENGING!
• Our senses act as a data reduction system. This allows us
to focus on specific stimuli when there is a great deal of
background stimuli. Example: air conditioner/heat vent,
traffic sounds, bad smell, swimming in the ocean..
• Repeated exposure to any stimulus can desensitize
someone so that they no longer attend to it= habituation.
• Our sensory experience is not stimulus alone. Feelings,
expectations & motivation all influence whether you
experience a stimulus. Signal detection theory explains
the relationship between stimuli and motivation.
• Hit- Miss- False alarm (Your phone…….)
SELECTIVE AND DIVIDED ATTENTION
Selective Attention
Cocktail party effect
Divided Attention
Inattentional blindness=
Gorilla example
Are you a multi-tasker?
Can the brain multi-task?
PERCEPTUAL DEFENSE=EXPLAINS WHY
DETECTING STIMULI MAY BE CHALLENGING
Whore
Rape
Bitch
Penis
Wharf
Rope
Batch
Pencil
ALL SENSES TAKE STIMULI AND CHANGE
(TRANSDUCE) IT INTO A SIGNAL
UNDERSTOOD BY THE BRAIN
• Receptor cells take energy and
change it into a neurological
signal which travels to the
thalamus.
• Except for smell
• (which has a direct root to the frontal lobe)
• Senses interact with each other.
THE EYE
Receptors:
Rods=night/peripheral.
Cones=
daylight/color(located in
the Fovea.
 Retina= contains
photoreceptors
Iris= controls size of pupil
Pupil= Opening
Lens=bends light/focus
Optic nerve=blind spot
THEORIES OF COLOR (HUE)
Trichromatic Theory
(Young-Helmholtz)
• Three different types
of color receptors
set to identify redblue-green
• Different rates of
neural processing
allow us to see
“other” colors
Opponent Process Theory
• Two kinds of cones
• One relates to red &
green
• One relates to blue &
yellow
• Rods relate to black &
white
• When one color is
excited- the other is
inhibited. This helps
explain afterimages
THE EAR (AUDITION)SOUND WAVES TRANSDUCED
BY RECEPTORS LOCATED ON THE MEMBRANE IN THE COCHLEA
Process:Sound
waves- auditory
canal-vibrates the
eardrum- which
vibrates three
ossicles-pass into the
cochlea (fluid)
Sensory information
carried to the
auditory cortex.
HAIR CELLS
Inner ear hair cells
Damaged inner ear hair
cells
CHARACTERISTICS OF SOUNDS
• Frequency= pitch(
high or low sounds)
• Amplitude=
loudness(volume)
• Place theory=
differences in pitch
from stimulation in
different areas of
the basil membrane
• Frequency theory=
differences in pitch
are due to speed of
neural impulses
CHEMICAL SENSES: NOSE=OLFACTORY
• Receptors located
along the olfactory
bulb.
• Olfactory cells
stimulated by gases
• Over 100 different
receptor sitescombinations
produce 10,000 +
different scents
THE TONGUE
GUSTATORY(CHEMICAL) SYSTEM
• Chemical-sensitive
receptors located in
taste bud (clusters)
• Taste buds regenerate.
• Decline with age.
• Stimulus must be
dissolved.
• Other influences on
taste: smell,
touch/texture,
temperature
BODY SENSES=SENSES OF TOUCH
• Pressure (only
skin sense with
identifiable
receptors)
• Warmth
• Cold
• Pain
PAIN=IT’S YOUR BODIES WAY OF
TELLING YOU SOMETHING IS WRONG…
• Pain is property of the
senses and the brain (we all
experience it differently)
• Phantom Limb Sensation
• Two systems- carry nerve
fibers from skin to spine
• A-delta fibers= sharp, fast
pain
• C-fibers=dull pain
(influenced by limbic
system)
• Gate-control theory of pain
(small fibers “open” the
gate- large fibers “close”
the gate)
YOU HAVE MILLIONS OF POSITION & MOTION SENSORS ALL
OVER YOUR BODY!
Kinesthetic System
• The sense of our body
part’s position &
movement
Vestibular System
• Monitors the head (and
body) position and
movement thru the
inner ear.