Transcript Attraction across cultures - Our Lady of Lourdes High School

Sensation and Perception
Unit 4
Sensation and Perception
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Sensory receptors bring information to the
brain to be processed
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BOTTOM UP PROCESSING
Detecting and interpreting information
We also construct perceptions based on
our past experiences
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TOP DOWN PROCESSING
Interpreting what is detected
Selective Attention
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Conscious awareness
Focusing on a specific set of stimuli
It is estimated that your senses take in
11MILLION bits of info every second
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You can consciously process about 40
Cocktail Party Effect – you can usually
hear/attend one voice at a time
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If you hear your name said by someone else, your
attention may be drawn to them instead
Focused Listening
Selective Attention
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Talking on the phone and driving
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Slower to detect traffic signals, billboards,
and other cars while on the phone
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Even hands free – 4x as likely to get into
an accident (University of Sydney 2005, 2007)
Selective Inattention
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When your attention is directed in one
area, it is hard to pay attention to
something else
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CHANGE BLINDNESS
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When focused on an area or a task, subjects
may not notice changes around them
Change deafness
Choice blindness – recognizing faces
Thresholds
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Psychophysics – relationships between
strength of stimuli and our experience of
them
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Intensity, brightness, loudness
Absolute threshold
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Minimum amount of intensity to detect a light,
sound, pressure, taste, or odor 50% of the
time
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When can you successfully detect these half the time
Thresholds
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Vary with age
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Senses decline with age
Hearing tests?
Signal Detection Theory
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Why do people respond differently to the same
stimulus?
When survival is threatened – heightened awareness
Failure to notice even small things can have an impact
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After 30 minutes – less likely to detect things
Subliminal Stimulation
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“Below Threshold”
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1. We can unconsciously sense subliminal
stimuli
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2. Without our awareness, these stimuli
have extraordinary suggestive powers
Subliminal Stimulation
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Absolute threshold is what we get 50% of
the time
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There are things that we hear/see/smell that
may not register all the time, but we still get
them sometimes
Priming
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Setting the stage for your perceptions
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Flashing images immediately before you
see an image can impact your feeling of
that image
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Self Help tapes/audio
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Implanting audio cues to make people feel
better about something
Difference Threshold
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The smallest amount of change that one can
notice between two stimuli half the time
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Just Noticeable Difference (JND)
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Weber’s Law – to notice a difference, there must
be a constant change in proportion, not amount
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Lights must differ by 8%
Weight – 2%
Tones – 0.3%
Sensory Adaptation
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Diminishing sensitivity to unchanging
stimulus
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Nerve fibers will fire less frequently as we
are exposed to stimuli
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Why doesn’t everything disappear?
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Our eyes are constantly moving
Sensory Adaptation
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Stabilized images on the retina
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Allows us to notice small informative
changes in our environment without being
overwhelmed
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Works with smell too
Vision
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Our eyes transduce (transform) light
energy into neural impulses
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Light energy
Wavelength distance
from one peak to the
next determines its
hue (color)
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Vision
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Amplitude – Determines how intense or
bright a color is
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Measure of the height of the wave
The Eye
Cornea – bends
Light entering the
Eye
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Pupil – where
Light enters the eye
ADJUSTABLE
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Iris – colored muscle
That controls size of the
Pupil
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Fovea –point of central focus
concentration of receptors
The Eye
Lens – focuses
Light onto the
Retina
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Retina –
Multilayered
Surface in the back of the eye where light
sensitive receptors begin the process of
vision
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Vision
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Rods – responsible for black and white
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Cones – color vision
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Way more than cones (120M vs 6M)
Better for dim light
Located on periphery of retina
Detail
Rods and cones activate bipolar cells,
which then trigger ganglion cells
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This information is sent optic nerve to be
carried to the brain
Vision
Vision
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Optic Nerve – carries information to the
brain
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Blind spot
Visual Processing
Feature Detectors –
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Edges, lines, angles, and movmt.
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Respond to specific features when you are
looking at something
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Different areas of the occipital lobe are activated
Visual Processing
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Parallel Processing
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Our brain sees many things at once
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Divides what we see into sub-dimensions
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Color, movement, form, and depth
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We construct what we see from these different images
Stroke victims with damage to areas of the brain
may lose some of these
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No longer perceive movmt
Color Vision
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Objects absorb and reject colored light
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We see what is rejected
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White light (sun light) contains all the colors of
the light spectrum
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Our eyes can pick up about 7 million different
colors
Color Vision
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Color Deficient – Color “blind”
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Trichromatic Theory 
Cones can perceive color in three different
ways
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Red Green and Blue
Each is more sensitive to one color
Color Vision
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Opponent Process Theory
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We see colors based on opposing cones
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One stimulated, one inhibited
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Red-green, yellow-blue, white-black
Creates after images
X
Hearing
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Audition – the act of hearing
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Molecules in the air vibrate and create
sound
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Frequency determines pitch (Hertz)
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Number of complete waves per second
Amplitude determines loudness (decibel)
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Loudness determined by number of active nerves in
the ear
Ear Structure
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Outer Ear channels sound to the ear drum
(tympanic membrane) thru ear canal
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Middle Ear – 3 tiny bones vibrate
(ossicles)
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Hammer hits the anvil which moves the stirrup
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(Malleus, Incus and the Stapes)
Those vibrations move onto the cochlea
Ear Structure
Ear Structure
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Inner ear
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Cochlea – Snail shaped tube filled with liquid
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Oval window receives vibration from stirrup
Vibrates the liquid causing hair cells to move
The hair cells transmit the impulses to the brain
through the auditory nerve
Auditory cortex in the temporal lobe
Damage to hair cells is most common link to
hearing loss
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Headphones or ear buds?
Ears ringing = ears bleeding?
Pitch
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Place Theory
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Diff. pitches activate different parts of the
cochlea
Brain recognizes which area is active
Only works for high pitched sounds
Frequency Theory
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Brain recognizes how frequent nerve signals
occur
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Volley principle
Locating Sounds
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Sound travels about 750 mph
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Your ears are about 6 inches apart
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Time lag from signals
Hearing loss
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Conduction Hearing Loss
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Damage to mechanical structure
Sensorineural Hearing Loss
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Damage to hair cells or nerves
Most common from age and exposure
Cochlear Implant
Why would people be against cochlear
implants?
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Ray Charles, Stevie Wonder
Touch
Four major sensations
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Pressure
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Only pressure has a specific receptor
Pain
Cold
Warmth
Hot
or Cold Test ?
Touch
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More than just bottom up processing
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Body position – kinesthesis
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Ian Waterman
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Vision plays a role – balance test
Vestibular sense
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Biological gyroscopes – semicircular canals
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Fluid rotates in the canals as your head rotates
Pain
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Your body’s way of telling you something
is wrong
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CIPA
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Detected all over your brain by
nociceptors
Pain
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No theory fully explains why we feel pain
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Melzack and Wall’s Gate Control Theory
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Spinal cord acts like a gate – allowing some
signals thru but blocking others
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Distraction (psychological)
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Endorphins (biological)
Pain
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Brain can create pain as well
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Phantom limb syndrome/sensations
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Phantom senses
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We see, feel, hear, taste, and smell with
our brain
Pain
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We also edit our memories of painful
events
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We remember the peak of pain and how much
it hurt at the end
We experience more pain when others
around us would expect us to get hurt
Taste
Sweet
 Bitter
 Sour
 Salty
 Umami – savory/MSG
 Chemical Sense
 Taste buds fade/are lost over time –
tastes change
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Taste
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Inside each taste bud is over 200 sensors
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Sensory interaction
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One sense may influence another
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Works with other senses
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McGurk effect – blending syllables
Smell
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Olfaction
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Smell is also a chemical sense
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10 million receptors in our nose picking up
molecules from the air
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Babies can smell their mothers
Like touch, no real specialized receptors,
but combinations to make different smells
Smell
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Women are better smellers than men
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Good experiences mixed with good smells
can create pleasurable experiences and
memories
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Cookies
Suntan lotion
Perfume/cologne
Perceptions
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Our interpretation of the stimuli coming in
from the world around us
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Perceptions are top down processing
Gestalt
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The whole is greater than the sum of the
parts
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When you see an image, you either see
pieces or the whole thing
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But not both at the same time
We organize our environment into figureground relationships
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Objects stand out from their surroundings
x
Grouping Principles
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People are predisposed to group objects
that seem to have something in common
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Similarity – most basic
 Items
that look the same are grouped that way
Grouping
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Proximity – if objects are close, we group
them together
Grouping
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Closure – tendency to look for a whole
item, not parts makes our brain fill in gaps
Grouping
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Continuity – once an object appears to
move in one direction, our brain continues
to follow it
Grouping
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Connectedness – single group rather than
smaller ones
Depth Perception
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The ability to see in three dimensions and
judge distances
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Visual cliff –device used to determine if
infants have depth perception or if it
develops over time
Depth Cues
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Binocular cues – both eyes working together
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Convergence – the closer an object gets, the closer your
eyes move together
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Retinal Disparity – comparing images between retinas
helps the brain compute distance
Depth Cues
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Monocular – only take
one eye
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Relative size –
farther away is
smaller
Depth Cues
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Relative motion – farther away is slower moving
Depth Cues
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Interposition – items that block others are in front
Depth Cues
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Relative height – farther objects are higher
Depth Cues
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Texture
gradient –
objects
farther
away look
much
smoother
Depth Cues
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Relative Clarity –
farther away
things get bluer
and more hazy
Depth Cues
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Linear Perspective –
Parallel lines come
together in the distance
Motion Perception
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We can perceive motion when there is no true
movement
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Stroboscopic motion – still images played in sequence
look like they are moving
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Movies, flipbooks
Phi Phenomenon – fixed lights turned on and off in a
sequence
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Road signs and scoreboards
Perceptual Consistency
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Size – we expect size to remain constant
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As things get closer, they appear larger even though they
are the same size
Shape – items keep their shape when viewing angle
changes
Perceptual Consistency
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Lightness – objects have the same lightness or
color in different levels of light
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White computer paper in the sun looks very bright
In a darker room, it looks gray
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Same color, nothing has changed, we know it is white
Perceptual Set
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Predisposition to something because of a particular
mindset
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Power of suggestion
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Subliminal messages
If you think something will be fun, it usually will
be
 Context
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Emotion and Motivation
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Walking – distances look farther when you are
already tired
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Hills look steeper
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Targets look farther when throwing heavier objects
Extrasensory Perception
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ESP – perception can occur apart from our sensory
input
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Telepathy – mind to mind communication
Clairvoyance – perceiving remote events
Precognition – predicting the future
Psychokinesis – moving things with your mind
Parapsychology – study of paranormal
phenomenon
Testing ESP
Why doesn't it work when tested?
 Psychics control what you see and hear
 Sometimes it may seem more than coincidence
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Senders and receivers
Nostradamus
fMRI
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Images “sent” were viewed differently when actually seen
Brain activity is different – as if they really saw it before