sensation and perception. what do you feel? you probably feel your rear against your seat. ok, now...
Post on 29-Dec-2015
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What do you feel? You probably feel your What do you feel? You probably feel your rear against your seat.rear against your seat.
Ok, now take a whiff around the room – Ok, now take a whiff around the room – different odors are entering your nose different odors are entering your nose (hopefully something pleasant)(hopefully something pleasant)
Now listen really closely, what do you hear? Now listen really closely, what do you hear? – probably the hum from the computer or – probably the hum from the computer or that guy next to you snoringthat guy next to you snoring
Now try to taste what’s in your mouth. – Now try to taste what’s in your mouth. – maybe you can dig out a piece of food from maybe you can dig out a piece of food from your breakfast or maybe you have that your breakfast or maybe you have that morning breath flavor funk going on.morning breath flavor funk going on.
Regardless, at this moment, in some Regardless, at this moment, in some distorted way, you are using all of your distorted way, you are using all of your senses.senses.
Sensation
• The process by which our sensory receptors (sense organs) receive stimulus from the environment.
• What that means is when your body (through our senses) takes in information from everything around us, we are experiencing sensation.
So So sensationsensation is is taking the stuff from outside of us and taking the stuff from outside of us and
bringing it inside our bodies bringing it inside our bodies
and and perceptionperception is is our body trying to understanding and our body trying to understanding and
organizing what we take in.organizing what we take in.
So how does your brain make sense of the So how does your brain make sense of the world and form what you understand as world and form what you understand as
reality?reality? Bottom-Up Processing Bottom-Up Processing (data driven)(data driven)
Our sense of reality starts with our sensations and Our sense of reality starts with our sensations and work up to the brainwork up to the brain
The brain takes the info from the senses and we The brain takes the info from the senses and we develop a sense of realitydevelop a sense of reality
Top-Down Processing Top-Down Processing (experience driven)(experience driven) Our sense of reality begins with our prior experiences Our sense of reality begins with our prior experiences The brain takes our prior experiences and new The brain takes our prior experiences and new
current info and together we develop a sense of current info and together we develop a sense of realityreality
(the brain compares what you are currently seeing with what (the brain compares what you are currently seeing with what you have experienced before)you have experienced before)
Bottom-UpProcessing
Detection viaReceptor cells
(flicker, crackle,Smell
TransmissionTo brain
Change of energyInto information
Organization andInterpretation
Experience, motivation,And expectations (fond
Campfire memories,Expectations of warmth
And friendshipTop-DownProcessing
Behavior, thoughtsAnd emotions(move nearer,warm hands,
Feel comfortable
OutputProcessing(perception)
Input(sensation)
Bottom-Up Processing
• Let’s start off with an important term – transduction
• The process by which our body transforms light, sound, touch, etc. into neural impulses that our brain can understand
TransductionConversion of one form of energy to
another. Stimulus energies changed to neural impulses.
Light Eyes Transduction Neural messages
What you consciously see
Sensory Adaptation• Diminished sensory sensitivity as a
result of constant stimulation.
When you first go into a restaurant you probably notice lots of different food smells. However, the longer you stay the less you notice them. The smells don’t disappear – people just become less sensitive to them.
Do you feel every sensation going on around you??
Can you recall a recent time when, your attention
focused on one thing, you were oblivious to
something else (perhaps to pain, to someone’s
approach, or to background music)?
Selective Attention•The ability to focus on some bits
of sensory information and ignore others
Illusionists hope you have very bad selective attention
Green Dot
Helps us screen out irrelevant stimuli and focus on relevant information
Inattentional Blindness
An example of selective attention is:
The ability to listen to one voice among many.
Cocktail Party Effect
What if we could sense everything?
Life would hurt.
So we can only take in a window of what is out there.
Psychophysics: the study of the relationship between physical stimuli and our psychological experiences to them. – i.e. is blue really blue??
Measuring the SensesMeasuring the Senses
• Psychologists assess the accuracy of the senses in two ways
Measuring thresholds
Applying the signal detection theorysignal detection theory
ThresholdsThresholds are the idea that our
senses have basic limits.
• There are two types of thresholds– Absolute threshold– Difference threshold (or just noticeable
difference)
Absolute ThresholdAbsolute Threshold The smallest amount of stimulus that a person The smallest amount of stimulus that a person
can reliably detectcan reliably detect If you can just barely hear a sound – then that If you can just barely hear a sound – then that
is your absolute threshold for soundis your absolute threshold for sound
Sight = a candle flame seen at 30 miles on a dark clear night Vision Threshold
Hearing = the tick of a watch under quiet conditions at 20 feet
Taste = 1 teaspoon of sugar in 2 gallons of waterSmell = 1 drop of perfume diffused in a small houseTouch = the wing of a bee falling on your cheek from a distance of 1 cm
Some common thresholds
Difference Threshold• The smallest amount of change
needed in a stimulus before we notice the change
• Also known as Just Noticeable Difference (jnd)
Can you tell the difference??Can you tell the difference??
Weber’s Law• Used to measure the difference threshold• The idea that, to perceive a difference between
two stimuli, the change must be proportional to the original intensity of the stimulus– What???– The more intense the stimulus, the more it will need
to change before we notice the difference.
Weight – 10%
Hearing – 5%
Vision – 8%How do businesses use Weber’s Law?? - Movie theater example
Signal Detection Theory• This theory examines how outside
influences effect our sensing of stimuli• The theory says …
– Absolute thresholds are not really absolute– Things like motivation or physical state can
effect what we sense.
Signal Detection Theory Cont.
• It is the belief that people respond differently to the same signal and the same person may detect a particular signal at one time but not another
• For example – if I am really hungry for meat, I am more likely to smell a hamburger than if I was not
– If I think I smell a hamburger, but it is not really there, that is called a false positive (perceiving stimuli that is not there)
– If a hamburger is grilling right in front of me but I fail to smell it, that is called a false negative (not perceiving a stimulus that is present)Which one is worse??
Subliminal Stimulation• Below one’s absolute
threshold or conscious awareness.
Does this work?
Yes and No
• A few studies did show some small emotional reactivity (called priming a response).
• However, the effects are subtle and fleeting.
SensationsSensations
We will be covering the following We will be covering the following sensessensesVisionVisionHearingHearingTouchTouchTasteTasteSmellSmellBody Position and MovementBody Position and Movement
Of The 5 Senses, Which Would You Choose To Lose? Why?
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SenseSense What Stimulates UsWhat Gets Stimulated
Hearing
Vision
Touch
Pain
Sound Waves
Smell
Taste
Light Waves
Potentially harmful stimuli
Molecules dissolved in fluid
Molecules dissolved in fluid
Pressure on Skin
Pressure-sensitive hair cells in cochlea of inner ear
Light-sensitive rods and cones in retina of eye
Sensitive ends of touch neurons in skin
Sensitive ends of pain neurons in skin and other tissue
Taste cells in taste buds on the tongue
Sensitive ends of olfactory neurons in the mucous membranes
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