Sensation and Perception

 What do you feel? You probably feel your rear against your seat.  Ok, now take a whiff around the room – different odors are entering your nose (hopefully something pleasant)  Now listen really closely, what do you hear? – probably the hum from the computer or that guy next to you snoring  Now try to taste what’s in your mouth. – maybe you can dig out a piece of food from your breakfast or maybe you have that morning breath flavor funk going on.  Regardless, at this moment, in some distorted way, you are using all of your 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.

Perception The process of organizing and interpreting sensory information

So sensation is So sensation is taking the stuff from outside of us and bringing it inside our bodies taking the stuff from outside of us and bringing it inside our bodies and perception is and perception is our body trying to understanding and organizing what we take in. our body trying to understanding and organizing what we take in.

Sensation Important Concepts

So how does your brain make sense of the world and form what you understand as reality? Bottom-Up Processing (data driven) Bottom-Up Processing (data driven) Our sense of reality starts with our sensations and work up to the brain Our sense of reality starts with our sensations and work up to the brain The brain takes the info from the senses and we develop a sense of reality The brain takes the info from the senses and we develop a sense of reality Top-Down Processing (experience driven) Top-Down Processing (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 current info and together we develop a sense of reality The brain takes our prior experiences and new current info and together we develop a sense of reality (the brain compares what you are currently seeing with what you have experienced before) (the brain compares what you are currently seeing with what you have experienced before)

Bottom-Up Processing Detection via Receptor cells (flicker, crackle, Smell Transmission To brain Change of energy Into information Organization and Interpretation Experience, motivation, And expectations (fond Campfire memories, Expectations of warmth And friendship Top-Down Processing Behavior, thoughts And emotions (move nearer, warm hands, Feel comfortable Output Processing (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

Transduction Conversion 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

Failing to see visible objects when we are focusing our attention elsewhere

An example of selective attention is: The ability to listen to one voice among many. Cocktail Party Effect

Sensory Interaction One sense may influence another Smell may influence taste

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 Senses Psychologists assess the accuracy of the senses in two ways Measuring thresholds signal detection theory Applying the signal detection theory

Thresholds Thresholds are the idea that our senses have basic limits. There are two types of thresholds –Absolute threshold –Difference threshold (or just noticeable difference)

Absolute Threshold The smallest amount of stimulus that a person can reliably detect The smallest amount of stimulus that a person can reliably detect If you can just barely hear a sound – then that is your absolute threshold for sound If you can just barely hear a sound – then that is your absolute threshold for sound Sight = a candle flame seen at 30 miles on a dark clear night Vision ThresholdVision Threshold Hearing = the tick of a watch under quiet conditions at 20 feet Taste = 1 teaspoon of sugar in 2 gallons of water Smell = 1 drop of perfume diffused in a small house Touch = 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??

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.

Sensations We will be covering the following senses We will be covering the following senses Vision Vision Hearing Hearing Touch Touch Taste Taste Smell Smell Body Position and Movement Body Position and Movement

Of The 5 Senses, Which Would You Choose To Lose? Why?

universe-review.ca/I10-13-senses.jpg

Sense What Stimulates Us What Gets Stimulated Hearing Vision Touch Pain Sound Waves Smell Taste Light Waves Potentially harmful stimuli 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