• What do we learn about each item shown using our different senses?
• Objectives:
• Identify the nature and functioning of the sense organs.
• Explain how the skin and body senses function.

SENSATION & PERCEPTION
INTRODUCTION

Process by which our sensory receptors & nervous system receive stimulus from the environment
Essentially the stimulation on the sense organs

Process of organizing & interpreting sensory information , enabling us to recognize meaningful objects & events.
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Selection
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Organization
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Interpretation of sensory input

Life would hurt.
So we can only take in a window of what is out there.
This is the study of psychophysics : relationship between physical stimuli and our psychological experiences to them.
Light : brightness
Sound : volume
Pressure : weight
Taste : sweetness

Analysis that begins with the sense receptors and works up to the brain’s integration of sensory information. You begin by examining small details and piece them together into a larger picture.
Information processing guided by higher-level mental processes
As when we construct perceptions drawing on our experience and expectations

Sax?
Or ‘saxy’ lady?
Which line is longer?
Really?

For a specific type of sensory input, it is the minimum stimulus intensity that an organism can detect .
Absolute thresholds are anything but absolute. When stimulus intensity increases, so does the subjects’ probability of responding to stimuli gradually increases.
*The minimum stimulation needed to detect a stimulus 50% of the time.*

Predicts how and when we detect the presence of a faint stimulus ( signal ) amid background stimulation ( noise ).
Assumes that there is no single absolute threshold.
We detect stuff based on our experiences, expectations, motivations & fatigue level.

Selective Attention:
Ability to listen to 1 voice among many
Our auditory system separates the input into distinct auditory channels.

Intensity (Brightness)
The amount of energy in a light wave is...
determined by the height of the wave
The higher the wave... the more intense the LIGHT is.

Conversion of one form of energy to another.
How is this important when studying sensation?
Stimulus energies to neural impulses. In the system transduction occurs when environmental energy is transformed into electrical or neural energy .
Receptor cells produce an electrical change in response to a physical stimulus .
For example:
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Light energy to vision.
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Chemical energy to smell and taste.
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Sound waves to sound.

Pupil - adjustable opening in the center of the eye
Iris a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening
Lens - transparent structure behind pupil that changes shape to focus images on the retina

Cornea - Transparent outer covering of the eye.
Retina - Contains visual sensory receptors.
Fovea Point of central focus. Contains most of the eye’s cones.
Optic Nerve Pathway to the brain’s visual cortex.
Blind Spot - Where optic nerve leaves eye - no receptors here.

AKA: Myopia . Nearby objects are seen more clearly than distant objects b/c eye is elongated & image focus before it hits the retina.
AKA: Hyperopia . Faraway objects are seen more clearly than near objects b/c eye is shortened & image would focus after it hit the retina.
Need for Bifocals. This issue can become more pronounced after the age of 40, when the lenses of the eyes become progressively less flexible and have trouble accommodating to focus on objects at different distances .

Blind spot experiment
To find the blindspot, draw a filled-in, 1/4"-sized square and a circle three or four inches apart on a piece of white paper.
Hold the paper at arm's length and close your left eye. Focus on the square with your right eye, and slowly move the paper toward you. When the circle reaches your blind spot, it will disappear! Try again to find the blind spot for your other eye. Close your right eye and focus on the circle with your left eye. Move the paper until the square disappears.
What happened when the circle disappeared? Did you see nothing where the circle had been?
No, when the circle disappeared, you saw a plain white background that matched the rest of the sheet of paper.
This is because your brain "filled in" for the blind spot - your eye didn't send any information about that part of the paper, so the brain just made the "hole" match the rest. Try the experiment again on a piece of colored paper. When the circle disappears, the brain will fill in whatever color matches the rest of the paper.

Rods
★ peripheral retina
★ detect black , white & gray
★ twilight or low light
★ near center of retina
★ fine detail & color vision
★ daylight or well-lit conditions

Feature Detection
Cells in the visual cortex of the brain that respond selectively to specific features of complex stimuli .
Edges, Angle, Length, & Movement
How is it possible that Frank Caliendo can possibly imitate so many different people so convincingly?

Perception of Color
The Eagle Uniform is anything but red .
The uniform rejects the long wavelengths of light that to us are red.
So red is reflected off and we see it.
Also, light has no real color.
It is our mind that perceives the color.

Opposite opponent colors are never perceived together.
There is no greenish-red or yellowish-blue.
You can create your own demonstration of these opponent systems by observing the effect of afterimages.
Look at the center of the the “X” on the next screen for approximately 30 seconds.
Then immediately look at the next white slide & blink to see the afterimage.

Stare at the middle of the “X” for 30 seconds.

Opposite opponent colors are never perceived together.
There is no greenish-red or yellowish-blue.
You can create your own demonstration of these opponent systems by observing the effect of afterimages.
Look at the center of the the “X” on the next screen for approximately 30 seconds.
Then immediately look at the next white slide & blink to see the afterimage.

In this fun optical illusion, you can see how your visual system and brain are actually able to briefly create a color image from a negative photo.
How to Perform the Illusion
Stare at the dots located at the center of the woman's face below for about 30 seconds to a minute. Then turn your eyes immediately to the center x of the white image on the right.
Blink quickly several times. What do you see? If you've followed the directions correctly, you should see an image of a woman in full-color. If you are having trouble seeing the effect, try staring at the negative image a bit longer or adjusting how far you are sitting from your computer monitor.

Did it work?

"If a tree falls in a forest and no one is around to hear it, does it make a sound?"
Philosophical thought experiment that raises questions regarding observation & knowledge of reality .
What is the difference between what something is, & how it appears?
"sound is the variation of pressure that propagates through matter as a wave"
If a tree exists outside of perception then there is no way for us to know that the tree exists.
So then, what do we mean by 'existence', what is the difference between perception & reality?
Also, people may also say, if the tree exists outside of perception (as common sense would dictate), then it will produce sound waves. However, these sound waves will not actually sound like anything.
Sound as it is mechanically understood will occur, but sound as it is understood by sensation will not occur.
So then, how is it known that 'sound as it is mechanically understood' will occur if that sound is not perceived?

Frequency
(pitch)
:
Dimension of frequency determined by wavelength of sound .
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Measured in hertz (Hz).
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Humans can hear sounds at frequencies from 20Hz to 20,0000
Hz.
(we hear best at around 3,000 to 4,000 Hz, where human speech is centered)
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Number of complete wavelengths that pass through point at a given time. This determines the pitch of a sound.
To human ears, a dog whistle makes only a quiet hissing sound.
The advantage of the dog whistle is that it doesn't produce a loud irritating noise for humans that a normal whistle would produce, so it can be used to train or command animals without disturbing nearby people.

Intensity
(loudness)
:
Amount of energy in a wave determined by amplitude relates to perceived loudness .
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Loudness is measured in decibels .
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Amplitude is how loud the sound is.
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Higher the crest of the wave is the louder the sound.

• Receptors in the skin are responsible for providing the brain with at least 4 kinds of information about the environment…
• Any guesses?
• Great! Pressure, warmth, cold, and pain!
• Believe it or not… a kiss does make the pain go away.
Why is this?

Taste Sensations sweet sour salty bitter
Sensory Interaction
★ the principle that one sense may influence another
★ as when the smell of food influences its taste

Some taste sensations are genetically programmed : sweetness.
Also, finding bitter and sour foods unpleasant.
A study of babies had sweet eliciting smiles , lip smacking, and sour eliciting protrusion of tongue
These reactions make good evolutionary sense
Animals tend to be neophobic, and human children are reluctant to try new things.
One experiment asked a group of subjects to taste two groups of food (that were the same). When the items were accurately named (chopped tomatoes, oatmeal, beefsteak) more willing them when given novel names (pendula fruit, lat, langua steak)
However, as true with other stimuli, mere exposure makes us like them more .

• Sensor neural Deafness- hearing loss that occurs from damage to the inner ear, the nerve that runs from the ear to the brain (auditory nerve), or the brain.
• http://www.youtube.com/watch?v=9WmyPg-AvLY
Conduction Deafness- earing loss due to problems with the bones of the middle ear.

• https://www.youtube.com/watch?v=4mSxiWypQOA