Heather Sellers is an acclaimed writer and teacher.
Her vision is perfect, but her perception is not.
It's possible that an inability to recognize familiar voices will make similar mistakes.
A man was flirting on the phone with someone he thought was his wife.
To avoid being seen as snobby, Sellers sometimes fakes recognition.
She smiles at people she passes.
She pretends to know the person she is talking to.
She doesn't recognize the person when she encounters someone who previously irritated her.
Unlike Sellers, most of us have a functioning area on the underside of our brain's right hemisphere that helps us recognize a familiar human face in only one-seventh of a second.
Human ears are sensitive to sound frequencies that include human voices.
Frogs have cells in their eyes that only fire in response to small, dark, moving objects.
A frog could not digest the flies.
The frog's "bug detector" cells will wake up if one zooms by.
One billionth of an ounce of chemical sex attractant is released by a female one mile away.
There are silkworms because of that.
We will look at what psychologists have learned about how we sense and perceive the world.
Some basic principles apply to all of our senses.
Our brain floats in darkness.
By itself, it doesn't see anything.
It doesn't hear anything.
It doesn't feel anything.
Let's look at the basics of sensation and perception.
She is normal when she looks at a friend.
Your nervous system would transmit the same information to her brain as hers.
She can recognize people from their hair, voice, or particular body part, just not from their face.
Her experience is similar to trying to recognize a penguin.
In normal circumstances sensation and perception blend into one continuous process.
Bottom-up processing works up to higher levels.
Drawing on your experience and expectations is what top-down processing does.
Your sensory systems are able to detect the lines, angles, and colors that form the flower and leaves as your brain absorbs the information.
You use top-down processing to interpret what your senses detect.
One form of energy is converted into another.
Light energy is processed by vision.
Hearing processes sound waves.
The process of converting one form of energy into another form that our brain can use is called Later in this chapter.
One of our sensory systems receives, transforms, and delivers information to our brain.
The relationship between the physical energy we can detect and its effects on our psychological experiences is studied in the field of psychophysics.
Our brain interprets sights, sounds, and smells as neural impulses.
There are some strengths and weaknesses in our ability to detect and interpret stimuli.
X-rays, radio waves, ultraviolet and IR light, and sound waves are all hitting us.
We are both blind and deafness.
Other animals are able to detect a world that is beyond our experience.
Birds rely on an internal magnetic compass to stay on course.
Bats and dolphins bounce sound off objects.
bees navigate on cloudy days by detecting light
Our senses open the shades just a crack, allowing us a restricted awareness of this vast sea of energy.
This is enough for our needs.
We are sensitive to some stimuli.
Most of us could see a candle flame atop another mountain 30 miles away.
The wing of a bee fell on us.
In a three-room apartment, we could smell a drop of perfume.
50 percent of the time, German scientist and philosopher Gustav Fechner studied the, sound, pressure, taste, or odor.
To test your absolute threshold for sounds, a hearing specialist would send tones at varying levels, half the time you could detect the sound and half the time you couldn't.
Your absolute threshold would be defined by that 50% point.
These thresholds are found by hearing tests.
Predicting when we will detect weak signals depends on our experience, expectations, motivation, and alertness, as well as our ratio of "hits" Signal detection theorists want to understand why people respond differently to the same stimuli, and why the same person's reactions vary as circumstances change.
It is assumed that detection depends on a person's experience, expectations and motivation.
50 percent of the time are below your absolute threshold.
One experiment showed the deep reality of sexual orientation.
A photo of a nude person was flashed on one side and a scrambled version of the photo on the other side as people looked at a screen.
Because the nude images were masked by a colored checkerboard, viewers were unable to see which side the nude had appeared.
The experimenters flashed a geometric figure to one side or the other to see if the unseen image attracted their attention.
This was followed by a mask.
Even when we are unaware of our evaluation, we can evaluate a stimuli even if we are not consciously aware of it.
After an image of a nude man or woman was flashed to one side or another, then masked before being perceived, people's attention was unconsciously drawn to images in a way that reflected their sexual orientation.
To function effectively, we need low thresholds to allow us to detect important sights, sounds, tastes, and smells.
There are small differences among stimuli.
When tuning an instrument, a musician must detect minute discrepancies.
The sound of a child's voice must be detected by parents.
I observed that not to their mother's.
If we listen to our music at 40 decibels, we can detect an additional 5 decibels.
We probably won't detect an additional 5-decibel change if we increase the volume to 110 decibels.
Depending on theStimulus, the percentage varies.
Two lights must have different intensities by 8 percent.
Two objects have different weights by 2 percent.
The frequencies of two tones must not be different by more than 0.1 percent.
Each line of the typeface increases slightly in this computer-generated copy of the Twenty-third Psalm.
You are overwhelmed by your seatmate's perfume as you sit on the bus.
You wonder how she is able to endure it, but within minutes you realize she has come to your rescue.
Our nerve cells fire less frequently when exposed to unchanging stimuli.
Our eyes are always moving.
As a person looks at a photograph of Edinburgh's Princes Street Gardens, their gaze jumps from one spot to another every third of a second.
The numbers indicate the time of fixation in milliseconds, and the circles represent visual fixations.
She sees fragments fading and reappearing instead of the full image.
To find out, psychologists devised ingenious instruments that maintain a constant image on the eye's inner surface.
Imagine if we fitted Mary with a miniature projector mounted on a contact lens.
The image from the projector moves with Mary's eye movement.
The scene is sure to go wherever Mary looks.
The complete image is what she sees first.
Things get weird a few seconds after her sensory system starts to fatigue.
The image disappears, only to reappear and disappear again in fragments.
Freedom to focus on informative changes in our environment is an important benefit of sensory adaptation.
Our phone's notifications are hard to ignore because of the attention- grabbing power of changing stimulation.
A new news story pops up and grabs our attention.
These intrusions can hurt our performance if we're performing other tasks.
One researcher marveled at how TV cuts, zooms, and pans distract, even during interesting conversations, because he couldn't stop glancing over to the screen.
Sensory adaptation can affect how we perceive emotions.
Researchers showed that our visual system can adapt to a static facial expression by creating a blend of angry and scared faces.
The effect is created by our brain.
The illusion works when we view the side image with one eye and the center image with the other.
Look at the center face for 20 to 30 seconds, then look at the angry face on the left.
Then look at the scared face on the right for 20 to 30 seconds, before returning to the center face.
Our sensory receptors are alert to novelty and can be used to free our attention from more important things.
The shoes provide stimulation.
We come to expect certain results from experience.
Those expectations may give us a set of mental tendencies and assumptions that affect, top-down, what we hear, taste, feel, and see.
The drawing can be influenced by the two unambiguous versions of it.
A friend can be shown either the left or right image.
Depending on which of the other two drawings was viewed first, your friend may report seeing an old woman's face or a young woman's profile.
The meaning is clear in each of those images.
When reading from left to right, our expectations cause us to perceive the middle script differently than when reading from top to bottom.
The most amazing pictures ever taken were published in 1972 by a British newspaper.
When a skeptical researcher looked at the original photos with different expectations, he saw a curved tree limb.
You can now see that the object is floating motionless, with ripples outward in all directions--hardly what a swimming monster would look like.
The co-pilot raised the wheels before they left the ground.
If you tell people about a couple that has suffered from bad sects, they will likely hear bad sex.
The inserted word was self-produced and people usually missed the switch.
Their perception of what they had just said was controlled by what they heard.
Our tastes can be influenced by our expectations.
In one experiment, preschool children thought french fries tasted better in a McDonald's bag than in a plain white bag.
The bar patrons at the Massachusetts Institute of Technology were invited to sample free beer.
When researchers added a few drops of vinegar to a brand-name beer and called it "MIT brew," the tasters preferred it--unless they had been told they were drinking vinegar-laden beer.
They usually experienced a worse taste in that case.
The way we apply top-down processing to interpret ambiguous sensations is influenced by our previous schemas for monsters and tree trunks.
Stereotypes about gender can color perception.
When the same infant was called "Diana", people thought he was bigger and stronger than David.
It seems that there are some differences in the eyes of their beholders.
The perceptual set has an influence on how we interpret stimuli.
Our context and motivation affect our interpretations.
When holding a gun, people become more likely to perceive another person as also gun-toting, a phenomenon that has led to the shooting of some people who were actually holding their phone or wallet.
The context creates an expectation that influences our perception of a previously heard phrase.
Most rural East Africans questioned said the woman was balancing a metal box or can on her head, a typical way to carry water at that time.
They thought the family was sitting under a tree.
The family was more likely to be perceived as being indoors when the woman was sitting under the window.
The Hope College volleyball team won the national championship.
Top-down processing draws on your experiences, assumptions, and expectations when interpreting stimuli.
As we work toward a goal, motives give us energy.
They can bias our interpretations of neutral stimuli.
Consider these findings: desirable objects, such as a water bottle viewed by a thirsty person, seem closer than they really are.
Our going for it is boosted by this bias.
A to-be-climbed hill can seem more steep when we are carrying a heavy backpack, and walking further away when we are tired.
It is possible to lighten our biological backpack by going on a diet.
Hills and stairs are no longer steep when heavy people lose weight.
Researchers observed that a softball appears bigger when a player chooses a circle the size of the ball they hit well or poorly.
When athletes focus on a target, it improves their performance.
When you hit the ball, it comes at you like a fruit.
Experiments show that emotions can push our perception in one direction or another.
A hill that people feel others understand is less steep.
People perceive a neutral face to be less attractive and likeable when they are made to feel upset by it.
People think solitary confinement, sleep deprivation, and cold temperatures are torture when they experience a small dose.
"He's just having a bad day, he's just having a bad day, he's just having a bad day, he's just having a bad day, he's just having a bad day, he's just having a bad day, he's
Our experiences, assumptions, expectations, and even our context can affect our views of reality.
You can check your answer by clicking on the e-book and Appendix C of the printed text.
According to research, trying to answer these questions on your own will improve retention.
We organize and interpret sensory information through a process called ________________.
Subliminal stimuli are not strong enough to be processed by the brain.
Weber's law states that for a difference to be perceived, there must be a fixed or constant energy amount.
We can use sensory adaptation to focus on the visual stimuli.
Our perception is influenced by our perceptual set.
Our mental tendency reflects our experiences.
You can find answers in the e-book and at the back of the printed text.
Our brain--in one of life's greatest wonders--then creates what we see.
On the spectrum's one end are the short gamma waves, no longer than the diameter of an atom.
The mile-long waves of radio transmission are on the other side.
The narrow band is visible to us.
Other animals can see other portions.
bees can see ultraviolet light but cannot see red
What we see as light is only a small part of a wide spectrum of energy, which can be seen as radio waves over a mile long.
The human eye can see the longer waves of red and blue light.
Light travels in waves, and the shape of those waves influences what we see.
Light's is the distance from one peak to the next.
The tulip's red petals or green leaves are examples of the color Wavelength determines.
The brightness is influenced by intensity.
The long and short waves of radio transmission are different.
The wave's height is used to determine intensity.
Your identity can be confirmed by an iris- scanning machine.
Light rays are reflected from a candle.
The thickness of the lens changes to bring objects into focus.
The candle's image on the eye is reversed.
Imagine a sunny sky and your iris will dilate; imagine a dark room and it will not dilate.
Dark eyes and dilated pupils signal your interest when you're feeling amorous.
The light rays are focused on the eyeball's sensitive inner surface by the lens.
Scientists have known for hundreds of years that an inverted mirror image on a dark wall is caused by an image of a candle passing through a small opening.
Leonardo da Vinci thought that the eye's watery fluids could bend the light rays to an upright position.
The answer today is that the retina doesn't see a whole image.
Rather, its millions of receptor cells convert particles of light energy into neural impulses and send them to the brain, which reassembles them into what we perceive as an upright-seeming image.
Along the way, visual information processing goes through more abstract levels.
The process is similar to taking a house apart and rebuilding it elsewhere.
It is awe-inspiring that all of this happens continuously.
It happens with incredible speed.
As a baseball pitcher's pitch approaches home plate, the light signals work their way from the batter's retina to the visual cortex, which then informs the motor cortex, which then sends out orders to contract the muscles.
Imagine if you could follow a single light-energy particle after it entered your eye.
You would have to thread your way through the sparse outer layer of cells.
Cones give rise to color sensations.
There is an information highway from the eye to the brain.
The nerve can send 1 million messages at once.
We pay for a small connection.
There is a blind spot in your eye, with no rcells.
You won't see a black hole if you close one.
Without asking for your approval, brain fills the hole.