Unit IV - Sensation & Perception Flashcards
What is sensation?
The process by which
our sensory receptors and nervous system receive and represent
stimulus energies from our environment.
What is perception?
The process of
organizing and interpreting
sensory information, enabling us
to recognize meaningful objects and events.
What does sensation actually mean?
Your nose, eyes or other sensory organs bring in information…. a smell… a color… a tall, blond boy with freckles…
What does perception actually mean?
Your brain makes sense of that information… oh.. that is my granddad’s rhubarb pie, that turquoise shirt is stunning, hey… is that my brother?
What is bottom up processing?
Starting with the sensory input, the brain attempts to understand/make sense.
What is top down processing?
Guided by experience and higher-level processes, we see what we expect to see.
Give an example of bottom up processing
You see a long, slim, slithering creature on the ground… you process… ah! A snake!
Give an example of top down processing
An experienced hiker, you expect to see snakes on your hike so windy stick, lizards, etc. all seem like snakes.
What is selective attention?
Our tendency to focus on just a particular stimulus among the many that are being received.
Although we are surrounded by sights and sounds, smells and tastes, we tend to pay attention to only a few at a time
What is the cocktail party effect?
you focused your attention on one particular voice (that person who called your name) amidst the crazy loudness of all those other voices.
How does selective attention relate to accidents?
It is not about the cell phone.. it’s about distracting your attention!
Using a cell phone (even a hands-free set)
carries a risk 4 times higher than normal—
equal to the risk of drunk driving
What is selective inattention?
At the level of conscious awareness, we are in only one place at a time and so we miss salient objects that are available to be sensed.
What is inattentional blindness?
failing to see visible objects when our attention or focus is directed elsewhere
What is change blindness?
failing to notice changes in the visual environment
What are the three steps involved in sensation?
Receive
Transform
Deliver
What is transduction?
conversion of one form of energy, such as light waves, into another form, like neural impulses that our brain can interpret
What is psychophysics?
The study
of relationships between the physical characteristics of stimuli,
such as their intensity, and our psychological experience of them.
Psychophysics example
what is it about the smell, taste, and texture of buttery popcorn that produces a delicious, satisfied, happy response in you?
What is the absolute threshold?
The minimum stimulation
needed to detect a particular stimulus 50 percent of the time.
What is the difference threshold?
The minimum difference between two stimuli required for detection 50 percent of the time
What is another name for the difference threshold?
just noticeable difference
How do we test for absolute threshold in a sense like audition?
A hearing specialist exposes both of your ears to varying sound levels
For each tone the test defines the pitch at which you can detect the tone 50% of the time.
Why are some people better at detecting signals than others?
Using phone in one class vs another
Exhausted parents still able to hear baby’s cries
What is too much onion on a burger
What is the signal detection theory?
A theory predicting how and when we detect the presence of a faint stimulus amid background stimulation
What two conditions does the signal detection theory depend on?
Strength of signal
Psychological state
What is Weber’s Law?
To be able to tell the difference between degrees of stimulation, two stimuli must differ by a constant minimum percentage
Two lights must differ by ___
Two objects must differ in weight by ___
Two tones must differ in frequency by ___
in order for a difference to be noticed
Lights 8%
Objects 2%
Tones 0.3%
How does Weber’s Law help explain the just noticeable difference (jnd) ?
Weber’s law tells us that the difference must vary by a constant percentage (as shown on the last slide), not a constant amount.
What are subliminal stimuli and how are we affected by them?
Subliminal stimuli are not detectable 50% of the time. They are below your absolute threshold.
You may not notice subliminal stimuli at all if they are weak.
What is priming?
activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response
Even if YOU don’t think YOU notice a stimuli, your brain might, and that can impact you.
What is sensory adaptation?
diminished sensitivity to stimuli as a consequence of constant stimulation
Evolutionary psychologists suggest that once we notice and evaluate a new stimuli as non-threatening, we can pay less attention to it.
This saves our attention for new incoming stimuli, or changes in the existing stimuli. This could be adaptive for survival.
why does sensory adaptation occur?
Being able to ignore unthreatening/unchanging stimuli leaves us free to focus on the stimuli that IS changing.
Our sense receptors are alert to novelty…a new situation means we need to evaluate and assess it and check for danger.
So it is functional…adaptive.
We perceive the world not exactly as it is, but as it is useful for us to perceive it.
What is a perceptual set?
a mental
predisposition to perceive one
thing and not another
…we see what we expect to see
Perceptual set example
Viewing picture and seeing it as an old women or young bride
How does top-down processing influence perceptual set?
our experience with numbers and letters
(13 comes between 12 and 14….
B comes between A and C)
influences our expectation…
How does context influence perceptual set?
Reading from left to right, our expectations
cause us to perceive the middle script differently than when reading from top to bottom.
How does cultural context impact perceptual set?
When asked what was above the woman’s head…. rural East Africans saw a woman with a box on her head and a family under a tree.
How does a different cultural context impact perceptual set?
Westerners,
used to running water and boxlike houses with corners, saw a woman sitting under a window and a family indoors.
What does research show about how motivation can influence perceptual set?
Desirable objects, such as a water bottle viewed by a thirsty person, seem closer than they really are.
(Balcetis & Dunning, 2010).
A to-be-climbed hill can seem steeper when we are carrying a heavy backpack, and a walking destination further away when we are feeling tired.
(Burrow et al., 2016; Philbeck &Witt, 2015; Proffitt 2006a,
Going on a diet can lighten our biological “backpack”. When heavy people lose weight, hills and stairs no longer seem so steep.
(Taylor-Covill & Eves, 2016).
What does research show about how emotion can influence perceptual set?
When angry, people more often perceive
neutral objects as guns.
Baumann & DeSteno, 2010)
Hearing sad music can predispose people to perceive a sad meaning in words that sound alike…mourning rather than morning, die rather than dye, pain rather than
pane. (Halberstadt et al., 1995)
When mildly upset by subliminal exposure to a scowling face, people perceive a neutral face as less attractive and likeable.
(Anderson et al., 2012)
What is parapsychology?
The study of
paranormal phenomena, including
ESP and psychokinesis (the ability of the mind to move objects).
What is ESP or extra sensory perception?
The controversial claim that awareness can occur apart from sensory input; includes telepathy (mind to mind communication),
clairvoyance (seeing remote events), and precognition (seeing the future).
How have researchers tried to test ESP claims?
In one study, psychologists
created a “mind machine” to see if people could influence or predict a coin toss.
Using a touch-sensitive screen, visitors to British festivals were given four attempts to call heads or tails, playing against a computer that kept score.
By the time the experiment ended, nearly 28,000 people had predicted 110,959 tosses—with 49.8 percent correct.
What have most researchers concluded regarding the veracity of ESP claims?
Researchers have been unable to replicate ESP claims under controlled conditions.
What light energy is visible to humans?
Quite small
We can see light waves with a frequency of a little less than 400nm and a little more than 700nm.
What are characteristics of light waves?
frequency (wavelength)
amplitude (height)
What does wavelength tell us about the light wave?
What color am I seeing?
Short=bluish
Long=reddish
What does amplitude tell us about the light wave?
How bright is the color I am seeing?
Great=bright
Small=dull
What structures of the eye help focus the energy?
Cornea pupil iris lens Retina
What is the cornea?
eye’s clear, protective outer layer covering the pupil and iris.
Light enters eyes through here first
What is the pupil?
small adjustable opening in the center of the eye through which light passes
What is the iris?
ring of muscle tissue that forms the colored portion of the
eye around the pupil
Controls size of pupil by expanding and contracting over pupil
What is the lens?
transparent structure
behind the pupil that changes shape
to help focus images on the retina.
How does the lens change shape?
lens changes its curvature and thickness in a process called accommodation.
Lens can focus on both far and near objects
What is myopia?
Nearsightedness
Lens only focusing on near objects
Can’t focus on distant objects clearly
What is hyperopia?
Farsightedness
Lens only focusing on far objects
Can’t focus on near objects clearly
What is the retina?
light-sensitive inner surface of the eye containing receptor rods and cones plus layers of neurons that begin the processing of visual information
Where is the retina located?
along the back of the eye and contains the sense receptor cells that will receive the incoming light waves.
What happens in the retina?
Light waves are transduced into neural impulses by the rods and cones, then passed to the bipolar cells and the ganglion cells
What are rods?
retinal photoreceptors that detect black, white, and gray, and are sensitive to movement.
necessary
for peripheral and twilight vision, when cones don’t respond.
What are some characteristics of rods?
Located along retina’s out periphery
remain sensitive in dim light, and they enable
black-and-white vision.
sensitive to faint light and peripheral motion.
no hotline to the brain…they share connections to a single bipolar cell sending a combined message to the brain.
What are cones?
retinal photoreceptors that are concentrated near the center of the retina and function in daylight or in well-lit conditions.
detect fine detail and create color sensations.
What are some characteristics of cones?
cluster in and around the fovea
Becomes unresponsive in dim light/no color
Own hotline to brain
One
cone transmits its message to a single bipolar cell, which relays the message to the visual cortex
What is the fovea?
central focal point in
the retina, around which the eye’s
cones cluster.
Area of GREATEST visual acuity/sharpness
What is the optic nerve?
comprised of the axons of the ganglion cells.
leaves through the back of the eye and carries the neural impulses from the eye to the brain
What is the blind spot?
optic disk is the point at which the
optic nerve leaves the eye, creating
a “blind” spot because no receptor
cells (rods or cones) are located there
What happens to the neural impulse after it exits the eye?
optic nerve carries the impulse to the thalamus and on to the visual cortex of the occipital lobes.
What are the functions of ganglion and bipolar cells?
Neural impulses –> bipolar cells –> ganglion cells
Transmit electrical impulses to the brain
What is the Young-Helmholtz trichromatic (three-color) theory?
The theory that the retina contains three different types of color receptors (cones)— one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color
What about people who cannot see color?
About one person in 50 is color blind.
Males are more affected since the defect is
genetically sex-linked.
Most people are not actually blind to all colors. They simply lack functioning red- or green-sensitive cones, or sometimes both.
Vision is monochromatic (one color) or dichromatic
(two-color) and seems ‘normal’ to them.
What is the Hering opponent-process theory?
The theory that cone photoreceptors are paired together (red-green, blue-yellow, white-black)
to enable color vision.
Activation of one color of the pair inhibits
activation of the other.
For example, some cells are stimulated by green and inhibited by red; others are stimulated by
red and inhibited by green.
How does color processing occur?
The retina’s red, green, and blue cones respond in varying degrees to different color
stimuli, as the Young-Helmholtz trichromatic theory suggested.
The cones responses are then processed by opponent-process cells, as Hering’s
opponent-process theory proposed
What are feature detectors and where are they located?
Feature detectors are nerve cells located in the visual cortex of the occipital lobe that respond to a scene’s edges, lines, angles and movements.
But what do feature detectors do?
Feature detectors receive information from individual ganglion cells in the retina and
pass it to other cortical areas, where
supercell clusters respond to more complex patterns.
How do feature detectors operate in real life?
Kicking a soccer ball into the goal requires instant processing
What is parallel processing
Parallel processing is thinking about many aspects of a problem simultaneously.
This is the brain’s natural mode of information processing for many functions, including vision.
How does parallel processing operate?
The brain delegates the work of processing motion, form, depth, and color to different areas.
After taking a scene apart, the brain integrates these subdimensions into the perceived image.
How do we recognize faces using parallel processing?
To recognize a face, your brain integrates information projected by your retinas to several
visual cortex areas and compares it with stored information
What are super cells or grandmother cells?
Cells that only respond to very selectively to faces
What are the steps in “seeing”?
Retinal processing
Feature detection
Parallel Processing
Recognition
How did the Gestalt psychologists understand perceptual organization?
people who are given a cluster of sensations tend to organize them into a gestalt, a German word meaning a “form” or a “whole.”
Gestalt psychologists believe that in perception,
the whole may exceed the sum of its parts.
