Sensation and Perception

Question 1

Depth Cues  

Answer 1

Researchers divide the cues that we use to perceive two categories:     

Monocular cues–Depth cues that do not depend eyes (e.g., linear perspective, interposition, shading gradient).  
 
Binocular cues -Cues that depend on having two e disparity and convergence). ext: Sensation and Perception  

Question 2

Constancy   

Answer 2

Every object we see changes minutely from moment to moment due to our changing angle of vision, variations in light, and so on.   
Constancy is our ability to maintain a constant perception of an object despite these changes.  

There are several types of constancy, including:

size constancy
shape constancy
brightness constancy   

Question 3

Gestalt Rules     

Answer 3

Developed by a group of researchers from the early 20th century who described the principles that govern how we perceive groups of objects (e.g., proximity, similarity, continuity, closure).
  
Based on the observation that we normally perceive images as groups, not as isolated elements. 
 
This process is believed to be innate and inevitable. 

Question 4

Cochlea

Answer 4

The process of transduction (where sound waves change neural impulses) occurs in the cochlea.   

Shaped like a snail’s shell and filled with fluid. As sound waves the fluid, hair cells move.

Neurons are activated by the movement of hair cells. 
 
Neural messages are sent to the auditory cortex in the temp

Question 5

Opponent-Process Theory 

Answer 5

A theory of color vision (the other theory is Trichromatic Theory). 
    
States that the sensory receptors arranged in the retina come in pairs: red/green pairs, yellow/blue pairs, and black/white pairs.  
If one sensor is stimulated, its pair is inhibited from firing.

This theory explains color afterimages. 
    
If you stare at the color red for a while, you fatigue the sensors for red. Then when you switch your gaze and look at a blank page, the opponent part of the pair for red will fire, and you will see a green afterimage. 
   
The Opponent-Process Theory explains afterimages and color blindness. 
  
Most researchers agree that color vision is explained by a combination of the Trichromatic and Opponent-Process Theories.     

Question 6

Bottom-Up Processing    

Answer 6

Opposite of top-down processing.  

Instead of using our experience to perceive an object, we use only the features of the object itself to build a complete perception.   
   
We start our perception at the bottom with the individual characteristics of the image and put all those characteristics together into our final perception.

Our minds build the picture from the bottom up using basic characteristics.  

Question 7

Perceptual Set    

Answer 7

Our experience creates schemas, mental representations of how we expect the world to be. Our schemas influence how we perceive the world.  
 
Schemas can create a perceptual set, which is a predisposition to perceive something in a certain way. 
  
For example, you may perceive a cloud as being shaped like a heart around Valentine’s Day.      

Question 8

Top-Down Processing     

Answer 8

When we use top-down processing, we perceive by filling in gaps in what we sense.   

Occurs when you use your background knowledge to fill in gaps in what you perceive. 

Our experience creates a schema, mental representation of how we expect the world to be. Our schemata influence how we perceive the world.     
Schemata can create a perceptual set, which is a predisposition to perceive something in a certain way.   

Question 9

Weber’s Law 

Answer 9

Named after psychophysicist Ernst Weber
.  
Describes the difference thresholds for different senses.  
 
The change needed is proportional to the original intensity of the stimulus. The more intense the stimulus is, the more it will need to change before we notice a difference.
 
For example, if you are playing very quiet music, you don’t have to raise the volume much before someone notices. If the music is very loud, however, you have to raise the volume a lot before anyone will notice.     

Question 10

Fovea 

Answer 10

Indentation at the center of the retina where cones are concentrated.  
 
When light is focused onto your fovea, you see it in color. 

Your peripheral vision, especially at the extremes, relies on rods and is mostly in black and white. 
 
Foveal vision, focusing light on the fovea, results in the sharpest and clearest visual perception.   

Question 11

Bipolar Cells and Ganglion Cells    

Answer 11

These cells make up different layers in the retina. 
  
In the retina, light activates rod and cone cells.  
  
Rods and cones send signals to the next layer of cells in the retina: bipolar cells. 
     
Bipolar cells send signals to the next layer of cells in the retina: ganglion cells.   
   
Ganglion cells send signals to the brain through the optic nerve. 

Question 12

Occipital Lobe    

Answer 12

Location of the visual cortex.   
   
Part of the brain that processes vision sensations. 
  
Receives impulses via the optic nerve. 
   
The optic nerve is divided into two parts.

Impulses from the left side of each retina (right visual field) go to the left hemisphere of the brain, and those from the right side of each retina (left visual field) go to the right hemisphere of the brain.      

Question 13

Optic Nerve 

Answer 13

Nerve leading from the retina that carries impulses to the occipital lobe of the brain.
   
The optic nerve is divided into two parts.

Impulses from the left side of each retina (right visual field) go to the left hemisphere of the brain, and those from the right side of each retina (left visual field) go to the right hemisphere of the brain.      

Question 14

Absolute Threshold      

Answer 14

Smallest amount of stimulus we can perceive.  
  
Technical definition-the minimal amount of stimulus we can detect 50 percent of the time. 

For example, the absolute threshold for vision is the smallest amount of light we can detect, which is estimated to be a single candle flame about 30 miles (48 km) away on a perfectly dark night.   

Question 15

Kinesthetic Sense 

Answer 15

Gives us feedback about the position and orientation of specific body parts.  

Receptors in our muscles and joints send information to our brain about our limbs.  
This information, combined with visual feedback, lets us keep track of our body.    

Question 16

Vestibular Sense  

Answer 16

Our vestibular sense tells us about how our body is oriented in space.

Three semicircular canals in the inner ear give the brain feedback about body orientation. 

When the position of your head changes, the fluid moves in the canals, causing sensors in the canals to move.     

The movement of these hair cells activate neurons, and their impulses go to the brain.    

For example, our vestibular sense helps us figure out which way is up or down when doing a flip.      

Question 17

Transduction      

Answer 17

The translation of incoming stimuli into neural signals.   
 
Neural impulses from the senses travel first to the thalamus and then on to different cortices of the brain. 
     
The sense of smell is the one exception to this rule. 

Question 18

Sensory Adaptation

Answer 18

Decreasing responsiveness to stimuli due to constant stimulation.
 
For example, we eventually stop perceiving a persistent scent in a room.  

Occurs at the senses (Bottom-up)   

Question 19

Shape Constancy   

Answer 19

Objects viewed from different angles will produce different shapes on our retinas, but we know the shape of an object remains constant.   

For example, the top of a coffee mug viewed from a certain angle will produce an elliptical image on our retinas, but we know the top is circular due to shape constancy.     

Question 20

Size Constancy

Answer 20

Objects closer to our eyes will produce bigger images on our retina but we take distance into account in our estimations of size.
   
We keep a constant size in mind for an object (if we are familiar the typical size of the object) and know that it does not grow or s in size as it moves closer or farther away.   

Question 21

Pitch Theories    

Answer 21

Theories that explain how we hear different pitches or tones.   
  
Place Theory explains that the hair cells in the cochlea respond to different frequencies of sound based on where they are located in the cochlea.  
  
Frequency Theory states that Place Theory accurately describes how hair cells sense the upper range of pitches but not the lower tones.

Lower tones are sensed by the rate at which the cells fire. 

We sense pitch because the hair cells fire at different rates (frequencies) in the cochlea

Question 22

Sound Waves 

Answer 22

Amplitude is the height of the wave and determines the loudness of the sound, which is measured in decibels.      

Frequency, which is measured in megahertz, refers to the length of the waves and determines pitch.    

Question 23

Hearing

Answer 23

Steps of Hearing:
 
1. Sound waves, vibrations in the air, travel through the air, and are then collected by our ears. 

Sound waves have amplitude and frequency.    
 
2. Vibrations enter the ear and vibrate the eardrum, which connects with three bones in the middle ear: the hammer (or malleus), the anvil (or incus), and the stirrup (or stapes).  
  
3. The vibration is transferred to the oval window, a membrane very similar to the eardrum.  

4. The oval window membrane is attached to the cochlea, where the process of transduction occurs and neural messages are sent to the auditory cortex in the temporal lobe. 

Question 24

Color Blindness   

Answer 24

Individuals with dichromatic color blindness cannot see either red/green shades or blue/yellow shades.      

Those who have monochromatic color blindness see only shades of gray.   

Question 25

Trichromatic Theory     

Answer 25

A theory of color vision (the other theory is Opponent-Process Theory.) 

Also called Young-Helmholtz Theory. 

Hypothesizes that we have three types of cones in the retina: cones that detect the primary colors of light-blue, red, and green. 
  
These cones are activated in different combinations to produce all the colors of the visible spectrum. 
     
Even though this theory has some research support and makes sense intuitively, it cannot explain such visual phenomena as afterimages and color blindness.  

Most researchers agree that color vision is explained by a combination of the Trichromatic and Opponent-Process Theories.     

Question 26

Signal Detection Theory 

Answer 26

Signal Detection Theory investigates the effects of the distractions and inferences we perceive while experiencing the world. 

This theory takes into account how motivated we are to detect certain stimuli and what we expect to perceive. These factors together are called response criteria.  
    
By using factors like response criteria, Signal Detection Theory tries to explain and predict the different perceptual mistakes we make

(such as not seeing a stop sign, or thinking that you see a friend in the distance when you are actually seeing a stranger).    

Question 27

Difference Threshold (also Just-Noticeable Difference)

Answer 27

The smallest amount of change needed in a stimulus before we detect a change.  
   
Computed by Weber’s law, named after psychophysicist Ernst Weber.
 
The change needed is proportional to the original intensity of the stimulus. The more intense the stimulus is, the more it will need to change before we notice a difference. 

If someone raises the volume on your phone and you notice the increase in volume, that increase in volume is above the difference threshold.    

Question 28

Blind Spot  

Answer 28

The spot on the retina where the optic nerve leaves the retina and there are no rods or cones. 
 
We cannot detect objects in our blind spot, but our brains and the movement of our eyes accommodate for the blind spot, so we usually don’t notice it.      

Question 29

Rods and Cones    

Answer 29

Special neurons in the retina that are activated by light.  

Cones are activated by color. 

Rods respond to black and white and motion.     

Question 30

Visible Light     

Answer 30

Color is perceived due to a combination of different factors:     

Light intensity-How much energy the light contains (the amplitude) determines how bright an object appears.  

Light wavelength-The length of the light waves determines the particular hue we see.

We see different wavelengths within the visible light spectrum as different colors.    

Question 31

Feature Detectors 

Answer 31

Perception researchers Hubel and Weisel discovered that groups of neurons in the visual cortex respond to different types of visual images.     

The visual cortex has feature detectors for vertical lines, curves, and motion, among others. What we perceive visually is a combination of these features

Question 32

Retina      

Answer 32

As the light passes through the lens, the image is flipped upside down and projected on the retina.  
 
Special neurons in the retina (cones, which detect color, and rods, which detect black and white) are activated by light and send impulses along the optic nerve to the occipital lobe of the brain.  

Question 33

Lens

Answer 33

Focuses light that enters the pupil.      
Curved and flexible in order to focus the light.     
 
As the light passes through the lens, the image is flipped upside down and inverted. 
     
The focused inverted image projects on the retina. 

Question 34

Pupil

Answer 34

Opening in the center of the eye.   
Similar to the shutter of a camera. 

Muscles that control the pupil (called the iris) open it (dilate) to let more light in and also make it smaller to let less light in.     

Question 35

Cornea

Answer 35

Protective covering on the front of the eye.    
Helps focus the light.  

Question 36

Vision

Answer 36

Dominant sense in human beings.
 
The process of vision involves several steps:   
1. Light is reflected off objects. 
 
2. Reflected light coming from the object enters the eye through the cornea and pupil, is focused by the cornea and the lens, and is projected on to the retina where specialized neurons are activated by the different wavelengths of light.  

3. Transduction occurs when light activates the special neurons in the retina and sends impulses along the optic nerve to the occipital lobe of the brain.  
4. Impulses from the left side of each retina (right visual field) go to the left hemisphere of the brain, and those from the right side of each retina (left visual field) go to the right side of the brain.
       
5. The visual cortex receives the impulses from the retina, which activate feature detectors for vertical lines, curves, motion, among others.  

What we perceive visually is a combination of these features.     

Question 37

Subliminal Messages     

Answer 37

Stimuli below our absolute threshold.  
   
Research does not support the claim that subliminal messages affect our behaviors in overt ways.      

Question 38

Habituation (also called Perceptual     
Adaptation)

Answer 38

Our perception of sensations is partially determined by how used to them we are.    
For example, no longer hearing traffic from the nearby freeway after having lived in a place for years.  
   
While sensory adaptation happens in the sensory organs, sensory habituation happens in the brain.

People who have habituated to something (e.g., a sound, a smell) can still perceive it if directed to focus their attention on it.  

Occurs in the brain (Top Down Processing_    

Question 39

Nerve Deafness    

Answer 39

Occurs when the hair cells in the cochlea have been damaged, usually by loud noise. 

In conduction deafness, the other type of deafness, something goes wrong with the system of conducting the sound to the cochlea (in the ear canal, eardrum, hammer/anvil/stirrup, or oval window).  
  
Difficult to treat because there is no method yet found that will encourage the hair cells to regenerate.   

Question 40

Cocktail-Party Effect

Answer 40

If you are talking with a friend and someone across the room says your name, or something else of particular interest to you, your attention will probably involuntarily switch across the room.  

An example of selective attention.    

Question 41

Sensation

Answer 41

Sensation occurs when one of our senses (sight, smell, hearing, touch, or taste) is activated by something in our environment. 
       

Question 42

Perception  

Answer 42

The brain’s interpretation of sensory messages. 

Occurs after the process of sensation (the activation of our senses of sight, smell, hearing, touch, and taste). 
 
The process of understanding and interpreting sensations.

Question 43

Energy Senses     

Answer 43

The senses of vision, hearing, and touch.
 
These senses gather energy in the form of light, sound waves, and pressure, respectively.

Question 44

Chemical Senses   

Answer 44

The senses of taste and smell.      

These senses work by gathering chemicals. 

Question 45

Gate-Control Theory     

Answer 45

Explains how we experience pain. 
   
Some pain messages have a higher priority than others. When a high-priority message is sent, the gate swings open for it and shut for low-priority messages, which will not be felt.   
   
Of course, this gate is not a physical gate swinging in the nerve; it is just a convenient way to understand how pain messages are sent. 
 
For example, when you scratch an itch, the gate swings open for your high-intensity scratching and shuts for the low-intensity itching; this stops the itching for a short period of time.    

Endorphins, or pain-killing chemicals in the body, also swing the gate shut. Natural endorphins in the brain, which are chemically similar to opiates like morphine, control pain  

Question 46

Touch

Answer 46

Sense of touch is activated when our skin is indented, pierced, or experiences a change in temperature. 
    
Some nerve endings in the skin respond to pressure; others respond      
to temperature.   

The brain interprets the amount of indentation (or temperature change) as the intensity of the touch, from a light touch to a hard blow. 

We sense placement of the touch by the place on our body where the nerve endings fire.    
Nerve endings are more concentrated in different parts of our body.     

If we want to feel something, we usually use our fingertip, an area of high nerve concentration, rather than the back of our elbow, an area of low nerve concentration. 

Pain is a useful response because it warns us of potential dangers.     

Question 47

Taste (or Gustation)    

Answer 47

Nerves involved in the chemical senses (taste and smell) respond to chemicals rather than to energy.  

Taste buds on the tongue absorb chemicals from the food we eat. 
  
Taste buds are located on papillae, the bumps you can see on your tongue. Taste buds are located all over the tongue and on some parts of the inside of the cheeks and roof of the mouth. 

Humans sense five different types of tastes: sweet, salty, sour, umami, and bitter. 

People differ in their ability to taste food. The more densely packed the taste buds, the more chemicals are absorbed, and the more intensely the food is tasted. 

The flavor of food is actually a combination of taste and smell.  

Question 48

Smell (or Olfaction)    

Answer 48

Molecules of substances rise into the air and are drawn into our nose.  

The molecules settle in a mucous membrane at the top of each nostril and are absorbed by receptor cells located there.  

As many as 100 different types of smell receptors may exist. These receptor cells are linked to the olfactory bulb, which gathers the messages from the olfactory receptor cells and sends this information to the brain.  
   
Nerve fibers from the olfactory bulb connect to the brain at the amygdala and then to the hippocampus, which make up the limbic system, which is responsible for emotional impulses and memory. 

This direct connection to the limbic system may explain why smell is such a powerful trigger for memories.