Sensation and Perception

Question 0

Transduction

Answer 0

Transforming information from an organ into electrical impulses that the brain can understand

Question 1

Proprioception

Answer 1

Your ability to be aware of your body’s motion and position.

Question 2

What did Gustav Fechner (XIXe) study?

Answer 2

Psychophysics: the way external stimuli affect us.

Question 3

Absolute threshold (or detection threshold)

Answer 3

The weakest possible stimulus that people can still perceive; the lowest intensity at which people perceive the stimulus 50% of the time (through signal detection analysis)

Question 4

Difference threshold

Answer 4

Ability to detect a change in a stimulus’ intensity.

Question 5

The just noticeable difference

Answer 5

Refers to the smallest amount two stimuli can differ so that a person can tell them apart 50% of the time.

Question 6

Ernst Weber’s law

Answer 6

The just noticeable difference in strength of a stimulus is proportional to the original intensity of the stimulus.

The same increase in strength of a stimulus may be more noticeable if the original strength is low, but less if it’s high.

Question 7

Sensory adaptation

Answer 7

A stop in perceiving a given stimulus, due to lengthy exposure.

Question 8

Selective attention

Answer 8

Choosing to focus on certain sensations over others.

Question 9

Supraliminal stimuli

Answer 9

Stimuli that can be detected (at or above the absolute threshold)

Question 10

X-linked disorder

Answer 10

The red and green photopigments are located in the X chromosome, while the blue photopigment is located in a somatic chromosome. As a result, men only have one copy of the red and green pigments and two of the blue one. Thus, mutations in one of the red or green pigments will invariably result in red-green color blindness in men, while women, who have two copies of the X chromosomes, will continue to express all three pigments and see colors normally. For women to suffer red-green color blindness, they will need to carry mutations in both X chromosomes. Thus, deuteranomaly is much more prevalent in men than women (8% vs. 1%).

Question 11

Path of a visual stimulus

Answer 11

Light –focused–> cornea —-> pupil —-> lens (accommodation) —-> retina (phototransduction) —-> optic nerve —-> thalamus

Question 12

Iris

Answer 12

Irises grow and shrink to make sure the right amount of light gets in and to protect the pupils.

Question 13

Full electromagnetic spectrum

Answer 13

Full range of light (energy)

Longer wavelengths are red (microwaves), while shorter wavelengths are purple (x-Rays).

Question 14

Visible spectrum

Answer 14

The tiny part of the full electromagnetic spectrum that human eye can perceive.

Question 15

Photoreceptor neurons

Answer 15

Rods: black, gray, and white

Cones: colors and details

Question 16

Feature detector neurons

Answer 16

In the visual cortex, these neurons can isolate things like shapes or lines to help us quickly interpret.

Question 17

Young-Helmholtz Theory (1800s)

Answer 17

Explains how the eye processes images.

Three kinds of cones: one for red, one for green, one for blue.

Question 18

Opponent-process Theory (1874, Ewald Hering)

Answer 18

Explains how the brain processes images. Can be tested with the afterimage effect.

Three spectra of opponent colors: red-green, yellow-blue, black-white.

Question 19

V4

Answer 19

Part of the brain that processes colors and shapes.

Question 20

MT

Answer 20

Part of the brain that processes motion information.

Question 21

Interposition

Answer 21

Monocular depth cue where an object overlaps another

Question 22

Linear perspective

Answer 22

Monocular depth cue where something disappears into the distance, seeming to have its edges converging as they reach the horizon

Question 23

Position cue

Answer 23

In a flat image, things that are farther away seem to get closer together and physically higher up

Question 24

Relative size

Answer 24

An object farther away appears smaller than the same object nearby

Question 25

Motion parallax

Answer 25

While moving, things nearby seem to move faster than things in the distance

Question 26

Texture gradient

Answer 26

Things in the distance look fuzzier and less distinct

Question 27

Aerial perspective

Answer 27

Things in the distance look foggier than things nearby

Question 28

Retinal disparity

Answer 28

Binocular depth cue whereby the brain merges two slightly different images to create a 3-D image

Question 29

Convergence angle (between the eyes)

Answer 29

Binocular depth cue whereby the brain figures out how far away something is (also from the curvature of the eyes’ lenses)

Question 30

Sound (waves)

Answer 30

Sound is made up of molecules vibrating in patterns called waves. When I bang on a drum, the drum’s vibrating surface disturbs the air in patterns that, once they reach my ear, can be interpreted as a sound. Unlike light, which can travel in a vacuum through space, sound waves need material to travel–they need some sort of matter to disturb.

Question 31

Amplitude

Answer 31

Another feature of a sound wave that is related to loudness; size or height of a sound wave; the bigger the wave, the louder the sound.

Question 32

Decibel

Answer 32

Logarithmic scale for saying how loud something is.

0 decibel is the human detection threshold. Prolonged exposure to noises above 85 decibels is harmful.

Question 33

The path of sound waves inside the human ear

Answer 33

• Pinna (folds of cartilage)
• Auditory canal
• Eardrum
• Ossicles (3 of them: malleus, incus, and stapes; help transform the sound from vibrations in the air to vibrations in the fluid inside the nearby cochlea)
• Cochlea (contains a fluid that regulates the vestibular system)
• Cilia (small fibers that sense vibrations in the fluid and send nerve impulses to nearby neurons)
• Auditory nerve
• Brain

Question 34

The frequency theory of hearing

Answer 34

Neurons attached to the cilia fire off at the same rate as the frequency of the sounds entering the ear.

The frequency theory of hearing generally accounts for sounds with a frequency of 1,000 hertz or less. Sounds between 1,000 and 5,000 hertz are processed using a combination of the frequency theory and place theory. Anything above 5,000 hertz is explained by the place theory.

Question 35

The place theory of hearing

Answer 35

Different parts of the cochlea react to different frequencies of sound; neurons firing from the opening of the cochlea indicate a higher pitch than neurons firing at the end of the cochlea.

Question 36

Taste

Answer 36

Closely related to smell, as the areas of the brain processing these two senses are next to each other; taste mechanism is mature at birth, although our tastes evolve overtime; taste buds (receptors on the tongue) tell neurons to fire off signals when certain substances touch them; between 2,000 and 8,000 taste buds; die off and regrow quickly; live on average five days; five basic tastes: sweet, bitter, salty, sour, umami (also known as savory; corresponding to the flavor of glutamate; Japanese, for ‘deliciousness’); the tongue can feel additional sensations that are not exactly tastes but that activate certain receptors (spicy, alcohol)

Question 37

Smell

Answer 37

Closely related to taste, as the areas of the brain processing these two senses are next to each other; smell mechanism fully developed by the age of 3; odor receptor neurons allow us to tell apart almost 10,000 odors; ‘lock-and-key’ system: odor receptor neurons fire off only if a particular odor molecule comes along and activates it; newborns develop their sense of smell early to be able to recognize their mothers.

Question 38

Touch

Answer 38

The sense of touch is mature at birth; part of the somatosensory system; the skin has four kinds of receptors: for pressure, hot, cold, and pain; other sensations are a combination of these basic sensations;

Question 39

Vestibular system

Answer 39

Controlled by the fluid in the cochlea; helps keep track of where your body is.

Question 40

Vision

Answer 40

Newborns have poor vision: from 20/120 to 20/400 (would need an object to be 6-20 times closer or more magnified to see it as an adult would), because the fovea (also responsible for color vision) is not fully developed at birth; grows enough to give infants 20/20 vision by 2 years of age.

Question 41

Proprioception

Answer 41

Neurons that fire off signals when your muscles move to help you keep track of your limbs.

Question 42

The organ of Corti

Answer 42

Housed within the cochlea is the ‘The Organ of Corti’, also known as the hearing organ, which houses sensory hair cells (cilia). Once the sound enters the cochlea, it causes the hair cells in the Organ of Corti to move. The sound is then converted into nerve impulses that are carried to the brain through the auditory nerve.

Question 43

Phantom limb syndrome

Answer 43

Science has discovered another oddity about our proprioceptive sense. Often when a limb has to be removed due to disease or injury the person reports still feeling the missing limb. This is called phantom limb syndrome. Scientists believe that this experience is caused by memories of the proprioceptive nerves in the brain and body that still remain. People with phantom limb pain can experience itching that they cannot scratch, feelings of movement, pain, temperature and many other sensations.

Question 44

lateral geniculate nucleus (LGN)

Answer 44

Within the thalamus, there is a cluster of brain cells referred to as the lateral geniculate nucleus (LGN), which is responsible for the opponent-processing of colors and the afterimage effect.

More specifically, these brain cells are sensitive to different colors: some are sensitive to red, some to blue, and some to white. These are the colors that activate these brain cells, while their opponent colors (green, yellow, and black respectively) are the colors that inhibit these brain cells. Therefore, when you stare at a red circle for long enough, the cells sensitive to red are activated and stimulated for an excessive amount of time. This makes the cells fatigued, which causes the opponent color (in this case green) to be perceived when your eyes are averted from the color red to inhibit the over-stimulated red sensitive cells.