SENSATION AND PERCEPTION Flashcards
1
Q
sensation
A
Sensation occurs when special receptors in the sense organs are activated, converting outside stimuli into neural signals in the brain.
2
Q
transduction
A
Transduction is the process of converting outside stimuli (e.g., light, sound) into neural activity.
3
Q
How do sensory receptors differ from other neurons?
A
Sensory receptors are stimulated by energy (light, sound, pressure, chemicals) instead of neurotransmitters from other cells.
4
Q
Weber’s Law
A
Weber’s Law states that the just noticeable difference (JND) between two stimuli is always a constant percentage of the original stimulus.
5
Q
absolute threshold
A
The absolute threshold is the minimum level of stimulation detectable 50% of the time.
6
Q
subliminal stimuli
A
Stimuli below the level of conscious awareness but still detected by sensory receptors.
7
Q
habituation
A
The brain filters out unchanging stimuli, making people stop noticing constant background noise.
8
Q
sensory adaptation
A
sensory receptors stop responding to constant stimuli, like getting used to a strong perfume over time.
9
Q
Why don’t our eyes experience sensory adaptation?
A
Tiny eye movements (microsaccades) prevent adaptation, keeping vision clear and preventing “blindness” from staring.
10
Q
light
A
Light consists of tiny “packets” of waves called photons, which have specific wavelengths associated with them. (Einstein’s theory)
11
Q
What are the psychological properties of light?
A
Brightness, color (hue), and saturation.
12
Q
What determines brightness?
A
The amplitude (height) of the wave—higher waves appear brighter, lower waves appear dimmer.
13
Q
What determines color (hue)?
A
The length of the wave—longer wavelengths are at the red end of the visible spectrum, shorter wavelengths are at the blue end
14
Q
visible spectrum
A
The small portion of the electromagnetic spectrum that is visible to the human eye (400–700 nm).
15
Q
saturation
A
The purity of a color—highly saturated colors contain only one wavelength, while less saturated colors contain mixed wavelengths.
16
Q
How does light enter the eye?
A
Light enters directly from a source (like the sun) or indirectly by reflecting off object
17
Q
refraction
A
The bending of light as it passes through different densities, which helps focus light onto the retina
18
Q
cornea
A
A clear membrane that protects the eye and focuses most of the incoming light.
19
Q
How can the cornea be reshaped?
A
Procedures like PRK and LASIK can change its curvature to improve vision.
20
Q
aqueous humor
A
A clear, watery fluid that nourishes the eye and is continually replenished.
21
Q
What is the pupil?
A
A hole in the iris that controls the amount of light entering the eye.
22
Q
What is the iris?
A
The colored part of the eye, which controls the size of the pupil to regulate light intake.
23
Q
What is the lens?
A
A flexible structure that changes shape (visual accommodation) to focus images on the retina.
23
Q
What is visual accommodation?
A
The lens adjusts its shape to focus on objects at different distances.
24
What is myopia?
Nearsightedness—the focal point falls short of the retina
24
What is presbyopia?
Age-related hardening of the lens, making it difficult to focus on close objects.
25
What is hyperopia?
farsightedness—the focal point falls behind the retina.
26
How are myopia and hyperopia corrected?
With glasses, contact lenses, or LASIK/PRK surgery.
27
retina
A light-sensitive area at the back of the eye that absorbs and processes light.
28
What are the three layers of the retina
Ganglion cells, bipolar cells, and photoreceptors (rods and cones).
29
rods
Photoreceptors responsible for black-and-white vision, found mostly in the periphery of the retina.
30
Why do rods work well in low light?
Many rods connect to a single bipolar cell, making them highly sensitive to dim light.
30
cones
Photoreceptors responsible for color vision and fine detail, concentrated in the fovea
31
Why do cones work best in bright light?
Each cone has its own direct pathway to the optic nerve, allowing for sharp vision.
32
What is the fovea?
The central area of the retina with the highest concentration of cones, responsible for sharp vision.
33
What is the blind spot?
The area in the retina where the optic nerve leaves the eye—there are no rods or cones, so no visual information is detected
34
Why don’t we notice our blind spot in daily life?
The brain fills in missing information, and our eyes are constantly moving.
35
What are saccadic movements?
Fast, jerky eye movements that prevent adaptation to constant stimuli and help process visual information smoothly.
36
How does light enter the eye and form an image?
Light travels through the cornea and lens, forming an upside-down and reversed image on the retina. The brain corrects this orientation.
37
What are the two halves of the retina called?
The temporal retina (toward the temples) and the nasal retina (toward the nose).
38
How does visual information reach the brain?
Light from the left visual field falls on the right side of the retina and is processed in the right visual cortex, while light from the right visual field falls on the left side of the retina and is processed in the left visual cortex
39
What do rods do?
Rods are sensitive to low light and help with night vision.
39
What is the optic chiasm?
The optic chiasm is the point where axons from the nasal halves of the retina cross over to the opposite side of the brain.
40
What is dark adaptation?
The process by which the eyes adjust to darkness after exposure to bright light. It takes about 30 minutes for full adaptation.
41
What is light adaptation?
the process where cones adjust to increased light, happening in just a few seconds.
42
What happens to dark adaptation with age?
It slows down, leading to night blindness.
43
What is the Trichromatic Theory of color vision?
The theory states that there are three types of cones sensitive to red, blue, and green light.
44
What are the three types of cones and their peak sensitivities?
1. Short-wavelength cones → Blue-Violet (~420 nm)
2. Medium-wavelength cones → Green (~530 nm)
3. Long-wavelength cones → Green-Yellow (~560 nm)
45
What is the Opponent-Process Theory of color vision?
Color is processed in pairs:
Red vs. Green
Blue vs. Yellow
Black vs. White
If one color is activated, its opponent is inhibited.
46
How do afterimages support the Opponent-Process Theory?
Staring at a color for too long fatigues the cones, so when looking at a white surface, the opposite color appears
47
Where does opponent-processing occur?
In the bipolar and ganglion cells of the retina and the lateral geniculate nucleus (LGN) in the thalamus.
48
How do Trichromatic Theory and Opponent-Process Theory work together
1. Trichromatic Theory explains color detection at the cone level.
2. Opponent-Process Theory explains how colors are processed in the brain and retina.
49
What are the types of color blindness?
1. Monochrome Color Blindness: No functioning cones → sees only shades of gray.
2. Dichromatic Vision: One cone type is missing → difficulty distinguishing certain colors.
- Red-Green Color Deficiency: Red or green cones are missing.
- Blue-Yellow Color Deficiency: Blue cones are missing.
50
Why is color blindness more common in men?
It is a sex-linked trait on the X chromosome.
1. Men (XY) need one defective X to have color blindness.
2. Women (XX) need two defective Xs, making it rarer in females.
51
What is the Ishihara Color Test?
A test using dot patterns to diagnose red-green color blindness.
52
Sound
1. Vibrations of air molecules (not in packets like photons).
2. Has wavelength (pitch), amplitude (volume), and timbre (tone quality).
53
How Sound Travels Through the Ear
1. Outer Ear
- Pinna: Collects sound.
- Ear Canal: Directs sound waves.
- Eardrum (Tympanic Membrane): Vibrates in response to sound.
2. Middle Ear
- Contains ossicles (smallest bones in the body):
> Hammer (Malleus)
> Anvil (Incus)
> Stirrup (Stapes)
- Vibrations are amplified and transmitted to the oval window.
3. Inner Ear
- Cochlea (fluid-filled, snail-shaped)
- Basilar Membrane: Vibrates, stimulating the Organ of Corti (hair cells).
- Hair Cells: Convert vibrations into neural signals sent through the auditory nerve to the thalamus and auditory cortex (processes sound).
53
Place Theory
1. Helmholtz & Békésy
2. Pitch is determined by which hair cells are stimulated in the cochlea.
3. Works for high-pitched sounds (> 1000 Hz).
54
Frequency Theory
1. Rutherford
2. Pitch depends on the speed of basilar membrane vibrations.
3. Works for low-pitched sounds (< 1000 Hz).
55
Volley Principle
1. Wever & Bray
2. Groups of neurons fire in a volley pattern for mid-range pitches (400–4000 Hz).
55
Hearing Impairments
1. Conduction Hearing Loss
2. Nerve (Sensorineural) Hearing Loss
55
Conduction Hearing Loss
1. Damage to outer/middle ear (eardrum, ossicles).
2. Sound waves can't reach cochlea.
3. Helped by hearing aids.
56
Nerve (Sensorineural) Hearing Loss
1. Damage to inner ear or auditory nerve (e.g., hair cell loss due to age/loud noise).
2. Tinnitus (ringing in ears) is common.
3. Cochlear implants can help by sending electrical signals directly to the auditory nerve.
57
Decibels & Hearing Safety
1. > 85 dB = Prolonged exposure causes hearing loss.
2. 120 dB = Pain threshold.
58
What percentage of what we deem as taste is actually smell?
About 90%.
59
gustation
The sense of taste.
60
How many basic taste sensations are there?
Five – Sweet, Sour, Salty, Bitter, and Umami.
61
umami
A savory taste, first identified by Dr. Kikunae Ikeda, associated with glutamate.
62
What happens to taste buds when you burn your tongue?
They get damaged but regenerate every 10–14 days.
62
Where are taste buds located?
Mostly on the tongue, but also on the roof of the mouth, cheeks, throat, and under the tongue.
63
What are supertasters?
People with a high number of taste buds who are more sensitive to flavors.
64
Does each taste sensation have a specific area on the tongue?
No, all taste sensations are processed all over the tongue.
65
What is the ability to smell odors called?
Olfaction
66
What are olfactory receptor cells?
Special cells in the nasal cavity that detect smells.
67
How often do olfactory receptor cells regenerate?
Every 5–8 weeks.
68
What part of the brain processes smell?
The olfactory bulbs, which bypass the thalamus
69
How do we actually "smell" things?
Molecules from the air enter the nose and stimulate olfactory receptors
70
What is the largest organ of the body?
The skin.
71
What are the three types of somesthetic senses?
Skin senses, kinesthetic sense, and vestibular sense.
72
What are Pacinian corpuscles responsible for?
Detecting pressure.
73
What is visceral pain?
Pain from internal organs.
74
What is congenital insensitivity to pain?
A rare disorder where individuals cannot feel pain, increasing their risk of injury.
75
Pacinian corpuscles
an encapsulated ending of a sensory nerve that acts as a receptor for pressure and vibration.
76
somesthetic senses
The somesthetic senses convey information about touch, pressure, pain, and out- side temperature.
77
What is kinesthesia?
The sense of movement and position of the body in space, from the Greek words kinein ("to move") and aesthesis ("sensation").
78
What are proprioceptors?
Special receptors located in muscles, tendons, and joints that detect body movement, joint position, and muscle stretch.
79
How do proprioceptors help us know our body’s position?
They send information to the brain about joint movement and muscle stretching, allowing us to sense our body's position even with closed eyes.
80
What is the vestibular sense?
The sense of balance, located in the inner ear, which tells us about body position relative to the ground and head movement.
81
What are the two types of vestibular organs?
the otolith organs and the semicircular canals.
82
How do the otolith organs function?
They contain a gelatin-like fluid with tiny crystals; when the head moves, the crystals shift, triggering hairlike receptors that detect direction (forward, backward, sideways, up, or down).
83
How do the semicircular canals function?
Three fluid-filled tubes oriented in the x-, y-, and z-planes detect rotational movement when the fluid inside them shifts.
84
Why does spinning make you dizzy?
When you stop spinning, the fluid in the semicircular canals keeps moving, making your body think you’re still in motion while your eyes say you’ve stopped, causing dizziness.
85
What is sensory conflict theory?
Motion sickness occurs when information from the eyes conflicts with the vestibular organs, causing dizziness, nausea, and disorientation.
86
How can motion sickness be reduced?
Focusing on a fixed point helps align sensory input, reducing the conflict.
87
What is space motion sickness (SMS)?
A condition experienced by astronauts in low gravity, affecting about 60% of space travelers, typically lasting a week before adaptation.
88
How can people overcome motion sickness?
Repeated exposure to the motion environment helps the body adjust.
89
What is perception?
The brain’s process of interpreting sensory information in a meaningful way.
90
What is size constancy?
The tendency to perceive an object as the same size regardless of its distance.
91
What is shape constancy?
he tendency to perceive an object’s shape as constant even when its retinal image changes (e.g., a tilted coin still looks circular).
92
What is brightness constancy?
The perception that the brightness of an object remains the same despite changes in lighting.
93
What are Gestalt principles?
Rules of perception that help the brain group objects into unified forms.
93
What is figure-ground perception?
The tendency to perceive objects as existing on a background, as seen in reversible figures like the Necker cube or face-vase illusion.
93
What is proximity
The tendency to perceive objects that are close together as a group.
93
What is similarity?
The tendency to perceive similar-looking objects as part of the same group (e.g., sports team uniforms).
94
What is closure?
The tendency to complete incomplete figures by mentally filling in gaps.
95
What is continuity?
The tendency to perceive continuous, smooth patterns rather than disjointed ones.
96
What is contiguity?
The tendency to perceive two events that happen close together in time as related (e.g., ventriloquism).
97
What is common region?
The tendency to group objects together if they share a common background or area.
98
What is depth perception?
The ability to see the world in three dimensions and judge distance.
99
How early does depth perception develop?
It is present very early in infancy, possibly from birth.
100
What are monocular depth cues?
Depth cues that require only one eye and are used in drawings or paintings to create depth.
101
What is linear perspective?
The tendency for parallel lines to appear to converge in the distance.
101
What is relative size?
When objects expected to be a certain size appear smaller, they are perceived as being farther away.
101
What is overlap (interposition)?
When one object blocks another, the blocked object is perceived as farther away.
102
What is aerial (atmospheric) perspective?
Distant objects appear hazy due to dust and pollutants in the air.
103
What is texture gradient?
Objects close to the viewer appear more detailed, while distant objects have a finer, less distinct texture
104
What is motion parallax?
Closer objects move faster across the visual field than distant ones when in motion.
104
What are binocular depth cues?
Depth cues that require both eyes and rely on the differences between the two visual fields.
104
What is convergence?
The inward movement of the eyes when focusing on a close object.
105
What is binocular disparity?
The difference in images between the two eyes; the brain interprets greater disparity as indicating closer objects.
106
What is an illusion?
An illusion is a perception that does not correspond to reality, causing people to see something different from what actually exists.
107
How do illusions differ from hallucinations?
Illusions involve distorted perceptions of real stimuli, while hallucinations originate in the brain without external stimuli.
108
Why do psychologists and neuroscientists study illusions?
Illusions help researchers understand how sensory receptors, sense organs, and the brain process and interpret sensory input.
109
What are the three levels at which illusions can occur?
1. Early sensory processes (e.g., opponent processes in the retina)
2. Subsequent processing (e.g., feature detection in the brain)
3. Higher-level assumptions made by the brain’s visual system
110
Who proposed that illusions can be based on early sensory processes, processing stages, or assumptions?
Researchers like Eagleman (2001) and Macknik et al. (2008).
111
What is the Hermann Grid illusion?
A visual illusion where gray blobs appear at the intersections of white lines but disappear when looked at directly.
111
What causes the Hermann Grid illusion?
It is attributed to neurons in the primary visual cortex that respond to bars of light at specific orientations.
112
Who discovered "simple cells" that respond to bars of light?
David Hubel and Torsten Wiesel (1959), who later won the Nobel Prize for their work.
113
How do straight edges affect the Hermann Grid illusion?
The illusion disappears when the edges of the grid are slightly curved (Geier et al., 2008).
114
What is the Müller-Lyer illusion?
A visual illusion where two identical lines appear different in length due to arrow-like endings.
115
What explains the Müller-Lyer illusion?
The carpentered world hypothesis—people are used to seeing corners in buildings and misinterpret depth cues.
116
How does culture affect susceptibility to the Müller-Lyer illusion?
People in Western cultures (with buildings and straight lines) are more susceptible, while people in non-Western cultures (like the Zulu, who live in round huts) are less affected (Segall et al., 1966; Gregory, 1990).
117
What is the moon illusion?
The moon appears larger on the horizon than when it is high in the sky.
118
What explains the moon illusion?
The apparent distance hypothesis—objects on the horizon have depth cues, making the brain perceive the moon as farther away and therefore larger.
119
Who first wrote about the moon illusion?
Greek-Egyptian astronomer Ptolemy (2nd century A.D.), later expanded by Al-Hazan in the 11th century.
120
What is the autokinetic effect?
A small, stationary light in a dark room appears to move due to a lack of surrounding cues.
121
What is stroboscopic motion?
The illusion of motion created by rapidly displaying a series of still images, as seen in movies or flipbooks.
122
What is the phi phenomenon?
The illusion of movement created by lights flashing in sequence, often seen in marquee signs and flashing arrows.
123
What is the "Rotating Snakes" illusion?
A static image that appears to move due to luminance, color arrangements, and brain processing.
124
What role do eye movements play in motion illusions?
Tiny eye movements (microsaccades) contribute to perceiving motion in static images like The Enigma (Troncoso et al., 2008).
125
What is perceptual set (perceptual expectancy)?
The tendency to perceive things a certain way based on past experiences or expectation
126
How does top-down processing influence perception?
It uses preexisting knowledge to organize features into a unified whole, like assembling a puzzle with a reference image.
127
How does bottom-up processing work?
It analyzes smaller features and builds up to a full perception without prior expectations, like assembling a puzzle without the box cover.
128
What cultural differences exist in perception?
People in Western cultures struggle with impossible 3D figures (like the "devil’s trident"), while people in less technologically oriented cultures see them as simple 2D drawings (Deregowski, 1969).
