Ch. 4: Sensation and Perception Flashcards
(124 cards)
1
Q
What is sensation?
A
Simple stimulation of a sense organ; the basic registration of light, sound, pressure, odour, or taste as parts of your body interact with the physical world
2
Q
What is perception?
A
Occurs in your brain as sensation is registered there; the organization, identification, and interpretation of a sensation in order to form a mental representation
3
Q
What is transduction?
A
When sense receptors convert physical signals from the environment into neutral signals that are sent to the central nervous system; physical energy from the world is converted into electrical signals, which are interpreted by the brain to construct a perception of the world
4
Q
What is sensory adaptation?
A
Sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current, unchanging conditions
5
Q
What is psychophysics?
A
Methods that systematically relate the physical characteristics of a stimulus to an observer’s perception
6
Q
What is an absolute threshold?
A
The minimal intensity needed to detect a stimulus in 50% of trials; the simplest quantitative measurement in psychophysics
7
Q
What is a threshold?
A
The boundary between two psychological states (awareness and unawareness, perceiving and not perceiving, etc.)
8
Q
What is sensitivity?
A
How responsive we are to faint stimuli; often assessed using absolute threshold
9
Q
What is acuity?
A
How well we can distinguish two very similar stimuli
10
Q
What is the just noticeable difference (JND)?
A
The minimal change in a stimulus (ex. loudness, brightness) that can just barely be detected; depends on the particular sense being detected, the intensity of the original stimulus, the environment, etc.)
11
Q
What is Weber’s law?
A
For every sense domain, the change in a stimulus that is just noticeable is a constant ratio of the standard stimulus, over a range of standard intensities (ex. you would likely notice the difference between a 30 g and a 60 g envelope, but not a 2 kg and 2.05 kg package because the needed ratio has not been reached)
12
Q
What is signal detection theory?
A
A way of analyzing data from psychophysics experiments that measures an individual’s perceptual sensitivity while also taking noise, expectations, motivations, and goals into account; whether or not a stimuli is perceived depends on the strength of the stimulus and the amount of evidence needed for your perceptual system to decide it is present
13
Q
What is a decision criterion? What factors influence it?
A
The amount of evidence necessary for your perceptual system to decide that a stimulus is present; if the sensory evidence exceeds the criterion, the stimulus is perceived regardless of whether it is actually present
- Expectations
- Relative “badness” of an error (ex. sometimes missing a call is better than checking your phone by mistake, and sometimes the opposite)
14
Q
What are the 2 ways to be right and the 2 ways to be wrong about faint sensory evidence?
A
- Hit: a radiologist correctly detects cancer on a scan
- Miss: a radiologist doesn’t detect cancer on a scan when it is actually present
- Correct rejection: a radiologist reports that a scan from a healthy person is clear
- False alarm: a radiologist erroneously detects signs of cancer
15
Q
What are the 2 types of decision criterion, and what do they mean?
A
Liberal criterion: not much sensory evidence is required; the radiologist identifies cancer whenever there is the slightest indication
Conservative criterion: stronger sensory evidence is required; more unnecessary biopsies are avoided, but more cancer goes undiagnosed
16
Q
What are the 3 physical dimensions of light waves, and what do they each determine?
A
Length: determine’s light’s hue
Amplitude: the intensity of a light wave/how high its peaks are; determines brightness
Purity: the degree to which a light source is emitting just one wavelength; determines the saturation/richness of colour
17
Q
Describe how the eye detects and focuses light.
A
- Light reaches the eye and passes through the cornea
- The cornea bends the light wave and sends it through the pupil (hole into the eye)
- The iris, a muscle, contracts and relaxes to control the amount of light allowed through the pupil
- Muscles inside the eye control the shape of the lens, which focuses light onto the retina
- The retina, a reflective layer of tissue, receives the light wave/image
18
Q
What is accommodation, in terms of sight?
A
The process by which the eye maintains a clear image on the retina; eye muscles make the lens flatter for objects that are far away and rounder for nearby objects
19
Q
What is myopia?
A
Nearsightedness; if the eyeball is too long, images are focused in front of the retina
20
Q
What is hyperopia?
A
Farsightedness; if the eyeball is too short, images are focused behind the retina
21
Q
What are the 2 types of photoreceptors cells, and what do they do?
A
Cones: detect colour, operate under normal daylight conditions, and allow us to focus on fine detail
Rods: become active only under low-light conditions for night vision; more sensitive than cones, but provide no information about colour
22
Q
What is the fovea?
A
An area of the retina where vision is clearest and there are no rods at all; the absence of rods decreases the sharpness of vision in reduced light
23
Q
Why are objects in your peripheral vision less clear?
A
The light reflecting off them falls outside the fovea, and the lower density of cones there results in a fuzzier image
24
Q
What are the layers of cells in the retina?
A
- Innermost: photoreceptor cells (rods and cones)
- Bipolar cells
- Retinal ganglion cells
25
What are bipolar cells?
Cells in the eyes that collect electrical signals from rods and cones and transmit them to the outermost layer of the retina where retinal ganglion cells are
26
What are retinal ganglion cells?
Cells in the eye that organize the signals from the bipolar cells and send them to the brain; the bundles of RGC axons form the optic nerve
27
What is the optic nerve, and why does it create a blind spot?
Bundles of retinal ganglion cells that leave the eye through a hole in the retina; contains neither rods nor cones, and therefore has no mechanism for sensing light
28
Why do we not usually notice our blind spots?
Our perceptual system automatically fills in the blindspot using knowledge of the colour/texture around the blindspot
29
Describe how the optic nerve carries neural impulses to the brain.
1. Streams of action potentials containing information encoded by the retina travel to the brain along the optic nerve
2. Information from the right visual field is relayed to the left hemisphere of the brain while information from the left visual field is relayed to the right hemisphere
3. Information travels to the lateral geniculate nucleus (LGN), located in the thalamus of each hemisphere
4. The visual signals then travel to the back of the brain to Area V1 (part of the occipital lobe that contains the primary visual cortex)
30
Which sense does the thalamus not receive inputs from?
Smell
31
What is the visible spectrum?
The rainbow of hues we can see and their accompanying wavelengths
32
What are the 3 types of cones, and what are each sensitive to?
L-cones: especially sensitive to long wavelengths
M-cones: especially sensitive to medium wavelengths
S-cones: especially sensitive to short wavelengths
33
What do the 3 cone types allow the brain to interpret, and how?
1. Brightness: signalled by the total amount of activity across all 3 cone types
2. Colour: signalled by the relative levels of activity between pairs of cone types
34
What causes colour vision deficiency?
One cone type (or, rarely, 2-3) is missing
35
What is a colour afterimage and why does it occur?
A sensory adaptation that occurs when an overload of one colour fatigues the cones that respond to that colour
36
What is the colour opponent system, and how does it explain the colour aftereffect?
Pairs of cone types (channels) work in opposition:
- L cone channel against the M cone channel
- S cone channel against the M cone channel
When one type of cone is fatigued, the opposing channel is more active in comparison and results in you seeing the "opposite" colour
37
What happens once the optic nerve carries the neural impulses to Area V1 in the brain?
Information is systematically mapped into a representation of the visual scene; Area V1 is sensitive to edge orientation and its neurons selectively respond to bars and edges in specific orientations
38
What are the 2 visual streams that visual processing areas are categorized into?
1. Ventral (lower) stream
| 2. Dorsal (upper) stream
39
What is the ventral visual stream?
The lower visual stream, often called the WHAT pathway because it represents what an object is; travels across the occipital lobe into the lower levels of the temporal lobes and includes brain areas that represent an object's shape and identity
40
What is the dorsal visual stream?
The upper visual stream, first known as the WHERE pathway and later called the PERCEPTION FOR ACTION pathway since it is crucial for guiding actions like aiming, reaching, or tracking with the eyes; travels up from the occipital lobe to the parietal lobes and some of the middle/upper levels of the temporal lobes; identifies where an object is, how an object is moving, and lets us perceive spatial relations
41
What is the binding problem?
How the brain links features together so that we see unified objects in our visual world rather than free-floating or miscombined features; we can simultaneously be aware of what an object is, where it is located, and how to pick it up even though those features are represented in different parts of the brain
42
What is a potential explanation for the binding problem?
Binding neurons, which receive input from other neurons and are involved in representing different features of an object
43
What is parallel processing?
The brain's capacity to perform many activities at the same time
44
What is illusory conjunction?
A perceptual mistake, or binding error, whereby the brain incorrectly combines features from multiple objects
45
What is Feature-Integration Theory?
Focused attention is not required to detect the individual features that make up a stimulus (colour, shape, size, location, etc.), but it is required to bind those individual features together
46
What is attention, and how is it involved in illusory conjunctions?
The active and conscious processing of particular information which provides the "glue" necessary to bind features together; illusory conjunctions occur when people cannot pay full attention to the features that need to be "glued" together
47
What about the brain is responsible for us being able to recognize something when some aspects of it are changed (ex. anew haircut, different lighting/angles, etc.)? What are the 2 possible explanations for this?
Different regions of the ventral stream respond preferentially to different kinds of objects (faces, bodies, scenes, tools, etc.)
1. Modular View
2. Conceptual Knowledge
48
What is the modular view when it comes to explaining brain regions that respond preferentially to visual information about certain objects?
Specialized brain areas (modules) detect and represent specific objects because different objects differ in their visual properties (shape, size, etc.)
49
What is the conceptual knowledge view when it comes to explaining brain regions that respond preferentially to visual information about certain objects?
An object's visual properties are analyzed in the ventral visual stream, which leads to the activation of conceptual knowledge at higher levels of the ventral stream closer to the front of the brain
50
What is perceptual constancy?
The idea that even as aspects of a sensory signal change, perception remains constant (ex. being able to recognize a friend in daylight and in dim nightclub lighting); the result fo your perceptual system organizing the sensory information into meaningful objects, then supplementing that with information about novel features or stripping away potentially distracting/unnecessary sensory data
51
What is perceptual contrast?
The idea that, although the sensory information from two things may be very similar, we perceive objects as different; the result of your perceptual system organizing sensory information into meaningful objects, then stripping away potentially distracting/misleading sensory data so you can more accurately perceive what the real object is (example: The Dress)
52
What is perceptual organization?
The process of grouping and segregating features to create whole objects organized in meaningful ways; our perceptual system automatically delivers us the interpretation that is the simplest and most meaningful based on our experiences and expectations
53
What are the 6 perceptual grouping rules?
```
Simplicity
Closure
Continuity
Similarity
Proximity
Common Fate
```
54
What is the perceptual grouping rule of simplicity?
When confronted with 2 or more possible interpretations of an object's shape, the visual system tends to select the simplest or most likely interpretation
55
What is the perceptual grouping rule of closure?
We tend to fill in missing elements of a visual scene, allowing us to perceive edges that are separated by an interruption/gap as belonging to complete objects
56
What is the perceptual grouping rule of continuity?
Edges or contours that have the same orientation have good continuation, and we tend to group them together perceptually (ex. in an X we perceive 2 crossing lines instead of 2 Vs)
57
What is the perceptual grouping rule of similarity?
Regions that are similar in colour, lightness, shape, etc. are perceived as belonging to the same object (ex. a grid of alternating dots and triangles will end up looking like columns or dots or triangles instead)
58
What is the perceptual grouping rule of proximity?
Objects that are close together tend to be grouped together in clusters
59
What is the perceptual grouping rule of common fate?
Elements of a visual image that move together are perceived as parts of a single moving objects (ex. the lights on a construction sign are perceived as a moving arrow)
60
What are the 2 clues our perceptual system uses to separate figure from ground?
1. Size: smaller regions are likely to be figures
| 2. Movement: a lecturer is perceived as a figure against a background because they move
61
What 2 dimensions do retinal images contain, and how do we perceive the 3rd dimension?
- Length and width
| - We perceive depth, as well as distance of the object from using monocular and binocular depth cues
62
What are monocular depth cues? Describe the 5 different kinds
-Aspects of a scene that yield information about depth when viewed with only one eye
1. Relative/familiar size: an object appears smaller when farther away and larger as it moves closer, so our brains can use differences in retinal image size to perceive distance
2. Linear perspective: parallel lines seem to converge as they recede into the distance
3. Texture gradient: textures look more detailed up close, but more uniform/smooth when farther away
4. Interposition: when one object partially blocks another, we perceive the blocked object as being farther away
5. Relative height in image: objects that are closer tend to be lower in a visual scene, whereas far away objects are higher up
63
What is the main binocular depth cue?
Binocular disparity: the difference in the retinal images of the two eyes; because our eyes are slightly separated, each registers a slightly different view of the world and allows the brain to compute the differences between the 2 retinal images to perceive the distance of an object
- If the image falls on very similar places, the object is perceived as farther away
- If the images are more disparate in their retinal location, the object is perceived as closer
64
What are forced perspective illusions? Describe an Ames room.
- When you view 2 objects and they project the same retinal image size, the object that is perceived as farther away will be perceived as larger
- In an Ames room, the room is shaped like a trapezoid but looks rectangular from one specific vantage point; the person in the shorter end of the room will appear much larger than the person on the opposite end of the room
65
Describe motion perception
1. As an object moves across a stationary observer's visual field, it first stimulates one location on the retina and then another location soon after
2. Neural circuits in the brain detect this change in position over time
3. When the observer moves their head/eyes, the brain takes these movements into account to allow them to perceive motions of objects correctly
66
What is the waterfall illusion?
Since perception of motion depends on relative activity in opposing sets of motion detector cells; if one set of motion detector cells is fatigued from detecting a certain motion, when that motion ceases there is relatively greater firing in the opposing set of cells (similar to colour aftereffects)
67
What is apparent motion?
Perception of movement as a result of alternating signals appearing in rapid succession in different locations (ex. "moving" neon signs)
68
What is spatial acuity?
The ability to distinguish two features that are very close together in space (our visual system's super power)
69
What is temporal acuity?
The ability to distinguish two features that are very close together in time (our auditory system's super power
70
What is the ventriloquist illusion?
The fact that you depend on your visual system for reliable information about spatial location (ex. when you watch a movie, you attribute voices to characters on screen instead of from the speakers behind you)
71
What is change blindness, and when is it most likely to occur?
Occurs when people fail to detect changes to the visual details of a scene, even major details we believe we couldn't miss; most likely to happen when people fail to focus attention on the object that undergoes a change
72
What is inattentional blindness?
A failure to perceive objects that are not the focus of attention (ex. not seeing a car coming when you are looking at your phone)
73
What are sound waves, and how are they involved in hearing?
- Changes in air pressure unfolding over time
| - Hearing involves transforming these sound waves into meaningful sound objects
74
What are the 3 physical dimensions of a sound wave, and how to we perceive them?
Frequency, perceived as pitch
Amplitude, perceived as loudness
Complexity, perceived as timbre
75
What is frequency?
Repetition rate; how often the peak in air pressure passes the ear, measured in cycles per second (hertz; Hz)
76
What is amplitude?
A sound wave's intensity relative to the threshold for human hearing, measured in decibels (dB)
77
What is complexity when it comes to sound?
The mixture of frequencies, which influences perception of timbre
78
What is timbre?
The quality of a sound that allows you to distinguish two sources with the same pitch and loudness; how we tell the difference between a piano and a guitar playing the same note
79
Name the 3 parts of the human ear.
Outer ear
Middle ear
Inner ear
80
What does the outer ear do, and what does is consist of?
- Collects sound waves and funnels them towards the middle ear
- Consists of the visible part on the outside of the head (pinna), auditory canal, and eardrum
81
What is the eardrum?
An airtight flap of skin that vibrates in response to sound waves gathered by the pinna and channeled into the canal
82
What does the middle ear do, and what does it consist of?
- Transmits the vibrations to the inner ear
| - Consists of a tiny air filled chamber behind the ear drum that contains the ossicles
83
What do the ossicles do, and what 3 bones are they made up of?
-The bones of the ossicles fit together into a lever that mechanically transmits and amplifies vibrations from the ear drum to the inner ear; press against the oval window and transmit the pressure waves to the fluid-filled cochlea
1. Hammer
2. Anvil
3. Stirrup
84
Describe the inner ear.
Embedded in the skull, where vibrations are transduced into neural impulses; contains the cochlea
85
What is the cochlea?
A fluid filled tube containing cells that transduce sound vibrations into neural impulses; divided along its length by the basilar membrane
86
What is the basilar membrane?
A structure in the inner ear that moves up and down in time with vibrations relayed from the ossicles, transmitted through the oval window; sound causes the basilar membrane to move up and down in a travelling wave
87
What is a travelling wave, and how can different frequencies stimulate the basilar membrane differently?
-The up and down movement that sound causes in the basilar membrane
-The frequency of the stimulating sound determines where on the basilar membrane the up and down motion is greatest
-Low frequencies = greater movement in the apex (floppy tip)
-High frequencies = greater movement in the base (narrow, stiff end closest to the oval
window)
88
What are inner hair cells, and what do they do?
- Specialized auditory receptor neurons embedded in the basilar membrane
- Long hairs stick out the tops and bend back and forth in the cochlear fluid
- The back and forth bending generates rhythmic action potentials in the auditory nerve axons that travel to the brain
- The auditory nerve axons that fire most are those connected to the hair cells in the area of the basilar membrane that moves most
89
How does the auditory nerve carry neural impulses to the brain?
From the inner ear, action potentials in the auditory nerve travel to several regions of the brainstem in turn, and then to the thalamus, and ultimately to an area of the cerebral cortex called Area A1
90
How does the brain perceive sound sources?
By using patterns of action potentials in the auditory nerve to perceive sounds in terms of their loudness, pitch, timbre, and location
91
What signals loudness?
The total amount of activity in hair cells (like how brightness of light is signalled by total amount of activity in photoreceptors)
92
What are the 2 aspects of auditory nerve activity that pitch depends on?
1. Place code: the brain uses information about the relative activity of hair cells across the whole basilar membrane to determine pitch
2. Temporal code: auditory nerve axons fire synchronously with sound wave peaks/hair cell movement; the brain uses the timing of the action potentials in the auditory nerve to help determine pitch
93
What does the perception of timbre depend on?
The relative amounts of different frequency components in a sound, and so the relative activity of hair cells across the basilar membrane
94
What are the 4 ways we can determine the location of a sound?
1. The folds of the pinna emphasizing some frequency components over others depending on where the sound is coming from
2. Sound arrives sooner at the era nearer to the source of the sound; the closer the object, the smaller the time different between it hitting the two ears
3. Higher frequency sounds are more intense in the ear closer to the sound because the listener's head blocks higher frequencies; the further a sound is off to the side, the greater the between-ear difference
4. Turning one's head side to side changes the relative intensity and timing of sound waves arriving in the ears and also allows you to use your eyes to located the source
95
What is perceptual grouping when it comes to hearing?
The brain figuring out which frequency components belong together in a single source
96
What is perceptual segregation when it comes to hearing?
The brain figuring out which frequency components belong to different sources
97
What are the 2 main causes of hearing loss?
1. Conductive hearing loss
| 2. Sensorineural hearing loss
98
What is conductive hearing loss? How can it be corrected?
- a "mechanical" problem that arises because the ear drum or ossicles are damaged and cannot conduct sound waves effectively to the cochlea
- medication, surgery, sound amplification from hearing aids
99
What is sensorineural hearing loss? How can it be corrected?
- Caused by damage to the cochlea, hair cells, and auditory nerve; many causes including genetic disorders, premature birth, infections, medications, accumulated damage from sound exposure, and aging
- Sensitivity decreases, so sounds have to be more intense to be heard
- Acuity decreases, so sounds smear together in the basilar membrane
- Hearing aids can help with reduced sensitivity, but not reduced acuity; cochlear implants can help with severe hearing loss by picking up sound with a microphone and transforming it into electric signals
100
What does somatosenses mean?
The body senses; "up close and personal" (as opposed to vision/hearing, which are "distance" senses)
101
What is haptic perception?
The active exploration of the environment by touching objects; using sensory receptors in muscles, tendons, joints, and skin to get a feel for the world around us
102
What is a tactile receptive field?
The small patch of skin that each touch receptor is sensitive to
103
What are thermoreceptors?
nerve fibres that sense cold and warmth; respond when skin changes temperature
104
What are the 2 types of fibres that transmit pain signals?
1. A-delta fibres: fast-acting axons that transmit initial sharp pain
2. C fibres: slower axons that transmit longer-lasting, dull pain
105
What two places are neural signals for pain sent to, and what happens there?
1. Somatosensory cortex: identifies where the pain is occurring and what sort of pain it is
2. Motivational and emotional centres of the brain (ex. hypothalamus, amygdala, frontal lobe): motivates us to escape or relieve pain
106
What is the gate-control theory of pain?
Signals arriving from pain receptors can be stopped by interneurons in the spinal cord via feedback from the skin or brain (rubbing a painful area closes the gate and stops the pain)
107
What is Periaqueductal Grey (PAG)?
A region in the midbrain where the brain's feedback to the spinal cord comes from; in extreme conditions, endorphins can activate the PAG to send inhibitory signals to neurons in the spinal cord and suppress pain signals; also responds to the action of opiate drugs
108
What is the pain facilitation signal, and why did it evolve?
- A feedback signal from the brain that increases the sensation of pain
- Evolved to motivate people who are ill to rest so their energy can be devoted to healing
109
What is bottom-up control?
Control of perception by senses
110
What is top-down control?
Perception being affected by one's knowledge, expectations, mood, motivational state, etc.; examples include visual illusions, the brain influencing experiences of pain, etc.
111
What is proprioception and how is it felt?
One's sense of body position in space; depends on stimulation os receptors in the muscles/tendons/joints or the inner ear
112
What is the vestibular system?
3 fluid filled semicircular canals and the adjacent organs next to the cochlea in the inner ears; movement of the fluid and hair cells allows us to maintain our balance
113
Why does motion sickness happen?
There is a mismatch between your vestibular system and what you are seeing, both of which work together to maintain balance
114
What is flavour?
The combined perceptual experience of smell and taste
115
What are odours?
Mixtures of different odorant molecules (chemicals like vanillin or hydrogen sulfide)
116
What is the olfactory epithelium?
Situated along the top of the nasal cavity and contains olfactory receptor neurons
117
What are olfactory receptor neurons?
Receptor cells that transduce odorant molecules into neural impulses; each ORN has receptors that bind to some odorants but not others
118
What is the olfactory bulb?
a brain structure located above the nasal cavity beneath the frontal lobes
119
What are the 5 main taste receptors? What is the recently added 6th?
1. Salt (sodium chloride)
2. Sour (acids)
3. Bitter
4. Sweet
5. Umami
6. Oleogustus (fattiness)
120
What are papillae?
Small bumps that cover the tongue and contain taste buds
121
What are taste buds?
The organs of taste transduction; contains microvilli which are taste receptor cells that react with tastant molecules in food
122
Besides the 5/6 tastes, what else is the mouth sensitive to?
- Temperature
- Spiciness
- Texture
123
What are perceptual hypotheses?
Assumptions the brain uses to make quick and automatic extrapolations based on perceptual rules, experience, expectations, motivations, and context; how the brain constructs reality
124
What is motion parallax?
Objects that are closer to us move faster across the visual field than objects in the distance
