Week 7 Readings Flashcards
1
Q
The physical process during which our sensory organs—those involved with hearing and taste, for example—respond to external (environmental) stimuli is called ______________
A
sensation
2
Q
The physical processing of environmental stimuli by the sense organs.
A
Sensation
3
Q
Sensation happens when you eat noodles or feel the wind on your face or hear a car horn honking in the distance. During sensation, our sense organs are engaging in ___________, the conversion of one form of energy into another.
A
transduction
4
Q
A process in which physical energy converts into neural energy.
A
Transduction
5
Q
What is perception?
A
The psychological process of interpreting sensory information.
6
Q
What is an absolute threshold in stimulation?
A
The smallest amount of stimulation needed for detection by a sense.
7
Q
What is the method called through which we measure absolute thresholds?
A
Signal detection
8
Q
What is signal detection?
A
Method for studying the ability to correctly identify sensory stimuli.
This process involves presenting stimuli of varying intensities to a research participant in order to determine the level at which he or she can reliably detect stimulation in a given sense.
9
Q
What is the differential threshold?
A
also known as just noticeable difference, or JND
The differential threshold is the minimum difference in intensity between two stimuli that a person can detect. It is the smallest change in stimulus intensity that can be noticed.
10
Q
How is the differential threshold similar to the absolute threshold?
A
Both the differential threshold and the absolute threshold involve the detection of stimuli. The absolute threshold refers to the minimum intensity of a stimulus that can be detected, while the differential threshold refers to the minimum difference in intensity between two stimuli that can be detected.
10
Q
What experiment can be used to demonstrate the differential threshold?
A
An experiment using objects of known weight can be used. For example, a person holds a 1 lb (or 1 kg) object, then it is replaced with a heavier one, such as a 2 lb (or 2 kg) object. The person can easily detect the weight difference when the second object is significantly heavier, but it is more difficult to detect smaller differences, such as between 10 and 11 lbs (or 5 and 5.5 kg).
11
Q
What is Weber’s Law?
A
Weber’s Law states that the ability to detect differences between two stimuli depends on the proportion of the difference to the original stimulus, rather than the absolute difference. Larger stimuli require greater differences to be noticed compared to smaller stimuli.
States that just noticeable difference is proportional to the magnitude of the initial stimulus.
12
Q
Define bottom-up processing
A
Building up to perceptual experience from individual pieces.
13
Q
Define top-down processing
A
Experience influencing the perception of stimuli.
14
Q
What is bottom-up processing?
A
Bottom-up processing is when we build perception from the individual pieces of stimuli, such as when we encounter something for the first time and use sensory information to form an understanding.
15
Q
What is top-down processing?
A
Top-down processing is when past experiences influence how we process new stimuli, using prior knowledge to interpret information more quickly or in a specific way.
16
Q
How do bottom-up and top-down processing differ in perception?
A
Bottom-up processing is data-driven and focuses on building up perception from individual stimuli, while top-down processing is influenced by prior knowledge and experiences to interpret new stimuli.
17
Q
Can you give an example of how bottom-up and top-down processing work in real life?
A
Bottom-up processing occurs when you hear a band for the first time and build your opinion from the music itself. Top-down processing happens when you hear a new song by a band you love, and your past experience with the band influences your perception of the song.
18
Q
How does reading illustrate the concepts of bottom-up and top-down processing?
A
When learning to read, you use bottom-up processing by focusing on individual letters and sounds. Once you become familiar with words, top-down processing allows you to read quickly by recognizing whole words based on prior experience.
19
Q
What is sensory adaptation?
A
Sensory adaptation is the process where we stop noticing a constant and unchanging stimulus because our sensory receptors stop responding to it.
(Decrease in sensitivity of a receptor to a stimulus after constant stimulation.)
20
Q
What role does the pupil play in vision?
A
The pupil regulates the amount of light entering the eye by contracting in bright light and dilating in dim light.
21
Q
What happens to light after it enters the pupil?
A
Light passes through the lens, which focuses the image onto the retina at the back of the eye.
22
Q
How does the lens help us see clearly?
A
The lens focuses light to form a clear image on the retina, allowing us to see the object in detail.
23
Q
What is the retina?
A
A thin layer of cells at the back of the eye.
24
25
26
What is binocular disparity?
Binocular disparity is the slight difference in the images focused on each retina due to the different locations of our eyes, contributing to our perception of 3D space.
27
How does binocular vision help us perceive 3D space?
Binocular vision allows us to perceive 3D space by combining the slightly different images from each eye to create depth perception.
28
What process occurs in the retina?
Light is transduced, or converted into electrical signals, by specialized cells called photoreceptors.
29
What are the two main types of photoreceptors in the retina?
Rods and cones.
30
What is the primary function of rods in the retina?
Rods are responsible for vision in dim light conditions, such as during the night.
31
32
What is the primary function of cones in the retina?
Cones provide the ability to see color and fine detail in brighter light.
33
Where are cones most concentrated in the retina?
Cones are most concentrated in the fovea, the central region of focus.
34
35
Where are rods more dominant in the retina?
Rods dominate the periphery of the retina.
36
Why does a dim star in the sky seem to disappear when you look directly at it?
The fovea, where cones are concentrated, doesn't have enough rods to process the dim light, making the star seem to disappear.
37
After light is transduced into electrical signals in the retina, through which nerve does the signal travel?
The optic nerve.
38
Which brain structure does the visual signal pass through after the optic nerve?
The thalamus.
39
Where in the brain does information about light orientation and movement begin to integrate?
The primary visual cortex.
40
What is the fusiform face area specialized for?
Processing faces.
41
What is the extrastriate body area specialized for?
Processing body parts.
42
What is agnosia?
A condition where a person loses the ability to perceive certain visual stimuli.
43
What is the ventral visual pathway also called, and what does it process?
It is called the "what" pathway and processes information about object recognition, including faces and body parts.
44
What is the dorsal visual pathway also called, and what does it process?
It is called the "where" pathway and processes information about location and movement.
45
What do optical illusions reveal about visual processing?
They provide misleading information to the higher areas of visual processing in the brain.
46
What is dark adaptation?
Dark adaptation is the process where rods recover after being bleached in bright light, allowing us to see in dim conditions. It takes around 10 minutes.
(Adjustment of eye to low levels of light.)
47
What causes the delay in night vision when moving from light to dark conditions?
The delay is caused by rods becoming bleached in normal light and needing time to recover.
48
What is light adaptation?
Light adaptation is when a large number of rods and cones are bleached at once, causing temporary blindness as we adjust to bright light.
(Adjustment of eye to high levels of light.)
49
How quickly does light adaptation occur compared to dark adaptation?
Light adaptation happens almost instantly, whereas dark adaptation takes longer (around 10 minutes).
50
How can you turn on a light without losing your night vision?
Use a red light, as this wavelength doesn't bleach your rods.
51
What is the trichromatic theory?
Theory proposing color vision as influenced by three different cones responding preferentially to red, green and blue.
52
What role do cones play in vision?
Cones allow us to see details in normal light conditions and perceive color.
53
Cones: what colors do they preferentially respond to?
Cones preferentially respond to red, green, and blue.
54
What is the trichromatic theory of color vision?
Theory proposing color vision as influenced by three different cones responding preferentially to red, green and blue.
55
What phenomenon does the trichromatic theory fail to explain?
It fails to explain afterimages, such as seeing colors on a white surface after staring at an image for a while.
56
What is the opponent-process theory of color vision?
The opponent-process theory suggests that retinal ganglion cells respond to pairs of colors (red-green, blue-yellow, black-white) and compute differences between these colors.
57
Why can't we see reddish-green or bluish-yellow according to the opponent-process theory?
The retinal ganglion cells compute differences between opposing colors, making it impossible to perceive both colors in the pair simultaneously.
58
How does the opponent-process theory explain afterimages?
Afterimages occur because the retinal ganglion cells become fatigued from processing one color in a pair, causing us to see the opposing color when we shift our gaze.
59
What can cause color-deficient vision?
Issues with cones or the retinal ganglion cells involved in color vision can lead to color-deficient vision.
60
What is audition?
Ability to process auditory stimuli. Also called hearing.
61
What does the amplitude of a sound wave code for?
The amplitude codes for the loudness of a sound; higher amplitude sound waves result in louder sounds.
62
How is the pitch of a sound coded?
The pitch is coded by the frequency of the sound wave; higher frequency sounds are higher pitched.
63
What aspect of sound allows us to distinguish between different sound qualities, like bright and dull sounds?
The quality, or timbre, of a sound is determined by the complexity of the sound wave.
64
What does the timbre of a sound help us differentiate between?
Timbre helps us tell the difference between natural and synthesized instruments, as well as between bright and dull sounds.
65
What part of the ear funnels sound waves into the auditory canal?
The pinna, the external part of the ear, funnels sound waves into the auditory canal.
66
What is the tympanic membrane, and what role does it play in hearing?
The tympanic membrane, or eardrum, is a thin, stretched membrane that vibrates in response to sound waves, helping to amplify them.
67
What are the three smallest bones in the body, and what are they collectively called?
The malleus (hammer), incus (anvil), and stapes (stirrup) are collectively called the ossicles.
68
What role do the ossicles play in hearing?
The ossicles amplify sound waves before they enter the fluid-filled cochlea.
69
What is the cochlea, and what happens there?
The cochlea is a snail-shell-like bone structure that contains auditory hair cells, where sound waves are converted into electrical signals.
70
What is tonotopic organization in the cochlea?
Tonotopic organization refers to the arrangement of auditory hair cells on the basilar membrane according to the frequency they respond to.
71
What is the normal range of detectable sound frequencies for humans?
Humans can normally detect sounds between 20 Hz and 20 kHz.
72
Where are sound waves converted into an electrical message in the ear?
Sound waves are converted into an electrical message inside the cochlea.
73
What is the auditory canal?
Tube running from the outer ear to the middle ear.
74
What are the ossicles?
A collection of three small bones in the middle ear that vibrate against the tympanic membrane.
the malleus (hammer), the incus (anvil), and the stapes (stirrup)
75
After being processed by auditory hair cells, where are electrical signals sent?
Electrical signals are sent through the cochlear nerve (a division of the vestibulocochlear nerve) to the thalamus and then to the primary auditory cortex of the temporal lobe.
76
What is the primary auditory cortex responsible for?
The primary auditory cortex is involved in processing various features of sound, though its exact role is still being explored.
77
How is tonotopic organization maintained in the auditory system?
The tonotopic organization of the cochlea is maintained in the primary auditory cortex.
78
Which nerve transmits the auditory signals from the cochlea to the brain?
The cochlear nerve, which is a division of the vestibulocochlear nerve, transmits auditory signals to the brain.
79
What is the vestibular system responsible for?
The vestibular system helps with balance and detecting the body's orientation in space.
80
What structures make up the vestibular system?
The vestibular system is comprised of three fluid-filled semicircular canals.
They respond to changes in the head’s orientation in space.
81
Which nerve transmits information from the vestibular system?
The vestibular nerve, a division of the vestibulocochlear nerve, transmits this information.
82
How does the vestibular system help us maintain focus on an object while in motion?
It sends information to muscles involved in the movement of our eyes, neck, and other body parts to help maintain gaze and balance.
83
What can disturbances in the vestibular system lead to?
Disturbances can result in balance issues, including vertigo.
84
What is somatosensation?
Ability to sense touch, pain and temperature.
transduces physical stimuli, such as fuzzy velvet or scalding water, into electrical potentials that can be processed by the brain.
85
Tactile stimuli—those that are associated with texture—are transduced by special receptors in the skin called __________
mechanoreceptors
86
What are mechanoreceptors?
Mechanical sensory receptors in the skin that response to tactile stimulation.
87
After tactile stimuli are converted by mechanoreceptors, where is the information sent for further processing?
Information is sent through the thalamus to the primary somatosensory cortex.
88
What is a somatotopic map?
Why are some regions of the body represented as larger in the somatotopic map?
A somatotopic map is an organized representation in the primary somatosensory cortex where different regions correspond to specific parts of the body, with sizes based on sensitivity.
Areas with more sensitivity, like the lips and fingertips, are represented as larger, while less sensitive areas like the shoulders or ankles are smaller.
89
What does the distorted proportions of the human body in the somatotopic map represent?
The distorted proportions represent the varying sensitivity of different body parts, with more sensitive areas shown larger.
90
Which side of the body is represented in the somatotopic map in the primary somatosensory cortex?
The opposite side of the body is represented in the somatotopic map.
91
What is the primary somatosensory cortex?
A strip of cerebral tissue just behind the central sulcus engaged in sensory reception of bodily sensations.
92
What is nociception?
Our ability to sense pain.
93
What is a phantom limb? What might be causing the sensation of a phantom limb?
A phantom limb is the sensation that a missing limb is still present, often accompanied by sensations such as itching or pain.
Damaged nerves from the amputation site may still send information to the brain, and the brain reacts to this information.
94
What is chemical senses?
Our ability to process the environmental stimuli of smell and taste.
95
What are odorants?
Chemicals transduced by olfactory receptors.
96
What is the olfactory epithelium?
Organ containing olfactory receptors.
97
How do olfactory receptors work in the perception of smell?
Odorants bind to olfactory receptors in the olfactory epithelium, triggering a pattern of neural activity that we perceive as smell.
98
What is the shape theory of olfaction?
The shape theory suggests that different odorants bind to specialized receptors based on their shape, similar to a lock and key.
99
What is an alternative theory to the shape theory of olfaction?
An alternative theory suggests that the vibrations of odorant molecules correspond to their subjective smells.
100
What might underlie our subjective experience of smell?
It is thought that our memories of the patterns of neural activity created by odorants underlie our subjective experience of smell.
101
How can head trauma affect the sense of smell?
Head trauma can cause anosmia (loss of smell) by severing the connections of olfactory receptors that project through the cribriform plate of the skull.
anosmia caused by head trauma is usually temporary, and the sense of smell often returns.
102
Where are taste receptor cells located?
Taste receptor cells are located in the taste buds, which are found in small divots around the bumps (papillae) on the tongue.
103
What are tastants, and how do they affect taste receptor cells?
Tastants are chemicals in the foods we eat that bind to taste receptor cells, resulting in the perception of taste.
104
What are the five basic tastes we can perceive?
The five basic tastes are sweet, sour, bitter, salty, and umami (savory).
105
Is there a "taste map" of the tongue where different areas respond to specific tastes?
No, the idea of a taste map is a misconception; all areas of the tongue with taste receptor cells can respond to every taste.
106
What two senses combine to give us the perception of flavor when we eat?
The senses of taste and smell combine to give us the perception of flavor.
As we chew, food odorants are forced back to areas that contain olfactory receptors, enhancing the perception of flavor.
107
What is multimodal perception?
Information from one sense has the potential to influence how we perceive information from another, a process called multimodal perception.
The effects that concurrent stimulation in more than one sensory modality has on the perception of events and objects in the world.
108
What is the superadditive effect of multisensory integration?
It is the phenomenon where we respond more strongly to multimodal stimuli than to the sum of each single modality alone.
109
How does the superadditive effect of multisensory integration help in noisy environments?
It helps us understand conversations in noisy environments, like a concert, by combining auditory and visual cues (e.g., watching someone speak).
110
What does the principle of inverse effectiveness state?
That you are less likely to benefit from additional cues from other modalities if the initial unimodal stimulus is strong enough.
111
What is the principle of inverse effectiveness
The finding that, in general, for a multimodal stimulus, if the response to each unimodal component (on its own) is weak, then the opportunity for multisensory enhancement is very large.
However, if one component—by itself—is sufficient to evoke a strong response, then the effect on the response gained by simultaneously processing the other components of the stimulus will be relatively small.
112
What is the super additive effect of multisensory integration?
The finding that responses to multimodal stimuli are typically greater than the sum of the independent responses to each unimodal component if it were presented on its own.
113
Julio stares at a yellow piece of paper for 30 seconds, and then he quickly looks at a white wall. The blue afterimage he sees supports which theory of color vision?
a) inverse effectiveness theory.
b) differential threshold theory.
c) multisensory integration theory.
d) opponent-processes theory.
e) trichromatic theory.
d) opponent-processes theory.
114
In which part of the brain do we perceive touch, temperature, and pain?
primary somatosensory cortex.
115
What is the most direct physical correlate of loudness?
The most direct physical correlate of loudness is sound intensity (or sound pressure) measured near the eardrum.
116
Besides sound intensity, what factors influence the perceived loudness of a sound?
Factors that influence loudness include frequency content, duration, and the context in which the sound is presented.
117
What method is often used to measure perceived loudness in psychophysical studies?
Magnitude estimation is a method where subjects assign numbers to tones of different sound levels to measure perceived loudness.
118
What role does pitch play in acoustic communication?
Pitch provides the basis of melody in music, prosodic information in non-tone languages like English, and helps define the meaning of words in tone languages like Mandarin Chinese.
119
What is pitch the perceptual correlate of?
Pitch is the perceptual correlate of waveform periodicity or repetition rate. The faster a waveform repeats, the higher the perceived pitch.
120
What are harmonic complex tones?
Harmonic complex tones are sounds that consist of more than one frequency, where the frequencies are integer multiples of a fundamental frequency (F0).
121
What is the "pitch of the missing fundamental" phenomenon?
It is the phenomenon where, even if the fundamental frequency (F0) is absent or masked, we still perceive the pitch as corresponding to the F0 due to the presence of its harmonics.
122
Over what frequency range can humans accurately perceive melodies and musical intervals?
Humans can accurately perceive melodies over a fundamental frequency (F0) range of about 30 Hz to 4-5 kHz, which aligns with the range of musical instruments.
123
What is timbre, and how is it described?
Timbre refers to the quality of sound, distinguished by descriptions like bright, dull, harsh, and hollow, allowing us to differentiate sounds with the same loudness, pitch, and duration
124
How does timbre help differentiate sounds?
Timbre allows us to distinguish two sounds that have the same loudness, pitch, and duration, such as a violin and a piano playing the same note.
125
What aspect of timbre relates to high-frequency and low-frequency energy?
Sounds with more high-frequency energy tend to sound brighter, tinnier, or harsher, while sounds with more low-frequency content may sound deep, rich, or dull.
126
What is the temporal envelope of a sound?
The temporal envelope refers to the outline of the sound, particularly how it begins (attack) and ends. For example, a piano has a rapid onset, while a clarinet's onset is more gradual.
127
How can changing the onset of a sound affect its timbre?
Artificially altering the onset of a sound, such as reversing a piano recording, can dramatically change its character, making it unrecognizable as its original instrument.
128
Why are spectro-temporal variations important in music?
Subtle changes in the spectrum over time are crucial for creating plausible imitations of natural musical instruments, enhancing the realism of the sound.
129
What are the three main parts of the ear?
The three main parts of the ear are the outer ear, middle ear, and inner ear.
130
What are the components of the outer ear?
The outer ear consists of the pinna, ear canal (auditory meatus), and tympanic membrane (eardrum).
131
How do two ears help in sound localization?
The brain compares subtle differences in signals at the two ears to localize sounds in space, which is particularly useful for sounds coming from the sides.
132
What role does the pinna play in sound localization?
The pinna's unique folds and bumps create distinct peaks and dips in the frequency response, helping to localize sounds and resolve front-back and up-down confusions.
133
How does the brain learn to associate spectral peaks and dips with sound locations?
The brain learns to associate certain patterns of spectral peaks and dips with specific spatial locations, a process that remains plastic even in adulthood.
134
What effect did a study using molds on the pinnae demonstrate?
The study showed that people could learn to use their altered pinnae accurately within weeks, indicating the brain's adaptability to new acoustic cues.
135
At what frequency range do acoustic cues from the pinna primarily occur?
Acoustic cues from the pinna are primarily found at high frequencies, above about 2 kHz.
136
How does the ear canal contribute to hearing?
The ear canal acts as a tube that amplifies sound in the frequency range of about 1 to 4 kHz, which is particularly important for speech communication.
137
What is the primary function of the middle-ear bones?
Their primary function is to transmit vibrations from the tympanic membrane to the oval window of the cochlea and to match the impedance of air with that of fluid in the cochlea.
138
What distinguishes the middle-ear bones from other bones in the body?
The bones use a lever action to amplify and transmit vibrations effectively, helping to transfer sound energy from the air to the fluid in the cochlea.
139
What is the function of the cochlea in the inner ear?
The cochlea transduces mechanical vibrations of sound into neural signals that are processed by the brain.
140
What shape is the cochlea, and what is it filled with?
The cochlea is a spiral-shaped structure filled with fluid.
141
What runs along the length of the cochlea, and what is its function?
The basilar membrane runs along the length of the cochlea and vibrates in response to pressure differences caused by vibrations of the oval window.
142
What is the organ of Corti, and where is it located?
The organ of Corti runs the entire length of the basilar membrane from the base to the apex of the cochlea and contains hair cells that sense vibrations.
143
How many rows of hair cells are found in the organ of Corti, and what are their types?
The organ of Corti contains three rows of outer hair cells and one row of inner hair cells.
144
What role do the outer hair cells play in hearing?
The outer hair cells mechanically amplify sound-induced vibrations.
145
What is the function of the inner hair cells?
The inner hair cells form synapses with the auditory nerve and transduce vibrations into action potentials, which are sent along the auditory nerve to the brain.
146
What is the principle of frequency analysis, and where is it established?
Frequency analysis is the breakdown of complex sounds into their constituent frequencies, established in the cochlea.
147
How does the cochlea resemble a prism?
Like a prism separates light into its constituent colors, the cochlea separates complex sounds into their individual frequencies, with low frequencies causing maximal vibrations near the apex and high frequencies near the base.
148
What is the significance of the tonotopic representation in the auditory system?
Tonotopic representation is a major organizational principle that maintains the frequency-to-place mapping from the cochlea to the primary auditory cortex, allowing for the decomposition of sound.
149
How does the cochlea allow us to hear more than one sound at a time?
By decomposing sounds into their constituent frequency components, the cochlea enables us to distinguish and hear multiple sounds simultaneously.
150
Besides place of excitation, how else is frequency represented in the auditory system?
Frequencies are also represented by the timing of spikes within the auditory nerve, a property known as "phase locking."
Phase locking is crucial for comparing time-of-arrival differences of sound waveforms between the two ears, aiding in sound localization.
151
How does auditory processing differ from visual processing in terms of the primary cortical areas?
Unlike vision, where the primary visual cortex (V1) is an early processing stage, auditory signals undergo many stages of processing before reaching the primary auditory cortex in the temporal lobe.
152
What evidence supports the existence of a "pitch center" in the auditory cortex?
Evidence from human neuroimaging studies and single-unit physiology studies supports the existence of a "pitch center" in the auditory cortex.
There are questions about whether a single area of the cortex is responsible for coding features like pitch or if the coding is more distributed across multiple areas.
153
What are some known exceptions regarding spatial localization in auditory processing?
There is some consensus on spatial localization and neurons that are tuned to certain locations in space, indicating some level of feature extraction related to spatial hearing.
154
What factors determine when one sound will mask another?
A more intense sound will mask a less intense sound, particularly when the frequency content of the sounds overlaps.
155
What is "suppression" in the context of masking?
Suppression occurs when the response to the masking sound reduces the neural (and sometimes mechanical) response to the target sound.
156
How does the frequency of sounds affect their masking ability?
Low-frequency sounds are more likely to mask high frequencies, especially at high sound intensities, a phenomenon known as the "upward spread of masking."
157
What physiological phenomenon contributes to difficulties experienced by people with hearing loss in noisy environments?
The loss of sharp cochlear tuning due to cochlear damage leads to broader filtering and more masking, contributing to difficulties in noisy environments.
158
What is informational masking in auditory perception?
Informational masking refers to forms of masking that cannot be easily explained by cochlear interactions and often involve difficulties in perceptually segregating the target sound from masking sounds.
159
What is known about the physiological origins of informational masking?
Most forms of informational masking can be attributed to a perceptual “fusion” of the masker and target sounds or a failure to segregate the target from the masking sounds.
Relatively little is known, but some forms of informational masking appear to originate in the auditory cortex rather than earlier in the auditory pathway.
160
What is interaural time difference (ITD) and how does it aid in sound localization?
ITD is the difference in the time it takes for a sound to reach each ear. A sound source on the left reaches the left ear slightly before the right ear, allowing the brain to compute the sound's location. Humans can detect an ITD as small as 10 to 20 microseconds.
161
What are interaural level differences (ILD) and how do they contribute to sound localization?
ILDs are the differences in sound level reaching each ear, primarily used for localizing high-frequency sounds (above 1 kHz). The head creates an acoustic "shadow," resulting in higher sound levels at the ear closer to the source. ILDs can be up to 20 dB, and humans can detect differences as small as 1 dB.
162
How do the pinnae contribute to sound localization in terms of elevation and front-back positioning?
The pinnae filter high-frequency sounds, creating spectral details that provide cues about the elevation of a sound source and help distinguish whether it comes from the front or behind.
163
What is the duplex theory of sound localization?
he duplex theory posits that we use different acoustic cues for sound localization based on frequency:
- interaural time differences (ITDs) are most useful for low frequencies (below about 1.5 kHz),
- while interaural level differences (ILDs) are more effective at high frequencies, where the head shadow is pronounced.
- For broad frequency sounds, our spatial perception is primarily influenced by ITDs.
164
What is auditory stream segregation?
Auditory stream segregation is the process by which the auditory system decomposes complex waveforms produced by multiple sound sources into distinct auditory objects or streams. This allows us to make sense of our acoustic environment, enabling us to follow individual sounds over time, even in noisy settings like a café.
165
What principles govern auditory stream segregation?
Auditory stream segregation is guided by heuristic principles similar to those of Gestalt psychology.
Key principles include:
- Sounds in close temporal or frequency proximity tend to be grouped together.
- Sounds that begin and end simultaneously are perceived as a single auditory object.
- Spatial location is less reliable as a grouping cue due to reverberation effects.
Additionally, studies have revealed auditory illusions, where non-present melodies emerge or sounds become perceptually lost in competing organizations.
166
Reverberation Effects
Definition: Persistence of sound in an environment after the original sound source has stopped due to reflections off surfaces.
Effects:
- Blurring of Sounds: Makes sounds less distinct, complicating speech and sound identification.
- Temporal Ambiguity: Overlaps and blends sounds, challenging the separation of sound sources.
- Spatial Localization: Confuses spatial cues, making it difficult to pinpoint sound origins.
Note: Some reverberation can enhance sound richness (e.g., concert halls), but excessive reverberation can reduce clarity.
167
Gregory and Peter are both violinists who play with their city’s orchestra. As they are warming up for a concert, Peter says to Gregory: “I think your A is a bit flat.” Peter is suggesting that the ______ of Gregory’s violin needs to be adjusted.
pitch
168
Mathilda is studying the parts of the brain and their various functions. When she gets to the sense of hearing, she should probably realize that the primary auditory centers are located in the ______ lobes of her brain.
temporal
169
If you were to go to a concert of your favorite band, you’d want to avoid sitting right next to the powerful speakers. Based on your reading, you know that a sound amplitude over ______ decibels (db) sound pressure level (SPL) is considered dangerously loud.
120
170
What is the somatosensory system responsible for?
The somatosensory system provides the brain with information about our own body (interoception) and properties of the immediate external world (exteroception).
171
What is interoception?
The sense of the physiological state of the body. Hunger, thirst, temperature, pain, and other sensations relevant to homeostasis. Visceral input such as heart rate, blood pressure, and digestive activity give rise to an experience of the body’s internal states and physiological reactions to external stimulation. This experience has been described as a representation of “the material me,” and it is hypothesized to be the foundation of subjective feelings, emotion, and self-awareness.
172
What is exteroception?
The sense of the external world, of all stimulation originating from outside our own bodies.
173
What are cutaneous senses?
The senses of the skin: tactile, thermal, pruritic (itchy), painful, and pleasant.
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What is nociception?
Our ability to sense pain.
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Where are somatosensory receptors located?
Somatosensory receptors are located all over the body, from the surface of the skin to the depth of the joints.
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How is the information from somatosensory receptors divided?
The information is generally divided into four modalities: cutaneous senses, proprioception, kinesthesis, and nociception.
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What do cutaneous senses respond to?
Cutaneous senses respond to tactile (touch), thermal (temperature), pruritic (itch), and painful stimuli.
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What does proprioception refer to?
Proprioception refers to the sense of body position.
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What does kinesthesis refer to?
Kinesthesis refers to the sense of body movement.
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What is the fifth modality in the somatosensory system that has been identified?
The fifth modality is specifically for pleasant touch.
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What initiates the experience of pain, and what types of receptors are involved?
The experience of pain begins with the activation of nociceptors, which are specialized receptors responding to potentially tissue-damaging stimuli. Nociceptors are primarily of two subtypes: chemoreceptors, activated by chemical substances released from damaged or inflamed tissues, and mechanoreceptors, which require intense mechanical stimulation to activate due to their high threshold.
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What is the organization of the somatosensory cortex?
The somatosensory cortex is somatotopically organized, meaning sensory signals are represented according to their origin in the body.
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How does the sensation of pain from stepping on a pin differ over time, and what neural pathways are involved?
When stepping on a pin, a sharp stab is first felt due to fast-conducting A-fibers, which project to the somatosensory cortex. This part of the cortex is organized somatotopically, representing sensations based on body location.
After the initial stab, a deeper aching pain is felt, transmitted by nociceptors via thin C-fibers or Aδ-fibers to the insular cortex, which processes emotions and interoception.
Thus, the experience is composed of two signals: a sensory-discriminatory signal that locates the stimulus and an affective-motivational signal indicating the negative consequence of stepping on the pin.
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What sensation is felt first when stepping on a pin, and how is it signaled?
The first sensation is a sharp stab, signaled via fast-conducting A-fibers that project to the somatosensory cortex.
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What sensation follows the initial sharp stab from stepping on a pin?
A wave of more aching pain follows, signaled by C-fibers or Aδ-fibers to the insular cortex and other brain regions.
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What are the two separate signals experienced when stepping on a pin?
One is a sensory-discriminatory signal for localizing the touch stimulus; the other is an affective signal indicating the unpleasantness of the experience.
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How is pain typically divided in the context of sensory processing?
Pain is commonly divided into sensory–discriminatory aspects (localization of stimulus) and affective–motivational aspects (the unpleasant experience).
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What are C-tactile fibers, and what do they respond to?
C-tactile fibers are a subtype of C-fibers that respond to gentle stroking touch, rather than painful stimuli.
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How do C-tactile fibers relate to the perception of touch?
The firing rate of C-tactile fibers correlates closely with how pleasant the stroking feels, indicating they code for gentle, social touch.
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What is the social touch hypothesis?
The social touch hypothesis proposes that C-tactile fibers form a system for touch perception that supports social bonding.
"Proposes that social touch is a distinct domain of touch. C-tactile afferents form a special pathway that distinguishes social touch from other types of touch by selectively firing in response to touch of social-affective relevance; thus sending affective information parallel to the discriminatory information from the Aβ-fibers. In this way, the socially relevant touch stands out from the rest as having special positive emotional value and is processed further in affect-related brain areas such as the insula."
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How is the C-tactile system organized similarly to the pain system?
Fast-conducting A-fibers contribute to sensory-discriminatory aspects of touch, while thin C-fibers contribute to affective-motivational aspects.
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What factors influence how we experience touch or pain?
Our experience of touch or pain is influenced by top-down factors such as motivation, expectation, mood, fear, and stress.
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What is C-fibers vs C-tacticle fibers?
C-fibers: Slow-conducting unmyelinated thin sensory afferents with a diameter of 1 μm and a conduction velocity of approximately 1 m/s. C-pain fibers convey noxious, thermal, and heat signals; C-tactile fibers convey gentle touch, light stroking.
C-tactile fibers: a subtype of C-fibers. C-tactile fibers convey gentle touch, light stroking
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How does the brain influence our experience of pain and somatosensory signals?
The brain interprets somatosensory and nociceptive signals subjectively, allowing us to function normally despite pain. This perception is highly malleable and influenced by factors such as motivation, attention, emotion, and context.
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What are the key features of ascending pain pathways in the nervous system?
Ascending Pain Pathways: Injury signals travel via fast Aα/Aβ-fibers (pressure/stretch) to the somatosensory cortex through the dorsal column nuclei and via slow C-pain/Aδ-fibers (nociceptors) to second-order neurons in the dorsal horn of the spinal cord. These neurons cross over, forming the ascending spinothalamic tract, which projects to the thalamus and then to the somatosensory and insular cortex, affecting the pain experience.
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What are the key features of descending pain pathways in the nervous system?
Motivational states activate pathways from the anterior cingulate, insular cortex, amygdala, and hypothalamus to the midbrain periaqueductal gray (PAG), modulating pain transmission via the rostral ventromedial medulla (RVM). This pathway can produce analgesia through the release of endogenous opioids, using ON- and OFF-cells for inhibitory or facilitatory control of nociceptive signals.
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What does the motivation–decision model propose about how the brain evaluates situations?
The motivation–decision model suggests that the brain automatically and continuously evaluates the pros and cons of any situation, weighing impending threats against available rewards.
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What activates the brain's descending pain modulatory system?
When something more important for survival than avoiding pain arises, it activates the descending pain modulatory system, which inhibits nociceptive signaling to allow attention to critical actions.
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What role do ON- and OFF-cells play in the descending pain modulatory system?
ON- and OFF-cells in the brainstem regulate the amount of nociceptive signal that reaches the brain, facilitating or inhibiting nociceptive signals from the body.
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How does the descending pain modulatory system relate to opioid signaling and analgesics?
The descending system is dependent on opioid signaling, and analgesics like morphine relieve pain through this circuit.
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What is analgesics
Pain relief.
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What is the brain’s descending pain modulatory system?
A top-down system involving several parts of the brain and brainstem, which inhibits nociceptive signaling so that the more important actions can be attended to
A top-down pain-modulating system able to inhibit or facilitate pain. The pathway produces analgesia by the release of endogenous opioids. Several brain structures and nuclei are part of this circuit, such as the frontal lobe areas of the anterior cingulate cortex, orbitofrontal cortex, and insular cortex; and nuclei in the amygdala and the hypothalamus, which all project to a structure in the midbrain called the periaqueductal grey (PAG). The PAG then controls ascending pain transmission from the afferent pain system indirectly through the rostral ventromedial medulla (RVM) in the brainstem, which uses ON- and OFF-cells to inhibit or facilitate nociceptive signals at the spinal dorsal horn.
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How can thinking about positive things, like loved ones, impact pain perception?
Focusing on positive thoughts, such as loved ones and future rewards, can be pivotal to survival and may relieve pain by activating the brain’s descending modulation circuit.
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What contributes to the placebo effect in pain relief?
The expectation of pain relief from medical treatments contributes to the placebo effect, which involves the brain's descending modulation circuit and its opioid system
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What everyday pleasurable activities can decrease pain?
Enjoyable activities like eating tasty food, listening to good music, or experiencing pleasant touch can reduce pain, likely through mechanisms in the brain similar to those involved in the placebo effect
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Describe the classic experiment by Dum and Herz (1984) involving rats and pain tolerance.
Rats fed highly rewarding chocolate-covered candy endured a heated metal plate at painful temperatures for twice as long as those expecting normal rat food. This effect was eliminated when the rats' opioid system was blocked, indicating endorphin release was responsible for the pain relief from reward anticipation.
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What does the experiment by Dum and Herz suggest about the relationship between reward anticipation and pain?
The experiment suggests that anticipating a reward can enhance pain tolerance by triggering the release of endorphins, demonstrating a direct link between psychological expectations and physical pain responses.
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What is allodynia?
Allodynia is a chronic condition where innocuous touch (normally pleasant and non-painful) is perceived as painful due to neuronal injury, particularly in the spinal dorsal horn.
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How does neuronal injury contribute to allodynia?
In allodynia, injury causes Aβ-afferents (activated by non-nociceptive touch) to access nociceptive pathways, leading the brain to interpret gentle touch as painful
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Why can sunburned skin be particularly sensitive to touch?
Sunburn can lead to increased sensitivity where even light touch feels painful, similar to the experience of allodynia.
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What is noxious stimuli?
A stimulus that is damaging or threatens damage to normal tissues.
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What typically initiates chronic pain conditions?
Chronic pain conditions often begin with an injury to a peripheral nerve or surrounding tissue, which releases hormones and inflammatory molecules that sensitize nociceptors.
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How does sensitization affect nerves in chronic pain conditions?
Sensitization makes injured nerves and neighboring afferents more excitable, leading uninjured nerves to become hyperexcitable and contribute to persistent pain.
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What role does the central nervous system play in chronic pain?
Sensitization can occur in the brain and the descending modulatory system of the brainstem, complicating the identification of altered pain perception levels in chronic pain patients.
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What psychological effects can chronic pain have on individuals?
Chronic pain can lead to depression, anxiety (due to fear or anticipation of future pain), and immobilization, which may exacerbate the pain further.
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How does attention and emotion influence pain perception?
Negative emotions and focusing on pain can increase sensitization, possibly keeping the descending pain modulatory system in a facilitation mode.
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What are some strategies used in hospitals to manage pain during treatments?
Distraction techniques are commonly used to help patients endure painful treatments, such as changing bandages on large burns.
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Why is diversion not a long-term solution for chronic pain patients?
For chronic pain patients, diverting attention may not provide a sustainable solution to managing pain.
Social support and positive emotional factors can help reduce the risk of chronic pain after an injury and aid in adjusting to bodily changes.
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What effect can the anticipation of a worse pain have on the perception of a moderate pain?
When a moderate pain represents relief from something worse, it can be perceived as pleasant instead of painful.
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What did the study involving heterosexual males and sensual caresses reveal about touch perception? How do brain responses to touch differ based on the perceived source?
Participants rated sensual caresses as unpleasant when they thought a male experimenter was administering them, despite the caresses being performed by a female.
Brain responses in the somatosensory cortex were reduced for touch believed to come from a male, illustrating the top-down regulation of touch perception.
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What do pain and pleasure share in terms of brain processing?
Pain and pleasure share modulatory systems in the brain and can be experienced vicariously, meaning we can empathize with others' experiences of pain or pleasure without being directly affected ourselves.
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Which brain areas are involved in processing both personal pain and the pain of others?
The anterior cingulate and insula are active when individuals feel their own pain and when they learn that a loved one is in pain.
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What similar effect has been found regarding pleasurable touch?
The posterior insula of participants watching videos of someone else's arm being gently stroked activated similarly to when they themselves receive pleasurable touch.
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What are some sensations that can be experienced vicariously?
Sensations such as pain, itch, and pleasurable touch can be experienced vicariously, indicating the brain's ability to process the experiences of others.
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High-threshold sensory receptors of the peripheral somatosensory nervous system that are capable of transducing and encoding noxious stimuli are known as:
Nociceptors
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What is the difference between Sensory adaptation and habituation?
Sensory adaptation:
Decrease in sensitivity of a receptor to a stimulus after constant stimulation
- Radio volume in car
Habituation:
Decreasing responsiveness to a stimuli as a result of repeated exposure, but you could draw your awareness back to it (not related to sensitivity of the receptor itself)
- e.g. annoying neighbours bad music
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A-fibers vs C-pain fibers quick summary
A-fibers project onto our somatosensory cortex
- super fast, fire right away, myelinated
C-pain fibers
- convey noxious, thermal, and heat signal to the insular cortex and other brain regions involved in processing of emotion and interoception (sense of your internal state)
- C-tactile fibers (different from C-pain fibers) respond to gentle stroking touch
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What is the size-weight illusion in brief?
When people compare the weight of a larger and smaller object of THE SAME WEIGHT, the smaller one feels heavier
This happens because people generally estimate the weight of the larger object to be heavier, and consequently generate excess muscular power to lift it.
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What is the brightness-weight illusion in brief?
When people compare the weight of a darker and brighter object of THE SAME WEIGHT, the BRIGHTER one feels heavier
same reason as size-weight illusion
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What is material-weight illusion
When people compare the weight of a heavy-looking material and a light-looking material of THE SAME WEIGHT, the LIGHTER one feels heavier
same reason as size-weight illusion
