C2 - Sensation And Perception Flashcards
1
Q
What is sensation
A
The taking of physical, electromagnetic, auditory, and other info from our internal and external environment to convert into electrical signals in the nervous system
2
Q
What is perception
A
The process of processing information within the CNS in order to make sense of the informations significance
3
Q
What is proximal and distal stimuli?
A
Proximal stimuli directly interacts with and affects the sensory receptors, this informs the observer about the presence of distal stimuli
4
Q
What is psychophysics
A
The study of the relationships between the physical nature of stimuli and the sensation/perceptions they evoke
5
Q
Ganglia
A
Collections of neurons cell bodies found outside of CNS
6
Q
What are osmoreceptors?
A
Receptors that respond to changes in osmolarity of the blood (water homeostasis)
7
Q
Sensory stimuli is transmitted where in the brain?
A
Projection areas, which further analyze the sensory input
8
Q
All sensory information is sent to the CNS in the form of…
A
Action potentials
9
Q
What is threshold
A
The minimum amount of stimuli that renders a difference in perception
10
Q
What are the 3 main types of thresholds
A
-Absolute threshold
-Threshold of conscious perception
-Difference threshold
11
Q
What is absolute threshold
A
The minimum intensity at which a stimulus must be to be transduced (converted into action potentials)
In other words it is about how bright, far, loud, or intense a stimulus must be before it is sensed
12
Q
What does the stimulus never reach if it is below the absolute threshold
A
The central nervous system
13
Q
What is the threshold of conscious perception
A
The level of intensity that a stimulus must pass in order to be consciously perceived by the brain
14
Q
What is subliminal perception?
A
Information that is received by the CNS but does not cross the threshold of conscious perception
15
Q
Main difference in being below absolute threshold vs below threshold of conscious perception
A
Below absolute threshold the stimulus will never be transduced and thus never reach the CNS
Below the threshold of conscious perception the stimulus arrives at the CNS but does not reach the higher-order brain regions that control attention and consciousness
16
Q
What else is the difference threshold called?
A
The just noticeable difference (jnd)
17
Q
What is the difference threshold?
A
The minimum change in magnitude required for an observer to perceive that two different stimulus are, in fact, different
18
Q
If below the difference threshold, 2 possibly different stimuli will seem to the observer as…
A
The same
19
Q
What happens in a common psychophysical discrimination testing experiment?
A
A participant is presented with a stimulus, it is then varied slightly until they report a change in stimuli, it is then recorded as the just noticeable difference
20
Q
The just noticeable difference or difference threshold is usually reported or recorded as…
A
A fraction or percentage
21
Q
Who was often credited with the observation that difference thresholds are proportional and must be computed as percentages?
A
Ernst Heinrich Weber
Often called the Webers Law
22
Q
What does the signal detection theory study?
A
The effects of nonsensory factors such as experiences (memory), motives, and expectations on perception of stimuli
Both external and internal factors
23
Q
Example in signal detection theory; how loud would someone have to tell your name in a crowd for you to notice? Well this comes down to what factors?
A
-Environmental factors
-Social factors
-Psychological factors
-Personality factors
24
Q
A basic signal detection experiments consists of many trials, what is presented in these trials?
A
During each trial a stimulus may or may not be presented
25
Trials in which the signal is presented, and those without a signal are called…
-Noisy trials- are those with a presented signal
-Catch trials- are those without a presented signal
26
What are the 4 possible outcomes for each trial in a signal detection theory expirement?
A hit - a trial in which the signal is presented and the subject correctly perceives the signal
A miss - a trial in which the subject fails to perceive the presented signal
A false alarm - a trial in which the subject indicates perceiving the signal, even though the signal was not presented
A correct negative - a trial in which the subject correctly identifies that no signal was present
27
Our ability to detect a stimulus can change over time through repeated stimulation, if we start to block it out of our notice this is due to?
Sensory Adaption
28
Most of the exposed portion of the eye is covered by a thick structural layer known as…
The sclera
29
What is the colored part of the eye?
The iris
30
What is the white part of the eye?
The sclera
31
What covers the frontmost portion of the eye?
The cornea
32
The eye is supplied from nutrients by what 2 sets of blood vessels?
The choroidal vessels - a complex intermingling of blood vessels between the sclera and retina
Also the retinal vessels
33
What is the innermost layer of the eye?
The retina
34
What does the Retina contain?
Photoreceptors that transduce light into electrical information the brain can process
Photons of light to electrical signals
35
Cornea function
Gathers and focuses the light
36
What are the 2 chambers and there locations in the eye?
Anterior chamber - lies in front of the iris
Posterior chamber - between the iris and lens
37
The iris is composed of what 2 muscles?
Dilator pupillae - opens the pupil under sympathetic stimulation
Constrictor pupillae - constricts the pupil under parasympathetic stimulation
38
What 2 things is the iris continuous with?
The choroid, and the ciliary body
39
What is the choroid and it’s function?
It is a vascular layer of connective tissue that surrounds and provides nourishment to the retina
40
What is the ciliary body function?
Produce the aqueous humor that bathes the front part of the eye
41
Where does the aqueous humor drain into?
The canal of schlemm
42
Where is the lens and what is its function?
The lens is right behind the iris and helps control the refraction of the incoming light
43
What muscle is a component of the ciliary body, and what does it do?
The ciliary muscle, it is under parasympathetic control, when contracted, it pulls on the suspensory ligaments and changes the shape of the lens to focus on a image as the distance varies
A phenomenon called accommodation
44
What type of humor lies behind the lens?
The vitreous humor, a transparent gel that supports the retina
45
What is the retina considered a part of?
The CNS, as it’s a developed outgrowth of brain tissue
46
What is the duplicity or duplicity theory of vision?
It states that the retina contains 2 types of photoreceptors
-those specialized for light and dark detection
-those specialized for color detection
47
The retina is made up of approximately how many cones and rods?
6 million cones and 120 million rods
48
What are cones used for?
Color vision and to sense fine details, most effective in bright light
49
What forms do cones come in?
Cones come in 3 forms which are named for the wavelengths of light they best absorb
-Short (blue) wave
-Medium (green) wave
-Long (red) wave
50
When are rods most functional?
In reduced light because they are highly sensitive to photons
Only allow sensation of light and dark
51
All rods contain only a single pigment called
Rhodopsin
52
Why are rods less useful for detection of fine details?
Because rods are spread over a much larger area of the retina
53
What is the central location of the retina called?
The Macula
54
What does the macula contain?
A high concentration of cones
55
What is the center most region of the macula called? And what does it contain?
The Fovea, contains only cones
56
The further away you move from the fovea the more concentration of what?
Rods, and less of cones
57
Visual acuity is best at…
The Fovea
58
What leaves the eye?
The optic nerve
59
Region of the retina which is devoid of photoreceptors?
The optic disk, gives rise to a blind spot
60
Rods and cones do not connect directly to the optic nerve, instead what do they connect to? Describe them
Layers of neurons in between
First they synapse directly to bipolar cells, which highlight gradients between adjacent rods and cones
Then bipolar cells synapse with ganglion cells, axons of which group together to form the optic nerve
61
Bipolar and ganglion cells are located in front of rods and cones too, what does this mean?
That a photon must actually navigate past several layers of cells to reach the rods and cones at the back of the retina
62
As the number of receptors that converge through the bipolar neurons onto one ganglion cell increases, the resolution…
Decreases
multiple input signals are combined, resulting in a lower level of detail or resolution.
63
What do amacrine and horizontal cells do?
help enhance the contrast and highlight subtle variations in visual information by collecting input from multiple retinal cells within a specific region. This allows them to refine the signals before passing them on to ganglion cells, ultimately aiding in the perception of finer details and contrasts in the visual scene.
64
If an object is to your left than the photons from that object stimulate what side in each eye?
The right side of retina in each eye
65
An object in the nasal field of the right eye stimulates what fibers in the right eye?
The temporal retinal fibers
66
An object in the temporal field of the left eye would stimulate what fibers if the left eye?
The nasal retinal fibers
67
As the retinal fibers from each eye travel from the optic nerves what happens at the optic chiasm?
The nasal retinal fibers from the left and right eyes cross paths (only the nasal fibers)
68
Why do the temporal retinal fibers not need to cross?
Because they are already the fibers stimulated on the opposite side of your body from the object
69
After leaving the optic chiasm the reorganized pathways are called…
Optic Tracts
70
From the optic chiasm some nerve fibers go through where in the thalamus? After of which how do they get to the visual cortex?
Some nerve fibers pass through the lateral geniculate nucleus (LGN) in the thalamus where they synapse with nerves that pass through radiation’s in the temporal and parietal lobes to the visual cortex in the occipital lobe
71
Other fibers from the optic chiasm branch from the optic tract, skip the thalamus and head directly where?
The superior colliculus in the midbrain
(For reflexes)
72
What is visual parallel processing
The brains ability to analyze information regarding color, form, motion, and depth simultaneously
73
What does form refer to?
Not only the shape of an object, but also our ability to discriminate an object of interest from the background by detecting its boundaries
74
Neurons carrying information from the fovea and surrounding central portion of the retina synapse with what cells?
Parvocellular cells in the Lateral Geniculate nucleus
75
What are the attributes of Parvocellular cells?
They have very high color spatial resolution; permit us to detect very fine details when thoroughly examining an object
However these cells can only work with stationary or slow moving objects due to very low temporal resolution
76
What are magnocellular cells well suited for detecting?
Motion, due to very high temporal resolution
But have low spatial resolution therefore they provide a blurry but moving image of an object
77
Where in our vision does magnocellular cells predominately receive inputs from?
Periphery of our vision
78
What is depth perception?
What does it heavily rely on?
Our ability to discriminate the 3-d shape of our environment and judge the distance of objects within
Heavily dependent on discrepancies between the inputs the brain receives from both eyes
79
What specialized cells in the visual cortex are responsible for comparing the inputs to each hemisphere and detecting the differences?
Binocular neurons
80
What do feature detectors help with?
Help out brain learn to associate patterns of stimuli with expected behaviors or outcomes
Each feature detector cell type detects a very particular, individual feature of an object in the visual field
81
What is our vestibular sense?
Our ability to both detect rotational and linear acceleration and to use this information to inform our sense of balance and spatial orientation
82
Where does a sound wave first reach?
The cartilaginous outside part of the ear called the pinna or auricle
83
What is the auricles function?
To funnel sound waves into the external auditory canal
84
External auditory canal function
Directs sound waves to the tympanic membrane
85
What happens when the sound waves reach the tympanic membrane
The tympanic membrane vibrates in phase with the incoming sound waves
86
What divides the outer ear from the middle ear?
The tympanic membrane
87
The middle ear houses what bones?
The ossicles which are the smallest 3 bones in the body
88
Ossicles function
Help transmit and amplify the vibrations from the tympanic membrane to the inner ear
89
What is the order of ossicles following the tympanic membrane?
Malleus, incus, then stapes
90
What does the baseplate of the stapes rest on?
The oval window of the cochlea, which is the entrance to the inner ear
91
How is the middle ear connected to the nasal cavity?
Via the Eustachian tube
92
Eustachian tube function
Helps to equalize pressure between the middle ear and the environment
93
What does the inner ear sit within?
A bony labyrinth which is a hollow region of the temporal bone containing the cochlea, vestibule, and semicircular canals
94
Inside the bony labryinth rests a continuous collection of tubes and chambers called…
The membranous labyrinth
95
The membranous, and bony labyrinth is filled with what?
Membranous labyrinth is filled with potassium rich fluid called endolymph; it’s suspended within the bony labyrinth by a thin layer of fluid called perilymph
96
What contains the receptors for hearing? What parts does it have?
The cochlea, it’s divided into 3 parts called scalae
97
What does the middle scala house?
The actual hearing apparatus called the Organ of Corti
98
What does the organ of corti rest on?
A thin, flexible membrane called the basilar membrane
99
Organ of corti contains thousands of what cells?
Hair cells that are bathed in endolymph
100
What is on top of the organ of corti?
A relatively immobile membrane called the tectorial membrane
101
What are the other 2 scalae composition and location?
The other 2 are filled with perilymph, surround the hearing apparatus, and are continuous with oval window and round window
102
When sound enters the cochlea through the oval window what does it cause transmitions to and vibrations in?
Causes vibrations in perilymph, which are transmitted to the basilar membrane
103
What is the round window?
A membrane covered hole in the cochlea
104
Because fluids are essentially incompressible, the round window permits the perilymph to do what?
Actually move within the cochlea
105
What does the hair cells of the organ of corti do?
Transduce the physical stimulus into electrical signals which is carried to the central nervous system by the auditory nerve (vestibulocochlear nerve)
106
Where and What does the vestibule contain? What is its function?
Located in the bony labyrinth it contains the utricle and saccule, which are sensitive to linear acceleration, and used as part of the balancing apparatus, determine one’s orientation in 3-D space
107
Utricle and saccule contain modified hair cells covered with…
Otoliths
108
As the body accelerates what does the otoliths do?
Resist the motion, this bends and stimulates the underlying hair cells sending signals to brain
109
What does the cochlea detect?
Sound
110
The utricle and saccule detect?
Linear acceleration
111
The semicircular canals detect?
Rotational acceleration
112
What is the auditory pathway? (Full pathway)
Cochlea to vestibulocochlear nerve to medial geniculate nucleus (MGN) of thalamus to auditory cortex
113
What is the visual pathway? (Full pathway)
Retina to optic nerve to optic chiasm to optic tracts to lateral geniculate nucleus (LGN) of thalamus to visual radiations to visual cortex
114
The semicircular canals each end in a swelling called
An ampulla
Where the hair cells are located
115
In the semicircular canals how are signals sent to brain when the head rotates?
When the head rotates. Endolymph in the semicircular canals resist this motion, bends underlying hair cells, sending signals to brain
116
Where does most electrical stimuli from sound go to through the vestibulocochlear nerve?
The brainstem, where it ascends to the medial geniculate nucleus of the thalamus
117
From the medial geniculate nucleus where can some info be sent? (For sound)
To the superior olive, which localized sound
Also the inferior colliculus, involved in the startle reflex
118
What are stereocilia?
The long tufts on top of the hair cells surface, play a crucial role in the process of hearing by converting sound vibrations into electrical signals that the brain can interpret
119
As vibrations reach the basilar membrane what happens to the stereocilia?
The stereocilia begin to sway, swaying causes the opening of ion channels, causing receptor potential
120
Certain hair cells are directly connected to tectorial membrane, what are they involved in?
The amplifying of incoming sound
121
What is place theory?
The location of a hair cell on the basilar membrane determines the perception of pitch when the hair cell is vibrated
122
Where would high frequency and low frequency vibrations occur?
High frequency vibrations would occur at the basilar membrane very close to oval window
Low frequency vibrations would occur at apex, away from oval window
123
The cochlea is tonotopically organized, what does this mean?
Means that which hair cells are vibrating gives the brain an indication of the pitch of sound
124
What is the only sense that does not pass through the thalamus?
Smell
125
Where are olfactory chemoreceptors located?
In the olfactory epithelium (upper part of nasal cavity)
126
What are pheromones
Chemicals secreted by one animal, once bonded with chemoreceptors, compel or urge another animal to behave a certain way
Have debatable effects on humans
127
Olfactory pathway
Odor molecules inhaled into nasal passages — contact the olfactory nerves in the olfactory epithelium — receptors cells are activated, sending signals to olfactory bulb — signals relayed via the olfactory tract to higher regions of brain, including limbic system
128
Taste is detected by what receptors?
Chemoreceptors
129
What are the 5 basic tastes
Sweet, sour, salty, bitter, umami (savory)
130
What is flavor?
The complex interplay between smell and taste, can be affected by nonchemical stimuli like texture and the individuals mood
131
Saltiness is a reaction to…
Alkali metals, generally triggered by the sodium found in table salt
132
Sourness is a reaction to…
Acid
133
Receptors for taste are groups of cells called what? Where are they located
Taste buds, located in little bumps on the tongue called papillae
134
Gustatory pathway
Taste buds — brainstem — ascends to the taste center in the thalamus — higher order brain regions
135
Somatosensation is often reduced to touch, but has what 4 modalities?
Pressure, vibration, temperature, pain
136
Pacinian corpuscles respond to
Deep pressure and vibration
137
Meisner’s corpuscles respond to
Light touch
138
Merkel cells (discs) respond to
Deep pressure and texture
139
Ruffini endings respond to
Stretch
140
Free nerve endings respond to
Pain and temperature
141
For somatosensation where does the signals from receptors go?
It eventually gets to the somatosensory cortex in the parietal lobe
142
What is a two-point threshold?
The minimum distance necessary between two points of stimulation on the skin such that the points will be felt as two distinct stimuli, below threshold = felt as same stimuli
143
What does the size of two point thresholds depend on?
The density of nerves in the particular area of skin being tested
144
Temperature is judged relative to physiological zero; what is physiological zero?
Normal temperature of skin (86•-97•)
Objects feel warmer above, colder below physiological zero
145
What is the gate theory of pain?
It proposed that there is a special “gating” mechanism to turning pain signals on or off, affecting whether or not we perceive pain; signals can either be processed to accentuate the perceived pain or attenuate it at the spinal cord itself
146
What is smell, and taste sensitive to
Smell is sensitive to volatile or aerosolized compounds while taste is sensitive to dissolved compounds
147
Kinesthetic sense is also called
Proprioception
148
What is proprioception/kinesthetic sense?
Ability to tell where one’s body is in space
149
What are the receptors for proprioception and where are they mostly found?
Proprioceptors, mostly found in muscle, and joints
150
What is bottom-up processing?
Object recognition by parallel processing and feature detection
Brain takes the individual sensory stimuli and combines them together to create a cohesive image before determining what the object is
-Takes longer but less prone to mistakes
151
What is top-down processing?
Driven by memories and expectations that allow the brain to recognize the whole object without analyzing little details to put together
-Faster but more prone to mistakes
152
When is deja vu evoked?
When we have recognition without an obvious reason
153
What is perceptual organization?
The ability to create a complete picture or idea by combining top-down and bottom-up processing with all of the other sensory clues gathered from an object
154
What is relative size?
Idea that objects appear larger the closer they are
155
What is interposition?
When 2 objects overlap, the one in front is closer
156
What is linear perspective?
The convergence of parallel lines at a distance; the greater the convergence, the further the distance
157
What is motion parallax?
The perception that objects closer to us seem to move faster when we change our field of vision (look at something else)
158
What is convergence referring to a secondary binocular cue?
The brain detecting the angle between the 2 eyes required to bring and object into focus
Difference in the degree of convergence is used to perceive distance
159
What is constancy referring to vision?
Our ability to perceive that certain characteristics of objects remain the same, despite changes in the environment
160
What are Gestalt principles?
A set of general rules that account for the fact that the brain tends to view incomplete stimuli in organized, patterned ways
161
What is the law of proximity?
Elements close to one another tend to be perceived as a unit
162
What is the law of similarity?
Objects that are similar tend to be grouped together
163
What is the law of good continuation?
Elements that appear to follow in the same pathway tend to be grouped together
164
What is subjective contours?
The way we perceive contours, therefore, shapes that are not actually present in the stimulus
165
What is the law of closure?
When a space is enclosed by a contour, the space tends to be perceived as a complete figure
166
The gestalt principles are governed by?
The law of Pragnanz
167
What does the law of pragnanz say?
That perceptual organization will always be as regular, simple, and symmetrical as possible
