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MCAT > Sensation and Perception (Behavioral Sciences) > Flashcards

Sensation and Perception (Behavioral Sciences) Flashcards

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MCAT flashcards
1
Q

Transduction

A
  • Conversion of physical, electromagnetic, auditory, and other information from our internal/external environment to electrical signals in the nervous system
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2
Q

Sensation

A
  • Performed by receptors in the peripheral nervous system, which foward the stimuli to the CNS in the form of action potientials and neurotransmitters (Raw signal)
  • Unfiltered and unprocessed until entering CNS
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3
Q

Perception

A
  • Processing of sensory information to make sense of the significance
  • Comprehending and responding to the sensory information
  • Include both external sensory experience and the internal activities of the brain and spinal cord
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4
Q

Sensory Receptors

A
  • Neurons that respond to stimuli and trigger electrical signals
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5
Q

Distal Stimuli

A
  • Stimuli which originate outside of the body (prior to reaching the body), part of the “outside world”
  • Distal= in the distance
  • A campfire is a distal stimulus
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6
Q

Proximal Stimuli

A
  • Directly interact with and affect the sensory receptors, informing the observer about the presence of distal stimuli
  • Proximal= in close proximity
  • The photons that reach the observer’s rods and cones, and the heat the observer feels during a campfire
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7
Q

Psychophysics

A
  • Relationship between the physical nature of stimuli and the sensations/perceptions they evoke
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8
Q

Ganglia

A
  • Collections of neuron cell bodies found outside the CNS
  • When transduction occurs, the electrochemical energy is sent along neural pathways to various projection areas in the brain (further analyze the sensory input)
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9
Q

Photoreceptors

A
  • Respond to electromagnetic waves in the visible spectrum (sight)
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10
Q

Hair Cells

A
  • Respond to movement of fluid in the inner ear structures (hearing, rotational/linear acceleration)
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11
Q

Nociceptors

A
  • Respond to painful or noxious stimuli (somatosensation)
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12
Q

Thermoreceptors

A
  • Respond to changes in temperature (thermosensation)
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13
Q

Osmoreceptors

A
  • Respond to the the osmolarity of the blood (water homeostasis)
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14
Q

Olfactory Receptors

A
  • Respond to volatile compounds (smell)
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15
Q

Taste Receptors

A
  • Respond to dissolved compounds (taste)
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16
Q

Threshold

A
  • Minimum amount of a stimulus that renders a difference in perception
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17
Q

Absolute Threshold

A
  • Minimum stimulus of energy that is needed to activate a sensory system (Sensation Threshold)
  • How bright, loud, or intense a stimulus must be before it is sensed
  • Minimum intensity at which a stimulus will be transduced (converted to AP)
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18
Q

Limina Threshold

A
  • Subliminal perception- The perception of a stimulus below a given threshold
  • Threshold of conscious perception
  • The stimulus arrives at the CNS, but does not reach the higher-order brain regions that control attention and consciousness
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19
Q

Discrimination Testing (Psychophysical Discrimination Testing)

A
  • Analyzes the limit in human perceptive ability
  • Participant is presented with a slightly varied stimulus, and is asked to identify whether there is a difference in the second stimulus
  • Difference is increased until the participant notices a change
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20
Q

Difference Threshold (Just Noticable Difference (jnd))

A
  • Minimum difference in the magnitude between 2 stimuli before one can perceive this difference
  • Weber’s Law- There is a constant ratio between the change in stimulus magnitude needed to produce a just noticable difference and the magnitude of the original stimulus
  • For higher magnitude stimuli, the actual difference must be larger to produce a jnd
  • Apply a ratio on MCAT
  • If the jnd is .68% for sound frequency, an individual would be expected to discriminate between sounds at 1000 Hz and 1006.8 Hz (6.8 Hz=0.68% of 1000 Hz)
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21
Q

Signal Detection Theory

A
  • The changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context
  • Allows to explore response bias, which is the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors
  • A basic signal detection experiment consists of many trials (signal may or may not be presented)
  • Catch trials- Signal presented
  • Noise trials- No signal presented
  • Four Outcomes: Hit (Correctly percieves signal), Misses (Fails to percieve a signal), False Alarms (Percieved a signal when none were given, and Correct Negatives (Correctly identifies when no signal was given)
  • A significant proportion of misses/false alarms= Response bias
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22
Q

Adaptation

A
  • Detection of a stimulus can change over time
  • Can have both a physiological (sensory) and psychological (perceptual) component
  • The mind/body try to focus attention on most relevant stimuli
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23
Q

Sclera

A
  • Thick structural layer covering most of the exposed portion of the eye
  • White of the eye
  • Does not cover frontmost portion of the eye (cornea)
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24
Q

Choroidal vessels

A
  • A complex intermingling of blood vessels between the sclera and the retina
  • Supplies eye with nutrients
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25
Q

Retina

A
  • Innermost layer of the eye
  • Contains the actual photorecpetors that transduce light into electrical information the brain can process
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26
Q

Cornea

A
  • Light first passes through
  • Clear, domelike window in front of the eye
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27
Q

Anterior chamber

A
  • Lies in front of the iris
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28
Q

Posterior chamber

A
  • Between the iris and lens
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29
Q

Iris

A
  • Colored part of the eye
  • Composed of two muscles:
  1. Dilator Pupillae- Opens the pupil under sympathetic stimulation
  2. Constrictor Pupillae- Constricts the pupil under parasympathetic stimulation
  • Continuous with the choroid and the ciliary body
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30
Q

Ciliary body

A
  • Produces the aqueous humor (bathes the front part of the eye before draining into the canal of Schlemm)
  • The ciliary muscle in the ciliary body contracts under parasympathetic control
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31
Q

Lens

A
  • Lies right behind the iris
  • Helps control the refraction of the incoming light
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32
Q

Accomodation

A
  • As the ciliary muscle contracts, it pulls on the suspensory ligaments and changes the shape of the lens
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33
Q

Vitreous

A
  • Behind the lens
  • Transparent gel that supports the retina
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34
Q

Retina

A
  • Located in the back of the eye
  • Screen consisting of neural elements and blood vessels
  • Converts incoming photons of light to electrical signals
  • Part of the CNS
  • Develops as an outgrowth of brain tissue
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35
Q

Duplicity Theory of Vision (Duplicity)

A
  • Retina contains two kinds of photoreceptors; those specialized for light/dark and those specialized for color detection
36
Q

Cones

A
  • Used for color vision and to sense fine details
  • Most effective in bright light
  • Come in 3 forms (Named for the wavelenghts of light they best absord)
  1. Short (S, also called blue)
  2. Medium (M, green)
  3. Long (L, red)
  • Cones are for color vision
37
Q

Rods

A
  • Rods function best in “roduced” light
  • More functional and only allow sensation of light/dark because they all contain a single pigment (Rhodopsin)
  • Low sensitivity to detail
  • Not involved in color vision
  • Night vision
  • Many more rods than cones
38
Q

Macula

A
  • The central section of the retina
  • High concentration of cones
  • The centermost point called the fovea, contains only cones (Best visual acuity)
  • As one moves further away from the fovea, the concentration of rods increases while the concentration of cones decreases
  • Fovea is most sensative to normal daylight vision
39
Q

Blind Spot

A
  • Where the optic nerve leaves the eye
  • No photoreceptors here
40
Q

Bipolar cells

A
  • Connects with rods and cones
  • Highlights gradients between adjacent rods or cones
  • These cells synapse with ganglion cells
  • Fall in between the rods and cones
  • Located in front of the rods and cones closer to the front of the eye
41
Q

Ganglion cells

A
  • Group together to form the optic nerve
  • Fall in between the rods and cones
  • Located in front of the rods and cones closer to the front of the eye
  • Each ganglion cell has to represent the combines activity of many rods/cones
  • Results in loss of detail as the information from the photoreceptors is combined
  • As # of receptors that converge through the bipolar neurons onto one ganglion cell increases, resolution decreases
42
Q

Amacrine and Horizontal Cells

A
  • Receive input from multiple retinal cells in the same area before the information is passed on to ganglion cells
  • Accentuate slight differences between the visual information in each bipolar cell
  • Important for edge detection
  • Increase our perception of contrasts
43
Q

Optic Chiasm

A
  • First event that occurs as the signal travels through the optic nerve toward the brain
  • Fibers from the nasal half (closer to the nose) of each retina cross paths
  • Carry the temporal visual field (further toward the side of head) from each eye
  • Temporal fibers (which carry the nasal visual field) DO NOT cross in the chiasm
44
Q

Optic Tracts

A
  • Reorganization means that all fibers corresponding to the left visual field from both eyes project into the right side of the brain
  • All fibers corresponding to the right visual field from both eyes project into the left side of the brain
  • These reorganized pathways occur after they leave the chiasm
45
Q

Visual Information Pathway

A
  • From the optic chiasm–> the lateral geniculate nucleus (LGN) of the thalmus——->Radiations in the temporal and parietal lobes–>Visual cortex in the occipital lobe
  • There are also inputs into the superior colliculus (which controls some responses to visual stimuli and reflexive eye movements)
  1. When there is a loud/sudden sound, the superior colliculus aligns the eyes with the likely stimulus “deer in the headlights”
46
Q

Parallel Processing

A
  • Ability to simultaneously analyze and combine information regarding color, shape, and motion
  • These features can then be compared to our memories to determine what is being viewed
  • Feature detection, our visual pathways contain cells specialized in detection of color, shape, and motion
47
Q

Parvocellular Cells

A
  • Detect shape
  • Have very high color spatial resolution (they permit us to see very fine detail when thoroughly examining an object)
  • Can only work with stationary or slow moving objects because they have a very low temporal resolution
48
Q

Magnocellular Cells

A
  • Detect motion
  • Have very high temporal resolution
  • Low spatial resolution
  • Detail of an object can no longer be seen once it is in motion
  • Blurry but moving image of an object
  • Magnocellular cells specialize in motion detection
49
Q

Vestibular Sense

A
  • Rotational and linear acceleration
50
Q

Pinna (Auricle)

A
  • Cartilaginous outside part of the ear
  • First place a sound wave reaches
  • Channels sound waves into the external auditory canal which directs sound waves to the tympanic membrane (eardrum)
51
Q

Tympanic Membrane

A
  • Membrane vibrates in phase with the incoming sound waves
  • The frequency of the sound waves determines the rate at which the tympanic membrane vibrates
  • Louder sounds have greater intensity which corresponds to an increased amplitude of this vibration
  • Divides outer ear from the inner ear
52
Q

Ossicles

A
  • Three smallest bones of the body in the middle ear
  • Transmit and amplify the vibrations from the tympanic membrane to the inner ear
  • Malleus (hammer): Affixed to the tympanic membrane which acts on the incus (anvil), which acts on the stapes (stirrup)
53
Q

Eustachian Tube

A
  • Connects the middle ear to the nasal cavity
  • Helps equalize pressure between the middle ear and the environment
54
Q

Bony Labyrinth

A
  • Inner ear sits within this
  • Contains the cochlea, vestibule, and semicircular canals, which are all continuous with eachother
  • Mostly filled by membranous labyrinth which is bathed with a potassium rich fluid called endolymph
55
Q

Membranous Labyrinth

A
  • Suspended within the bony labyrinth by a thin layer of another fluid, perilymph.
56
Q

Perilymph

A
  • Simultaneously transmits vibrations from the outside world and cushions the inner ear structures
57
Q

Cochlea

A
  • Spiral-shaped organ divided into 3 parts called scalae
  • All 3 scalae run the entire length of the cochlea
  • Other 2 scalae, filled with perilymph, surround the hearing aparatus and are contnuous with the oval and round windows of the cochlea
  • Sound entering the cochlea through the oval window cause vibrations in the perilymph which are transmitted to the basilar membrane
  • Converts the physcial stimulus into an electrical signal, which is carried to the CNS by the auditory (vestibulocochlear) nerve
58
Q

Organ of Corti

A
  • Located in the middle scala
  • Actual hearing aparatus
  • Rests on a thin flexible membrane, basilar membrane
  • Composed of thousands of hair cells which are bathed in endolymph
59
Q

Tectorial Membrane

A
  • Lies on top of the organ of corti
  • Relatively immobile membrane
60
Q

Round Window

A
  • A membrane covered hole in the cochlea
  • Permits perilymph to actually move with the cochlea
61
Q

Vestibule

A
  • Portion of the bony labyrinth which contains the utricle and saccule (which are sensitive to linear acceleration)
  • The utricle and saccule are used as part of the balancing aparatus and to determine orientation in 3D space. They contain modified hair cells covered with otoliths (as the body accelerates, the otoliths resist that motion). This bends and stimulates underlying hair cells which send signals to the brain
62
Q

Semicircular Canals

A
  • Sensitive to rotational acceleration
  • Arranged perpendicularly to each other, each ends in a swelling called an ampulla (where hair cells are located)
  • When head rotates, the endolymph resists motion, bending underlying hair cells which send signal to brain
63
Q

Auditory pathways

A
  • Sound information passes through the vestibulocochlear nerve, to the brainstem
  • The information goes from the brainstem to the medial geniculate nucleus (MGN) of the thalmus, and from there projects to the auditory cortex in the temporal lobe for sound processing
  • Some information is sent to the superior olive (localizes sound) and the inferior colliculus (startle reflex and helps keeps eyes fixed on a point while the head is turned (vestibulo-ocular reflex))
  • The Lateral geniculate nucleus is for Light, the Medial geniculate nucleus is for Music
64
Q

Stereocilia

A
  • On top of a hair cells surface
  • Sway back and forth within the endolymph
  • Swaying results in the opening of ion channels, which cause a receptor potiential
65
Q

Place Theory

A
  • Sound perception theory
  • The location of a hair cell on the basilar membrane determines the perception of pitch when that hair cell is vibrated
  • Highest frequency pitches causes vibrations of the basilar membrane very close to the oval window
  • Low frequency pitches cause vibrations at the apex, away from the oval window
  • Cochlea is tonotopically organized, which hair cells are vibrating gives the brain an indication of the pitch of the sound
66
Q

Olfactory Pathway

A
  1. Odor molecules are inhaled into the nasal passages
  2. They contact the olfactory nerves in the olfactory epithelium
  3. Receptor cells are are activated which send signals to the olfactory bulb
  4. Signals are relayed via the olfactory tract to high regions of the brain
  5. Does not pass through the thalmus, travels unfiltered to the higher order brain centers
67
Q

Taste Buds

A
  • Groups of cells which are receptors for taste
  • They are found in little bumps on the tongue called papillae
  • Taste information travels from taste buds to the brainstem, and then ascends to the taste center in the thalmus before traveling to higher brain order regions
68
Q

Pacinian Corpuscles

A
  • Respond to deep pressure and vibration
69
Q

Meissner Corpuscles

A
  • Respond to light touch
70
Q

Merkel Cells (discs)

A
  • Respond to deep pressure and texture
71
Q

Ruffini Endings

A
  • Respond to stretch
72
Q

Free Nerve Endings

A
  • Respond to pain and temperature
73
Q

Two-point Threshold

A
  • Minimum distance necessary between two points of stimulation on the skin such that the points will be felt as two distinct stimuli
  • Size of the threshold depends on the density of nerves in the particular area of skin being tested
74
Q

Physiological Zero

A
  • Normal temperature of the skin
75
Q

Gate Theory of Pain

A
  • There is a special “gating” mechanism that can turn pain signals on or off, affecting whether or not we perceive pain
  • The spinal cord is able to preferentially foward the signals from other touch modalities (pressure/temperature) to the brain, thus reducing the sensation of pain
  • That is why rubbing a knee after you fall seems to reduce the pain
76
Q

Proprioception (Kinesthetic Sense)

A
  • Ability to tell where one’s body is in space
  • Receptors for proprioception are mostly found in muscles and joints
  • Crucial role in hand-eye coordination, balance, and mobility
77
Q

Bottom-up Processing

A
  • Data driven
  • Object recognition by parallel processing and feature detection
  • The brain takes the individual sensory stimuli and combines them together to create a cohesive image before determining what the object is
78
Q

Top-down Processing

A
  • Conceptually Driven
  • Driven by memories and expectations that allow the brain to recognize the whole object and then recognize the components based on these expectations
  • Quickly recognize objects without analyzing specific parts
79
Q

Perceptual Organization

A
  • Ability to use both bottom-up and top-down processing in combination with all other sensory clues about an object to create a complete picture
  • Most images in everyday life are incomplete, we fill in the gaps using Gestalt principles
80
Q

Depth Perception

A
  • Monocular (one eye) cues include the relative size of objects, convergence of parallel lines at a distance, lighting, and shadowing
  • Binocular (both eyes) cues are slight differences in images projected on the two retinas and the angle required between the 2 eyes to bring an object into focus
81
Q

Form of an object

A
  • Determined through parallel processing and feature detection
82
Q

Motion of an object

A
  • Perceived through magnocellular cells
83
Q

Constancy

A
  • The idea that we perceive certain characteristics of objects to stay the same despite environmental differences
84
Q

Gestalt Principles

A
  • Ways for the brain to infer missing parts of a picture when a picture is incomplete
  1. Law of proximity: Elements close to one another tend to be perceived as a unit
  2. Law of similarity: Objects that are similar tend to be grouped together
  3. Law of good continuation: Elements that appear to follow the same pathway tend to be grouped together
  4. Subjective Contours: Perceiving contours, shapes are no actually present in the stimulus
  5. Law of closure: When a space is enclosed by a contour it tends to be perceived as a complete figure
85
Q

Law of pragnanz

A
  • Governs Gestalt principles
  • Perceptual organization will always be as regular, simple, and symmetric as possible

MCAT (9 decks)

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