Sensory Perception Flashcards
Inferences and perceptual organization through depth, form, motion, constancy
visual cues
depth d/t retinal disparity with eyes about 2.5 in apart
binocular cues
binocular convergence based on how the eyeball is turned
far away = muscle relaxation
close up= muscle contraction/strain
Name monocular cues
- size (closer the object, the bigger it looks)
- interposition (overlap, object in front is closer)
- relative height (higher looks further away)
- shading/contour (light and shadows to perceive form depth/contours)
- motion (motion parallax: things further away seem slower i.e. airplane)
- constancy (object does not change even if the image cast on the retina is different)
Types of constancy of monocular cues
-size constancy (appears larger because closer but still the same object)
- shape constancy (changing shape still maintains the same shape perception i.e. closing door is still a rectangle)
- color constancy (changes of light on an object does not change our perception of the object)
How do senses change sensitivity to stimuli?
sensory adaptation
How does the inner ear protect the eardrum in hearing adaptation?
Muscle contraction. Works slowly for 2-hour concert but not at all for a quick gunshot
How do touch and smell adapt?
desensitized receptors to stimuli over time
hanging upside down, eventually, I would flip everything right side up because of
Proprioception adaptation: sense of body in space
During sight adaptation, downregulation causes pupils to –.
constrict. Downregulation (light adaptation – bright lights cause pupils to constrict so that less light enters the retina and rods/cones become desensitized to light)
measure of when we can notice a change in sensation, just noticeable difference (JND) aka difference threshold
Webers Law
During sight adaptation, upregulation causes pupils to –.
Dilate. Upregulation (dark regulation – pupils dilate and rods/comes start synthesizing light sensitive molecules) to light intensity
Equation for Webers Law
Change of intensity (JND) / initial intensity = k (constant)
predicts a linear relationship between incremental threshold and background intensity
the minimum intensity of stimulus needed to detect a particular stimulus 50% of the time
Absolute threshold of sensation
What type of stimuli is below the absolute threshold of sensation?
subliminal stimuli
T/F. Stimulus detection varies amongst individuals and absolute threshold is not the same as JND
T
What is stimulus detection influenced by?
expectations, experience, motivation, alertness
Types of somatosensation/tactile sensation/touch
Thermoception (temperature)
Mechanoception (pressure)
Nociception (pain)
Proprioception (position)
How are neuron firing speed and intensity related?
directly.
The sensation throughout the surface of the skin is arranged in discrete segments that correlate to levels of the spinal cord. What are these segments called?
Dermatomes
a type of sensation; balance and spatial orientation from inner ear and limbs
the vestibular system
Where are the semicircle canals (posterior, lateral, anterior; each orthogonal to each other) filled with endolymph?
Inner ear.
Endolymph moves in ear canal during rotation signaling the brain
What helps us detect linear acceleration and head positioning?
Otolithic organs (utricle and saccule)
“otolith” greek for ear stones
What crystals are in the otolithic organs (utricle and saccule)?
Contains calcium carbonate (CaCO3) crystals that move in viscous gel pulling on hair cells to trigger action potential (AP). Would not work well without gravity, buoyancy or visual cues
What causes vertigo?
endolymph doesn’t stop spinning when you stop. You or objects around you are moving
how we make decisions under conditions of uncertainty – discerning between important stimuli and unimportant “noise”. Ex. Experimenters give participants a list of words and then a second list of words and ask which words were repeated.
signal detection theory
Signal detection: subject response affirmative when a signal was present
hit
Signal detection: subject perceived a signal when there was not present
false alarm
Signal detection: negative response when a signal was not present
correct rejection
Signal detection: a negative response to a present signal
miss
How does strength of signal impact signal detection?
d’ strength
hit > miss (when there is a strong signal)
miss > hit (weak signal)
Strategies for signal detection
Conservative strategy – always say no unless 100% sure signal is present
Liberal strategy – always say yes, even if get false alarms
How to interpret this graph
Signal Detection Theory – part 2: For any signals, graph noise distribution (background noise) and signal distribution
- The mean of the strength of the signal (d’) is on the x-axis, so to the left is weak and right is strong.
- The strategy C can be expressed via choice threshold.
Name this type of processing:
o No preconceived cognitive constructs of the stimulus (never seen before)
o Data driven, stimulus directs cognitive awareness
o Inductive reasoning, always correct
Bottom Up: stimulus -> perception
Name this type of processing:
o Theory driven, perception influenced by our expectation
o Deductive reasoning
o Not always correct
Top-down Processing: background knowledge -> perception
Gestalt Principle: brain groups items that seem similar
similarity
Gestalt Principle: reality organized to simplest form possible
Pragnanz
Gestalt Principle: objects close together are grouped together
proximity
Gestalt Principle: lines are seen as following the smoothest path
continuity
Gestalt Principle: objects grouped together are seen as a whole. Mind fills in missing information.
closure
Gestalt Principle: the mind perceives objects as being symmetrical and forming around a central point
symmetry
Gestalt Principle: groups of dots moving up and dots moving down are seen as two distinct groups
common fate
Gestalt Principle: some visual stimuli are categorized according to past experiences. If two objects tend to be observed within close proximity, the objects are likely to be perceived together
Law of past experiences
Gestalt Principle: context and processes of perceptual organization of stimuli contribute to how people perceive those stimuli. The context can also establish organization of stimuli
contextual effects
areas of skin that are supplied by a single dorsal root of the spinal nerve
dermatomes, the location of sensation
Representation of the human body, based on a neurological map of the areas and proportions of the brain dedicated to either motor or sensory functions for different parts of the body
Homunculus
Region of brain responsible for receiving sensory information
Located in the parietal lobe
Contains homunculus
primary somatosensory cortex
neuronal firing constant
non adapting
neuronal firing gradually decreases
slow adapting
neuronal firing at onset and offset of stimulus, but not between
fast adapting
Dictated by frequency of neuronal firing
intensity
Binocular cues provide depth perception, also known as stereopsis, by relying on both eyes. Relies on two factors:
Retinal disparity = difference each eye receives of a given object
Convergence = inward angulation of eyes for close objects
Monocular cues rely on only one eye, and usually rely on comparisons between objects. Examples include:
Relative size = closer objects appear bigger
Interposition = overlap when one object is in front of another
Motion parallax = farther objects move slower
Linear perspective = distances between parallel lines appear more narrow as they go farther
Perception of an object remains constant even if retinal projection changes
constancy
size projection on retina changes with distance, but size of object is constant
size constancy
shape projected on retina can change based on angle, but shape of object is constant
shape constancy
light on retina changes with ambient factors, but color of object is constant
color constancy
Speed, thickness, and myelination of A-beta nerve fibers
Speed, thickness, and myelination of A-delta nerve fibers
Speed, thickness, and myelination of C fiber nerve fibers
Rod detection type
black/white
Rod sensitivity
high (function even in dim light)
Rod location
periphery of the retina
Rod quantity
120 million
Rod recovery time
slow
Cone detection type
color
Cone sensitivity
low (function best in bright light)
Cone location
macula and fovea
Cone quantity
6 million
Cone types
red, blue, and green
Cone recovery time
fast
Found in the retina, between the photoreceptors (rods and cones) and ganglion cells
bipolar cell
Act to transmit signals from photoreceptors to ganglion cell
bipolar cell
Type of neuron found in the retina, near the inner surface of the retina
ganglion cell
Receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and retina amacrine cells
ganglion cell
Created by axons from the ganglion cells
optic nerve
Exits retina through optic disc, giving rise to blind spot
optic nerve
Contains visual information from nasal (medial) and temporal (lateral) portions of visual field, for each eye
optic nerve
Partial crossing of optic nerves.
Nerves from the temporal portion of the retina remains on the same side.
Nerves from the nasal portion of the retina cross to opposite side (contralateral).
optic chiasm
Light sensitive receptor protein contained within rods
rhodopsin
Light sensitive receptor protein contained within cones
photopsin
Binds to opsin proteins
Rearranges from cis to trans upon light exposure
retinal
Protein in rods and cones
Attached to rhodopsin until exposed to light, upon which it detaches and becomes active
transducin
Visual field summary:
High density of cones
Bright light conditions
Color and detail perception
Low light sensitivity, high acuity
Central (foveal)
Visual field summary:
High density of rods
Dim light conditions
Motion perception
High light sensitivity, low acuity
peripheral
Occurs when energy is transformed from one form to another, such as light energy transduced to electrical energy by rods and cones.
In other words, the photoreceptors convert light to neural impulses
transduction
Phototransduction cascade
Light in the eye → rods and cones → optic nerve → optic chiasm → optic tracts → lateral geniculate nucleus → visual cortex
Visual mapping in the brain
Due to the optic chiasm, the right visual field is received by the left side of the brain, and vice versa
Color vision is receptive to 3 different types of photoreceptors: red, green, and blue
Also known as the Young-Helmholtz theory
trichromatic theory of color vision
Color information from cones is combined such that we perceive three opposing pairs:
black/white, blue/yellow, and red/green
opponent processing theory of color vision
Specific neurons that preferentially fire to a highly specific stimulus.
Three components of color, form, and motion
Feature detectors
Feature detection involves perceptual discrimination of specific aspects of a given stimulus via feature detectors.
Detection by Parvocellular pathway, which is responsible for perception of finer detail, such as form and color
form feature detection
Mnemonic: Pink Pyramid = Parvocellular pathway
Detection by Magnocellular pathway, which is responsible for perception of coarser detail, such as depth and motion
motion feature detection
Mnemonic = Motion = Magnocellular pathway
Ability of the brain to simultaneously process various components (e.g. color, motion) of a visual stimulus, allowing the brain to divide stimuli into four features - color, motion, shape, and depth/distance.
parallel processing
Pinna (auricle), external auditory canal, tympanic membrane
Mnemonic: PET
outer ear
Connected to nasopharynx via Eustachian tube
Contains ossicles
middle ear
Malleus, incus, and stapes
Footplate of stapes rests in oval window of cochlea
Mnemonic: MIS
ossicles of ear
Contains bony labyrinth and membranous labyrinth
Responsible for sound detection and balance
inner ear
Filled with perilymph
Comprised of three components: vestibule of the ear, semicircular canals, and the cochlea
bony labyrinth of the inner ear
Contained within the bony labyrinth. Consists of the utricle and saccule, two membranous sacs, plus ducts within the cochlea and semicircular canal
Ducts are filled with endolymph
Membranous labyrinth of the inner ear
Translates vibrations into neural impulses
Sends signals to the auditory nerve which transmits to the medial geniculate nucleus
cochlea of the inner ear
Located within the cochlea and contains hair cells
organ of corti of the inner ear
Main function is to regulate balance
Part of the vestibular system
semicircular canals of the inner ear
Auditory pathway (distal)
Outer ear (pinna, external auditory canal, tympanic membrane) → middle ear (ossicles) → inner ear (cochlea, semicircular canals, utricle/saccule) → auditory nerve
Auditory pathway (proximal)
Auditory nerve (part of vestibulocochlear nerve) → medial geniculate nucleus (MGN) → auditory cortex
Function is to localize sound
Located in the brain stem
Superior Olive
Function is startle reflex
Component of vestibulo-ocular reflex, which keeps eyes fixed on single point as head rotates
Inferior colliculus
Theory that the perception of different pitches is due to various frequencies activating different portions of the cochlea basilar membrane
Place theory
Hair cells at the base of the basilar membrane are activated by high frequency sounds, whereas hair cells at the apex are activated by low frequency sounds
Place theory in practice, whereby hair cells in the cochlea are preferentially activated at specific frequencies, allowing the brain to distinguish between high and low frequency sounds
Basilar tuning
Hair cells at base of cochlea are activated by high frequency sounds
Hair cells at apex of cochlea are activated by low frequency sounds
Brain region that processes auditory information
Located within the temporal lobe
Mnemonic = Time Ticking = Temporal lobe
Primary auditory cortex
Neurons within the auditory cortex are organized according to the frequency of sound to which they respond best
Tonotopical mapping
Sense of smell
olfaction
Chemical signal that triggers an innate response in members of the same species
pheromone
Inability to perceive odor
anosmia
Vibrational frequency of a molecule is responsible for its specific odor profile
Vibrational theory of olfaction
Also known as shape theory, this asserts that odorous molecules fit into receptors similar to a lock-and-key mechanism
Steric theory of olfaction
Specialized epithelium inside nasal cavity that contains olfactory receptor neurons
Olfactory epithelium
Specialized region of brain that receives sensations of smell
Input = olfactory receptor neurons of olfactory epithelium
Olfactory bulb
Olfactory bulb projections
Olfactory bulb projects directly to the amygdala and hippocampus
Unlike other senses, olfaction bypasses the thalamus
Portion of ethmoid bone with small holes called the olfactory foramina, allowing passage of the olfactory nerves
Cribiform plate
Olfactory bulb sits atop the cribriform plate
Humans have 5 main tastes(gustation):
Bitter
Salty
Sweet
Sour
Umami (Glutamate)
Contain gustatory cells
Provides for detection of all 5 tastes anywhere on the tongue
taste bud
Three types of taste buds:
Mnemonic: Fun in the front = fungiform, foliage on the sides = foliate, Circle around the back = circumvallate
Fungiform papillae (anterior)
Foliate papillae (side)
Circumvallate papillae (posterior)
Do not contain taste buds
Located all over tongue, most densely at the center of the tongue, accounting for the lack of taste sensation in this region
Filiform papillae
Nerve innervation of the tongue
Anterior 2/3 of tongue sends taste signals via the VII cranial nerve
Posterior 1/3 of tongue via the IX (glossopharyngeal) and X (vagus) cranial nerves
Receptors utilized in sweet, umami, and bitter taste profiles
G protein-coupled receptors (GPCR)
Channels utilized in salty and sour taste profiles
Ion channels
Mnemonic: SOdium, which is an ion channel is SOur and salty
