week 3 sensation Flashcards
what are sensory receptors
specialized neurons that respond to specific types of stimuli
describe the simple process of sensation
- light
- chemical info sent to the eye
- creates an action potential
- transduction
absolute threshold
minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time
when does a stimulus reach a psychological threshold
when it is strong enough to excite sensory receptors and send nerve impulses to the brain
what is the just noticeable difference/ difference threshold
how much difference in stimuli is required to detect a difference between them
what makes the difference threshold change
stimulus intensity
what does webers law suggest
the difference threshold is a constant fraction of the original stimulus
what is the bottom up process
perceptions are built from sensory input
what is the top down process
how we interpret sensations is influenced by knowledge and experiences
sensory adaption
we don’t perceive stimuli that remain constant over prolonged periods of time
inattention blindness
failure to notice something that is completely visible due to lack of attention
signal detection theory
ability to identify a stimulus when it is embedded in a distracting background
what did Stratton do
wore goggles that inverted the world but he adjusted well
what are the 4 stages of conversion in sensation
- accessory structures modify physical stimulus eg lens of eye
- transduction - physical energy detected by receptors and converted into neural energy
- sensory nerves send traduced neural energy to brain, first the thalamus (relay station) then different parts of cortex
- sensation is produced once message reaches brain
psychometrics
measuring senses and thresholds
noise
random excitation or inhibition of neurons that either increase or decrease sensed intensity of a physical stimulus
3 implications of noise
- repeated presentations of the same physical level of intensity don’t always produce the same internal sensation
- if a physical signal is doubled, doesn’t always double sensation
- absolute threshold
webers fraction relationship
difference threshold increases in proportion to the standard
webers law formula
change in intensity of stimulus/intensity of standard = C
what is general rule of webers law
as background intensity increases, difference threshold increases
amplitude
height of the wave measured from the highest point of the wave (peak) to the lowest point of the wave (trough)
wavelength
length of a wave from one peak to the next
frequency
number of waves that pass a given point in a given period - measured in Hz
how are the frequencies in shorter wavelengths
higher
visible spectrum
portion of larger electromagnetic spectrum humans can see
what is the amplitude of light waves associated with
our experience of brightness or color intensity, larger amplitudes appearing brighter
what is the frequency of sound waves associated with
perception of the sounds pitch
what is timbre and what is it affected by
a sounds purity, affected by the complex interplay of a frequency, amplitude and timing of sound waves
The visible spectrum includes light that ranges from about
400-700 nm
cornea
transparent covering over the eye - serves as a barrier
what does the cornea do
helps focus light waves
what happens to the pupil when its really light
pupil constricts to decrease amount of light entering eye
what controls the size of the pupil
muscles connected to the iris
what happens to a lens in a normal sighted person
lens will focus perfectly on a small indentation on the back of the eye called fovea
job of the fovea
light sensitive lining containing densely packed specialized photoreceptive cells eg cones
give 5 facts about cones
- concentrated at fovea
- work best in light conditions
- sensitive to acute detail
- very good spatial resolution
- what helps us perceive color
give 6 facts about rods
- work well in low light conditions
- lack spatial resolution
- very sensitive to light and helps us to see in the dark
- low visual acuity
- black and white
- helps with perception of movement and periphery of visual field
where are rods located
located throughout the retina but absent in the fovea.
what are rods and cones connected to
retinal ganglion cells
what forms the optic nerve
axons from the retinal ganglion cells converge and exit through the back of the eye to form the optic nerve
what does the optic nerve do
carries visual information from the retina to the brain
what is the optic chiasm and where is it located
x shaped structure sits below the cerebral cortex at the front of the brain. information from the right visual field is sent to the left side of the brain and vice versa
where is information received to the brain then passed onto
occipital lobe
what does the trichromatic theory suggest
all colors of the spectrum can be produced by combining red, green and blue. and there are 3 types of cones receptive to one of the 3 colors
what is the opponent process theory
color is coded in opponent pairs: black-white, yellow-blue, and green-red. some cells of the visual system are excited by one of the opponent colors and inhibited by another.§
give an example of the opponent process theory with green and red
a cell excited by wavelengths associated with green would be inhibited by wavelengths associated with red.
what are 2 implications of the opponent process theory
- we do not experience greenish-reds or yellowish-blues as colors
- negative afterimages
what is an afterimage
the continuation of a visual sensation after the removal of the stimulus
binocular disparity
slightly different view each of the eye receives
linear perspective
we perceive depth when we see 2 parallel lines that seem to converge in an image
interposition
monocular visual cue in which two objects are in the same line of vision and one patially conceals the other, indicating that the object concealed is further away
what is the visible part of the ear called
pinnea
3 bones that make up ossicles
- hammer - malleus
- anvil - incus
- stirrup - stapes
what’s the part of the ear that helps with balance and movement called
semi-circular canals
cochlea
fluid-filled structure containing sensory receptor cells of the auditory system
after sound waves travel along the auditory canal where do they go
tympanic membrane where it vibrates
what happens after sound waves vibrate in the tympanic membrane
3 bones of ossicles move and stapes press into thin membrane of cochlea causing fluid inside it to vibrate
what happens after fluid inside the cochlea vibrates
hair cells are stimulated causing cells to activate and a neural impulse is generated that travel along the auditory nerve to the brain
what happens when neural impulses from sound waves reach the brain?
auditory information shuttles to the inferior colliculus then to the auditory cortex in the temporal lobe of the brain for processing.
inferior colliculus
the medial geniculate nucleus of the thalamus
what does the temporal theory of pitch perfection suggest
pitch is determined by the timing of neural firing patterns in the auditory nerve
focuses on time-based characteristics of sound waves and how theyre encoded by the auditory system
what’s a limitation of the temporal theory of pitch perfection
we detect such broad range of frequencies 20-20,000 Hz, that the frequency of AP’s fired by hair cells cannot account for this entire range.
because of the properties related to sodium channels, there is a point at which a cell cannot fire any faster
what does the place theory of pitch perfection suggest
different portions of the basilar membrane are sensitive to sounds of different frequencies. the base of the basilar membrane responds best to high frequencies (high-pitch receptors) and the tip to low (low-pitch receptors).
what does the place theory suggest about the location of sound
we can locate the place from which a sound is emitted because of the distance between our ears
What 4 things form part of the inner ear?
- oval window
- semi-circular canals
- cochlea
- the saccule
What forms part of the middle ear?
ossicles
what is the name given to cues used to localize sound
monaural and binaural
what are monaural cues
why are monaural cues essential
These are cues that rely on input from one ear.
Monaural cues help with vertical localization (determining whether a sound is above or below you) and recognizing the distance of a sound source.
what are binaural cues
why are binaural cues essential?
cues that rely on input on both ears
they provide information on the location of a sound along a horizontal axis by relying on differences in patterns of vibration of the eardrum between 2 ears.
what are interaural LEVEL differences?
difference in the intensity (loudness) of a sound as it reaches each ear.
a sound coming from the right side of your body is more intense at your right ear than your left because of the attenuation of the sound wave as it passes through your head
what are interaural TIMING differences?
small difference in the time at which a given sound wave arrives at each ear.
congenital deafness
born deaf
how does hearing aid work
amplifies incoming sound waves to make a vibration of the eardrum and movement of the ossicles are more likely to occur.
what is conductive hearing loss
failure in the vibration of the ear drum and or movement of the ossicles
what is sensorineural hearing loss
failure to transmit neural signals from the cochlea to the brain.
what is Ménière’s disease?
- results in sensorineural hearing loss
- degeneration of inner ear structures
- leads to tinnitus, vertigo
what are cochlear implants
- electronic device that translates sounds into electrical signals the brain can understand
- receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain
problem for place thoery
below 1000 Hz, no specific place on the membrane vibrates more than any other but we can distinguish between tones that are below that frequency
problem for frequency theory
above 1000 Hz, cells can’t fire any faster - refractory period
volleying
alternation in the firing of hair cells
problem for volley theory
very high frequencies would need complex framework
what is the term given to photopigments breaking down in response to light
bleaching
what photopigment do rod cells contain
rhodopsin
what photopigment do cone cells contain
iodopsin
what are the 3 subtractive mixture colors
red blue yellow
what are 3 additive mixture colors
red blue green
what distinction can dichromats not make
red from green
monochromatic colour-blindness
only have one type of iodopsin, see only shades of monochrome
problem for trichromatic theory
Dichromats can see yellow. Yellow is (supposedly) the sensation when both red
and green iodopsin is bleached. How can both be bleached if dichromats don’t
have either green or red iodopsin?
optic disk
place where optic nerve leaves the eye
tactile sense
touch
what’s relative temp
32 celcius
what do endorphins decrease
pain
what is released in anticipation of pain from electrodes in the brain
endorphins
how may acupuncture work
stimulates endorphins
olfactory sense
smell
overtime our ability to detect odor drops to__%
30
how many percent of people lose sense of smell
8
what 3 factors adds flavor to food
olfaction, mood and texture
what are taste buds called
papillae
Whereas humans can hear up to about ______Hz, dogs can hear up to about _______Hz.
20000, 80000
Roger is seated in a totally dark room. An experimenter presents a circle of light projected on the far wall and instructs Roger to indicate when he believes the light spot is either brighter or dimmer than it was originally. The experimenter is establishing Roger’s ________.
difference threshold
Suppose you want to measure Linda’s absolute threshold for hearing. You fit her with earphones and present tones of four different intensities. The number of times she detects and misses each tone are tabled below. what intensities represents Linda’s absolute threshold?
10 correct detections; 10 errors
Not counting umami, we have sensors that are sensitive to ________ different tastes.
4
what are the 4 tastes excluding umami
sweet, sour, salty, bitter
Damage to the _______ might prevent an elderly from hearing certain high pitches.
basilar membrane
Visual information from the rods and cones is first conveyed to ________ before being sent to the brain.
ganglion cells
For electromagnetic spectrum, we can see only about 400 to 700 between ______ and ______.
ultraviolet and infrared
The eardrum is connected to the oval window by _____
bones
Suppose Dr. Martin’s laboratory has shown that low- frequency sounds stimulate hair cells throughout the entire basilar membrane. This evidence would be most problematic for _______.
place theory
where do high frequency sounds stimulate
the base near the oval window
where do low frequency sounds stimulate
apex near the helicotrema
why is the frequency theory different to place theory
it focuses on temporal patterns rather than spatial localization
The __________ provides/provide evidence for opponent pairs of cone photoreceptors.
colour afterimages
gustation
taste
what is umami a taste for
monosodium glutamate
What do Meissner’s corpuscles detect?
pressure and lower frequency vibrations
what do Merkel’s disks respond to
light pressure
what do Ruffini corpuscles detect
strech
nociception
signal indicating potential harm and maybe pain
congenital analgesia
inability to feel pain from birth
Which part of the brain is involved in pain and taste perception, but not smell perception?
thalamus
what does the vestibular sense contribute to
ability to maintain balance and body posture
