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Psychology 2A > Perception > Flashcards

Perception Flashcards

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1
Q

What are sound waves?

A

waves of pressure changes in the air, caused by the vibrations of a source

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2
Q

What is Loudness?

A
  • the percept associated with sound pressure level
  • the amplitude of a sound pressure wave
  • smaller amplitude = smaller loudness
  • bigger amplitude = higher loudness
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3
Q

What is Loudness measured in and how can you measure it?

A

decibels (dB) - a physical measure of sound amplitude, or sound pressure level

measured by comparing two tones and deciding which one is louder
(measured in phones)

perceived loudness also varies with frequency

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4
Q

What is Pitch?

A
  • the percept associated with sound frequency
  • differences in pitch are due to changes in frequency of sound pressure waves
  • high pitched tone = more waves / higher frequency of waves
  • low pitched tone = less waves / lesser frequency of waves
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5
Q

What is Pitch measured in and why can it be considered to be a ‘metameric’ percept?

A

frequency is measured in (Hz) - a physical measure of sound oscillation rate
(1Hz = 1 oscillation per second)

metameric:
- you can get very different sounds giving you the same pitch
- e.g. the same note being played by a different musical instrument

Sounds are separated by an octave - same note but different frequency
- known as a ‘chroma’ which is basically pitch 2x

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6
Q

What is Timbre?

A
  • the percept of the shape of sound waves
  • has a negative definition - everything that is not loudness, pitch or spatial perception
  • it is a multidimensional percept
  • on instruments, you have the same notes but different frequencies
    HARMONICS = integer multiples of the fundamental frequency
  • related to the relative amplitude of harmonics
  • breaking down sound waves into its component processes
  • adjusting the harmonics changes the timbre
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7
Q

Describe the physiology of the outer ear

A

Pinna and Concha

  • gather sound energy and focus it via the auditory meatus onto the tympanic membrane (the ear drum)
  • selectively filter sound frequencies to provide cues about the source’s elevation (where it comes from)
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8
Q

Describe the physiology of the middle ear

A
  • tympanic membrane (ear drum) and the 3 ossicles; Mallues, Incus and Stapes
  • role in impedance matching
  • need to change the vibrations of the ‘sound’ so that the vibrations of the air match up the vibrations of the fluid in the cochlea
  • done because air moves faster than liquid
  • basically changes the amplitude - pressure boost up to 200x
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9
Q

Describe the physiology of the inner ear

A
  • contains the cochlea
  • vestibular canals which are important for balance
  • where transduction happens; vibrations / pressure waves changed into neural signals
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10
Q

Describe the Cochlea and its functions

A
  • coiled structure
  • bisected from base to apex by two membranes:
    1. basilar membrane
    2. tectorial membrane
  • these contain the hair cells that do the transduction
  • fluid (perilymph) that fills the chambers on each side
  • vibrating because of the oval window (a membrane-covered opening at the base of the cochlea)
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11
Q

Describe the Organ of Corti

A
  • the sensory organ which the equivalent of a retina
  • runs along the whole of the basilar membrane
  • contains hair cells with stereocillia transducers
  • these convert the vibrations / motions of sound pressure waves into neural signals
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12
Q

What are the two different types of hair cells?

A

Inner and Outer hair cells

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13
Q

Describe Inner Hair cells

A
  • the sensory receptors that send information to higher cerebral levels
  • do the transduction - converting to neural signals
  • 95% of the fibres in the auditory nerves
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14
Q

Describe the Outer Hair cells

A
  • receive projections from upper cerebral levels
  • roles in active filtering; modify the frequency of inner hair responses
  • basically modify signals from the inner cells
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15
Q

Inner and Outer Hair Cells - Mechano-electrical Transduction

A

Vibrations:

  • opens and closes ion channels
  • by electrical depolarisation
  • gives you action potentials to work with
  • how mechanical vibrations are transduced into neural signals
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16
Q

What are the two important aspects in the Auditory Nerve?

A

Phase locking and Tonotopic Organisation

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17
Q

Describe Phase locking

A

need something firing at 20Hz - fire it at 20Hz in one go, keep sending these bursts of 20Hz?

  • phase locking - in time firing
  • one cue to sound frequency
  • 260Hz at 260Hz - fire it at the right times
  • each nerve fibre is tuned to a best frequency
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18
Q

What are the problems of Phase Locking and how can can we overcome this?

A
  • nerve fibres can’t fire all the time - if something needs to be fired at 20Hz, may not be able to do that all the time?
  • there are limits on transmitting
  • can’t just do it along one fibre - so transmit multiple frequencies along multiple nerve fibres!
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19
Q

Describe the frequency decomposition along the basiliar membrane

A

Base = narrow and stiff; can’t vibrate very fast - low frequencies!

Apex = wide and flexible; can vibrate fast - high frequencies!

  • different parts of the BM are ‘tuned’ to certain frequencies
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20
Q

What is Tonotopic organisation?

A

In the auditory cortex, different sounds are persevered in different areas

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21
Q

Pitch Perception: Place Model vs Rate Model

A

Place - argues that the position of excitation / vibration on the basiliar membrane determines how a frequency is encoded

Rate - encoding depends on the precise timing of individual spikes

The perceptual system appears to use a combination of the two techniques

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22
Q

Describe the Auditory Pathway - Primary Pathway

A
  • cochlea
  • auditory nerve
  • cochlear nucleus
  • superior olivary complex in the brain stem
  • lateral lemniscus
  • inferior colliculus in the midbrain
  • medial geniculate body in the thalamus
  • auditory cortex
23
Q

Describe the Auditory Pathway - Secondary Pathway

SONIC MG

A
  • cochlea
  • auditory nerve
  • superior olivary complex in the brain stem
  • inferior colliculus in the midbrain
  • medical geniculate body in the thalamus
    auditory cortex
24
Q

Why do we have a secondary pathway for auditory pathway?

A
  • normally in perception / senses, info from one side of the body is processed in the opposite hemisphere

eg RFV goes to LH and LVF goes to RH

  • this happens in sound too - R Ear goes to L auditory cortex and L Ear goes to R auditory cortex
  • BUT need to have information from both ears to go to both auditory cortices too - helps to determine certain information, such as localisation of sound
25
Q

Tuning in Auditory Cortex

A
  • have both narrow and broadly tuned neurones

- prefer certain frequency tuning

26
Q

Beyond the primary auditory cortex - what and where pathways

A

where:
- identifying where sounds come from
- useful for evolutionary terms?
- useful for guiding actions?
- is it more myelinated so we can react quicker?

what:
- identifying sounds
- who is talking
- the nature of the sound
- less myelinated, can take time deciding etc

27
Q

What is the function of smell as a sense?

A
  • to detect chemical properties of gas
28
Q

What is the function of taste as a sense?

A
  • to detect chemical properties of solids and liquids in contact with the tongue
29
Q

Describe ‘Taste’ and its functions

A
  • the ‘gatekeeper’ to the body
  • tongue allows us to discriminate between different things
  1. Sweet things - high in calorific values
    - evolutionary advantages
    - disadvantages for nowadays
  2. Bitter things - tell us what things should be avoided
    - strong bitter = not good for us at all
  3. Salty things - important if we are dehydrated
    - nowadays have to be careful
    - important for our bodies however
30
Q

What are the five basic tastes?

A

Sweet, Sour, Slat, Bitter and Umami (meatiness/savouriness)

31
Q

What do we measure taste (gustation)?

A

Magnitude estimation like colour!

amount of salt, sweet, sour and bitter in a chemical applied to the tongue

(most of the work done before umami was established as a basic taste)

32
Q

What is the tongue covered in and describe them

A

TASTE BUDS

  • embedded in a pore of the skin, called papillae
  • research has shown that there are not particular regions of the tongue for each particular taste
  • is it down to the distribution of papillae instead?
33
Q

How is taste information encoded?

A

2 different suggestions
- highly debated area in research

  1. Labelled-line model
    - separate taste receptors
    - dedicated privates nerve fibres that go across to the brain for each taste
  2. Across-fibre model
    a) separate receptors and then get mixed up in the nerve fibres before transmission
    b) totally mixed up in receptors and firers and then get decoded in the brain later on
34
Q

Taste Receptors and Transduction

A
  • lock and key model
  • appropriate tastant molecules attaches to the receptor
  • depolarises the cells
  • sends a signal down one of the gustatory nerves
35
Q

What are the typical tastants for each of the basic tastes?

A

Sweet - glucose, sucrose, fructose

Sour - acids: critic (lemon juice), acetic (vinegar)

Salt - Sodium Chloride

Bitter - Quinine (tonic water), caffeine

Umami - Monosoduim Glutamate (MSG) – soy sauce

36
Q

Describe the taste pathway - Different Nerves

A

Signals from the taste cells travel along:

  1. the chorda tympani nerve (front and sides of tongue)
  2. the glossopharyngeal nerve (back of the tongue)
  3. vagus nerve (mouth and throat)
    - gag reflex and choking!
  4. the superficial petronasal nerve (soft palate)
37
Q

Taste pathway after the various nerves

A

make connections to the brain stem in the Nucleus of the Solitary Tract (NST)

From the NST to the thalamus, to the insula and the frontal operculum cortex (OFC) in the frontal lobe

38
Q

Taste - links to the hypothalamus, amygala, OFC and orbitofrontal cortex

A

hypothalamus - hunger!

amygdala - emotional responses

OFC - getting olfactory signals too!

orbitofrontal cortex - representation of reward value of food

39
Q

Do we need smell?

What are its functions?

A
  • not as crucial as it is for other animals
  • useful for detecting pheromones? mates?
  • helps us to appreciate food alongside taste
  • acts as a danger detector - smoke, gas, predators
  • anosmia (total loss of smell) does reduce quality of life like achromatopsia (loss of colour)
40
Q

Measuring Smell

A
  • again can measure detection thresholds for different odorant concentrations
  • measured in parts per billion

recognition threshold - normally requires about 3x the concentration compared to simple detection

  • interaction between odour labelling and identification - often easier to detect the presence of a smell when you can give it a name
41
Q

Problems with measuring smell

A

Olfactometer - need highly controlled conditions (air flow and humidity)

  • two very similar molecules can smell completely different
  • two completely different molecules can smell the same
42
Q

Ways of measuring smell

A

Olfactometer

  • controlling concentrations in stimulus presentations
  • sniff carefully controlled concentrations
  • controlled air flow and humidity
  • expensive?

Sniffin Sticks

  • look like marker pens
  • well-valdiated
  • easier to use that olfactometer
  • but expensive!
43
Q

Describe the olfactory system, how we smell

A
  • odorants are dissolved in the air and inhaled
  • go through the nasal pathway
  • flow over olfactory mucosa and get dissolved
  • these odorant molecules stimulate the Olfactory Receptor Neurones (ORNs) embedded in the mucosa which produce a neural signal
  • this signal is then passed to the glomeruli in the olfactory bulb
44
Q

Smell - after the olfactory bulb

A
  • signals from the olfactory bulb travel to the primary olfactory cortex and the amygdala
  • then pass onto the orbitofrontal cortex (OFC)
45
Q

Role of amygdala in smell?

A
  • emotions
  • may play a role in the emotional reactions that odours often elicit
  • due to the direct pathway?
46
Q

Other areas that smell goes to

A

Hippocampus - memory connections?

Hypothalamus - hunger - smelling food may remind you that you are hungry?

47
Q

Encoding smells

A
  • different odorants cause neural activity across a range of olfactory receptor classes
  • this pattern is thought to underlie olfactory recognition
  • similar to the distribution of light across cones?
  • 350 different types of Olfactory Receptor Neurones (ORNs)
48
Q

Encoding smells - ORNs

A

350 different classes of Olfactory Receptor Neurones in humans

  • 1000 of each class making around 4 million ORNs in total
  • all ORNs of one type send their output signals to just one or two glomeruli in the olfactory bulb
49
Q

Olfactory Perceptual Organisation

A
  • group certain odorants together, e.g. morning kitchen smells
  • similar to vision where we perceive overlapping objects as separate
  • hearing - perceiving individual instruments within an orchestra
50
Q

Flavour

A
  • taste = flavour
  • flavour is a combination of gustation and olfaction
  • flavour perception deteriorates when he nose is blocked
  • other factors like the burning of hot peppers also deteriorate flavour perception
51
Q

Flavour Perception

A
  • odorant molecules released by food travel to the naval cavity via the ‘retronasal’ route
52
Q

Physiology of Flavour

A
  • Orbito-frontal cortex (OFC) is thought to be important; the first place where taste and smell information are combined
  • bimodal neurones in the OFC respond to taste and smell or taste and visions
  • evidence that activity in these neurones reflects the pleasantness of flavours?
53
Q

What is sound?

A
  • a pressure wave
  • caused by the vibrations of molecules in the air
  • need to have a medium to transmit sound, aka air
  • no sound in a vacuum

Psychology 2A (4 decks)

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