Perception Flashcards

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1
Q

face pareidolia

A

tendency of visual system to see faces in inanimate objects

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2
Q

exteroception

A

information about external environment, involves the somatic nervous system

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3
Q

interoception

A

processing central information inside bodies, used to control motor output, involves autonomic nervous system

  • afferent (sensory input)
  • efferent (motor output)
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4
Q

reduced afferent sensory input:

A

continuous input is so important that individuals deprived of external stimulation become severely disoriented, vivid hallucinations and delusion, especially when deprivation is involuntary

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5
Q

generalised senses

A

sensory receptors scattered throughout the body, simple anatomical structures located in skin, muscles, joints and internal organs

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6
Q

specialised senses

A

sensory receptors localised within specialised organs in the head, complex anatomical structures

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7
Q

types of sensory receptors

A

mechanoreceptors - respond to movement and pressure, audition and touch

chemoreceptors - respond to airborne and soluble chemicals, smell and taste

photoreceptors - respond to visible light, vision

nocioceptors - respond to pressure, temperature, chemicals, somatic senses

thermoreceptors - respond to changes in temperature, chemical and mechanical stimuli through somatic senses, autonomic sensory pathways

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8
Q

stages of processing information

A
  1. Sensory receptors are stimulated by the appropriate environmental energy
  2. Sensory transduction: sensory receptors transduce (convert) physical energy into neural energy
  3. Sensory coding: resulting neural activity is encoded into patterns of neural activity and transmitted to and further processed in the CNS
  4. Neural processing in the cortex produces perception
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9
Q

absolute threshold

A

smallest amount of energy needed to detect a stimulus, not fixed, most physical intensities will be a mixture of supraliminal (perceived) and subliminal (not perceived) intensities

  • the minimum amount of energy that can be detected 50% of the time
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10
Q

difference threshold

A

otherwise known as just noticeable difference

  • the smallest detectable difference between stimuli
  • smallest amount something has to change for a person to notice it 50% of the time
  • therefore the more intense the stimulus, the larger the detectable difference must be
  • used to show how what we percieve and what is in the physical environment differs
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11
Q

Weber’s Law

A

says the just noticeable distance is always a constant fraction of the stimulus intensity

  • highlights the difference between physical and perceptual and dimensions, what physical instruments record and what we perceive are two different things
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12
Q

dynamic aspects of sensory processing

A
  • response properties of our sensory and perceptual systems are not fixed
  • the sensitivity of our sensory systems constantly change due to differing levels of stimulation and exposures to new physical environments
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13
Q

sensory adaptation

A
  • A reduction in sensitivity to a stimulus after constant exposure to it
  • It reduces our awareness of a constant stimulus and helps to free out attention and processing resources to other (novel) stimuli in our environment
  • Present in all sensory modalities but much reduced in pain
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14
Q

rapidly adapting receptors (phasic) are:

A

most sensitive to changes in stimuli

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15
Q

slowly adapting receptors (tonic)

A

respond as long as the stimuli is applied

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16
Q

chemical senses

A

olfaction and gustation

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17
Q

olfaction

A

sensations evoked by airborne chemical compounds (odorants) that are able to stimulate olfactory receptors in the nose

  • distance sense - provides information about chemicals suspended in the air around us
  • strongly linked to emotional and memory processing
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18
Q

odorant (olfaction)

A

a molecule that is capable of stimulating olfactory receptors, require characteristics to stimulate sense of smell

  • these include: volatility, hydrophobicity, small molecular weight
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19
Q

olfactory transduction

A

odorants enter the nasal cavity via a retronasal passage (nose or mouth)

  • through the respiratory epithelium and olfactory epithelium

olfactory epithelium: site of olfactory transduction, converting physical energy to neural energy

  • size is proportionate to the ability to smell, bigger epithelium the more sensitive the nose is
  • located on roof of nasal cavity, where it traps odorants and connects them to receptors
  • amount of olfactory receptors correlates to the sense of smell

respiratory epithelium: filter, humidify and warm the air we breath

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20
Q

transduction process for olfaction

A

dendrites of olfactory receptors activate in olfactory epithelium - sensory neurons activate in the olfactory bulb

Signals are sent to:
- The primary olfactory cortex (in cerebral cortex)
- Amygdala and limbic system (involved in emotional reactions to odours)

After primary olfactory cortex, it signals to second olfactory cortex (frontal lobe) and is integrated into other systems

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21
Q

Types of Sensory Coding in Olfaction

A

shaped-based coding, population coding, vibrational coding

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22
Q

Olfactory Sensitivity

A
  • Early findings suggest that humans can discriminate between 100,000 different odours but latest estimates suggest differentiation between 1 trillion
  • Detection sensitivity differs across different chemical compounds: some chemicals need lower concentration to be detected than other (lower absolute thresholds/better sensitivity)

Factors affecting sensitivity
- Women have lower thresholds
- Worst sensitivity in smokers and drinkers
- Better in the morning
- After 85, 50% unable to detect most smells

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23
Q

Recognition threshold, and olfactory example

A

level at which a stimulus can be recognised, labelled as something

  • Generally, olfactory identification is poor, and cannot be determined with great accuracy
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24
Q

Porter (2007) - work on the ability to smell

A

humans can scent track, improve with practice, nostrils sample spatially distinct regions

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25
Q

pheromones

A

chemicals released by one animal detected by another that shape the second animal’s behaviour or physiology
- not clear role in humans (alteration of mood, menstrual synchrony)

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26
Q

major histocompatibility complex genes (MHC) and odour preference

A

preference for smells replicate a preference for genes that don’t match

  • if the genes were to match their children would be less healthy (weaker immune systems), so their odour preference replicates gene compatibility
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27
Q

anosmia

A

inability to smell, most often resulting from various infections in the nasal cavity or head trauma
- rare - congenital
- profound loss of taste as well
- associated with decreased well-being and decrease quality of life

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28
Q

specific anosmia

A

the inability to smell one specific compound amid otherwise normal smell perception

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29
Q

gustation

A

sensations evoked by solutions in the mouth that contact receptors there

  • receptors located on tongue and roof of mouth in clusters, in taste buds
  • the distribution of receptor types on the tongue is even in humans
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30
Q

sensory coding of gustation

A
  • simpler than olfaction
  • labelled-line coding: modality specific receptors transfer the information through a line to higher levels of processing
  • stimulus –> receptor –> perceived taste
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31
Q

taste central pathway

A
  • signals from taste cells travel along various cranial nerves
  • these pathways first synapse in the spinal cord and then the thalamus
  • finally they terminate in the primary taste cortex and then project to the orbitofrontal cortex
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32
Q

taste threshold

A

minimal concentration of a substance detectable by taste

  • people are most sensitive to bitter substances, higher preference for sweet and sour substances
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33
Q

genetic variations in bitter taste

A

Fox (1931) - certain bitter substances taste dramatically different to different people.

Gene for PTC/PROP
- Individuals with two recessive genes are nontasters
- Individuals with one or more of the genes are tasters

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34
Q

hypotaster, normal taster, super taster

A

hypotaster - indifferent or likes bitter, seeks spicy, adventurous eater

normal taster - tolerates bitter and spicy food, moderate

supertaster - avoids bitter and spicy food, picky eaters

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35
Q

somatic senses

A

touch, temperature, pain and proprioception

the components of the CNS and PNS that receive and interpret sensory information from the skin, joints, ligaments and muscles

skin senses - touch, pain, temperature

proprioception -

kinesthesia - the sense of position of our body parts with respect to each other that allows us to perform movement

vestibular sense - provides information about the position of body in space by sensing gravity, movement and acceleration (factors that are critical for maintaining our sense of balance)

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36
Q

Sensory Coding of Touch

A
  • mechanoreceptors

Four different types of mechanoreceptors embedded in
- outer layer
- underlying layer of skin
- epidermis
- dermis

Each mechanoreceptor responds to a touch stimulus in a specific area of the skin (the receptive field of the receptor)

  • All mechanoreceptors respond to touch but have different anatomy, adaptation rate and receptive field (RF) size
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37
Q

slow adapting mechanoreceptors

A

fire continuously as long as pressure is applied

primary functions
- fine detail (pattern, form perception)
- texture perception
- finger position

those with small RF sizes encode information from a smaller area of the skin than larger RF sizes

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38
Q

fast adapting mechanreceptors

A

fire at onset and offset of stimulation

primarily functions
- flutter
- vibration
- fine texture perception (moving fingers across something)
- stable grasp

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39
Q

Measuring Tactile Sensitivity and Acuity (3 ways)

A

absolute detection threshold –> finding the smallest pressure to be detected

two-pointed discrimination –> minimal distance between two points that can be detected, determining if your being touched by one needle or two needle

grating acuity –> distinguishing the minimal amplitude of grooves that can be discriminated to determine if something is a smooth and grooved surface

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40
Q

touch sensation

A

represented somatotopically in the brain

  • Adjacent areas on skin connect to adjacent areas in the brain
  • Certain body locations have a disproportionate amount of cortical area because of the increased sensitivity in those areas
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41
Q

phantom limb sensations (an example of neural plasticity)

A
  • Feel limb sensations when amputated
  • Result of cortical remapping that occurs in response to amputation: cortical regions that represent the lost limb before amputation can become responsive to stimuli from other adjacent cortical regions after the amputation
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42
Q

Encoding Temperature (through thermoreceptors)

A

→ types: warmth fibres, cold fibres

  • Thermoreceptors respond when you make contact with an object warmer or colder than your skin
  • Stimulating cold and warm fibres togethers produces a hot feeling (instead of the expected lukewarm)
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43
Q

Pain Perception

A

→ free nerve endings, source of information that relates to tissue destruction
→ pain perception is adaptive to a degree as it motivates behaviours to terminate the source of the pain

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44
Q

congenital analgesia

A

unable to feel pain

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45
Q

factors that lessen the experience of pain

A
  • expectation, when told what to expect they feel less pain
  • shifting attention, attention on stimuli other than the pain-inducing one lessens pain
  • content of emotional distraction lessens pain to something else
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46
Q

Gate Control Theory (Melzak & Wall)

A
  • theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain
  • the gate can open by the activity of pain signals travelling up small nerve fibres
  • the gate can close by activity in larger fibres or by information coming from the brain
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47
Q

Visual-Vestibular Sensory Integration

A

brain just using eyes and inner ear to coordinate eyes and head movement

examples of where it goes wrong

  • vection - illusory sense of self motion produced when you are not moving
  • motion sickness - results when there is a disagreement between the motion and orientation signals provided by the semicircular canals, otolith organs, and vision
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48
Q

audition

A

auditory perception is the ability to identify and localise the sound signals in environment

Sound is the periodic vibration of air molecules, originates from a disturbance of the air by any object, the local religion of air has increased energy caused by the motion of the air molecules

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49
Q

physical properties - amplitude

A

amplitude: determined by how much the sound source displaces the waves from the equilibrium

  • Sound amplitude is the difference between the peak and the trough of a sound wave (spatial extent of pressure oscillations)
  • measured in decibels

Decibel: the difference between two sounds as the ratio between two sound pressures

  • Every increase of 10dB is equal to a 10-fold increase in sound pressure level
  • 0dB, absolute threshold of hearing
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50
Q

physical properties - frequency

A

Determined by the rate of displacement caused by the sound source - how fast it reaches its displacement from the equilibrium

  • The number of complete waveforms, or cycles, that pass a given point in space every second
  • Measured in hertz (1hz is one cycle per second)
  • Human range: 20-20,000 hz, infrasound and ultrasound are outside of hearing range
  • All animals seem to have much wider hearing than voicing range
  • Many animals have wider range of frequencies than is possible for humans
  • Humans are most sensitive to sound frequencies between 1000-5000 hz (lowest auditory thresholds to these sounds)
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51
Q

physical properties - complexity

A

Combining multiple sound waves together makes it complex
- Sounds are typically more complex and contain energy at multiple frequencies
- Lowest frequency: fundamental frequency
- Integer multiples of lowest frequency are called harmonics

More complex = more frequencies
- Sounds complexity contributes to the perceptual quality of timbre
- Pitch of complex waves determined by fundamental frequency

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52
Q

perceived properties

A

loudness, pitch and timbre

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53
Q

acoustic to neural energy

A

sound vibrations are collected by outer ear and are funnelled into the ear canals, sound waves are transmitted through the middle to the inner ear which is filled with fluid that is much denser than air

  • Outer ear and middle ear function is to amplify the intensity of the sound so that it can adequately stimulate the cochlear fluid
54
Q

Outer ear

A
  • Sound waves funnelled into ear and then resonates and amplifies
55
Q

Two Factors in Sensory Coding for Pitch Perception

A
  1. Which hair cells are stimulated: specific groups of hair cells are sensitive to specific frequency and inturn activate a specific set of auditory nerve fibres
    - Preferred frequency is at the lowest point of each tuning curve
    - Positioned at different places in the cochlear, information about the particular frequency is coded by the place in the cochlear with the maximal response
    - tonotropic organisation
  2. How auditory nerve fibres are firing: rate or pattern of firing of nerve impulses to specific auditory frequencies
    - use volley principle and frequency matching
56
Q

Problems with Hearing

A

Hearing loss during conduction, Sensorineural hearing loss, Central auditory processing disorders

57
Q

auditory localisation

A

the ability to determine where in space a sound originates

  1. interaural intensity difference
    - For certain directions of the sound source, the head creates acoustic shadow, reducing the sound intensity on one side
  2. interaural timing differences
    - Sound wave coming from the side will hit the nearer ear first, creating a time lag between the two ears
    - Perception of the sounds location depends on the sound that reaches the ear first
  3. spectral cues from the filtering properties of the Pinna
    - Above, in front and behind when trying to localise a sound, the shape of the ear is used to hear different sounds
58
Q

vision

A

process of discovering from images what is present in the world and where it is

physical stimulus energy –> receptors –> neurons –> brain –> perceptual experience

59
Q

visible light

A

portion of the electromagnetic spectrum that can be detected by the human eye (400-700 nm), shorter wavelengths correspond to high frequency and higher energy and vice versa for longer wavelengths

60
Q

Reflectance:

A

the proportion of the incoming light that is reflected by a surface

Reflect light with a particular reflectance spectrum
- Red - primarily longer wavelength
- Green - middle wavelength
- White, grey, black - reflect all wavelengths equally, white reflect 90%, black 3%

Chromatic (colours) surfaces have selective reflectance properties: absorb some reflect others

Achromatic (black, whites) surfaces reflect all wavelengths equally

61
Q

Input: (vision)

A

light reaching the eye is the product of illumination and surface reflectance
- Surface reflectance properties do not change with different illumination conditions, but luminance reflected from any surface changes as illumination does

62
Q

shaped based coding

A

Shaped-based coding: assuming a simple correspondence between molecular shape and perceived smell

  • However, it is argued that molecules with similar shapes have different smells, similar smells come from molecules with different shapes
63
Q

population coding

A

Population Coding: assuming odorants are coded by combinations of olfactory receptors, specific time order of activation of receptors might be important, intensity of odorant might change which receptors are activated

64
Q

vibrational coding

A

Vibrational Coding: odours associated with different chemicals molecules or compounds are determined not by their shape but by their molecular vibrations

65
Q

Sensory transduction

A

sensory receptors transduce (convert) physical energy into neural energy

  • second stage of sensory processing
66
Q

Sensory coding

A

resulting neural activity after transduction is encoded into patterns at, transmitted to and further processed in the CNS

  • third stage of sensory processing
67
Q

sinusoid

A

simplest possible wave shape

Tuning fork gives a simple sound waves, with oscillations at only one frequency

68
Q

volatility (to determine if it is odorant)

A

how easy an odorant will vaporise, or turn into a gas, and then reach receptors

69
Q

hydrophobicity (to determine if it is odorant)

A

extent to which it is repelled by water

  • important as it ensures interaction between odorants and receptors despite the presence of mucus
70
Q

small molecular weight (to determine if it is odorant)

A
  • important because smaller molecules tend to produce more intense smells, except methane and carbon monoxide
71
Q

tonotopic organisation

A

tuning of different parts of the cochlea to different frequencies

  • Organised distribution of receptors to different properties
  • important in sensory coding pitch perception, through which hair cells are stimulated in the ear
72
Q

frequency matching theory

A
  • important in sensory coding pitch perception (determining how nerve fibres are firing)

Information about the particular frequency of an incoming sound wave is coded by matching the frequency of neural firing
- Potential problem: no neurons can fire faster than 1000hz

73
Q

Volley principle (population coding)

A

instead of one neuron, multiple neurons can provide a temporal code for frequency by firing action potentials at distinct points in the period of a sound wave, but not on every period

  • important in sensory coding pitch perception, through how nerve fibres are firing
74
Q

The precedence effect

A

phenomenon where an acoustic signal arriving first at the ears suppresses the ability to hear any other signals, including echoes and reverberation of that signal that arrive up to about 40ms after the initial signal

  • provided that the delayed signals are not significantly louder than the initial signal
75
Q

middle ear

A
  • Eardrum vibrations moves the middle ear bones (ossicles) so that they can be processed as sound in the inner ear, waves amplified a second time
  • relay station
  • Vibrate against membrane between the middle and inner ear
76
Q

inner ear

A
  • vibration of membrane displaces fluid in the cochlea
  • Movement of the cochlear fluid stimulates the auditory receptors (hair cells) which transduce mechanical into neural energy
77
Q

Hearing loss during conduction

A

conduction: transmission of excitation

when transmission can’t reach the inner ear

  • Fluid, wax, infection: air into ear canal can’t get through etc
  • Middle and external ear
78
Q

Sensorineural hearing loss

A

hearing loss due to damage to the inner ear or nerves stemming from the brain

  • Middle ear and inner ear and auditory nerve
  • Tumor, trauma, malformations, exposure to loud noise, or familial
79
Q

Central auditory processing disorders

A

inability to process sound

  • Damage to cortical areas ultimately can affect auditory discrimination, Pattern recognition, Sound localisation
80
Q

Function of Hearing

A
  • Detection and identification of signals (knowing something is around)
  • Speech perception
  • Music perception
  • Sound localisation (where the sound is coming from)
81
Q

features of light and why vision is useful

A
  • Light travels quickly, gives an almost immediate quantification of surroundings
  • Light travels in straight lines it preserves geometric structure of environment
  • Contains information about properties of surfaces in the world
82
Q

Equal loudness curves

A

to be perceived as equally loud, low and high frequency sounds need to have higher physical intensity compared to the intermediate frequency (3000-5000 hz) sounds

83
Q

tastes correlation to survival values

A

the tastes someone has may signal different dangers in society

  • bitter might signal poison
  • sour to detect acidic solutions that might harm the body
84
Q

senses in relation to brain

A

different senses take up different cortical areas of the brain

85
Q

fundamental frequency

A

lowest frequency present in a series of sound waves

86
Q

harmonics

A

integer multiples of the lowest frequencies

87
Q

timbre

A

Timbre, in relation to complexity, is the sounds distinctive tonal quality determined by the non-fundamental frequencies
- Causes the same note to sound different on different instruments
- Also affected by the change in sound over time

88
Q

retina

A

where light receptors are located

  • photoreceptors transduce electromagnetic energy into neural energy

receptors are split into rods and cones

89
Q

rods

A
  • more sensitive to light than cones
  • 120 million
  • important at low levels of light
  • contribute little to colour vision
90
Q

cones

A
  • 6 million
  • important for colour and spatial detail
  • see only in daylight
91
Q

rods and cones are unevenly distributed in the retina

A
  • cones are predominantly in the centre
  • rods exclusively in the periphery
92
Q

retinal ganglion cells

A

blind spots in each retina contain no photoreceptors and is a place where the axons of retinal ganglion leave the eye and carry the visual information to higher processing regions in the brain

93
Q

central vs peripheral vision

A

encoding of fine detail is only represented with the focus of vision

  • the periphery has the lowest acuity, the parafovea has moderate acuity and the fovea and has high acuity
94
Q

topographic mapping on the retina

A

external visual field is mapped onto the retina, preserving the spatial relationships between positions in the visual field and retinal projections

95
Q

primary visual cortex

A

where most retina output goes to

  • majority of axons of retinal ganglion cells terminate in the Lateral Geniculate Nucleus (LGN) in the thalamus and carry information to the primary visual cortex
96
Q

retinotropic mapping

A

connections between neurons in different parts of the visual system remain spatially specific, so each structure contains a map of the visual field which corresponds to the spatial representation of the visual scene

97
Q

path of retina to primary visual cortex

A

crosses to the opposite hemisphere of the brain before it reaches LGN and then primary visual cortex

  • receives left visual field from right side of brain and vice versa
98
Q

cortical maginifcation of part of the retina

A

larger region of primary visual cortex devoted to the fovea

  • therefore there is uneven interpretation
99
Q

Visual Processing in Primary Visual Cortex

A

neurons in visual cortex respond to specific features, including

  • colour
  • direction of movement
  • contour
  • depth
100
Q

dorsal pathway

A

“where or how” pathway

  • motion perception, moment-to-moment representation of spatial layout
  • process information necessary for visual control of skilled actions and navigation
101
Q

ventral pathway

A

“what” pathway

  • colour processing and object recognition
  • representation of stable characteristics of objects and there relations
102
Q

akinetopsia

A

stems from damage to dorsal pathway

  • cortical motion blindness (seeing something in low shutter speed)
103
Q

object agnosia

A

struggling to interpret visual objects

  • stems from damage to ventral pathway
104
Q

prosopagnosia

A

struggling to interpret/process faces

  • stems from damage to ventral pathway
105
Q

sensory coding of vision (through colour)

A

Colour provides salient and useful information in an image, aids in object recognition and segmentation of different regions

  • Colours are not a physical colour it is a subjective experience, created by our visual system
106
Q

physical dimensions of vision

A

wavelength, intensity, spectral purity

107
Q

perceived dimensions of vision

A

hue, lightness, saturation

108
Q

trichromatic theory

A

there are three colour channels when perceiving colour

  • red
  • blue
  • green

operating at the receptor level, 1st stage of colour processing

109
Q

opponent-process theory

A

perception of colour is determined by the outputs of three independent mechanisms, composed of a pair of opponent colours

  • red-green
  • yellow-blue
  • black-white

colour processing occurs at post-receptoral level

110
Q

Colour receptors

A

three different types of cone, each with different spectral selectivity

  • The cones differ in photopigment and as a result differ in their sensitivity to light of different wavelengths
  • Cone type named for location of the peak of its sensitivity on the spectrum (short, medium, long)
    Activity in any single cone type does not result in a colour experience
  • Cone responses - relative activity across cone types can be used for code for experienced colours
111
Q

colour-vision deficiency

A

people who suffer red-green deficiency is more prevalent in males (genetic deficiency carried on X-chromosome)

112
Q

colour constancy

A

we are able to perceive surfaces as having the constant colour even if the light they reflect changes (due to changes in light or illumination)

  • light reflecting from a surface is as much at influence by how it is illumination as it is by the reflectance of the surface
113
Q

colour assimilation

A

colour segments look more similar to their immediate surroundings

114
Q

simultaneous colour contrast

A

colours look different when next to different backgrounds

115
Q

depth cue

A

information about the third dimension of visual space

116
Q

binocular depth cue

A

depth cues require information of both eyes

117
Q

monocular depth cue

A

depth cues available with one eye

118
Q

stereopsis

A
  • Binocular visual field is the proportion of the visual field visible with both eyes
  • Two eyes have slightly different views of environment together
  • Difference can be utilised to provide information about depth (stereopsis)
  • binocular
119
Q

convergence

A

Degree to which eyes have to converge to nose to look at something close

  • binocular
120
Q

occlusion

A

Relative depth order in which the object that partially obstructs the view of another object is perceived as in front

  • monocular
121
Q

elevation

A

For objects touching ground, those higher in visual field appear further away

  • monocular
122
Q

texture gradient

A

Textures more dense appear further away

  • monocular
123
Q

aerial perspective

A

Objects further away appear fuzzier

  • monocular
124
Q

interaural intensity difference

A

For certain directions of the sound source, the head creates acoustic shadow, reducing the sound intensity on one side

125
Q

interaural timing differences

A
  • Sound wave coming from the side will hit the nearer ear first, creating a time lag between the two ears
  • Perception of the sounds location depends on the sound that reaches the ear first
126
Q

spectral cues from the filtering property of the pinna

A
  • Above, in front and behind when trying to localise a sound, the shape of the ear is used to hear different sounds
127
Q

vestibular sense

A

provides information about the position of body in space by sensing gravity, movement and acceleration (factors that are critical for maintaining our sense of balance)

128
Q

kinesthesia

A

the sense of position of our body parts with respect to each other that allows us to perform movement

129
Q

bottom up processing

A

brain processes sensory information and uses clues to understand stimuli

130
Q

top down processing

A

using what you already know to perceive new sensory information