Psychology: Perception

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Florenciana
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Psychology: Perception
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2014-11-06 00:17:48
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Psychology Perception
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  1. What is absolute threshold?
    The minimum amount of physical energy that supports reliable detection - this is where you sense the presence of stimuli
  2. What is interpretation dependent on in distinguishing between noise from a signal?
    Sensitivity of the signal and the observer's own criterion for identifying a sensation as a signal
  3. What is input dependent on?
    The product of illumination (how much light a source emits - sources might be a light bulb, or natural sunlight) and the surface reflectance (property of the object/surface you are looking at).
  4. What are the two classes of photoreceptors?
    Rods and cones
  5. What is the difference between rods and cones?
    Rods are more sensitive to light than cones so have a lower absolute threshold. However, rods contribute little to colour vision (achromatic) and have a lower spatial resolution so do not contribute to fine details. There are around 120 million rods in our retina.

    Cones have a higher spatial resolution than rods and allow for greater detail(they capture light from a narrow region of space). Cones are critical for colour vision. There are approximately 8 million cones in our retina.
  6. What does just noticeable difference refer to?
    The differences in the quality of a sensation (whether something is louder/quieter/ does it taste or smell different)
  7. What is Weber's law?
    The just noticeable difference (jnd) is a constant proportion to the physical stimulus intensity
  8. What is neuron signalling?
    It is the rate of signalling when neurons communicate via action potentials
  9. Name a strategy to limit neuron signalling?
    Adaptation - when you smell a new strong scent, it might be unpleasant at first but after a few days, your sense of smell adapts and the smell is no longer as bad - your sensory system minimises the need to signal this particular smell, reducing the amount of neural signalling.
  10. What is the pathway/sequence when light enters our eyes?
    light enters through the cornea, passes through the pupil of the iris then passes through the lens which focuses light onto the retina.
  11. What is the retina
    A layered sheet covering the inner surface of the back of the eye
  12. What happens when light reaches the retina?
    light is captured by photoreceptors, which stimulates bipolar cells (attached to the photoreceptors), which then stimulates ganglion cells and then signals are then transmitted out of the eye via the optic nerve
  13. What are photoreceptors and where are they located?
    Incoming light is captured by photoreceptors at the back of our retina. Basically, our retina is a mosaic of photoreceptors which tile the retina.
  14. What are bipolar cells attached to and what is their function?
    Bipolar cells are connected to one or more photoreceptors (either one or more rods or one or more cones, but not both). They transmit graded information about how much the photorececptor was activated to the ganglion cells.
  15. What is the function of ganglion cells?
    Ganglion cells integrate graded information (sum together the activity) received from bipolar cells. If the summed activity is sufficiently high, the ganglion cell fires an action potential (spike).
  16. What type of organisation does the ganglion cell consist of?
    Centre-surround organisation: an excitatory centre component and an inhibitory surrounding component. These components make up the receptive field.
  17. What is lateral inhibition?
    Lateral inhibition refers to the centre-surround organisation of the ganglion cell with its excitatory centre component and inhibitory surrounding component.
  18. How is the lateral inhibition configured?
    Either ON-centre or OFF-centre, that is, increments and decrements of light respectively.
  19. What is a consequence of lateral inhibition in ganglion cells?
    Ganglion cells transmit changes in light intensity across space, so they don't respond well to roughly uniform light. If you have dramatic changes in light intensity (such as the edges of a building or people) then you get a response from the Ganglion cell.
  20. What is the function of the optic nerve?
    It gathers the Ganglion cell activity and sends it out to the eye.
  21. What are the three dimension of colour?
    • Hue
    • Saturation
    • Value
  22. Which aspect of the visible spectrum do the dimensions of colour refer to?
    • Hue - precise wavelength
    • Saturation - width of spectral wavelength  
    • Value - peaks/amplitude of wavelength
  23. How many cones does a person with normal coloured vision have?
    3 cones: SM, and L
  24. What are the peak sensitivities of the three different cones?
    • S-cone = approx. 420 nm (if light has a wavelength of 650 nm, the S-cone photorecptor will not absorb that light)
    • M-cone = 535 nm
    • L-cone = 565 nm
  25. What colours do the three cone photorecptors correspond to?
    • S-cone = blue
    • M-cone = green
    • L-cone = red
  26. From our three different cone photorecptors, what are the two opponent-colour representations that under lie our perception of colour?
    The trichromatic representation we receive from our S, M and L cones is transformed into two opponent-colour signals: red/green and blue/yellow
  27. Once the Ganglion cell activity is sent out from the eye via the optic nerve where does it go?
    It reaches the optic chiasm
  28. Which statement is correct?

    (A) The nasal part of each retina crosses hemispheres, and the temporal part of each retina stays in the same hemisphere

    (B) The nasal part of each retina stays in the same hemisphere, and the temporal part of each retina crosses hemispheres.

    (C) The nasal part of each retina stays in the same hemisphere, and the temporal part of each retina stays in the same hemisphere.

    (D) The nasal part of each retina crosses hemispheres, and the temporal part of each retina crosses hemispheres.
    • (A) The nasal part of each retina crosses hemispheres, and the temporal part of each retina stays in the same hemisphere
  29. Which statement is correct?

    (A) The left visual field gets processed in the right hemisphere and the right visual field is processed in the right hemisphere.

    (B) The left visual field gets processed in the right hemisphere and the right visual field is processed in the left hemisphere.

    (C) The left visual field gets processed in the left hemisphere and the right visual field is processed in the right hemisphere.

    (D) The left visual field gets processed in the left hemisphere and the right visual field gets processed in the left hemisphere.
    (B) The left visual field gets processed in the right hemisphere and the right visual field is processed in the left hemisphere.
  30. What is the primary pathway from the eye to the brain?
    The lateral geniculate nucleus of the thalamus (LGN)
  31. What is the secondary pathway from the eye to the brain?
    The superior colliculus
  32. Which statement is correct about the lateral geniculate nucleus?

    (A) The signals coming from the left eye are merged with the signals coming from the right eye in the LGN.

    (B) The signals coming from the left eye are scattered amongst the signals coming from the right eye in the LGN.

    (C) The signals coming from the left eye are kept separate from the signals coming from the right eye in the LGN.

    (D) The signals coming from the left eye are initially separated and later merged with the signals coming from the right eye in the LGN.
    (C) The signals coming from the left eye are kept separate from the signals coming from the right eye in the LGN.
  33. How are LGN cells similar/different to Ganglion cells in their organisation?
    • They both have a centre-surround organisation (excitatory centre region and inhibitory surround region). 
    • However, the effect of the inhibitory surround region is more potent in the LGN cells than the Ganglion cells so the LGn has a greater lateral inhibition.
  34. Which statement is correct?

    (B) The LGN re-transmits/passes nearly all (100%) of the signals/spikes it receives from the retina Ganglion cells.

    (C) The LGN re-transmits/passes most (75%) of the signals/spikes it receives from the retina Ganglion cells.

    (D) The LGN re-transmits/passes on around half (50%) of the signals/spikes it receives from the retina Ganglion cells.

    • (D) The LGn re-transmits/passes on around half (50%) of the signals/spikes it receives from the retina Ganglion cells.
  35. What is the next destination after the LGN?
    • The main (though not exclusive) projection is to the very back of the brain called the occipital cortex
  36. What is the region called that signals go to after the LGN?
    They head towards the occipital cortex, belonging to the region of the primary visual cortex (V1)
  37. What are some other names for the primary visual cortex?
    V1, striate cortex or area 17
  38. Which statement is correct?

    (A) V1 and retina Ganglion cells depend on orientation selectivity, while LGN don't.

    (B) Only retina Ganglion cells depend on orientation selectivity, while V1 and LGN cells don't.

    (C) Only LGN cells depend on orientation selectivity, while V1 and retina Ganglion cells don't.

    (D) Only V1 cells depend on orientation selectivity, while retina Ganglion cells and LGN cells don't.
    (D) V1 cells depend on orientation selectivity. Retina Ganglion cells and LGN cells are not concerned about the orientation of information in the receptive field.
  39. What do we mean by orientation selectivity?
    It refers to the light pattern in the receptive field. For V1 cells in the brain for example, it will tend to only respond to visual input with a specific orientation. This is why we say that V1 cells depend on orientation selectivity.
  40. What is the difference in response between simple and complex V1 cells?
    • Both cells, being V1 cells, depend on orientation selectivity so care about the orientation of the light pattern in the receptive field. 
    • For simple cells, they require the light pattern to be in a precise location within the receptive field. However, for complex cells, they are responsive to light pattern wherever it is within the receptive field.
  41. What is the pathway beyond the primary visual cortex, V1?
    • There are a whole set of other visual areas - there are at least 20 identified visual areas int he brain.
    • Usually we say there is the dorsal ('how/where' pathway) and ventral ('what' pathway) pathways.
  42. Where does the dorsal and ventral pathways lead to?
    Dorsal goes up to the posterior parietal cortex and ventral goes down to the inferotemporal cortex
  43. What are the key components of sound waves?
    • Frequency
    • Complexity
    • Amplitude
  44. What perceptual dimension does the frequency of sound refer to?
    Pitch - low frequency, low perceptual pitch
  45. What sit he relationship between frequency and wavelength?
    They have an inverse relationship - shorter the wavelength, the higher the frequency
  46. If a sound wave has a particular amplitude, what does its perception of loudness depend on?
    Its frequency. So tones of the same amplitude but different frequency may differ in their perceived loudness.
  47. What perceptual dimension does sound complexity contribute to?
    Timbre
  48. If a particular sound has many frequencies, what is pitch determined by?
    Pitch is determined by the fundamental frequency when you have many frequencies.
  49. If you have many frequencies in a sound, what is timbre determined by?
    Non-fundamental frequencies
  50. What is amplitude?
    It refers to the intensity of pressure oscillations and is related to the perceived loudness.
  51. What is the measurement for amplitude? What is the absolute threshold for audition and pain threshold?
    • Amplitude is measured in decibels.
    • 0 dB is the absolute threshold for audition
    • 140 dB is the pain threshold (10 million times the amplitude of the absolute threshold)
  52. When we sense sound, what happens when sound enters our outer ear?
    Sound waves are funnelled into the ear where they resonate in the auditory canal and become amplified (increase in sound intensity). The waves make the eardrum vibrate.
  53. When we sense sound, what happens when sound enters our middle ear?
    When the eardrum is affected by a sound wave and vibrates, this affects the bonds in the middle ear called the ossicles. The ossicles include the bones: the hammer, anvil and stirrup. The bones amplify the waves. The stirrup vibrates against the 'oval window' membrane.
  54. When we sense sound, what happens when sound enters our inner ear?
    When the stirrup vibrates against the 'oval window' membrane, it affects the fluid waves in the cochlea. The fluid waves affect the hair cells in the basilar membrane of the cochlea, where sound receptors are capable of triggering action potentials in the neurons that form the auditory nerve.
  55. What is the place theory?
    The place theory suggests that the location of stimulation on the basilar membrane is linked to the sound wave frequency.
  56. According to the place theory, what is the trend as you transition across the surface of the basilar membrane, starting closest to the cochlear?
    Positions closest to the base of the cochlear respond best to high frequency sound waves. As you move across, they start to respond beter to lower frequencies.
  57. What is a limitation of the place theory?
    At very low frequenciesthe whole of the basilar membrane vibrates, so we cannot use the place theory approach to truly understand the frequency content of the sound wave.
  58. What is the frequency theory?
    The frequency theory says that the frequency of hair cell firing is linked to sound wave frequency. By increasing frequency of the sound wave, you increase the hair cell response.
  59. When is it best to use the place theory and frequency theory?
    Place theory is good to explain high frequencies (base of cochlea is activated) while frequency code is good for explaining low frequencies (little hair cell response)
  60. Which theory (place / frequency) should we use if we have a intermediate frequency sound wave?
    Use both place and frequency coding to work out frequency structure of the sound wave.
  61. From the auditory nerve, where do sound waves go?
    Signals travel through various subcortical structures. Most, but not all, signals cross over opposite hemisphere (left ear to right hemisphere and vice versa). It eventually reaches a region in the temporal lobes called the primary auditory cortex.
  62. What kind of representation is seen in the auditory cortex?
    A tonotopic representation where there is a frequency preference across the cortical surface. There seems to be an over-representation of middle frequencies maybe because the auditory cortex is particularly sensitive to voices.
  63. What do gas molecules from vapours enter through to get into our bodies?
    • Nasal cavity of the nose of mouth.
  64. What happens after odours enter our nasal cavity?
    The olfactory epithelium, basically the 'retina of the nose'
  65. What happens after odours stimulate the olfactory epithelium?
    The molecules become trapped in the olfactory mucus which then stimulates the olfactory receptor cells, sending signals to the olfactory bulb.
  66. What happens after signals are sent to the olfactory bulb?
    Signals travel to different areas of the cortex such as the thalamus and limbic system.
  67. What information can we gather from odours?
    We may be able to determine the emotional state of a person just by smelling their underarm sweat.
  68. How are taste and smell related?
    • Both combine to give us the perception of flavour.
    • Smell is the ability to sense chemical molecules in the air, while taste is our sensitivity to molecules soluble in saliva.
  69. What are the basic tastes?
    There are four basic tastes: sweet, salty, sour, bitter
  70. What is an additional candidate for the list of basic tastes?
    Umami (savoury)
  71. What physical stimulus gives us the sensation of a sweet taste?
    Sucrose and other carbohydrates
  72. What physical stimulus gives us the sensation of a salty taste?
    Sodium and other chlorides
  73. What physical stimulus gives us the sensation of a sour taste?
    Acids
  74. What physical stimulus gives us the sensation of a bitter taste?
    Toxic chemicals (chemicals or materials that are harmful to the organism)
  75. What physical stimulus gives us the sensation of a umami/savoury taste?
    Certain amino acids such as glutamate, aspartate and related compounds.
  76. Where are taste buds located?
    Mostly are on our tongue (specifically on the papillas) but some are in our mouth but not on our tongue
  77. What structures are found on the surface of our tongue?
    • Papillas which hold a set of taste bud receptors to signal responses
  78. Which statement is correct?

    (A) Taste bud receptors are constant, they never change.

    (B) Some taste bud receptors are constant, while some are regenerated and replaced every so often.

    (C) Taste bud receptors are regenerated and replaced only depending on the kinds of foods we eat.

    (D) Taste bud receptors are regenerated and replaced approximately every 10 days.
    (D) You don't have a constant set of taste buds - they change every 10 days.
  79. Which statement is correct?

    (A) Different regions of the tongue are sensitive to different tastes.

    (B) Receptors for different tastes are distributed over the entire tongue.

    (C) All receptors are sensitive to the same tastes across the entire tongue.

    (D) None of the above.
    (B) Receptors sensitive to different tastes are distributed over the entire tongue.
  80. Where do taste receptor signals travel to?
    To the primary taste cortex (insula) or to the limbic system which mediates automatic responses and associations, underlying the reflexive spitting out response when you taste something disgusting.
  81. How does transduction occur in the skin?
    When skin is moved or displaced, mechanical energy is transduced by the mechanoreceptors.
  82. What are the two types of mechanoreceptors?
    Slow-adapting fibres and rapid-adapting fibres.
  83. When are slow-adapting fibres activated and what is its function?
    When the pressure on the skin is continuous. It's primary function is to sense fine detail and texture.
  84. When are rapid-adapting fibres activated and what is its function?
    When there is an onset and offset of pressure stimulation (not to maintained stimulation). The primary function is detecting low and high frequency vibrations.
  85. What is the difference in receptive field sizes between rapid-adapting fibres and slow-adapting fibres?
    Rapid-adapting fibres have larger receptive field size than slow-adapting fibres.
  86. What is the difference between absolute sensitivity and difference sensitivity?
    • Absolute sensitivity - can you feel this pressure change or not
    • Difference sensitivity - here's a pressure change, here's another pressure change - where they different?
  87. Where on our bodies are we highly sensitive in detecting pressure?
    Moving away from the body, our sensitivities increase so our fingers and face hold the highest sensitivities.
  88. Where are we least sensitive on our bodies?
    Lease sensitive on our legs.
  89. What is our perception when we hold one warm and one cold pipe together?
    We perceive extreme heat. Our cold receptors also signal extreme temperatures, both hot and cold.
  90. Why are we not equally sensitive to pressure across our bodies?
    When signals travel to the somatosensory cortex, different regions of the body are mapped and have different amounts of area devoted to them.
  91. What is proprioception?
    It involves the registration of body position and movement.
  92. What are two senses arising from proprioception?
    Vestibular and kinaesthetic
  93. What is the function of our vestibular system?
    It signals head motion and orientation with respect to gravity.
  94. Where are our vestibular organs located in?
    Inner ear
  95. What is the key limitation to the vestibular system?
    It cannot signal motion of constant velocity - it only detects acceleration and deceleration of translation and rotational movements.
  96. What is the function of our kinaesthetic system?
    It signals the movement and position of parts of our body relative to one another.
  97. Is the kinaesthetic system conscious or an unconscious system?
    It is largely unconscious.
  98. Where are our kinaesthetic receptors located in?
    Joints, tendons and muscles
  99. What is the Gestalt approach?
    It is an attempt to explain how we organise visual input such that we perceive the form of an object.
  100. What are the 6 Gestalt principles?
    • We assign elements to a figure (foreground) and a background. (Bistability may occur)
    • We group elements that are similar (in some dimension e.g. colour)
    • We group elements that are in close proximity
    • We prefer contours to be organised into continuous flows
    • We arrive at the simplest perceptual interpretation.
    • We preceptually complete absent sensory information.
  101. What is the recognition-by-components theory?
    This theory suggests that simple features are combined into a small number of elementary geometrical forms - "geons". The 'alphabet' of geons then combine to represent the form of many complex objects.
  102. What is the region of the visual field visible to both eyes called?
    Binocular visual field
  103. What is stereopsis?
    It refers to the different views of the visual environment gathered from our two eyes which can be utilised to provide information about depth.
  104. What is the cue to depth called when an object blocks another?
    Interposition is a monocular cue to depth - where one object blocks another, the blocked object is behind
  105. What is the cue to depth called when there are higher objects on the ground plane?
    Elevation is a monocular cue to depth  - higher objects on the ground plane signify they are further away
  106. What is the cue to depth called when objects appear fuzzier relative to others?
    Aerial perspective is a monocular cue to depth - objects that are further away appear fuzzier.
  107. How can we judge the position of auditory sources?
    We can use two different types of information: inter-aural intensity differences (mostly only useful for high frequencies) and inter-aural time differences.
  108. What does inter-aural intensity differences refer to?
    Because of our head blocking some of the sound wave, one ear will receive a slightly higher intensity sound than the other ear.
  109. What kind of frequencies does the head bock more effectively?
    Head blocks higher frequencies more effectively than low frequencies.
  110. What does inter-aural time differences refer to?
    Sound will reach our two ears at slightly different times.
  111. Which regions of our brain are particularly important for perceiving visual motion?
    The MT and MST regions within the dorsal 'where/how' pathway.
  112. What is the 'bottom-up' view of perception?
    It emphasises the role of sensory data.
  113. What is the 'top-down' view of perception?
    It emphasises the role of previous experience, expectations and knowledge (high-level functions).
  114. How can visual information affect perceived sound?
    Expectations based on visual information can affect perceived sound e.g. McGurk Effect
  115. What are schemas?
    Patterns of thinking about a domain that produce expectations about its structure. e.g. the word 'kitchen' evokes a set of expectations about the likely layout of the environment and objects contained within it.
  116. How can our perception be affected without knowledge?
    The context of sensory information can strongly affect our perceptual interpretation.
  117. What is the tilt illusion?
    It refers to the context of sensory information affecting our perceived orientation.
  118. What is surround suppression?
    It refers to the context of sensory information affecting our perceived contrast.
  119. What are the three ways in which context of sensory information can affect particular perceptual qualities?
    Orientation, contrast and colour.

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