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perception > Problem 1 - DONE > Flashcards

Problem 1 - DONE Flashcards

measuring Perception

1
Q

perceptual processes

A
  • journey from stimuli to responses

- continuously changing process

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2
Q

7 steps of perceptual processes

A
  1. environmental stimulus
  2. light is reflected and transformed
  3. receptor processes
  4. neural processing
  5. perception (knowledge)
  6. recognition (knowledge)
  7. action
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3
Q

step 1 - environmental stimulus

A

what person observes (tree)

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4
Q

step 2 - stimulus on receptors

A

light is reflected and transformed

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5
Q

principle of transformation

A

stimuli and responses created by stimuli are transformed/changed between the environmental stimulus and perception
- central principle of perception

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6
Q

first transformation

A

light hits object (tree) –> reflected from object to the person’s eyes

nature of reflected light depends on

  • properties of the light energy hitting the tree
  • properties of the tree
  • properties of the atmosphere through which the light is transmitted
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7
Q

second transformation

A

reflected light reaches the eye –> focused by the eye’s optical system –> form an image on the receptors of the retina

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8
Q

step 3 - receptor processes/transduction

A

transduction = transformation of one form of energy to another form

receive light reflected from tree –> (1) transduction + (2) shape perception by the way they respond to stimuli

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9
Q

step 4 - neural processing

A

neural processing = changes in signals that occur as they are transmitted through network of neurones

transduction –> electrical signals –> signals enter interconnected network of neurones –> retina –> out the back of the eye –> brain

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10
Q

step 5 - perception

A
  • person perceives object (tree)

- conscious awareness of object (tree)

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11
Q

step 6 - recognition

A
  • recognises object (tree)

- playing an object in a category that gives meaning

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12
Q

step 7 - action

A
  • action that involves motor activities
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13
Q

knowledge

A

any information that perceiver brings to situation; acquired years ago or just recently acquired
- can affect a number of steps in perceptual processes

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14
Q

bottom-up processing

A

(data-based processing)

  • processing that is based on stimuli reaching the receptors
  • stimuli provide starting point for perception
  • -> everything that comes from the outside to the inside
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15
Q

top-down processing

A

(knowledge-based processing)

  • processing that is based on knowledge
  • -> anything that we add (prior knowledge/experience/memory)
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16
Q

method 1: measuring thresholds

A
  • Gustav Fechner
  • psychophysical methods
  • -> absolute threshold
  • Fechner’s law
  • Ernst Weber
  • -> difference threshold
  • Weber’s law
17
Q

method 2: scaling - measure private experience

A
  • S. S. Stevens
  • -> magnitude estimation
  • Stevens’ power law
18
Q

other methods to measure perception

A
  • phenomenological method = person is asked to describe what he or she is perceiving or to indicate when a particular perception occurs
  • visual search = observer’s task is to find one stimulus among many, as quickly as possible
  • -> reaction time = time between presentation of the stimulus and the observer’s response to the stimulus
19
Q

Gustav Fechner

A
  • German scientist-philosopher
  • psychophysics = methods and theory to formally describe the relationship between sensation (mind) and the energy (matter)
  • absolute threshold = minimum stimulus intensity that a subject can detect a given proportion of the time (50% or 75%)
20
Q

psychophysical methods

A
  • how to measure an absolute threshold
  • method of constant stimuli
  • method of limits
  • method of adjustment
21
Q

method of constant stimuli

A
  • repeatedly present stimuli
  • stimuli ranging from rarely to almost always perceivable
  • stimuli are presented one at a time –> participants respond to each presentation ‘yes/no’, ‘same/different’
  • weaknesses: time consuming, relies on subjects’ reports
22
Q

method of limits

A
  • present stimulus far below/above threshold –> increase/decrease intensity until subject responds differently (reports detection/no detection of stimuli)
  • weaknesses: time consuming, relies on subjects’ reports
23
Q

method of adjustment

A
  • experimenter/observer adjust amplitude of a stimuli until observer can just barely detect the stimulus
  • method of limits in which the subject can control the change
24
Q

Fechner’s law

A
  • principle describing the relationship between the stimulus and resulting sensation
    –> says the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity
    y = k*log(S)
  • began with Weber’s law
  • calculation based on some assumptions about how sensation works
  • assumes that all JNDs are perceptually equivalent –> incorrect
  • indirect scaling = based on discrimination ability
25
Q

Ernst Weber

A
  • German anatomist, physiologist
  • two-point touch threshold = minimum distance at which two stimuli are just perceptible as separate
  • difference threshold = JND (just-noticeable difference) = smallest detectable difference between two stimuli
26
Q

Weber’s law

A
  • principle describing the relationship between stimulus and resulting sensation
    –> says the JND is a constant ratio of the standard stimulus
  • Weber fraction = constant of proportionality in Weber’s law
    k = JND/S
  • involves clear objective measurement —> we know how much we varied the stimulus
  • observers can tell that the stimulus changed or they cannot
27
Q

S. S. Stevens

A
  • psychologist
  • magnitude estimation = psychophysical method; participant assigns values according to perceived magnitudes of the stimuli –> ask observer to rate experience
28
Q

Stevens’ power law

A
  • principle describing the relationship between stimulus and resulting sensation
    –> says the magnitude of subjective sensation is proportional to the stimulus magnitude raised to an exponent
    estimation = k S^p
  • describes rating data quite well –> rating data are qualitatively different from the data that supported Weber’s law
  • can record the subjects’ ratings
  • direct scaling = have subjects produce numbers proportional to the magnitude of a given stimulus dimension
29
Q

how do we measure perception?

lecture

A
  1. psychophysics
  2. electrophysiology
  3. neuropsychology
  4. cognitive neuroscience
30
Q
  1. psychophysics

lecture

A

stimulus –> perception

  • present a stimulus and determine the person’s response
  • first task (laws)
31
Q
  1. electrophysiology

lecture

A

stimulus –> brain processes

  • present a stimulus and measure direct brain activity
  • in animals (invasive) –> watch neural firing due to stimulus
32
Q
  1. neuropsychology

lecture

A

brain processes –> perception

  • study the effects of brain damage on behaviour
  • how does brain damage influence perception?
33
Q
  1. cognitive neuroscience

lecture

A

stimulus –> brain processes –> perception

  • present a stimulus and measure both brain activity and perceptual responses
  • fMRI (where in the brain?; passively measure)
  • EEG (when in the brain?)
  • TMS (local, temporary disturbance of brain function; actively measure)
34
Q

sensation

A

= process by which our senses (vision, hearing, smell, taste, touch) receive and relay outside stimuli
- more basic level than perception not really perceive consciously

35
Q

perception

A

= way our brains organise and interpret sensory information and put it into context

  • consciously perceive something
  • active process
  • -> bottom-up processing
  • -> top-down processing

perception (9 decks)

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