01. Psychophysics & research methods Flashcards

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1
Q

What is single-cell recording?

A
  • electrode measures activity of one cell in response to different stimuli
  • stimuli = light bars at different angles
  • each cell responds to only one specific angle
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2
Q

Types of brain imaging?

A
  • PET scans
    -fMRIs
    -Diffuse optical tomography (DOT)
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3
Q

PET scans?

A
  • one of the first types of brain imaging
  • measures bloodflow to see brain activity during different actions
    Problems:
  • same action/stimuli for a long time to be accurate
  • involves radiation
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4
Q

fMRI?

A
  • more modern
  • oxygen level in blood
  • more activity = more oxygen
  • better spatial resolution
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5
Q

DOT?

A
  • diffuse optical tomography
  • oxygen in brain by detecting light reflected by brain
  • temporal resolution = fMRI, spatial resolution is a little worse
  • Portable equipment!!
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6
Q

Psychophysics def

A

study of relationship between physical energy in a stimulus and the perceptual experience it produces

helps make inferences without directly observing brain activity

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7
Q

Absolute threshold def

A
  • minimum intensity of a stimulus required to produce a sensation
  • defined as stimulus detected 50% of the time
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8
Q

Difference threshold def

A

minimum difference in intensity that can be detected
–> Just noticeable difference (JND)

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9
Q

Method of limits?

A
  1. present series of stimulus intensities IN ORDER
  2. ask if they detect it at each presentation
  3. Threshold = midpoint between where the response changed
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10
Q

2 potential problems of method of limits (and solutions)?

A
  1. they keep reporting that they heard it –> error of habituation (present ascending and descending series)
  2. they remember how many stimuli they detect (start the series at a different point each trial)
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11
Q

Method of adjustment

A
  • same as limits
  • except the subject (or experimenter) CONTINUOUSLY adjusts the stimulus until they can’t detect it
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12
Q

Method of constant stimuli

A
  • more accurate than limits, but more trials needed
  • fixed set of stimulus intensities, including extremes
  • presented in RANDOM order
  • each intensity is presented several times
  • graph is an elongated S curve

compare “classical threshold theory” graph to actual “psychophysical function”

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13
Q

Staircase method

A
  • begin at an extreme (far above/below) threshold
  • increase 1 step if not detected, decrease 1 step if detected
  • stop after a predetermined number of response reversals
  • threshold = average intensity at response reversal
  • more efficient than constant stimuli (don’t waste trials on stimuli we know they will/won’t detect)
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14
Q

Method of constant stimuli for difference threshold

A
  • use pre-selected stimulus intensities presented RANDOMLY
  • on each trial, present TWO stimuli
    –> one standard (reference stimuli)
    –> one comparison (varies each trial)
  • possible responses:
    –> C is bigger/brighter/heavier than S
    –> C is smaller/dimmer/lighter than S

Key terms:
- point of subjective equality: stimulus intensity judged greater/less than standard 50% of the time
- point of objective equality: actual value of standard
- constant error: diff. btw PSE & POE
- Diff threshold –> 1/2(75%-25%)

Look at powerpoint 01.methods for ex

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15
Q

Size-weight illusion

A
  • the larger of 2 equal-weight objects feels lighter
  • context influencing perception
    ex –> envelopes with coins
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16
Q

Metamers?

A

any 2 stimuli that are physically different, but perceived as identical