PSY 368 Human Memory

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PSY 368 Human Memory

• Memory
• Recognition cont.

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Experiment 2

• Signal Detection (Download details from BB)
• Like last time, find 3 participants
• Youll need index cards for the words (write one
  word per card)
• Read instructions to participants, the IV is
  manipulated with different instructions for each
  condition, so make sure that you read the correct
  instructions. Youll need to print out 3 copies
  of the memory test (1 for each participant)
• Fill out the datasheet and bring it to class on
  Monday (March 5th, date in assignment is old Fall
  date). I will compile data for whole class and
  bring it on Wednesday March 7th
• Reports will be due the Wednesday after Spring
  Break (March 21st),

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Experiment 1 results

• Overall (N 18)
• Immediate 7.6 items
• Delayed 6.0
• Distraction 3.5

• General report comments
• Dont identify your participants
• Stick to APA style as much as you can
• Include your datasheet

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How does Recognition work?

• Two classes of theories
• Single process theories - retrieval is one
  process regardless of task
• Tagging Model (Yntema Trask, 1963)
• Strength Theory (Wickelgren Norman, 1966)
• Dual process theories - two processes needed for
  retrieval - can be task dependent
• Generate-recognize model (G-R)
• e.g., Anderson Bower (1972)s HAM
• Remember/Know processes model (R/K)

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Dual-process theories

• Generate-recognize model (G-R)
• Recall is made up of two processes
• First, generate a set of plausible candidates for
  recall (Generation stage)
• Second, confirm whether each word is worthy of
  being recalled (Recognition stage not the same
  as the recognition test)
• Recognition is made up of only one process
• Because the experimenter provides a candidate,
  recognition does not need the generation stage

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Dual-process theories
Remember versus Know Process Model

• (Tulving, 1985 Gardiner, 1988)
• Relatively recent change in recognition
  methodology
• When you recognize something, do you
• Specifically remember (linked to Episodic memory)
• Conscious recollection of the informations
  occurrence at study
• Just somehow know (linked to Semantic memory)
• Knowing that it was on the list, but not having
  the conscious recollection, just a feeling of
  knowing

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Dual-process theories
Remember versus Know Process Model

• Tulving (1985)
• Present subjects with 27 category-member pairs
  (FRUIT pear)
• Recall tests
• Free recall test
• Cued recall test (category) FRUIT
• Cued recall test (category first letter of
  target) FRUIT- p
• Results
• The proportion of remember judgments decreased
  over the three kinds of tests

Prob(remember) 0.88 0.75 0.48
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Dual-process theories
Remember versus Know Process Model
Gardiner et al (1990, 1991, 1993)

• Remember/Know processes
• Make R/K judgment for Old items
• Remember consciously recollect details of the
  items presentation
• Know sure an item was presented, but cant
  recall any of the details of presentation

• R/K differ by

• Picture superiority effect
• R P gt W
• K W gt P

• Generation effect
• R G gt R
• K R G

• Word frequency effect
• R L gt H
• K H L

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Remember Versus Know
Remember versus Know Process Model
Gardiner et al (1990, 1991, 1993) gives an
explanation

• Remember judgments are influenced by conceptual
  and attentional factors
• Know judgments are based on a procedural memory
  system
• This is similar to a distinction between explicit
  and implicit memory (more on this next week)

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Techniques used to distinguish dual processes

• Signal Detection Theory
• A technique for separating discrimination (true
  detection) from response bias
• Process Dissociation (next week)
• A technique for separating intentional
  (effortful) retrieval processes from incidental
  (automatic) retrieval processes
• May want to go back and review pages 111-114

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Signal Detection Theory

• Signal Detection Theory
• A model for explaining recognition memory
• Based on auditory perception experiments
• Typical Task
• Ask participants to detect a faint tone (signal)
  presented against a background of noise
• The tones loudness against the background noise
  is manipulated

Volume
Background Noise
Easy-to-DetectSignal
Hard-to-DetectSignal
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Signal Detection Theory

• Brief History
• In World War II radar waves were used to detect
  enemy aircraft.
• The soldiers had to determine if the little spots
  of light are enemies, or simple noise (I.e.
  birds).
• There was no clearly defined criteria for making
  these kinds of decisions.

SIGNAL Are the spots on the screen enemies?

• Consequences
• If an enemy went undetected, people could be
  killed.
• If noise was interpreted as an enemy, time and
  money would be lost and people would be put in
  harms way

yes
no
DECISION Should you scramble the jets?
Hit False alarm
Miss Correct reject
yes
no
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Signal Detection Theory

• Response bias is based on a participants
  preference for a particular outcome.
• Preferences are based on costs rewards

• For example,
• People will die because I failed to detect enemy,
  that is a very high cost.
• If congress yells at me for spending money, that
  is not a very high cost.

SIGNAL Are the spots on the screen enemies?
yes
no
DECISION Should you scramble the jets?
Hit False alarm
Miss Correct reject
yes
no
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Signal Detection Theory

• Criterion level (C or ß) is set based on outcome
  preferences.
• Criterion level The intensity at which a signal
  will be reported as being present (Not the
  intensity at which it is perceived).

• High Criterion less hits but also less false
  alarms
• Low criterion more hits but also more false
  alarms

SIGNAL Are the spots on the screen enemies?
yes
no
DECISION Should you scramble the jets?
Hit False alarm
Miss Correct reject
yes
no
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Signal Detection Theory

• Criterion level (C or ß) is set based on outcome
  preferences.
• Criterion level The intensity at which a signal
  will be reported as being present (Not the
  intensity at which it is perceived).

• High Criterion less hits but also less false
  alarms
• Low criterion more hits but also more false
  alarms

- Criterion
No alert
Call for jets
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Signal Detection Theory

• d (Dee-prime) Discriminability
• The difference between the means

Low d

• If d is low, then this means there is low
  discriminability.
• The noise and stimulus are highly overlapping.
• d 0 pure chance
• If d is high, then this means there is high
  discriminability.
• d 1 moderate performance
• d 4.65 optimal (corresponds to hit
  rate0.99, false alarm rate0.01)

high d
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Signal Detection Theory

• Recognition accuracy depends on
• Whether a signal (noise/target memory) was
  actually presented
• The participants response
• Thus, there are four possible outcomes
• Hits
• Correctly reporting the presence of the signal
• Correct Rejections
• Correctly reporting the absence of the signal
• False Alarms
• Incorrectly reporting presence of the signal when
  it did not occur
• Misses
• Failing to report the presence of the signal when
  it occurred

CORRECT
INCORRECT
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Signal Detection Theory

• Assumptions
• Memory traces have strength values (i.e.
  activation levels)
• Activation levels dictate how familiar a
  stimulus feels
• Traces vary in terms of their familiarity, based
  on
• Attention paid to the stimulus during encoding
• The number of repetitions

• Familiarity values for old and new items are
  each normally distributed
• On average, new items are less familiar than
  old items
• However, some distractors are quite familiar
  because they appear often in other contexts or
  are similar to old items
• Thus, there can be overlap between the
  distributions
• Items that surpass a threshold (i.e. response
  criterion) of familiarity are judged old

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Signal Detection Theory

• Everything more familiar than (to the right of)
  the response criterion (beta or ß) will be judged
  old
• A centrally placed ß is unbiased
• Everything less familiar (i.e. to the left of ß)
  will be judged new.
• Hits (in green)
• Misses (in red)

• Above, the same distribution with the focus on
  the lure distribution to highlight
• Correct rejections (in green)
• False alarms (in red)
• D prime (d) represents
• The distance between the distributions
• The participants ability to discriminate the two
  distributions

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Signal Detection Theory

• A more liberal guesser will
• Have a response criterion shifted to the left
• Accept more targets as old (i.e. hits)
• Accept more lures as old (i.e. false alarms)
• A more conservative guesser will
• Shift ß to the right
• Have fewer hits
• Have fewer false alarms
• Thus, the overlap in the distribution leads to
• Trade offs between hits and false alarms
• Depends on the placement of the response criterion

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Signal Detection Theory

• Calculating d and C (or ß)
• Discriminability (d)
• Step 1) Look up the z-score for the average Hit
  and False Alarm rates.
• Step 2) Apply the formula d zHIT zFA, where
  zFA is the z-score for FAs and zHIT is the
  z-score for Hits.
• Criteria C (or ß)
• Take the negative of the average of zHIT and zFA.
  This is the criterion value C.
• Remember that positive C values indicate a
  conservative response bias, while negative C
  values indicate a liberal response bias.
• We will go over this in class again next week
  when we have our data for Experiment 2
• http//memory.psych.mun.ca/models/dprime/

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Face Recognition

• Special recognition ability

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Face Recognition

• Evidence for special ability
• Prosopagnosia
• The inability to recognize previously seen faces,
  with relative sparing of other perceptual,
  cognitive and memory functions.
• Intact ability to identify people using nonfacial
  features (voice)
• Due to brain injury (typically to the right
  temporal lobe)
• Broad Subtypes
• 1. Apperceptive - failure to generate a
  sufficiently accurate percept to allow a
  successful match to stores of previously seen
  faces.
• 2. Associative - accurate percept, but failure to
  match because of loss of facial memory stores or
  disconnection from them.

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Face Recognition

• Evidence for special ability
• (2) Newborn preferences
• Studies done by Fantz (1961, 1963) - had kids
  look at three kinds of figures
• Morton and Johnson (1991) report that new-born
  babies will preferentially view faces

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Face Recognition

• Evidence for special ability
• (3) Face inversion effect

• Yin (1969) found that whilst people are generally
  better at recognising upright faces than they are
  other objects. They are worse for inverted faces
  than they are for other inverted objects.

• This suggests that the processing underlying
  normal face recognition is different from those
  underlying object recognition.

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The Thatcher Illusion
(Thomson, 1980)
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The Thatcher Illusion
(Thomson, 1980)
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Why does the Thatcher illusion occur?

• Bartlett and Searcy (1993) conducted experiments
  to measure face grotesqueness.
• Their results supported the configural
  processing hypothesis
• i.e. We have a difficulty in understanding the
  configuration of features when faces are
  inverted.
• We arent aware of the odd configuration of
  elements within the inverted Thatcher image.

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Face Recognition

• Evidence for special ability
• (4) Pop-out effect for faces (Herschler
  Hochstein, 2005)

Find the human face in the display as fast as you
can. Ready?
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Face Recognition
Find the human face in the display as fast as you
can. Ready?
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Face Recognition

• Evidence for special ability
• (4) Pop-out effect for faces (Herschler
  Hochstein, 2005)

Now find the animal face. Ready?
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Face Recognition
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Summary

1. Recognition is an explicit memory test.
2. Single- and dual-process theories of recognition
3. Single-process cant account for differences
   across recall and recognition
4. G-R theory cant account for items that are
   recalled, but not recognized
5. Face recognition seems to be a special ability

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The Mirror Effect

• Observed when The type of stimulus that is
  accurately recognized as old when old is also
  accurately recognized as new when new. The type
  that is poorly recognized as old when old is also
  poorly recognized as new when new. (Glanzer
  Adams, 1985, p.8)
• Pervasive in recognition tests
• High/low word frequency and hit/false alarm
  rates, presentation rate, age of subject, ...

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The Mirror Effect - Example
The Mirror Effect and the Word Frequency Effect The Mirror Effect and the Word Frequency Effect The Mirror Effect and the Word Frequency Effect
Word Frequency Word Frequency
High Low
Hits 27.84 31.00
False Alarms 10.20 7.63
Source Human Memory, p. 214 Source Human Memory, p. 214 Source Human Memory, p. 214
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The Mirror Effect

• Significance It eliminates all theories of
  recognition based on a unidimensional conception
  of strength or familiarity (single process
  models)
• May be able to be explained by dual process
  models
• Explanations for the mirror effect are still
  being formed

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Dual-process theories
Dissociating Recollection and Familiarity

• Process Dissociation Procedure (Jacoby, 1991)
• Task
• Participants study two sets of items in different
  contexts
• Two different recognition tests follow
• Inclusion Condition
• Say yes if they recognize an item from either
  context
• Correct recognition Recollection Familiarity
• Exclusion Condition
• Say yes only if they recognize an item from one
  of the two contexts
• Familiarity False alarms in exclusion condition
• Recollection Inclusions correct recognition
  minus Familiarity