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PSY 368 Human Memory Memory Recognition cont.

PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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Page 1: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

PSY 368 Human Memory

Memory Recognition cont.

Page 2: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Experiment 2

• Signal Detection (Download details from BB)• Like last time, find 3 participants

• You’ll 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. You’ll 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),

Page 3: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Experiment 1 results• Overall (N = 18)

• Immediate 7.6 items

• Delayed 6.0• Distraction 3.5

• General report comments• Don’t identify your participants• Stick to APA style as much as

you can• Include your datasheet

Primacy effect in all three conditions

Recency effect strongest in immediate

condition

Page 4: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

• 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)

How does Recognition work?

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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

Dual-process theories

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Dual-process theories

(Tulving, 1985; Gardiner, 1988)

Relatively recent change in recognition methodologyWhen you recognize something, do you:

Specifically remember (linked to Episodic memory)

Conscious recollection of the information’s 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”

Remember versus Know Process Model

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Dual-process theories

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

Remember versus Know Process Model

Prob(remember)

0.88

0.75

0.48

Page 8: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

• Remember/Know processes • Make R/K judgment for “Old” items

• Remember = consciously recollect details of the item’s presentation

• Know = sure an item was presented, but can’t recall any of the details of presentation

Dual-process theories

Picture superiority effect

• R: P > W• K: W > P

Generation effect

• R: G > R• K: R = G

Word frequency effect

• R: L > H• K: H = L

Gardiner et al (1990, 1991, 1993)Remember versus Know Process Model

• R/K differ by:

Page 9: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Remember Versus Know

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)

Remember versus Know Process ModelGardiner et al (1990, 1991, 1993) gives an explanation:

Page 10: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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

Page 11: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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 tone’s loudness against the background noise is manipulated

Easy-to-DetectSignal

Hard-to-DetectSignal

Background NoiseVo

lum

e

Page 12: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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.

HitFalse alarm

MissCorrect reject

yes

no

SIGNAL: Are the spots on the screen

enemies?

DECISION:Should you

scramble the jets?

yes no• 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 harm’s way

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Signal Detection Theory

• Response bias is based on a participant’s preference for a particular outcome.• Preferences are based on costs & rewards

HitFalse alarm

MissCorrect reject

yes

no

SIGNAL: Are the spots on the screen

enemies?

DECISION:Should you

scramble the jets?

yes no

• 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.

Page 14: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Signal Detection Theory

HitFalse alarm

MissCorrect reject

yes

no

SIGNAL: Are the spots on the screen

enemies?

DECISION:Should you

scramble the jets?

yes no• High Criterion: less hits but also less false alarms

• Low criterion: more hits but also more false alarms

• Criterion level (C or β) 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).

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Signal Detection Theory

• Criterion level (C or β) 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

stimulus intensity

pro

babili

ty

Noise

Signal(enemy)

Call for jets

No alert

- Criterion +

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Signal Detection Theory

• d’ (“Dee-prime”) = Discriminability• The difference between the means

• 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 rate=0.99, false alarm rate=0.01)

stimulus intensity

pro

babili

ty

NoiseSignal(enemy)

stimulus intensity

pro

babili

tyNoise

Signal(enemy)

Low d ’

high d ’

Page 17: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Signal Detection Theory

• Recognition accuracy depends on:• Whether a signal (noise/target memory) was

actually presented• The participant’s 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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Page 19: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Signal Detection Theory

• Everything more familiar than (to the right of) the response criterion (beta or β) will be judged “old”• A centrally placed β is unbiased

• Everything less familiar (i.e. to the left of β) 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 participant’s ability to discriminate the two distributions19

Page 20: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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 β 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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Page 21: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Signal Detection Theory

• Calculating d’ and C (or β)• 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 β):• 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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Page 22: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

• Special recognition ability

Face Recognition

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• Evidence for special ability:(1)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.

Face Recognition

Page 24: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

• 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

Face Recognition

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• 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.

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

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

Face Recognition

Page 26: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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The ‘Thatcher Illusion’(Thomson, 1980)

Page 27: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

27

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 aren’t aware of the odd configuration of

elements within the inverted Thatcher image.

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

2005)

Face Recognition

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

Page 30: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Face Recognition

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

Page 31: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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

2005)

Face Recognition

Now find the animal face. Ready?

Page 32: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

Face Recognition

Page 33: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

(1) Recognition is an explicit memory test.

(2) Single- and dual-process theories of recognition

(3) Single-process can’t account for differences across recall and recognition

(4) G-R theory can’t account for items that are recalled, but not recognized

(5) Face recognition seems to be a special ability

Summary

Page 34: PSY 368 Human Memory Memory Recognition cont.. Experiment 2 Signal Detection (Download details from BB) Like last time, find 3 participants You’ll need

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

Word Frequency

High Low

Hits 27.84 31.00

False Alarms 10.20 7.63

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

• 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 = Inclusion’s correct recognition minus Familiarity

Dissociating Recollection and Familiarity