Cognitive ProcessesPSY 334

Chapter 7 – Human Memory: Retention and Retrieval

What is Forgetting?

Do memories still exist in mind when we cannot remember? Penfield – stimulated areas of the brain and

got reports of recall from childhood. No way to check the accuracy of reports.

Nelson – some savings are evident even when subjects cannot remember items: Savings found with recall (78% unchanged,

43% changed) and recognition (34% & 19%).

Brain Areas Important to Memory

The Retention Function

Wickelgren – studied the retention function: Performance is a function of delay. Log (d’) = A – b log T Where: T is delay, d’ is performance

(memory strength). Power law of forgetting -- power function

becomes linear when plotted on log-log scales.

Power Law of Forgetting

Rate of Forgetting

Retention function shows diminishing loss (forgetting) with delay.

Theory of short-term memory predicts sharp drop-off followed by stable memory. Since all retention functions are like this,

there is nothing special about short-term memory compared to long-term memory.

Practice postpones the point of decay.

Long-Term Retention

Bahrick – studied retention of English-Spanish vocabulary over 50 years. Substantial practice effect. Slow decline after 3 yrs. Drop-off at end due to physical aging.

Barnes – decrease in long-term potentiation with delay. Mirrors retention function. Decay theory of forgetting – LTP changes.

Bahrick’s Retention of Spanish

Notice that retention only drops off at the end when subjects are 65+ in age.

Decay – Decline in LTP

Interference

Interference paradigm – two groups defined: Experimental group – learns new

associations for previously learned list Control group – learns entirely new list

Typically the experimental group does worse after a delay.

Does this mean that it is difficult to maintain multiple associations?

Typical Interference Experiment

A-D Experimental C-D Control

Learn A-B Learn A-B

Learn A-D Learn C-D

Test A-B Test A-B

A-D produces more interference than C-D

Fan Effect

There is a limit to how much activation can spread within a network: The more associations, the less activation

can spread to any particular structure. Anderson – fan effect:

Recognition time increases with the number of facts about a person and a location (e.g., lawyer, church).

The brain works harder with “high” fans.

Anderson’s Experiment

Mean Recognition

Time for Different Numbers of Sentences

1 2

1 1.11 1.17

2 1.17 1.22

Preexisting Memories

Does knowledge brought into an experiment interfere with new learning?

Lewis & Anderson – facts about Napoleon: Fantasy facts – learned during experiment True facts – from the real world False facts – not studied in experiment and

not true in the real world Fan effect occurs with all three fact types

Interference from Preexisting Facts

Interference vs Decay

Less forgetting during sleep than when awake. Occurs because material is retained better

when learned at night. Night is period of highest arousal.

Forgetting functions may reflect interference from unknown sources.

Decay theories do not specify any mechanism for decay.

Effects of Redundancy

Interference occurs only when learning multiple memories that have no relationship to each other.

Bradshaw & Anderson – compared relevant and irrelevant fact learning: Irrelevant facts interfere. Relevant facts aid memory compared to

single fact learning.

Relevant vs Irrelevant Information

Immediate Recall %

Recall at 1 week %

Single fact 92 62

Irrelevant facts 80 45

Relevant facts 94 73

Retrieval and Inference

Much of memory is inference at the time of recall – not actual retrieval of facts.

Bransford et al. -- inference can lead to incorrect recall: Turtles resting on or beside a log and a

fish swam beneath them. Subjects were most confused by test

sentences whose meaning was implied by the studied sentences (“beneath it”).

Carol Harris’s Story

Carol Harris was a problem child from birth. She was wild, stubborn, and violent. By the time Carol turned eight, she was still unmanageable. Her parents were very concerned about her mental health. There was no good institution for her problem in her state. Her parents finally decided to take some action. They hired a private teacher for Carol.

Inference-Based Intrusions

Sulin & Dooling – subjects add details not present during learning: Carol Harris vs Helen Keller “She was deaf, dumb and blind.” 5% Carol Harris but 50% Helen Keller

subjects falsely recognized the sentence. Inferences are made at test-time.

More inferential errors occur with delay.

Plausible Retrieval

Reder – much of recall is plausible inference not actual recall. Darth Vader inferred to be evil, not

remembered to be evil. Heir to hamburger chain story – subjects

asked to recall exact details and make plausible inferences.

After a delay, plausible inference is faster and does not decay as much as exact memory, with no fan effect.

Plausible Retrieval after a Delay

Inference and Elaboration

Elaboration leads to more inferences. Information added as a “theme” to a story

results in better recall of studied material and more inferences (Nancy & the doctor).

Intruded inferences are not necessarily “errors” but help guide our thinking and behavior.

Listerine court case – false inferences, not just false statements, not permitted.

Memory Errors

When exact memory is needed, inferences and reconstructive processes can be misleading.

Loftus -- additional details and suggestion can change what is recalled.

John Dean’s recall vs what Nixon recorded – gist was right but not details.

False memory syndrome – memories that never happened can be “planted.”

Deese-Roediger-McDermott “False Memory” Paradigm

Participants study lists of words: Thread, pin, eye, sewing, sharp, point, prick, thimble,

haystack, thorn, hurt, injection, syringe, cloth, knitting Bed, rest, awake, tired, dream, wake, snooze,

blanket, doze, slumber, snore, nap, peace, yawn, drowsy

Later shown 3 types of words: True (sewing, awake), False (needle, sleep), New

(door, candy) Participants accept 88% of true words & 12% of new,

but also accept 80% of false words.

False Memories and the Brain

The parahippocampus retains the sensory experience of seeing the word. The hippocampus extracts and stores the meaning.

Context Effects

Recall is better if the physical context during learning is also present during testing. Experimenter clothing, setting. Under water.

Eich suggests that context effects depend on integrating context and the material to be learned.

Context Effects

Mood Congruence

Bower et al. – hypnotized subjects and induced positive or negative mood. Recall better if hypnotized into the same

mood during testing as during learning. Again, the effect may depend upon

integration of mood with material learned. Mood congruence – easier to remember

memories congruent with the current mood.

Mood Congruence

State-Dependence

Material is easier to recall if people return to the same emotional and physical state as during learning. Drinking – some state dependence

together with overall debilitating effect on memory.

Marijuana and tobacco. Caffeine.

Studying when not intoxicated is better.

State-Dependent Learning

Cigarette Marijuana Average

Cigarette 25 20 23

Marijuana 12 23 18

Encoding Specificity

The other items presented during learning provide a context too. Presentation of cues in as close to the

original learning context aids recall. Encoding specificity principle:

The probability of recalling an item depends on the similarity of its encoding at test to its original encoding at study.

Test of Encoding Specificity

Watkins & Tulving: Study pairs of words Generate associates for words & indicate

which were among studied words. Cued with first word of pair. 61% recall in cued task, <54% in associate

recognition task. Recognition generally produces higher

scores so result should have been the opposite of what occurred.

Amnesia

Studies of amnesics tell us how memory is organized in the brain.

Amnesia occurs with damage to the hippocampus (and some other areas).

Kinds of amnesia: Korsakoff syndrome Retrograde vs anterograde amnesia

Patient H.M.

Types of Amnesia

RA: Retrograde Amnesia

AA: Anterograde Amnesia

What is Spared in Amnesia?

Memory for facts, knowledge of meanings of words, language.

Memory for how to do things (e.g., play the piano, tie shoes), skills.

Priming Incidental learning – memory for

experience that was not consciously attended to.

Working memory – short term memory.

What is Affected by Amnesia?

Episodic memory – memory for the details and experiences of one’s own life.

Learning and recall of new material --anterograde amnesia Because conscious learning starts out as

an episodic experience.

Implicit vs. Explicit Memory

Explicit memory – knowledge we can consciously recall.

Implicit memory – knowledge we cannot recall but which aids performance on a task.

Amnesics can do a word-completion task but not recall learned words.

Normal subjects also show an explicit-implicit dissociation – Jacoby’s study.

Recall vs Stem Completion

Jacoby’s Study of Normal Subjects Three conditions were presented:

Study a word alone Study a word with its antonym Generate the word as an antonym

Two tests were used: Recognition task (old/new items) – explicit Perceptual ID task (see for 40 ms) –

implicit Opposite effects for the two tasks.

Recognition vs Perceptual ID

Procedural Memory

Procedural memory can be for skills, but also for doing cognitive tasks.

Berry & Broadbent – control output of hypothetical sugar factory by changing size of workforce (computer simulation): Non-obvious formula involved. After 60 trials subjects were good at task

but could not state the rule involved. Amnesics can learn to do this too.

Squire’s Varieties of Memory