Remembering and forgetting

Question 1

How can we measure forgetting

Answer 1

recall test

recognition test

Question 2

What is a recall test

Answer 2

recall of events, story recall (hard to score)

free recall of lists of nameable items (% recalled),

cued recall e.g. paired associates (% recalled)

serial recall (% in correct position)

Question 3

What is a recognition test

Answer 3

ability to discriminate “old” from “new” items (% correct)

Question 4

Who was Ebbinghaus (1885) and what did he do?

Answer 4

learned many lists of 13 nonsense syllables to criterion (2 correct serial recalls), and then relearned each after a variable interval

Question 5

Forgetting is orderly, explain

Answer 5

forgetting, measured appropriately, can often be described by a simple mathematical function of the retention interval (here a power function)

Question 6

What causes forgetting?

Answer 6

orderliness of forgetting might suggest some inevitable decay process: loss from storage.

but this can’t be the whole story:

• information not recalled now may be recalled later
• further prompts or cues may succeed in eliciting recall

so some cases of “forgetting” due to retrieval failure not loss

moreover, some memories show essentially no loss over time

Question 7

Why does a longer retention interval not necessarily increase forgetting?

Answer 7

no forgetting of school class-mates over 30 years (assessed using yearbooks (Bahrick et al., 1975, J.Exp.Psy:Gen)

“flashbulb” memories (e.g. JFK assassination, 9/11 attack)

but forgetting of former students by teachers does increase with interval —>

Why?
teachers subsequently encounter many more students
so, forgetting attributable to interference from other similar memories?

Question 8

How can we test ‘interference’ v decay theories?

Answer 8

under normal circumstances, retention interval — time in storage — is confounded with the number of other experiences accumulated during the interval.

so, control the interval, vary intervening experiences

if forgetting due to interference, then p(recall) should decrease with more exposure to similar stuff, with time held constant

Question 9

How is some forgetting clearly attributable to interference?

Answer 9

‘paired associate” learning (1940s,1950s): participant must learn (say) 10 arbitrary pairings between “stimulus” and“response” words.

P learns List 1 to criterion

then learns List 2 to criterion

test on either List 1 or List 2

later recall of List 1 worse when List 2 was learned afterwards - retroactive interference

later recall of List 2 worse when List 1 has been learned before - proactive interference

implication: retrieval difficulty increases when other similar material has been learned, holding retention interval constant.

Question 10

How are time v intervening (similar) experiences predictors of event forgetting?

Answer 10

at end of season, two rugby teams recalled games played: clear forgetting over a season (though some games are more memorable)

each player missed some games:

• if control for time, the number of games played during the interval is a significant predictor of forgetting
• but not vice versa.

in general, there is ample evidence that retrieval failure is increased by interference from similar material

Question 11

What factors influence p(retrieval)?

Answer 11

processing at encoding/acquisition

consolidation after encoding

(more on) Interference from other memory traces at retrieval

similarity of encoding and retrieval contexts

[underlying theme: memory is an associative system, not a container]

Question 12

What is organisation at acquisition

Answer 12

deliberate rote rehearsal does increase later recall

hence the primacy effect in free recall – first few items get more rehearsals

but mere rote rehearsal is a relatively ineffective learning strategy

Question 13

What do incidental memory exps show?

Answer 13

processing the meaning of, and actively organising, the material are effective learning strategies

Question 14

Mandler (1967) study

Answer 14

groups 1 and 2 sorted words on cards into 2-7 categories of their own devising

group 1 were also told to try to learn the words. Group 2 were not

no difference in a later recall test (if control for N of categories).

group 3, who just placed the cards into columns while trying to learn the list, remembered less than Groups 1 and 2.

Question 15

Moral of organisation at acquisition

Answer 15

organising the material is what produces effective acquisition, not effort to learn (by itself)

Question 16

What is depth of processing at acquisition?

Answer 16

Craik and Tulving (1975) study

Question 17

Craik and Tulving (1975) study

Answer 17

showed a series of unrelated words, and gave one of three orienting tasks:

is it written in upper/lower case?

does it rhyme with X?

does it fit into a sentence(e.g. “The man broke his ____”)

later unexpected recognition test

Question 18

Moral of depth of processing at acquisition

Answer 18

processing the meaning is better than processing surface form

(unless: details of surface form are what you are required to remember – “transfer-appropriate processing”)

Question 19

What do mnemonics demo?

Answer 19

the power of appropriate elaboration at acquisition

one-is-a-bun mnemonic for sequence learning

first, learn the rhyme

to learn a sequence: form a vivid image representing the rhyme item for position X in interaction with what you want to remember at position X

remembering: Just go through the rhyme

Question 20

Method of loci

Answer 20

first, memorise a route around a familiar building or garden, so that you can walk around it in your “mind’s eye”

learning the speech: At each point in the route, form a striking image representing the idea you want to mention at that point

remembering: Traverse the route, reading and interpreting the images.

Question 21

What does learning form?

Answer 21

associations

Question 22

What does retrieval do to associations?

Answer 22

activates them

Question 23

Why do mnemonics work?

Answer 23

they bind ideas to a pre-established framework which organises them (e.g. serial order, in the case of the method of loci and ‘one-is-a-bun’)

imagery encourages formation of rich nexus of associations between the frame “hook” and the concept attached to that hook.

forces exhaustive retrieval attempts

Question 24

General moral of associations, retrieval and mnemonics

Answer 24

effectiveness of learning involves forming associations among representations that already exist in the mind, including representations of

elements of the new experience/fact

elements of the context

elements of prior knowledge

Question 25

Retrograde memory loss after concussion

Answer 25

John Terry (at that time at Chelsea) “I remember walking out for the second half and nothing else until waking up in the ambulance on the way to the hospital”.

Question 26

What is phase 1 of consolidation?

Answer 26

after traumatic brain injury (e.g. concussion) or ECT, there is often retrograde memory loss spanning many minutes, even hours (way beyond duration of “working memory”),

disruption of process of consolidation of memory trace in hippocampal/medial temporal cortex system

Question 27

What does consolidation of novel traces suffer from?

Answer 27

interference from consolidation of further novel traces

sleep improves memory for material learned in last few hours (Jenkins & Dallenbach, 1924)

alcohol and barbiturates impair learning (disrupt consolidation)

but improve memory for material learned just before! (“retrograde facilitation”)

Question 28

What is phase 2 of consolidation?

Answer 28

over a longer timescale (months, years), recent LTM traces are more vulnerable to hippocampal damage than older traces

amnesic patients with damage to hippocampus/ medial temporal cortex typically show gradient of retrograde amnesia over years – older memories better preserved, more robust [“Ribot’s law”, 1882] – e.g. HM

over time, re-activation of distributed representations in cortex from hippocampal trace reinforces direct links between elements of those representations, creates robust traces no longer dependent on hippocampus.

Question 29

What is associative interference at retrieval?

Answer 29

E.g. In paired-associate experiments, can vary similarity of stimulus terms, response terms, etc.

interference maximal when the same (or similar) stimulus terms are used for each list: competition between two associative links from the same retrieval cue

Question 30

What is the ‘fan effect”

Answer 30

in fact retrieval as e.g. of associative interference

S learns 0-4 new “facts” about each of set of famous people, e.g.

Napoleon had a wart on his nose

later, true/false RT measured for test statements, e.g.:

Napoleon was Emperor of France (actual true)

Napoleon had a wart on his nose (experimental true)

Napoleon was six feet tall (false)

Question 31

Mitigating the effects of associative interference

Answer 31

the fan effect seems paradoxical: the more you know about Napoleon, the harder it is to retrieve any one fact about him?

in the Lewis & Anderson experiment, the N facts learned were unrelated.

it has been claimed that if the facts are thematically related, the fan effect is eliminated. E.g.:

the princess went to the dockyard

the princess christened the ship

the princess broke a bottle of champagne (Smith et al, 1978 – but see Reder & Anderson, 1980)

the thematic relationship enables the learner to form associations between the separate facts using pre-existing knowledge schemas, which provide multiple retrieval paths.

Question 32

Moral of mitigating the effects of associative interference

Answer 32

when studying, work to create multiple links among the facts you are learning about a topic, and to prior knowledge

Question 33

What is remembering as reconstruction vulnerable to ?

Answer 33

associative intrusions

Bartlett’s (1932) “War of the Ghosts” story experiment

we interpret what we see and hear via learned “schemas” [schemata], or “scripts” – knowledge of typical patterns or event sequences

when we try to remember, we recover only fragmentary associations, from which we reconstruct the event/fact, filling in the gaps using

general knowledge schemas (in semantic memory) E.g. a restaurant meal —> a waiter (as part of the “script”)

fragments remembered from other episodic sources.

Question 34

False memories

Answer 34

the “recovered memories” controversy: “Complete or partial memory loss is a frequently reported consequence of experiencing certain kinds of psychological traumas, including childhood sexual abuse. These memories are sometimes fully or partially recovered after a gap of many years…within or independent of therapy…..Although clear memories are likely to be broadly accurate, they may contain significant errors…Sustained pressure or persuasion by an authority figure could lead to the retrieval or elaboration of memories of events that never happened.” (British Psychological Society working party on recovered memories, 1995)

too cautious! It is easy to create false memories: “recognition”, “recall”, and “recollection” of events that did not happen, because:

source amnesia (retrieval of information coupled with inability to remember its source) is common,

recall is reconstructive (Bartlett): fragments of actual experience recovered from memory get combined with other information in memory whose source is lost (e.g the implicit or explicit suggestions of an interrogator or therapist).

Question 35

Loftus’ ‘EWT’ exps

Answer 35

E.g. Loftus & Palmer (1974):

100 Ss see film of car crash
then answer a series of questions, including “About how fast were the cars going when they smashed into/hit each other?”

group 1 (“smashed into”)

group 2 (“hit”)

one week later, they answer some more questions, including“Did you see any broken glass?” [There was none.]

group 1 16/50 say “yes”
group 2 7/50 say yes (p

Question 36

False memories of realistic and emotionally salient material

Answer 36

1992 El Al crash in Amsterdam: 10 months later : “Did you see the television film of the moment the plane hit the building?” >50% said “yes”, some with incidental detailsCrombag, Wagenaar, Van Koppen (1996, Applied Cognitive Psychology)

Loftus’s “lost in the mall” study: ~25% of subjects “remembered” (after several probing interviews) being lost in a public place as a child. Loftus & Pickrell (1995, Annals of Psychiatry)

Initial interview on memory for real childhood events included a strong suggestion of a false one, e.g. - “At a wedding reception when you were 5, when you ran into the table and spilled the punch bowl on the bride’s parents”. No memory reported then, but in later interviews 20-40% of participants reported this as a memory, and up to a half of these described “clear” recollections, with incidental details.

Question 37

What are context effects and ‘encoding specificity?’

Answer 37

as a general rule, information is more easily retrieved if tested in the same context in which it was acquired.

E.g.: environmental context (Godden & Baddeley, 1975):

divers learned word lists either on dry land or under water.

they were tested on land or under water

in between, all subjects moved between environments

Eich, Weingartner, Stillman & Gillin (1975)

sensitivity of retrieval to congruence with the“internal” context at the time of learning is sometimes calledstate-dependent learning

similar effects of induced sad and euphoric moods (e.g. Teasdale & Russell, 1983).

encoding-specificity is causal in the maintenance of depression: negative memories are more accessible in the depressed state, and their retrieval reinforces the depression.

Question 38

the power law of forgetting

Answer 38

if an appropriate measure of “trace strength” is used,

forgetting functions are linear in log-log plots

Question 39

what is the principal determinant of forgetting?

Answer 39

the time in storage