Title: A pioneer of the scientific study of memory: Hermann Ebbinghaus (1850
1A pioneer of the scientific study of
memoryHermann Ebbinghaus (1850 1909)
- worked as philosopher at university in Berlin
- inspired by lawfulness of relation between
physical properties of perceptual stimuli and
psychological sensations discovered in field of
psychophysics - e.g. Fechners law Webers law
2Classic finding in psychophysics Webers law
standard line just-noticeably-longer line
3A pioneer of the scientific study of
memoryHermann Ebbinghaus (1850 1909)
- performed experiments on himself published in
classic volume entitled Über das Gedächtnis
(1885) - famous because - pioneer of empirical approach
- inventiveness as experimenter
4Memory experiments by Ebbinghaus
- new systematic and controlled study of
memory in laboratory - e.g. - created new stimulus material
- - applied scientific accuracy (use of
metronome) - established method to quantify
memory performance and describe regularities
5Memory experiments of Ebbinghaushow to
investigate retention of newly learnt material
- invented lists of 16 nonsense syllables to
minimize influence of - learners history
- goal study memory in pure form
- introduced criterion for successful learning
- (2 errorless recitations)
- introduced savings method to measure retention /
forgetting of lists
6Memory experiments of EbbinghausExample of
memory task
- memorize the following (shortened) list
-
- falem
- zeb
- xalvo
- monul
- rull
- namak
-
-
7Memory experiments of Ebbinghaus Examination of
forgetting curve with savings method
- calculation of savings scores to measure
performance - finding
- most forgetting occurs right after learning
- -gt approx. 50 in first 40 min
- -gt relationship between delay and forgetting
not linear
8Memory experiments of Ebbinghaus Other important
findings
- list-length effect amount of information and
ease of learning not related in linear one-to-one
fashion disproportionate increase in difficulty
with more than 7 syllables - beneficial effects of distributed practice for
repetitions
9Memory research of Ebbinghaus Why is it such a
major contribution?
- discovery of important regularities (basic
findings) - memory can be studied empirically with
experiments - mental phenomena can be studied even if they are
not linked directly to physical world via
perceptual organs
10Memory research of Ebbinghaus What was missing?
- research criticized as atheoretical
- but emphasis on observations rather than
theories typical for early research in new field
11The Ebbinghaus Legacy Verbal-learning research
1950s 1970s
- behaviourist tradition (S-R / S-S associations)
- mind as black box
- systematic study of factors affecting verbal
learning - e.g. numbers of repetitions, presentation time
word frequency - later replaced by information-processing
approach growing emphasis on mental
representations
12Richard Semon (1859 1918) An early memory
theorist
- work strongly influenced by evolutionary biology
(Darwin) - interest in commonality between heredity and
memory - aspect of biological tissue that allows effects
of experience to be preserved over time - three stages of memory (new terms invented)
- Engraphy acquisition of new information
- Engram enduring change in nervous system
that allows for retention - Ecphory recovery of stored information
13Richard Semon (1859 1918) An early memory
theorist
- concept of engram motivated much research on
brain basis of memory in 20th century - What are the manifestations of memory traces in
the brain? - concept of ecphory strongly influenced
cognitive psychology of memory in 1970s
(Tulving) - How can a dormant memory trace be awoken?
-
- -gt emphasis on processes at time of retrieval
(recovery) of info from memory - -gt emphasis on presence of suitable retrieval
cues -
14Information-processing approach to
memory(starting 1960s)
- motivated by emerging of computers and computer
science as scientific discipline - human mind can be understood with computer
metaphor - e.g. storage of information in different
memory buffers - RAM vs hard-disk lt-gt STM vs LTM
- central importance of information and mental
representations (mind not a black box) - focus on cognitive processes that deal with (e.g.
create, access, compare) mental representations
15Information-processing approach to memoryA
practical example
16Information-processing approach to memoryBasic
framework
- 3 stages of processing for manipulation of mental
representations - Encoding (acquisition of info)
- Storage (retention of info)
- Retrieval (recovery of info)
17Information-processing approach to
memoryTypical research questions
- do we store different types of memory
representations? Are they retained equally well? -
bear
e.g.
18Information-processing approach to
memoryTypical research questions (contd)
-
- do we need attentional resources to encode new
information into memory? - e.g. can be studied through examination of
influence of distraction - can information in memory influence our thoughts
and actions unconsciously? - e.g. can be studied in patients under
anesthesia
19Information-processing approach to
memoryApplication to Ebbinghaus research
- what were the syllables you memorized in the
example I gave earlier? -
20Information-processing approach to
memoryApplication to Ebbinghaus research
- which of the following syllables was on the list?
-
- halek or xalvo
- -gt forgetting curves will vary depending on
whether syllables need to be recalled or
recognized - -gt more detailed analysis of cognitive processes
required to understand regularities in forgetting
21Information-processing approach to
memoryApplication to Ebbinghaus research
- e.g. zeb may or may not make you think of
zebra at encoding - -gt consequences for subsequent remembering
- -gt even learning of simple stimuli such as
non-sense syllables is affected by variations in
cognitive processing and pre-existing knowledge - -gt memory cant be investigated in pure form
22Cognitive-neuroscience approach to memory
- multidisciplinary approach (psychology, computer
science, neurology, radiology) - emphasis on relationship between behaviour,
cognition, and the brain - central question how dos the brain allow humans
to learn and remember? -
- general idea to understand the organization of
memory (e.g. how many different types?) we should
focus on neurological and cognitive aspects
23Cognitive-neuroscience approach to
memoryDifferent types of investigation
- lesion studies in neurological patients
- examination of effects of different types of
brain damage on memory processing - functional neuroimaging
- examination of brain activity in healthy
individuals while they perform memory tasks - computational modeling
- testing of quantitative memory theories with
computer models that incorporate a brain-like
organization (neural networks connectionist
models)
24Cognitive-neuroscience approach to
memoryExample of functional neuroimaging study
- do different parts of the brain become active
when we try to remember pictures as compared to
words?
pictures
words
25Memory experiments of Ebbinghaus Examination of
forgetting curve with savings method
- most forgetting happens immediately after
learning -
-
-
-gt approx. 50 in first 40 min
26Forgetting on Brown-Peterson taskwith consonant
trigrams
- Repeat HLM
- 2. Distractor task Count in 3s from 492
- 3. What were the letters?
- many trials with different delays
- after 6 sec only 40 correct recall
27Forgetting on Brown-Peterson taskwith consonant
trigrams
- findings suggest short-lived memory component
different from type of memory studied by
Ebbinghaus
28Something special about short lists
- Ebbinghaus lists with up to 7 nonsense syllables
are forgotten at different rate than lists with
more items -
- G. Miller (1956) immediate memory span
- Magical number seven, plus or minus two
-
- holds for digits, letters, words
- (digit span, letter span, word span)
-
- -gt suggests that short lived memory
component has limited capacity
29 Further examination of immediate memory span
-
- integration of information through chunking
possible -
- e.g. letters in meaningful word
- letters in acronyms (USA, IBM)
- area code in phone number
- chunks are basic storage units in short-lived
memory component
30Chunking produces similar forgetting curve on
Brown-Peterson task with words and trigrams
31Consequences of findings with Brown-Peterson task
and with memory span in 1960s
- new notion memory is not unitary
- there may be at least two separate stores that
work with different cognitive mechanisms - they seem to differ in terms of forgetting rates
and capacity - -gt longer lasting component may not have any
capacity limitations - e.g. Ebbinghaus could remember lists of 40
and more nonsense syllables - everyday observations suggest that
memory capacity for life events unlimited
32W. James Primary vs secondary memory
- Primary memory
- it was never lost its date was never cut off
in consciousness from that of the immediately
present moment in fact, it comes to us as
belonging to the rear-ward portion of the present
space of time, and not the genuine past - -gt extended present
- Secondary memory
- the knowledge of a former state of mind after
it has already once dropped from consciousness
or rather it is the knowledge of an event, or
fact, of which we have not been thinking, with
the additional consciousness that we have thought
or experienced it before
33Different proposals for two-store models
- W. James (late 1800s)
- primary memory vs secondary memory
- still in consciousness vs lost from
consciousness - Atkinson Shiffrin (1968)
- short-term memory (STM) vs long-term memory
(LTM) - Baddeley (1980s)
- further theoretical development of concept of
STM -gt renamed working memory (WM)
34Consequences of findings with Brown-Peterson task
and with memory span in 1960s
- controversy over need to postulate two stores
- philosophy-of-science argument relevant
- more parsimonious theory better than more
complicated one if it can explain the same
findings (principle of Ochams razor) - -gt is there sufficient number of critical
findings that single-store theory cannot
explain?
35Forgetting mechanisms in STM vs LTM
- typical explanation of forgetting on
list-learning tasks (à la Ebbinghaus) and others
task studied in verbal-learning research
interference - e.g. paired-associate learning task
- First list Second list
- car ball car fridge
- tree screen tree foot
- table paper table ocean
-
-
- door sports door hair
36Forgetting mechanisms in STM vs LTM
- retroactive interference on paired-associate
learning task -
- What was linked word from first list? tree
? - door ?
-
- -gt learning of second list impairs recall of
first list - interpretation in behaviourist learning theory
- associations between pairs in first list
weakened through learning of second list - application in everyday life
- previous postal code after move
-
37Forgetting mechanisms in STM vs LTM
- suggestion for forgetting on Brown-Peterson task
trace decay (fading) - - occurs as soon as stimulus absent
- - can be prevented through active rehearsal
- - thought to be different from
interference-related forgetting on LTM tasks
(notion later challenged) -
38Other evidence to support distinction between STM
and LTMSerial-position curve in free recall task
recency effect
primacy effect
39Effects of presentation rate and delay on serial
position curve (Glanzer Cunitz, 1966)
40Interpreting effect of presentation rate and
delay in Glanzer Cunitzs experiment
- presentation rate
- more rehearsal allows for better transfer of
info from STM into LTM in primacy portion - delay
- trace-decay in STM eliminates recency
- -gt different experimental manipulations have
different effects on recency and primacy
portion of curve - -gt suggests that primacy and recency effects
reflect operation of different stores (LTM,
STM)
41What makes a list difficult for STM (Baddeley,
1966)?
unrelated
semantically similar
acoustically similar
detrimental effect of acoustic but not semantic
similarity on immediate recall of short word lists
42Interpretation of difficulty findings in
Baddeleys STM experiment
- detrimental effect of acoustic similarity on
recall of brief lists suggests that info is
coded phonologically (in terms of sound) in STM
43Evidence suggesting semantic code for LTM
- prose passage experiment by Sachs (1967)
- e.g. sentence heard as part of story
- she watched the kids on their way home
- LTM test after 20 min delay
- Was the following sentence part of the story?
- - she watched the birds on their way home
- (no easy few errors)
- - the kids were watched by her on their way home
- (no difficult many errors)
- - she observed the kids on their way home
- (no difficult many errors)
-gt good recognition of semantic but poor
recognition of verbatim information
44Interpretation of findings on retention of
verbatim info in LTM
- poor recognition of verbatim info with good
recognition of semantic info suggests that info
is coded semantically (in terms of meaning) in
LTM
45What kind of memory is impaired in neurological
patients suffering from amnesia?
- amnesia can occur as result of sudden brain
damage - (e.g car accident, stroke)
- - patients do not remember anything from time
since injury - - patients have difficulty keeping track of
daily events - - patients have difficulty learning names of new
people (e.g. physicians and nurses on ward) - - patients have difficulty learning way around
in new environment (e.g. hospital) - critical question does amnesia affect STM, LTM
or both?
46What kind of memory is impaired in neurological
patients suffering from amnesia?
- general findings in amnesic patients
-
- normal STM capacity on digit-span task
- normal forgetting curve on Brown-Peterson
task - normal receny effect on list learning task
- suggests that LTM but not STM is affected by
amnesia
47Additional evidence showing that memory deficit
is specific to LTM in amnesiaFindings with
span 1 task (Drachman Arbit, 1966)
lists larger than STM span extremely difficult to
learn for patients
48What do patient studies tell us about distinction
between STM and LTM?
- observed pattern of deficits across studies
- one type of brain damage leads to
impairments in LTM but not STM - other type of brain damage leads to
impairments in STM but not LTM - -gt suggests that LTM and STM rely on proper
functioning of different brain structures - -gt suggest that LTM and STM have distinct neural
basis
49Characteristics of two separate memory stores (as
widely accepted in 1970s)
Note concept of STM different from use of term
in everyday life
50Atkinson Shiffrins modal memory model