a pioneer of the scientific study of memory: hermann ebbinghaus (1850 – 1909) worked as...
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A pioneer of the scientific study of memory:
Hermann Ebbinghaus (1850 – 1909)
• Worked as philosopher at university in Berlin• Was inspired by lawfulness of relation between
physical properties of perceptual stimuli and psychological sensations in psychophysics e.g. Fechner’s law; Weber’s law
Classic finding in psychophysics: Weber’s law
A pioneer of the scientific study of memory:
Hermann Ebbinghaus (1850 – 1909)
• performed experiments on himself published in classic volume entitled: ‘Über das Gedächtnis’ (1885)
Memory experiments by Ebbinghaus
• Fame: pioneer of empirical approach; inventiveness as experimenter
• New: systematic and controlled study of memory in laboratory
e.g. - created new stimulus material - applied scientific accuracy (metronome),
- established method to quantify memory performance and describe regularities
• invented lists of 16 nonsense syllables to minimize influence of meaningful associations and learner’s historygoal: study memory in ‘pure’ form
• introduced criterion for successful learning (2 errorless recitations)
• introduced savings method to measure retention/forgetting of lists
Memory experiments of Ebbinghaus:Focus on retention of newly learnt material
• Memorize the following list:
falemzebxalvomonulrullnamak
Memory experiments of Ebbinghaus:Example of memory task
• most forgetting happens immediately after learning
-> not a linear relationship between forgetting and delay
Memory experiments of Ebbinghaus: Examination of forgetting curve with savings
method
• List-length effect: ease of learning and amount of information not related in linear one-to-one fashion; disproportionate increase in difficulty with more than 7 syllables
• Beneficial effects of distributed practice for repetitions
Memory experiments of Ebbinghaus Other important findings
• discovery of important regularities (basic findings)
• memory can be studied empirically with experiments
• mental phenomena can be studied even if they are not linked momentarily to physical world via perceptual organs
Memory research of Ebbinghaus Why is it such a major contribution?
• research criticized as atheoretical
• But: emphasis on observations rather than theories typical for early research in new field
Memory research of Ebbinghaus What was missing?
• systematic study of factors affecting verbal learning:e.g. numbers of repetitions, word frequency
• behaviourist tradition (S-R / S-S associations)
• mind as black box
• later replaced by information-processing approach: growing emphasis on mental representations
The Ebbinghaus Legacy: Verbal-learning research 1950s – 1970s
Richard Semon (1859 – 1918): An early memory theorist
• work strongly influenced by evolutionary biology (Darwin)
• emphasis on commonality between heredity and memory:elasticity of biological tissue that allows effects of experience to be preserved over time
• three stages of memory (new terms invented)Engraphy – acquisition of new informationEngram – enduring change in nervous
system that allows for retentionEcphory – recovery of stored information
• concept of ‘engram’ motivated 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 starting in 1970s (Tulving):
How can a dormant memory trace be awaken?
-> emphasis on processes at time of retrieval (recovery) of info from memory -> emphasis on presence of suitable retrieval cues
Richard Semon (1859 – 1918): An early memory theorist
Information-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 <-> 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
Information-processing approach to memory:
A practical example
correct
• 3 stages of processing for manipulation of mental representations:
Encoding (acquisition of info)Storage (retention of info)Retrieval (recovery of info)
Information-processing approach to memory:
Basic framework
time
Encoding Retrieval
• do we store different types of memory representations? Are they retained equally well?
Information-processing approach to memory:
Typical research questions
‘bear’ e.g.
• do we need attentional resources to encode new information into memory?
e.g. can be studied through examination of influence of distraction
• can we access information in memory unconsciously?
e.g. can be studied in patients under anesthesia
Information-processing approach to memory:
Typical research questions (cont’d)
• what were the syllables you memorized in the example I gave earlier?
Information-processing approach to memory:
Application to Ebbinghaus’ research
• which of the following syllables was on the list?
halek or xalvo
-> forgetting curves will vary depending on whether syllables need to be recalled or recognized
-> more detailed analysis of cognitive processes required to understand regularities in forgetting
Information-processing approach to memory:
Application to Ebbinghaus’ research
• e.g. ‘zeb’ may or may not make you think of ‘zebra’ at encoding
-> consequences for subsequent remembering
-> even learning of simple stimuli such as non-sense syllables is affected by variations in cognitive processing and pre-existing knowledge
-> memory can’t be investigated in pure form
Information-processing approach to memory:
Application to Ebbinghaus’ research
Cognitive-neuroscience approach to memory
• multidisciplinary approach (psychology, computer science, neurology, radiology)
• emphasis on relationship between behavior, cognition, and the brain
• Central question: How is memory organized in the mind and brain?
• General idea: to understand the organization of memory (e.g. how many different types?) we should focus on neurological and cognitive aspects
• Lesion studies in neurological patientsexamination of effects of different types of brain damage on memory processing
• Functional neuroimagingexamination of brain activity in healthy individuals while they perform memory tasks
• Computational modelingtesting of memory theories with computer models that incorporate a brain-like organization (neural networks; connectionist models)
Cognitive-neuroscience approach to memory:
Different types of investigation
Cognitive-neuroscience approach to memory:Example of functional neuroimaging study
• do different parts of the brain become active when we try to remember pictures as compared to words?
pictureswords
Cognitive-neuroscience approach to memory:Example of early finding in patient with brain lesion
• amnesic patient of Claparède (1911):
pin-prick episode-> behavior can be influenced by past
without conscious remembering
• supports distinction between implicit (unconsious) and explicit (conscious) form of memory proposed 70 years later