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