+

Chapter 1

What is Memory?

+ Psychological Theories

Theories are comparable to maps, helping to:

Summarize knowledge in a simple and structured manner

Pose new, testable questions that advance further discovery

Theories, like maps, can be specialized to address questions

on a variety of related levels of explanation, which can

sometimes inform other levels, through a process called

reductionism:

Re

du

cti

on

ism

m

The practice of explaining

complex phenomena in terms

of lower-level processes

Atoms

Molecules

Neurons

Processes

Awareness

+ A Brief History of Learning and

Memory Concurrent

+ 19th Century Germany

Ebbinghaus (1850-1909)

Nonsense syllables

PIM DAG ZOL CEK

Learning curve – massed vs spaced practice

Forgetting curve – forgetting occurs rapidly

Overlearning – studying after something is learned

Savings – decreased effort needed to relearn

Bartlett (1886-1969) – a critic

How does prior knowledge influence memory

Reconstruction is guided by schemas (concepts)

+ Ebbinghaus Forgetting Curve

+ Importance of Practice

10/07/08 Slide

The more repetition (practice), the more likely information is to be remembered later.

+ Massed vs Spaced Study

Ebbinghaus, H. Memory: A contribution to experimental psychology. New York: Dover, 1964 (Originally published, 1885). Keppel, Geoffrey. A Reconsideration of the Extinction-Recovery Theory. Journal of Verbal Learning & Verbal Behavior. 6(4) 1967, 476-486

+ Bartlett’s “War of the Ghosts”

Bartlett (1932) used multiple repetition of recalled

material to study distortions over time.

Participants were given a 328 word Native American

folk tale “The War of the Ghosts” to read twice and

then reproduce 15 minutes later and also hours to

months later.

Total recall declined.

What was recalled was shaped by the need to form a

coherent understandable story in the context of their own

cultural knowledge (schemata – concepts).

He considered memory an active process of construction.

+ Contributions of Gestalt

Psychology

Gestalt movement (Kohler, Koffka, Wertheimer)

The whole is different that the sum of its parts.

Anti-reductionistic

But they did acknowledge the importance of understanding the components of thought.

Memory is influenced by the configuration of elements and context.

Isomorphism of mental representation – material is represented mentally in the same configuration as it exists in the world.

+ Behaviorism

Behaviorism (Pavlov, Thorndike)

Psychology should be the study of observable behavior not structure of mind.

Behaviorism is associated with the term “learning”.

Later behaviorists (like Tolman) used mental explanations and representations (e.g., cognitive maps).

Classical and operant conditioning both depend upon memory – associations are remembered.

+ Verbal Learning

A behaviorist approach to the learning of

verbal materials (words, sentences,

stories).

Developed from Ebbinghaus’s work.

Memorization is the “attachment of

responses to stimuli.”

Forgetting is the “loss of response

availability.”

+ Paired Associates Paradigms

Paired associate learning – people

memorize pairs of items (BIRD-GLOVE):

A-B -- the first item (A) is the cue and the second item (B) is

the response

A-B C-D paradigm (two lists are learned)

A-B A-D paradigm (two associations learned to one cue)

A-B A-B’ paradigm (B and B’ are synonyms)

A-B A-Br paradigm (Br is a response previously associated

with a different cue – these recombinations are hard!)

A B

+ Sample Paired Associate Task

Stimuli can be visual (like these) or verbal (pairs of words)

In the learning phase subjects see pairs of items.

In the test phase subjects see one item of the pair and must identify the other.

+ Early Neuroscience -- Lashley

Lashley (1890-1958) searched for the brain engram (the physical memory trace).

First, rats learned a maze.

Next, Lashley progressively removed larger and larger portions of rats brains from different locations and tested them in the maze to see how memory changed.

Memory was affected more by the amount of brain tissue removed, not the location.

+ Hebb’s Theory

Hebb (1949) proposed that cortical

organization occurs through “cell assemblies”

and “phase sequences.”

Cell assembly -- a set of associated neurons that work

together because they are activated together.

Phase sequences incorporate several cell

assemblies. They form systems involving multiple

interconnected areas of the brain.

Repeated stimulation produces structural changes at

the synaptic level – Hebb’s rule: “What fires together

wires together”

+ The Cognitive Revolution

Thought is a valid subject for study

This is the field of psychology associated with

the term “memory”

Cognitive psychologists adopted the

methodological rigor of the behaviorists.

The computer metaphor

hardware (brain) vs. software (thought

processes)

+ Three Definitions of Memory

1. The location where memory is stored.

2. The physical entity that holds the

memory:

a) Trace

b) Engram

3. The processes used to acquire (learn),

store (encode) or remember (retrieve)

information.

+ Metaphors for Memory

Recorder of experience

Wax tablet

Record player

Writing pad

Tape recorder

Video camera

Organized storage

House

Library

Dictionary

Interconnections

Switchboard

Network

Jumbled Storage

Birds in an aviary

Purse

Junk drawer

Garbage can

+ Metaphors Emphasizing Specific

Aspects of Memory

Temporal Availability

Conveyor belt

Content Addressability

Lock and key

Tuning fork

Reconstruction

Rebuilding a dinosaur

Forgetting of Details

Leaky bucket

Cow’s stomach

Acid bath

Active processing

Workbench

Computer program

+ The Information Processing

Metaphor

Like a computer, human memory consists of three

interacting components:

+ Atkinson and Shiffrin's (1968)

Modal Model

Unlike a unitary, associative memory system, the modal model assumes multiple memory structures:

Information from the external environment is perceived and then very briefly stored in sensory memory, which is considered to be a perceptual, rather than a purely mnemonic process

Information is then passed to a limited-capacity, short-term memory store

Finally, information can be encoded in the unlimited long-term store, more or less permanently

Evidence now suggests that the information flow is actually bidirectional

+ Sensory Memory

The perceptual system stores the most recently acquired static image just long enough to integrate it with the next, in order to create apparent motion

Sperling (1960) investigated the number of items available for report in visual memory by randomly sampling items from a matrix of letters presented to participants

Recall decreases when:

The delay between the original presentation and the signal indicating which items from the matrix to report is increased

A visual mask (e.g. a bright flash of light or a contoured pattern) is presented following the matrix display, thereby interfering with the memory trace

22

A medium auditory tone signals subjects to report letters on the middle line of the matrix.

+ Iconic Memory

Estimated number of letters available using the partial report method, as a function of recall delay. From Sperling (1963). Copyright © 1963 by The Human Factors and Ergonomics Society. All rights reserved. Reproduced with permission.

+ Echoic Memory

Serial recall of a nine-item list when an additional item, the suffix, is either the spoken word zero or a sound made by a buzzer. From Crowder (1972). Copyright © 1972 Massachusetts Institute of Technology by permission of the MIT Press.

+ A Two-Step Process

Peripheral Visual Store

Recognition Buffer

100 letters per second read out

Iconic Memory

More durable but also much slower

+

Do Iconic and Echoic Memory

Function Similarly?

Both forms of memory show interference by masking

(lights or extra sounds at the end of the presentation).

Echoic memory is disrupted by a final speech sound but

not a buzzer.

Iconic memory is disrupted by a final light mask but not a

dark mask, and by masks that interfere with perception.

Iconic memory shows a primacy effect whereas echoic

memory shows a recency effect – perhaps due to a

precategorical acoustic store important to speech

perception.

+ Short-Term Memory (STM) and

Working Memory (WM)

Short-Term Memory (STM): The temporary storage of small

amounts of material over brief delays

While initially thought to be primarily verbal in nature, STM can hold

material from almost any modality, including from the visuo-spatial

domains

It is thought that rehearsal is often used to maintain items in the

short-term store

Working Memory (WM): A mental workspace, linked to

attention, which provides a basis for thought and the symbolic

manipulation of items being held within this temporary store

+ Multiple Memory Systems

Memory is not unitary but consists of several

subcomponents (parts).

Tulving’s Triarchic Theory:

Episodic Autonoetic (self)

Semantic Noetic (formal knowledge)

Procedural Anoetic (automatic skills)

Squire’s Implicit vs Explicit Theory:

Implicit Unconscious

Explicit Conscious

Declarative

+ Long Term Memory

10/07/08 Slide

Components of long-term memory as proposed by Squire (1992a).

+ Long-Term Memory (LTM)

Explicit/Declarative Memory:

Long-term memory for facts and

events

Episodic Memory: Memory for

specific events that can be vividly

recalled through what Tulving calls

“mental time travel”

e.g. I celebrated my last

birthday in Madrid

Semantic Memory: General

knowledge of the world and

society

e.g.The capital of Spain is

Madrid

Implicit/Non-Declarative or

Procedural Memory: Long-

term memory for information

that is reflected through

performance, rather than overt

remembering

e.g. Motor skills like learning

to ride a bike, classical

conditioning, and priming

Priming: An unconscious

tendency to recall a

previously seen or related

item

+ Long-Term Memory

One indication that long-term memory can be subdivided into

distinct systems comes from the study of people with amnesia.

Amnesia is a memory disorder that can have psychological

(functional) or physical (organic) causes.

Regardless of cause, amnesics typically:

Have significant impairments in episodic encoding/retrieval

Have difficulties forming new semantic memories

This suggests that semantic memories are normally formed by

generalizing information first encoded episodically

Have a preserved (unimpaired) ability to acquire and use implicit

memories

Amnesia

+ Memory In and Out of the

Laboratory

Researching in the Laboratory

Pros:

More experimental control

Easier to develop and rigorously test theories in rapid succession

Cons:

Overrepresentation of certain participant populations (students)

Reduced generalizability of findings

Less ecological validity (not like real life)

Researching in the Real World

Pros:

Validates theory by testing various populations while advancing therapeutic treatments

Highlights important gaps in current understanding and advances future theory development

Cons:

Less experimental control; more confounding variables

Harder to isolate causes of observed phenomena

+ Neuropsychological Studies of

Memory

Disease-Related Studies

Involves characterizing the deficits and preserved abilities in patients suffering from specific diseases (e.g. Alzheimer’s)

Pros:

Provides a direct route to advancing diagnosis and treatment of diseases

Cons:

Often difficult to separate memory impairments from other deficits related to the disease

Lesion Studies

Involves profiling patients with organic brain damage to relatively focal regions (like HM’s hippocampal lesions)

Pros:

Helps identify causal links between brain and behavior

Cons:

Such cases are relatively rare

Lesions are almost never entirely confined to a specific region of interest and/or patients’ deficits are not entirely pure

+ The Human Brain

+ Electroencephalography (EEG)

Since the early 1900s, researchers have used electrodes placed on the scalp to record the electrical signals generated by the brain’s neurons

The characteristics of the continuous brainwaves can help identify abnormal brain activity and different stages of sleep and arousal

By dividing the continuous wave into segments called evoked response potentials or event-related potentials (ERPs), each beginning with a particular event, one can characterize the response elicited by that particular occurrence

Pros:

Millisecond temporal resolution

Relatively low cost to perform and non-invasive

Cons:

Inability to precisely locate the brain region generating the recorded signal

+ Neuroimaging Techniques

The use of newly developed technologies that allow researchers to study the structure and function of the brain by tracking indicators of brain activity

+ Current Issues

Neurological bases for memory

Impact and importance of emotion on

memory

Use of multiple memory sources (fuzzy

trace theories)

Embodied cognition – how our grounding

in the world influences memory