+

Chapter 1What 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:

Red

uct

ion

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

10/07/08Slide

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

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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

10/07/08Slide

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