Chapter 1. What is Memory?

Transcription

1 + Chapter 1 What is Memory?

2 Reductionism m + 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: The practice of explaining complex phenomena in terms of lower-level processes Awareness Processes Neurons Molecules Atoms

3 + A Brief History of Learning and Memory Concurrent

4 + 19 th Century Germany Ebbinghaus ( ) 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 ( ) a critic How does prior knowledge influence memory Reconstruction is guided by schemas (concepts)

5 + Ebbinghaus Forgetting Curve

6 + Importance of Practice The more repetition (practice), the more likely information is to be remembered later. Slide 10/07/08

7 + 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,

8 + 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.

9 + 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.

10 + 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.

11 + 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.

12 + 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

13 + Sample Paired Associate Task 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. Stimuli can be visual (like these) or verbal (pairs of words)

14 + Early Neuroscience -- Lashley Lashley ( ) 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.

15 + 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

16 + 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)

17 + 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.

18 + 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

19 + 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

20 + The Information Processing Metaphor Like a computer, human memory consists of three interacting components:

21 + 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

22 + Sensory Memory 22 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 A medium auditory tone signals subjects to report letters on the middle line of the matrix.

23 + 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.

24 + 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.

25 + A Two-Step Process Iconic Memory Peripheral Visual Store Recognition Buffer 100 letters per second read out More durable but also much slower

26 + 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.

27 + 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

28 + 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) Declarative Squire s Implicit vs Explicit Theory: Implicit Unconscious Explicit Conscious

29 + Long Term Memory Components of long-term memory as proposed by Squire (1992a). Slide 10/07/08

30 + 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: Longterm 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

31 + Long-Term Memory Amnesia 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

32 + 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

33 + 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

34 + The Human Brain

35 + 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

36 + 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

37 + 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