memory

Our essence

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A huge problem

• Eye witness testimony

• Witnesses are not always

right, even if they are certain

• Picking the wrong “rapist”

• How could this happen?

Memory overview

• A complex concept

• Refers to both the process of retaining information, and

the information retained

• Many types, uses, and tests

• What are we without it?

Three Processes

• Encoding – getting the info and then transforming it into a form that the brain can retain

• Storage – holding the info

• Retrieval – pulling it out

Three models

• Levels of processing – how long and how intensely we work with a memory determines how well we retain and retrieve it

• Parallel distributed processing – we remember things in many different forms all at once, in parallel

Information processing view

• Based on a computer model conception of memory

• Proposes that information enters the system, is processed and coded in various ways and then stored

• Sets out three components

Sensory store

• The first filter

• A very brief capture of sensory information

• Images involve iconic memory

• We can attend to anything in our visual field – lasts for ½ second

• But if we do not attend to something, it is lost

Short-term memory

• Temporary storage of information you have just experienced

• Lasts for about 20-30 seconds, unless rehearsed

• Holds 7 (plus or minus 2) items, like a crowded elevator holds passengers

• Can be effectively extended by memorizing information in chunks – meaningful units

Was Dori right?

• That adorable tang claimed to have a problem with her short term memory.

• Did she?

• Could she hold 7 or so items in mind if she continued rehearsing them?

Long-term memory

• Unlimited capacity

• Lasts (usually) as long as you do

• Weakened by interference

• Also vulnerable to loss of retrieval cues

• Usually located in the frontal lobes

• Meaningful, distinctive material goes in quickly

The working memory theory

• Over time, the information processing theory’s concept of short term memory sprung more and more leaks

• How do long term memory and short term memory work together?

• From these and many other concerns, the concept of working memory began to emerge

More “working”

• A system for processing or ‘working’ with current information

• The thoughts, facts, ideas, and feelings in our current sphere of attention, a mix of current experience and retained memories

• Some of these new items might eventually be stored in LTM, others might not

Three systems within working memory

• Central executive – controls and coordinates the

• Visuospatial sketchpad and the

• Phonological loop

The crucial focus

• “How does this information apply to some experience in my own life?”

• Make it your own and it will be yours forever.

• Also known as elaborative rehearsal

Long-term memory storage

• To improve our memory we must improve the way we store information

• Just repeating things, over and over again, will not help us remember them

• We must process (work with) them deeply, by focusing on meaning

Levels of processing

• Our ease in retrieving a memory depends on the number and types of links we make with it

• The more links or connections we make with the information, the better we will remember it

• Use links that mean something to you

Memory systems

• Implicit Memory – memories which are influenced by experiences, often without awareness

• Easier to do than explain

• This memory system is often primed, or prepared, by events on the fringe of our attention

• The cocktail-party effect

Procedural memories

• Memory of skills, procedures, habits, even conditioned responses

• A subset of the implicit memory system

• There are plenty of things that we can easily do, but have great difficulty describing

• Very hard to “forget”

• Riding a bike, typing, tying a tie, etc.

Declarative memory

• Contrasts with implicit/procedural memory

• Consists of memories we can easily state in words

• What we know verbally

• We can lose this type of memory and yet retain implicit/procedural memories

More memory types

• Semantic – memory of general principles• Quite resistant to decay

• Episodic – memory of specific events• Vulnerable to decay• Combination leads to source amnesia• “I heard about that, but I can’t remember

where.”

The importance of cues

• Retrieval cues – prompts or stimuli to aid remembering

• The more the merrier

Encoding specificity

• Associations formed while learning are the most effective retrieval cues

• This classroom

• This time of day

• Same chair

• Same people

State-dependent memory

• Tendency to remember something better if your body is in a similar condition when you attempt to recall it, as it was when you first learned it

• Mood – cognitive view of depression

• Drugs – if you studied under the influence, you should …..

• Small effects

Assessing memory

• 1) Recall – Producing the desired information without any cues or hints

Short answer/essay tests

Vulnerable to interference

• 2) Cued recall – Producing the information with hints

Class picture for kindergarten names

• 3) Recognition – Picking out the desired information from a number of alternatives

Multiple choice tests

• 4) Relearning – learning something for the second time

Usually reveals “savings”, information relearned much more quickly

The Serial Order Effect

• Primacy – we always remember the first one

• Recency – and the last

Flashbulb memories

• Traumatic, highly emotional and compelling memories seem to be automatically encoded

• These memories are indelibly seared into our memories

• We remember in astonishing detail

• Or do we?

• President Kennedy’s

assassination

• The Challenger explosion

• But research conducted

in the wake 9/11, show that

even these memories decay

Memory reconstruction

• The problem is more than just forgetting

• We exaggerate, distort, and construct what we “remember”

• Above all, memory is selective

• We typically remember best the gist of the event

• The details can be much more elusive

Ebbinghaus & Interference

• Pioneered systematic study

• Memorized thousands of strings

of nonsense syllables

• Years later, novices trounced him in tests

• How?

Proactive interference – work with similar material in the past makes learning new material more difficult

Losing cues – losing memories

• We need cues to retrieve memories that we have not processed for a while

• The memories are likely still there, but finding them among billions of neurons can be near impossible

The Biology of Memory

• We don’t gain memories without chemical and structural changes in our neurons

• For short-term memory changes consist of a temporary change in the ability to release neurotransmitters

A Change in Structure

• For long-term memory the neuronal changes are more basic and lasting

• A new long-term memory causes changes in synaptic responsivity – long-term potentiation

• Exchanges between these neurons are chemically strengthened, and much more likely to communicate in the future

More changes

• Not only are these neurons synapses chemically strengthened,

• The neurons grow more dendrites and forge more synapses

• This happens over time, a process called consolidation

The strange case of h. m.

• Suffered from severe, recurrent epileptic seizures

• In desperation, his hippocampus was removed

• Sure, his seizures decreased in severity and frequency,

• But, forever after, he “was preoccupied, with 1955”

Who is that?

• H. M. suffered almost complete anterograde amnesia – no new LTM

• Every day, even 20 seconds, his memory was wiped clean

• He couldn’t recognize his wife as she aged, even himself

• He also demonstrated some retrograde amnesia

Amazingly though, ..

• H. M. despite his appalling deficits, could learn new skills, aspects of procedural memory

• On the other hand, he did not know that he had acquired the new skill, an aspect of declarative memory

A preference for the mundane

• What we “remember” of events is often a mixture of surviving memories and what we expect must have happened

• We alter some memories so that, in hindsight, they make sense

• But life is truly stranger than fiction

Emotional arousal

• We usually remember emotionally arousing events but the accuracy of the memory can suffer

• Arousal increases hormone levels which excite the amygdala, which works with the hippocampus to ensure storage

A Common Wild-Card – Source Misattribution

• Often it is far easier to remember something than it is to recall where we heard it

• Since we experience or pick up so much information, from sources which vary greatly in credibility, this can lead to errors

• Others call it source amnesia

But where are they?

• Short-term – frontal lobes

• Long-term – hippocampus is essential, but after processing, they go to the cerebral cortex areas involved in their perception

• Any single memory is a complex relationship of neurons scattered throughout the cerebral cortex, linked together at the start by the hippocampus

Mnemonic devices

• Any memory aid that relies on encoding each piece of information in a specific way

• String items together in a story• Method of loci – linkconcepts or ideas withplaces, or a path• Clever, unusual imagesare essential

More interference

• Retroactive interference – work with new material makes old material harder to remember

• Effect weakened by going to sleep right after learning information

• No wonder ads shown during TV programs with violent/sexual content are routinely forgotten

timing

• Timing – spreading studying sessions over time aids retention

• Even if you are able to devote a significant amount of uninterrupted attention to the material in one setting, you won’t remember it as well

Repression

• Are some things so traumatic that we involuntarily push them out consciousness

• Into the unconscious?

• Though Freud based many of his theories on this phenomenon, it doesn’t work that way.

• In fact, we often find it difficult to stop thinking about horrible experiences