PSYC111

What is memory? + subprocesses

The recording of the past for later use in the present. Involves several subprocesses - encoding, storage, retrieval

What is encoding?

The conversion of info into a form that can be stored in memory

What is storage?

The creation of a trace of this info within a nervous system (retaining this info over time)

What is retrieval?

An attempt to recover a memory trace (access stored info)

Outline Hermann Ebbinghaus’ experiment

First person to investigate memory scientifically. Tested remembrance of nonsense syllables. 100% immediately after learning, decay to 60% after 20 mins, continues to decrease - rapid drop off followed by slower decline.

Limitations: Only testing one type of memory, not using real words (not meaningful)

Outline Peterson and Peterson’s (1959) experiment

Letters and numbers appeared briefly, then participants had to count number backwards for a period, then had to recall letters. Decline of memory retention over time, after about 20 seconds without rehearsal.

Miller (1956) - What is the average number of information retained in memory?

7 +- 2 (5-9)

What are the problems with the unitary model of memory?

In actual memory, info can be lost very rapidly or retained, not consistent. Capacity can also be more immediately limited.

4 types of memory

Semantic, episodic, autobiographical, emotional memory.

Semantic memory

The recollection of ideas, concepts, and facts

Episodic memory

Memory of personal life experiences

Autobiographical memory

Memory for one's person history. Combination of episodic and semantic memory.

Emotional memory

Emotion-memory interactions. Often important in episodic memory.

Levels of explanation for memory

Biological (brain systems, neurochemistry, genetics).

Individual (ind differences, perception and cognition, behaviour).

Social (interpersonal behaviour, social cognition).

Cultural (thoughts, actions, behaviours - in different societies and cultural groups).

Outline Patient HM

Temporal lobes removed to deal with seizures. Seizures reduced but lost ability to form new memory (but intelligence etc remained the same). Could still remember things from distant past, and had brief short term memory (could have a convo with him), but quickly forgot things - suggests distinction between short and long term memory.

Medial temporal lobe damage produces dense anterograde amnesia (LTM - no new memories), but STM intact. Also had retrograde amnesia, couldn’t remember memories a period of time before surgery (but could remember very old memories).

Outline Patient KF

Motorcycle accident, removal of left parietal subdural haematoma. LTM tested with incomplete words/pictures test (fill in then see if can remember from base scratches after some time). Found LTM intact, but STM impaired.

Outline short vs long term memory

Short term mem lasts for around 15-20 secs, limited capacity (7+-2). Temporarily holds limited amount of info. Rapid forgetting.

Long term memory has retention for decades (very slow or no forgetting) and massive capacity.

Outline Atkinson and Shiffrin’s multi-store model of memory

Outline sensory memory

Storage of info prior to STM. Briefly holds incoming sensory info. Lasts for 0.3-3 seconds (echoic longer than iconic).

Outline the serial position effect.

Tested on recall of 15 words (immediately). Would expect latest numbers to be remembered more than earlier numbers. Found increase in % recalled at start and end (surge in remembering early and later words, not middle - primary and recency effect).

Theory is a lot of time to rehearse earlier items, getting into LTM more than middle items. Later items still in STM.

This reinforced by asked to recall items after a distraction/period - removes recency effect.

What is memory stored most by in STM?

Memory stored more by sound, surface features (e.g. shape) - phonetic. Means poor recall for words that sound the same.

What is memory stored most by in STM?

Stored much more in terms of meaning (semantic). Means poor recall for words that mean the same.

Outline Baddeley and Hitch (1974) working model of memory

Primary task was audio presentation of word list, secondary task (at same time) was visually presented digits. Found that high load in secondary task did not impact performance on primary task as expected. Suggests separation between visual and audiotory memory.

4 components to working memory (STM):

Central executive (in command)

Visuospatial sketchpad (inner eye - briefly stores visual and spatial information)

Phonological/articulatory loop (inner ear and inner voice - briefly stores mental representations of sounds)

Episodic buffer (temporary storage, chunking, LTM, VSS, AL integration).

What does the working model of memory (STM) suggest?

Focuses on active manipulation of info rather than passive maintenance. Capacity limitation because of processing rather than storage limitation.

What is chunking?

Grouping individual items into larger (and usually more familiar) units of meaning. Gets around limited capacity of working memory based on processing (STM).

Outline maintenance rehearsal - Craik and Watkins

Hold words starting with G in memory until next one occurs (keep repeating them in mind - maintenance rehearsal). Amount of time between varied, would expect words with longer rehearsal time to be remembered better. Found didn’t actually impact things particularly - suggests more than maintenance rehearsal required to get info from STM to LTM, need active rehearsal/thought about info.

Stein and Bransford (1979) - what factors influence encoding?

Base sentence with elaboration had much better recall. Adding a narrative/story. Info more likely to be remembered if can be elaborated on and incorporated into info you know already.

What is elaborative rehearsal?

Process by which the subject organises and relates new info into material already held in LTM. Contrasts with maintenance rehearsal. Deep depth of processing (meaning/semantic structure, elaboration), vs shallow (e.g. sound, shape). Stores new info into semantic network in LTM, incorporated, easier encoding.

Outline Bransford and Johnson’s (1972) passage experiment

Ambiguous passages, some people given prior context, some not. Informed group had higher rated understanding and higher recall. Elaborative encoding improves comprehension and meaning.

What is a schema?

An example of prior knowledge. Mental framework or organised pattern of thought about some aspect of the world.

When info is transferred into LTM, is it immediately stable (resistant to damage)? - Patient HM example

No. Period of time (maybe up to several years) during which a memory is labile, can be damaged by trauma. Over time memories can get more stable and resistant to damage so remain intact following trauma (consolidation). HM had retrograde amnesia for a 2 year period prior to the surgery.

Anterograde vs retrograde amnesia

Anterograde = no longer to create new memories (following trauma). Retrograde = loss of memories prior to trauma.

What is consolidation?

Strengthening of a memory trace over time (after storage).

What are mnemonics?

Memory aids. Reorganise info into meaningful units and provide cues to help retrieve info from LTM.

Outline visual imagery mnemonics

Associating a word with a visual situation in mind - elaborative. Works better if create a weird or amusing image.

Outline the method of loci (visual imagery mnemonic)

Imagining self walking through a location, creates mental imagery of each item in familiar locations. Helps if weirder.

Outline encoding-retrieval context (context-dependence of memory)

Group able to recall more words if learnt dry and then recalled dry, or if learnt underwater then recalled underwater. If learnt dry and recalled under water, recall decrease, and vice versa.

Suggests memory context-dependent, info intertwined with context, easier to retrieve if in similar context.

Outline HM’s (temporal lobe amnesia) semantic memory

Asked general knowledge questions, did as well as control patients or better. Semantic memory encoded prior to the trauma intact. But ability to gain new semantic knowledge impaired following trauma (very slow learning).

Outline HM’s (temporal lobe amnesia) skill learning

Intact post trauma. Improved on mirror-drawing task, drop from 30 errors to 20 after first trial. Didn’t remember doing trial but did develop the skills through practice.

Outline HM’s (temporal lobe amnesia) priming

Word fragment completion task. Briefly shown full word (e.g. HARE). Then shown H_R_ later. People exposed to prime more likely to answer HARE. Priming spared in temporal lobe amnesia (nervous system implicitly affected).

Outline HM’s (temporal lobe amnesia) habit formation

Habit formation (process by which behaviour control shifts from goal dependence to context dependence) intact. Prior habits intact and could learn new habits.

What type of memory is skill learning, habits, priming, and conditioning all examples of?

Procedural or implicit memory.

What is procedural memory

Type of implicit memory that enables you to carry out commonly learned tasks without consciously thinking about them. E.g. tying a shoe.

Overall, what type of memory does temporal lobe amnesia impact?

Explicit (declarative) memory. Episodic memory impacted severely, semantic impacted (but slow semantic learning could take place).

What are 4 memory errors contributing to forgetting, and 1 contributing to remembering?

Forgetting: Trace decay, interference (retroactive and proactive), blocking/retrieval failure (feeling of knowing), absentmindedness/encoding failure

Remembering: memory persistence (PTSD)

What is trace decay?

Change in biology of memory trace, weakening connections between neurons. Things fade away/are forgotten.

What is retroactive and proactive interference?

Retroactive: New learning interferes with old (e.g. new language makes old one worse).

Proactive: Old learning interferes with new (e.g. park car in new spot and forget where).

Outline blocking/retrieval failure (feeling of knowing)

Due to insufficient activation in a semantic network. Know you know it, but insufficient neural activation to retrieve info.

Outline absentmindedness/encoding failture

Result of shallow encoding of events usually due to a failure to pay attention. E.g. going into a room and forgetting why.

Outline memory persistence - PTSD

3 primary symptom clusters after an event that elicited fear, helplessness or horror. Avoidance (socially and emotional detachment), psychophysiological (to trauma related stimuli, startle, shortness of breath, hyper vigilance), re-experiencing traumatic event through intrusive thoughts, nightmares, flashbacks often produced by reminders of event. Enhances the memory.

How can poor memory occur after trauma?

May be result of context effects or disruption of biological process (e.g. from too much arousal, can interfere). Less common than having very good memory (as with persistence, PTSD).

What are 3 errors contributing to memory distortion + what is memory distortion?

Misattribution, bias, suggestibility. Change in stored info or creation of new info.

What is misattribution - source monitoring error?

When the source of a memory is incorrectly attributed to a source/recollected experience.

What is bias (memory distortion)? + example

British participants presented a Native American story. Shortened story (more after longest gap), confabulated details (changed unfamiliar parts of story to familiar ideas in line with schemas), rationalised (removed or explained away baffling parts, making unusual details conform to general experiences).

Outline suggestibility (memory distortion) with 2 experiments

Watched video of traffic accident. After video, asked how fast were the cars going when they hit each other, or how fast when smashed into each other. 1 week later asked if any broken glass (there wasn’t), about 15% smashed said yes vs about 6% hit and control.

Photoshopped picture of younger person in hot air balloon, asked to recollect trip, 50% of people could remember the fake event by interview three. Memory can be manipulated by provdiing false information.

Why is memory an active/reconstructive process?

Distortions can occur during memory, through provision of misleading info or by inferring something happened after event itself. Builds on previous and current knowledge

Outline the interpretation of smell by the brain

nervous system responds to molecules floating in air when they encounter receptors. Molecules themselves don’t have pleasant or unpleasant characteristics, but brain’s interpretation of molecular signals creates this experiment. Evolved to be this way, e.g. rotten food = smells bad.

Outline the interpretation of colour by the brain

Colour doesn’t exist externally, just light being reflected and detected by photoreceptors in retina of eye. Diff frequencies of light experienced as diff colours - experience of colour being created by NS.

What is Pareidolia?

Seeing faces in objects that aren’t faces, animals in clouds, etc. Detecting objects/images where there are none.

Outline the human central and peripheral nervous system.

Central NS is the brain and spinal cord. Sends signals to peripheral NS, which sends these signals to muscles etc. Peripheral NS captures information (sensory) from external enviro, which is sent back to central NS for interpretation.

What are the 4 main lobes of the human cerebral cortex?

Front, parietal, occipital, temporal.

What does the frontal lobe do

Higher order processing, decisions, choices, complex calculations. Inhibits reflexive responses/basic behvaiours.

What does the parietal lobe do

Speech and where limbs are relative to rest of enviro.

What does the occipital lobe do

Receives and processes visual info

What does the temporal lobe do

Auditory info, memory encoding, language comprehension

What is the central sulcus

Groove that separates frontal and parietal lobe.

What is the insular cortex?

A lobe of the cerebral cortex that is deeper into the brain, behind the lateral sulcus

What is the lateral sulcus?

Groove that separates the temporal lobe from the frontal and parietal lobes.

What is the cerebellum?

“Little brain”-like structure attached to brain stem. Involved in motor control.

What does the brainstem regulate?

Breathing, temp, sleep (basic survival things)

Grey matter vs white matter of brain

Cells that do processing found more in the grey matter. White matter the wiring/connections of the brain (white due to myelin around many of the fibres).

What is a neuron?

Brain’s processing unit, specialised nerve cell.

Outline the structure of a neuron.

(presynaptic terminal aka axon terminals)

Green = myelin, insulates neuron.

Outline how neurons transmit info.

Signals sent from cell body down axon, released by presynaptic terminals, recieved by dendrites of next neuron.

Inside of a neuron is neg charged compared to outside, gives it a resting membrane potential (-70 mv). When stimulated, flow of ions in and out of the cell membrane change electrical charge (e.g. from -70 to -60 mv) of resting potential, producing an action potential (nerve impulse)

Outline membrane depolarisation (neurons)

Sodium (pos ions) want to travel into cell due to lower concentration. When ion channel opens, sodium ions (and other ions) move in, change electrical charge. Leads to a graded potential.

What is a graded potential?

A change in a neuron’s membrane potential within the dendrites caused by membrane depolarisation (e.g. from -70 mv to -60mv)

What are the 2 types of summation?

Spatial and temporal

What is spatial summation

When there are 2 inputs to a neuron’s dendrites separated by space (come in at different points) which then join together, creating a stronger signal (orange)

What is temporal summation?

When multiple signals come into same location at slightly different times (one after the other), then join together, creating a stronger signal (pink)

How do action potentials occur?

If a graded potential is strong enough to reach a threshold (all or nothing), action potential occurs in the axons (e.g. from -70 mv to +10 mv)

What are 2 substances that can disrupt ion channels so NS can no longer generate action potentials?

Tetrodotoxin (TTX) and pyrethrin

Outline tetrodotoxin (TTX)

Found in porcupine and puffer fish. Blocks ion flow through channels that generate action potentials, causing paralysis and stopping mental processes.

Outline pyrethrin

Insecticide. When insect touches or eats it, causes its sodium channels to remain open, resulting in neuron depolarisation and mass action potential generation (like a seizure) before death after complete depolarisation.

Overall, how is information transmitted with the neuron?

By transient alterations in the membrane potential (graded potential in the dendrites, action potential in the axons).

What is the synapse?

Junctions that neurons communicate over.

What happens when an axon potential arrives at an axon terminal?

Neurotransmitters (chemicals) released from vesicles into the synaptic cleft, bind to receptors on the postsynaptic neuron, which respond to the neurotransmitter and generate a graded potential.

What can happen to neurotransmitters after being released into the synaptic cleft after binding to receptors of postsyn neuron?

Can be reuptaken in the axon terminal of the postsynaptic neuron (neurotransmitter reuptake).

Drugs can have an effect by altering neurotransmitter…

• synthesis (might increase or reduce amount amount of neurotransmitters available)

• storage (e.g. make vesicles leaky so less neurotransmitters released)

• Release (slow or speed up/increase likelihood of release)

• Binding (can block receptors, preventing neurotransmitters from binding)

• Reuptake (can slow down reuptake, making signal stronger)

What is an agonist?

A drug that binds to the receptors of a cell and triggers a response. Often mimics action of naturally occurring substance.

What is an indirect agonist?

A drug that enhanced release or action of an endogenous neurotransmitter.

What is an antagonist?

A drug that blocks or suppresses agonist-mediated responses.

Examples of neurotransmitters

acetylcholine, dopamine, noradrenaline, glutamate, serotonin

What is acetylcholine involved in?

Memory processes and movement (e.g. neuro-muscular junction)

What synapse uses the neurotansmitter acetylcholine?

The cholinergic synapse

What are agonists of the cholinergic synapse and why?

Nicotine (stimulates receptor sites), black widow spider venom (lots of signals to muscles, causes paralysis)

What are antagonists of the cholinergic synapse and why?

Scopolamine (motion sickness meds), botulinum toxin (can no longer control muscles, flaccid paralysis)

Outline Parkinson’s Disease (symptoms + cause)

Tremor, muscular rigidity, slow movement (bradykinesia), postural instability, involuntary shifts of posture (dustonia and dyskinesia), shuffling, wide gait, forward learning posture leading to festination.

Caused by low levels of dopamine - associated with degeneration of neurons (in sbstantia nigra, midbrain nucleus) that release dopamine.

How can Parkinson’s disease be treated?

With dopamine agonists (e.g. L-Dopa) or Deep Brain Stimulation (generates electrical pulses in neurons in deep part of brain, suppressing symptoms)