Memory & forgetting

How long do sensory stores hold information?

<500ms (can be increased by maintaining attention)

How long does ST memory stores last for?

A few seconds (longer with rehearsal)

How long does LT memory last?

Minutes to a lifetime

Cause of retrieval failure from LT memory?

Interference - too many similar memories

Types of encoding for LT memory

• Physical - does the word have capitals?

• Acoustic - does it rhyme?

• Semantic - does it fit in a sentence?

Which kind of encoding has the greatest recall?

Semantic - requires a higher level of processing = reducing interference with other memories

Context dependency in LT memory

Refers to the match between the environment when recalling the memory

• eg: words learnt underwater = better recall underwater than on land

Mood dependency in LT memory

A depressive mood can lead to the recall of upsetting events, leading to sad thoughts and a depressive mood.

Why do we forget information from our short term memory?

Information is rapidly lost when distracted

Why do we forget information from our LTM?

• ineffective cues - impact our access to memories

• interference - memories are too similar for cues to differentiate

• Involuntary retrieval when encoding and retrieval states match

What area of the brain is damaged with amnesia?

Medial temporal lobe

• hippocampus and associated structures

Causes of amnesia

• Viral infection

• Alcoholism (korsakoff’s syndrome)

• Anoxia

• Head injury

• Alzhiemer’s disease

Retrograde amnesia

Memory loss of events prior to accident

Anterograde amnesia

Memory loss of events following accident - can still recall previous memories

Why do childhood memories remain intact following amnesia - what does this tell us?

Memories are less dependent on hippocampus following consolidation

• LT memories are stored in the neocortex surrounding hippocampus

Semantic memory

Normal retention of factual knowledge

What does the preservation of semantic memory in amnesia tell us about the hippocampus?

It is not the final store of knowledge

What does the preservation of procedural memory in amnesia tell us?

Hippocampus is not required for some types of non-conscious LT memory

2 kinds of LTM?

• Declarative/explicit

• Non-declarative/ implicit

2 kinds of declarative/explicit memory?

• Episodic (damaged in amnesia)

• Semantic

3 kinds of non-declarative/implicit memory?

• Procedural

• perceptual priming

• Classic conditioning

Role of hippocampus in memory?

Binding process of people, place and object

What kind of memory is impacted in semantic dementia?

Semantic memory

• Gradual loss of conceptual ideas

• reverse temporal gradient to amnesia

where is episodic memory stored?

In hippocampus (damaged in amnesia)

Semantic memory store?

Anterior temporal lobe

• Damaged in semantic dementia