Transcript Document 337304

Unit 3 - Neurobiology and Communication
CfE Higher Human Biology
18. Memory
Learning Intentions
I can define memory as storage, retention and retrieval of information
I can state that memories include past experiences, knowledge and thoughts
I can describe the path of information entering the brain as from sensory memory to short term memory and transferral to
LTM
I can state that information not transferred to long term memory is discarded
I can define that sensory memory lasts a few seconds and retains all of the visual or auditory input
I can state that short term memory lasts approximately 30 seconds and can hold 7 +/- 2 pieces of information = memory span
I can explain how the capacity of short term memory can be improved using chunking
I can explain how rehearsal of information improves retention within the short term memory
I can explain serial position effect
most recent items recalled as still in STM
items in middle of sequence displaced/discarded
first items recalled as transferred to long term memory by process of rehearsal
I can state that information can be transferred from STM to LTM due to rehearsal, organisation and elaboration
I can define rehearsal as the repetition of items
I can define organisation of memories as the grouping together of similar information
I can define elaboration as adding meaning to information
I can state that retrieval of memories is aided by the use of contextual cues
I can describe contextual cues as pieces of information stored at the same time or link memories together
I can state that different types of memories are stored in different areas of the brain
I can describe episodic memory as memories of events and experiences
I can describe semantic memory as those involving facts and concepts
I can describe procedural memories as those used to perform skills
I can state that episodic and semantic memories are stored in the cortex
I can state that procedural memories are linked to the motor cortex and cerebellum
I can state that emotional memories involve links between the cerebral cortex and the limbic system
Memory
• Memory is the capacity of the brain to store information,
retain it and retrieve it as and when required.
• The brain can capture images of sights, sounds, smells, tactile
sensations and emotions from any moment.
• Memories include past experiences, knowledge and thoughts.
They allow us to deal with current and future experiences
based on the past memories.
• All information which enters the brain passes through sensory
memory and enters the short term memory (STM).
• Information can then be transferred to the long term memory
(LTM) or is discarded.
Selective Memory
• The brain is constantly receiving information from sense organs
which transmits the information to the brain.
• The brain has to select what information it stores or else it
would become cluttered.
• The brain must encode this chosen information into a form that
it can process to store in the short term or for a longer term.
• If this information is encoded and stored correctly then it can
be retrieved later.
Three Levels of Memory
Level 1
Level 2
Level 3
Level 1 - Sensory memory
• Sensory memory retains all visual and auditory input but for a very short
period of time e.g. 0.5s for visual stimuli and 2s for auditory.
• The brain selects relevant pieces of information to send to the short-term
memory (STM)
Level 2 - Short term memory (STM)
• Short term memory (STM) has a limited storage capacity or ‘memory span’
holding about seven items of information for roughly 30 seconds. During
this time the retrieval of items is very accurate.
• The information in the STM must be passed to the long term memory or it
will be lost by:
• displacement – the pushing out of ‘old’ information by new information
• decay – the breakdown of a fragile ‘memory trace’ formed when a group
of neurons briefly became activated.
Short term memory (STM)
Rehearsal
• Items can be maintained within the short term memory for longer periods
of time through rehearsal.
• Rehearsal involves repeating a piece of information many times, either
silently or aloud.
• This also helps to transfer this information to the long term memory
(LTM).
Short term memory (STM)
Chunking
• ‘Chunking’ is the term given to the organisation of many pieces of information
into smaller chunks of information.
• e.g. the area code for Glasgow is 0141. Individually, this can be thought of as
four pieces of information but chunking allows us reduce this to one piece of
information.
• Grouping many pieces of information into smaller chunks allows us to improve
our short term memory span.
Short term memory (STM)
Serial position effect
• When information is viewed in a sequence, the first and last few pieces of
information are remembered best. This memory pattern is known as the serial
position effect.
Short term memory (STM)
Serial position effect
• The first few pieces of information are remembered as there has been
enough time for rehearsal, and the information has been transferred to long
term memory.
• The middle pieces of information are quickly forgotten because the short
term memory is crowded with information.
• The last pieces of information are remembered because they have not yet
been displaced from the STM.
Short term memory (STM)
Serial position effect
• Advertisers pay more for the first and last advert slots to take advantage
of the serial position effect.
• Jim Davidson’s generation game
• http://www.youtube.com/watch?v=Fm5ygKN4PKs
Short term memory (STM)
Working memory
• Working memory is an extension of the STM.
• It allows us to actively process information while it is held in the STM and
allows us to carry out simple cognitive tasks, such as counting.
• e.g. allows you to picture your home and count the number of doors within.
Level 3 - Long term memory (LTM)
• The long term memory is thought to be able to hold an unlimited amount of
information.
• In order for information to be transferred from the STM to the LTM,
information must be encoded (converted to a form that the brain can process
and store).
• During encoding the items are organised into categories such as skills,
personal memories or facts.
Encoding
• The quality of the memory depends on the attention given to the encoding
of it.
• Encoding is the conversion of one or more nerve impulses into a form that
can be received and stored by the brain. This means that it can be retrieved
from the STM or LTM at a later date.
• Information can be encoded using:
• shallow encoding, such as repetition, or
• elaborative encoding, such as linking with previous memories, which is
considered as a deeper form of encoding.
Long term memory (LTM)
• Information can be transferred to the LTM successfully by:
• Rehearsal
• Organisation
• Elaboration of meaning
Long term memory (LTM)
Rehearsal
• Rehearsing a piece of information helps to extend the length of time it is
retained within the STM.
• Rehearsing also facilitates the transfer of information from the STM to
the LTM.
• Students who stop and repeat what they have just read helps commit the
knowledge to their long term memory when compared with students who
read continuously.
Long term memory (LTM)
Organisation
• Organising information into logical groups or categories
makes it more easily transferable into the LTM.
• e.g. List 1 is jumbled, List 2 is organised
into logical categories.
List 1
List 2
cow
cow
jacket
sheep
• Through organisation, the information is
more likely to be successfully encoded and
transferred to the LTM.
tin
chicken
cat
cat
sheep
jacket
iron
trousers
trousers
shirt
chicken
tin
shirt
iron
lead
lead
Long term memory (LTM)
Elaboration of meaning
• Elaboration allows us to make information easier to transfer and store in
the LTM by building it into a bigger ‘story’.
• For example, the name of a person is much more likely to be transferred to
the LTM if it is associated with mental images, personality, experiences
and smells, such as their perfume/aftershave.
Long term memory (LTM)
• Information which is stored in the LTM should be able to be retrieved.
• To aid retrieval, information is stored in categories e.g. family, holidays, etc.
• Retrieval is also aided by ‘contextual cues’, these are signals or reminders
relating to the conditions which were present at the time the memory
encoded into the LTM.
• The more elaborate and detailed the memory, the more easily it is
retrieved.
Memory overview
• The link between the sensory, short term and long term memory is shown in
the diagram below:
Rehearsal
level 2
level 1
sensory
memory
Selected info.
ENCODED
short term
memory
(STM)
level 3
some info.
transferred
long term
memory
(LTM)
Retrieval
most sensory
images are
short-lived and
quickly
forgotten
many items
forgotten
“displaced”
Location of memory in the brain
• Different types of memories are stored in different areas of the brain.
Episodic and semantic memory – ‘remembering that…’
• Episodic memory is the recall of personal facts, experience and events.
• Semantic memory is the recall of general knowledge, non-personal facts
and concepts.
• Both episodic and semantic memories are stored in the cerebral cortex
such as the temporal lobes at the sides of the cerebrum
Location of memory in the brain
Procedural memory – ‘remembering how to…’
• Procedural memory contains information on how to perform particular skills,
such as motor skills (e.g. how to swim) and mental skills (e.g. how to read).
These skills are recalled without conscious control.
• Procedural memories are stored within the motor region of the cerebral
cortex.
Location of memory in the brain
Emotional memory
• Emotional memories are formed as a result of positive or negative
associations with particular stimuli.
• Emotional memories involve links between the cerebral cortex and limbic
system.
Location of memory in the brain
Spatial memory
• Spatial memory holds a record of our environment and its spatial
orientation.
• i.e. where the fridge is in your kitchen.
• Spatial memory is stored within the limbic system.
Location of memory in the brain
Type of memory
Location within the brain
Episodic and semantic
Cerebral cortex
Procedural
Motor area of the cerebral cortex
Emotional
Cerebral cortex and limbic system
Spatial
Limbic system
Questions 1
1. State what memory and what it includes
2. Describe how information entering the brain reaches long term
memory (LTM).
3. Describe the features of the sensory memory.
4. Describe the span of the short term memory (STM).
5. Explain the serial position effect.
Answers 1
1. State what memory and what it includes
Memory involves storage, retrieval and retention and includes past
experience, knowledge and thoughts.
2. Describe how information entering the brain reaches long term
memory (LTM).
All information which enters the brain passes through sensory memory
and enters the short term memory.
Information can then be transferred to the long term memory (LTM).
Answers 1 (continued)
3. Describe the features of the sensory memory.
Sensory memory retains all visual and auditory input but for a very
short period of time, only 1 or 2 seconds.
4.Describe the span of the short term memory (STM).
It holds about seven items of information for roughly 30 seconds.
5. Explain the serial position effect.
When information is viewed in a sequence, the first and last few pieces
of information are remembered best.
Questions 2
6.Describe how STM can be improved or maintained
7.State the two ways in which information is lost from the STM.
8. Describe the methods which aid transfer of information into the
LTM.
9.Define the term ‘encoding’ & describe the different methods of
encoding.
10.Describe how contextual cues aid memory retrieval.
11.State the locations of episodic, semantic, procedural, emotional and
spatial memories within the brain.
Answers 2
6.Describe how STM can be improved or maintained
Rehearsal or chunking
7.State the two ways in which information is lost from the STM.
Displacement and Decay
8. Describe the methods which aid transfer of information into the
LTM.
Rehearsal, organisation, elaboration of meaning
Answers 2 (continued)
9.Define the term ‘encoding’ & describe the different methods of
encoding.
converted to a form that the brain can process and store
shallow encoding e.g. repetition
elaborative encoding e.g. linking with previous memories
10.Describe how contextual cues aid memory retrieval.
these are signals or reminders relating to the conditions which were
present at the time the memory encoded into the LTM.
Answers 2 (continued)
• 11.State the locations of episodic, semantic, procedural, emotional and
spatial memories within the brain.
• episodic and semantic memories -cerebral cortex.
• Procedural memories -motor cortex.
• Emotional memories -between the cortex and limbic system.
• Spatial memory -the limbic system.