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Higher Human Biology
Unit 3
Neurobiology & Communication
KEY AREA 2: Perception and Memory
Neurobiology & Communication Learning Intentions
KEY AREA 2 – Perception and memory
Perception
1) Segregation of objects
2) Perception of distance
3) Recognition
Memory
1) Sensory memory
2) Short-term memory (STM)
3) Long-term memory (LTM)
4) Location of memory in the brain
2a) Perception
Perception is the process by which the brain analyses and makes sense out of
incoming sensory information
Perception allows us to segregate objects from one another and their background,
recognise what they are and to judge their distance from us
The 3 areas of perception involve:
Segregation of objects
Perception of distance
Recognition
Old or Young Lady?
2b) Perception – Segregation of objects
1st stage in visual perception is appreciation of an object’s shape
When an object appears to stand out from its background in an obvious manner this
perceptual organisation is called “Figure and ground” – what is the figure and what is
the background?
2c) Perception – Segregation of objects
2nd stage in visual perceptual organisation involves the brain organising stimuli into
coherent patterns e.g. patterns of size, superimposition and relative height in field
The brain tends to organise visual stimuli into patterns rather than individual parts
2d) Perception – Judgement of distance
Binocular disparity
•Each eye looks at an object from a slightly different position so a slight
difference (disparity) occurs between the images
•The closer the object, the greater the disparity
•The 2 images are merged into 1 image in the brain producing a binocular image
•This image indicates depth and distance more effectively than a monocular
image
1. Take your pen
2. Look out the window
3. Close one eye and place
the tip of the pen at a
structure e.g. a house
4. Swap eyes that are closed
5. What happens?
2e) Perception – Judgement of distance
As distance increases from an object, the object is
perceived as getting smaller
As distance decreases from an object, the object is
perceived as getting bigger
As objects become nearer and the viewing angle changes,
we don’t believe that the object gets smaller or bigger
due to Perceptual Constancy
Perceptual Constancy depends upon past experience,
stored knowledge and relative size
2f) Perception – Recognition
Object recognition is the ability to perceive an object’s
physical properties e.g. shape, colour, and texture
The importance of shape is more important than colour or
texture in recognition
During early learning, the objects shape is used to
characterise and differentiate it from another object e.g. the
shape of a banana compared to an apple
Matching perceived shapes
•When a person perceives a shape, they subconsciously try to
match this shape with one of the “visual descriptions” already
stored in their brain.
•If the shape is familiar, it will quickly be matched and the
object will be recognised.
•If unfamiliar, you would not be able to name it, but could say
what it was similar to
2g) Perception – Recognition
The perceptual set is the tendency of a person to perceive certain aspects of
sensory information and ignore others.
Perceptual set is affected by where past experience, context or expectation
as they influence the way a stimulus is perceived
Rat or man?
Number or letter
Unfamiliar object
2h) Memory
• Memory involves storage, retention and retrieval of information
• Memories include past experiences, knowledge and thoughts
• The brain can capture images of sights, sounds, smells, tactile
sensations, and emotions all experiences at one time and retain them
as memories
• Memory involves 3 interacting levels. All information entering the
brain passes through: Level 1 - Sensory Memory(SM)
Level 2 - Short Term Memory(STM)
Level 3 - Long Term Memory (LTM) or discarded
2i) Memory
Memory involves 3 interacting levels
2j) Sensory Memory
Level 1 - Sensory memory
Stimuli from the environment are continuously being perceived as
sensory images by the brain.
These impressions are VERY SHORT LIVED
(only last for 0.5 seconds for visual images & 2 seconds for
auditory images)
2k) Short-term Memory (STM)
Short-term memory (STM) only holds a limited amount of information –
usually about 7 items at one time (memory span), and the items are only held
for a short time. The information is either:Transferred to Level 3
OR
Lost by displacement (pushing out old information by new info)
Lost by decay (breakdown of memory trace when neurons are activated)
2l) Short-term Memory(STM) – Serial Position Effect
The Serial Position Test
1. Show 20 objects one at a time to an individual
2. Each object is observed for 5 seconds
3. After the last object, the subject has to write down as many of the objects that they
can remember, in any order
Try the AHS Serial Position Effect Test!
2l) Short-term Memory(STM) – Serial Position Effect
The Serial Position Effect
Recall is best for items shown at the end of the test, followed by items shown at the
start. Items shown in the middle of the test are poorly remembered. This is due to the
items at the beginning of the test have been transferred into the LTM, and items at the
end are still held in the STM
2m) Short-term Memory(STM) – Rehearsal
Rehearsal involves repeating information over and over again in order to
help you to memorise
This process helps to transfer Short-term memory into Long-term
memory and is the most effective method to use for learning
Rehearsal is used to help pass your Highers, pass your driving test!
Investigation Opportunity
Effect of rehearsal on motor memory skills
2n) Short-term Memory(STM) – Chunking
Short- term memory can be improved by chunking
Chunking is when several units are put together to create one
meaningful unit
e.g. the numbers 95015 are easier to remember as 01595 (code for
Lerwick) as you are already familiar with it! Chunking can improve STM
Lists of letters to remember :Set 1 - ICL, TPT, OML, MVM, EZQ, CPG, UPR, MCA, RPA,
Set 2 – HIV, FBI, UFO, BBC, AHS, RIP, USA, VAT, NYC
Which set is easier to remember? Why?
“Learning is not just remembering! It is about making sense of something!”
2o) (iii) Long-term Memory(LTM)
Long-term memory (LTM) is thought to be able to hold an unlimited amount of information
Information is constantly being transferred between the STM and the LTM
If during STM the item is encoded, then this item will be transferred for storage in the
LTM. LTM will then be able to retrieve the item
Successful transfer of information from STM to LTM is promoted due to rehearsal,
organisation and elaboration of meaning
2p) Long-term Memory(LTM)
Organisation
Information that is organised into logical categories is more easily transferred from
the STM to the LTM
Which list is the easiest to remember?
2q) Long-term Memory(LTM)
Elaboration:
Elaboration involves analysing the meaning of the item to be
memorised and taking note of features and properties
Encoding:
The conversion of one or more nerve impulses into a form that can
be received & held by the brain and retrieved later from the STM
or LTM
Shallow encoding: Information encoded by repetition
Example: Names of people in the class
Elaborative encoding (deeper encoding)
Information encoded by associating it with other information such
as a meaning or linking it with previous memories
Example: Name of people in class & what they look like
2r) Long-term Memory(LTM) – Retrieval
Classification of information in the LTM
The LTM stores information in distinct categories
e.g. types of fruit, colours, numbers, names of family members
Retrieval of items in the LTM
LTM contains a vast store of items constantly being revised, reorganised and
enlarged and new materials flows in. A search is required to retrieve
information from the LTM. The search is aided by contextual cues (a reminder)
Contextual cues somehow trigger an impulse through a “memory circuit”
A memory whose encoding in the LTM is accompanied by unusual, emotional or
dramatic events (e.g. a wedding day) possess powerful contextual cues. These
enable the experience to be retrieved and recalled clearly throughout life
2s) Location of memory in the brain
Type of Memory
Possible location
Function
Episodic
Many regions of
Cerebral cortex
Recall of personal facts,
experiences & events
Semantic
Many regions of
Cerebral cortex
Recall of general knowledge,
non-personal facts, ideas
Procedural
Motor region of
cerebral cortex
Memories needed to perform
motor skills (e.g. swimming) &
mental skills (e.g. reading)
Emotional
Limbic system &
cerebral cortex
Memories formed as a result of
positive or negative
associations
Spatial
Limbic System
Memories about environment
and spatial orientation (e.g.
location of kitchen sink)
Neurobiology & Communication Questions
KEY AREA 2 – Perception and memory
1.Testing Your Knowledge
Page 234
Q’s 1-4
2.Testing Your Knowledge
Page 246
Q’s 1-5
3.What You Should Know
Page 246
Q’s 1-15
4.Quick Quiz