Transcript Cognitive Psychology

Lesson Three: Encoding, Capacity, and Duration
1.
2.
Specification
Homework
A – Models of Memory
Bring in a photograph from your childhood (if
you do not have one bring in an item
from your childhood)
The multi-store model including
concepts of encoding, capacity and
duration. Strength and weaknesses of
the model
Draw a diagram to demonstrate the function
of the Multi-Store Model of Memory
(6 marks)
The working memory model including
its strengths and weaknesses
B – Memory in everyday life
1.
Eyewitness testimony and factors
affecting the accuracy of EWT
including anxiety and age of witness
2.
Misleading information and the use of
cognitive interview
3.
Strategies for memory improvement
Starter
Think of an example of each type of memory:
Iconic, Echoic, and Haptic
Lesson Objectives:
By the end of this lesson, you will be able to:
•
Apply the concepts of capacity and duration to
memory stores
•
Understand the factors affecting capacity and
duration and describe how they have been
measured
Key Words to know by the end of
the lesson:
•
•
•
•
•
•
•
Capacity
Duration
Digit span technique
Serial recall
Rehearsal
Chunking
Trigrams
Link to last lesson
Can you describe the evidence for a
distinction between STM and LTM?
A case study was carried out on Peter whose brain was damaged
in a motorcycle accident. Psychologists tested how many
numbers he could hold in his short-term memory. They did this
by reading him lists of numbers and asking him to recall the
numbers immediately in the right order. He could recall a
maximum of two items. The psychologists found that his longterm memory was normal.
Eye on the exam
• C) Identify one ethical issue associated
with this case study of Peter. Suggest
how psychologists could deal with this
ethical issue. (4 marks)
– Ethical issue
– How psychologists could deal with this
ethical issue
Multistore Model
Information is
registered
through the
sensory &
attentional
systems
The rehearsal loop
allows info to be
maintained in STM
for longer periods
STM
A limited amount
of info is held for
a short time in
STM
LTM
Rehearsal allows info to
be moved to LTM for
long term storage
Capacity in LTM
• LTM has an unlimited capacity
(as far as we know)
Capacity in STM
• can
Do the
following
• Your LTM
never
be full!!!mental arithmetic…
*4 + 7= * 11 + 35= *6 + 3 + 4 – 2 x 30 =
• The problems that you may have had with
the last one demonstrate the limited
capacity of STM
• As you try to work out the subsequent parts
of the equation, you have to lose
information to make room for new items
• The size of the capacity of STM depends on
how we measure it
Key Terms Explained:
• Digit Span Technique: a way of
measuring capacity in STM. Participants
have to repeat back strings of digits
(that increase in size) until they can no
longer repeat the sequence of digits
correctly
• Serial Recall: a way of testing STM
where participants are required to
recall items in the correct order of
presentation
Try This!
• This is an example of a serial recall task…
• How far can you get before you start to
forget the order of presentation?
• George Miller (1956) – ‘The Magical Number
Seven, Plus or Minus Two’
• We can hold about 7 ‘items’ in out STM with a
range between 5 – 9.
Items?
ITEMS?
What do we mean by items?!
• Miller
• The capacity of STM: determined by the
number of ‘chunks’ (7, + or – 2 chunks)
rather than the number of individual letters
or numbers.
• Try and remember the numbers on the
following page in the correct order…
•
•
•
•
•
•
•
•
•
999
911
54321
118118
22002
34250
6168133
00353749721680
14177113504400
How did you do?
• See how meaningful pieces of information
can stay in your STM longer than others?
• You have rehearsed these before and in
this way your LTM helps your STM
• Miller
• Semantic (meaningful chunks) which are
recognisable, make recall easier.
• So memory span can be increased by
chunking!
• Too vague? – how much information can
me contained in a chunk?
• Simon (1974)
• Immediate serial recall of one-syllable, twosyllable, three-syllable words & two word and
eight word phrases.
• He found that the span in chunks was less with
eight word phrases than with smaller chunks.
• So the capacity depends on the nature of the
material to be remembered.
• Unlike a
There is no way of defining a
basic unit of information to be
stored in human STM.
Factor affecting capacity
• Rhythmic grouping
Question…
• What could affect the capacity of STM?
–
–
–
–
Influence of LTM: (Cowan, 2000)
Reading Aloud (Baddeley, 1999)
Pronunciation time (Hitch et al, 1984)
Individual differences (McLeod and Donnelly, 1993)
– Using p12 in your textbook and the Baddeley et al.
(1975) study in you course pack write down (on the
same page as this study) how the above factors affect
capacity.
Duration in STM
Let’s try Peterson and Peterson’s (1959)
experiment….
AIM: To find out how long items would
remain in STM without rehearsal.
PROCEDURE: They presented participants
with a consonant Trigram (3 consecutive
letters that do not form a pronounceable
unit, e.g. CKM, FNW)…..
BPN
TPB
TGK
QTK
Peterson & Peterson…..
• FINDINGS: This procedure was repeated
several times (trials) using different
trigrams on each presentation.
• Ps were able to recall:
• 80% correctly after 3 second interval
• Fewer than 10% correctly after 18 second interval
• CONCLUSION: information disappears or decays
very rapidly from STM when rehearsal is prevented
Methodological issues…
• Read through the Peterson & Peterson study in
your course pack - what do you think may be
potential methodological issues?
• Ecological validity (artificiality of trigrams?)
• Capacity or Duration? (displacement –
remember the mental arithmetic?)
• They might have mixed up the trigrams with
those experienced in earlier trials (proactive
interference)
Factors that affect the duration in
STM
• Rehearsal
• Intention to recall (Sebrechts et al., et al
1989)
• Amount of information to be recalled
(Murdock, 1961)
• Underneath Peterson & Peterson study
explain how the above factors can affect
duration.
Duration in LTM
Answer the following questions ..…
1. Write down (in as much detail as
possible) your first memory
2. What factors could affect our ability to
keep memories long-term?
Duration in LTM
• Bahrick et al. (1975)
• AIM:
• PARTICIPANTS:
• PROCEDURE:
• Read through study in course pack.
Factors affecting duration in LTM
p 14-15
•
•
•
•
Experimental techniques
Depth of learning (Bahrick & Hall, 1991)
Pattern of learning
Nature of material to be learned (Conway
et al., 1991)
• Briefly explain these factors at the bottom
of the study sheet.
Check your key words:
•
•
•
•
•
•
•
Capacity
Duration
Digit span technique
Serial recall
Rehearsal
Chunking
Trigrams
Plenary - Eye on the exam
• Using the list below, complete the table to distinguish between longterm memory and short term memory.
(3 marks)
•
•
•
•
•
•
Unlimited
Up to a lifetime
7 +/-/2 items
Mainly acoustic
Seconds
Mainly semantic
Short-term memory (STM)
Capacity
Duration
Encoding
Long-term memory
(LTM)
Plenary - Eye on the exam
Outline the key features of the multi-store model
of memory. (6marks)
• This straightforward question that asks you to demonstrate your
knowledge about the multi-store model. Remember, this question
requires AO1 skills and you are expected therefore to demonstrate
your knowledge and understanding. You are not required to provide
any analysis or evaluation of this model.
• You must also remember that a model is an explanation or theory. It
is not a study.
• Take care to provide a balanced answer. If for example you spend
too much time describing (rather than briefly outlining) the memory
stores, you will not have enough time to do justice to the other
aspects of the model.
Your answer should include an
short account of:
• The three separate stores (sensory, short-term and longterm) and their main characteristics in terms of encoding,
capacity and duration.
• The processes used to transfer information from one
store to another (attention to pass information on from
the sensory store and rehearsal to pass information from
the STM to LTM). Recoding may also be needed
between one store and the next.
• Why information may be lost from each store (through
decay from sensory, through decay and displacement
from STM and through interference and retrieval failure
from LTM).
Homework
Bring
in a photograph from your childhood (if you do not
have one bring in an item from your childhood)
•Draw a diagram to demonstrate the function of the MultiStore Model of Memory (6 marks).
This will provide a useful revision tool for
you on the MSM but remember it’s the
detail that’s marked so don’t spend too
long making it pretty ……