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Cognitive
Psychology PSY 504
VU
Lesson
33
Memory
Long
Term Memory
Forgotten
Memories Exist
Nelson
(1971) conducted an experiment
and indicated that forgotten
memories still exist. He
had
subjects
learn 20 number- non paired
associates; they studied the
list until they reached
a
criterion
of one errorless trial.
Subjects returned for a
retest two weeks later,
recalling 75 percent
of
the items on this retention
test. However, interest
focused on the 25 percent
items for which
the
subjects were given new
learning trials on the 20
paired associates. The
paired associates
they
had missed were either
kept the same or changed. In
a changed case, a new
response was
associated
to an old stimulus. If subjects
had learned 43 dog but
failed to recall the
response to
43,
they might now be trained on
either 43-dog (unchanged) or
43- house (changed).
Results
Subjects
were tested after studying
the new list once. If
subjects had lost all
memory for forgotten
pairs,
there should be no difference
between changed and
unchanged pairs. However,
subjects
correctly
recalled 78% of the
unchanged items and only 43
percent of the changed
items.
This
large advantage for
unchanged items indicates
that subjects had retained
something about
the
paired associates even
though they had been
unable to recall them
initially. This
retained
information
was reflected in the savings
displayed in relearning.
Recognition
of lost memories
Nelson
(1978) also looked at the
situation in which the
retention test involved
recognition. Four
weeks
after learning, subjects
failed to recognize 31 percent of
paired associates they
had
learned.
As, in the previous
experiment, Nelson had
subjects relearn the missing
items. For half
the
stimuli the responses were
changed and for the
other half they were
left unchanged.
Results
After
one relearning trial,
Subjects recognized 34% of
the unchanged items but
only 19 percent of
the
unchanged items. The
recognition-retention test should
have been very sensitive to
whether
subjects
have anything in memory.
Even when the subjects
fail this sensitive test,
there appears
to
be some evidence that a
record f the items is still
in memory- the evidence that
relearning was
better
for the unchanged than
the changed pairs. Here is
one example where
recognition is worse
than
recall yet memory is still
there.
Representation
of knowledge
It
is an issue of long term
memory. That deals in what
form the knowledge store in
long term
memory.
The man issues of
representation of knowledge
are;
Digital
versus analog
Propositional
networks versus
images
Dual
Code Theory
Categories
and concepts
Defining
features
Necessary
and sufficient
features
1.
Digital versus
analog
2.
Propositional networks versus
images
In
the propositional analysis
only the meaning of an event
is represented like fan
effect. The
unimportant
details- details that humans
tend not to remember- are
not represented. In
this
97
Cognitive
Psychology PSY 504
VU
network
the information, relations,
and the arguments are
connected to each other and
they make
a
network.
Dual
Code Theory
Propositional
Network Code
For
example, my house is in Lahore.
This line is stored in our
memory. If one asks about
the
distance
between our house and a
hotel. Then to explain the
distance we make
different
sentences
and make links between
different roads and stops
then we are able to tell
the distance.
So,
these sentences are stored
in our memory. The
information of abstract things
are also stored
n
our mind like intelligence,
love, honesty etc.
Images
are stored
For
example, The image of my
house is stored.
There
is a visual representation in our
mind. Like different scenes.
The presentation, smell,
or
taste
of food is also stored in
our memory. We can recall
them even they are
not there.
Categories
Cognitive
psychology is a merger/union/meeting
point of different types of
knowledge e.g.
philosophy,
computer science, artificial
intelligence, psychology, social
work etc. etc.
The
category fruits groups a lot
of different kinds of objects
that have essential features
in
common.
It also excludes many
objects belonging to other
categories such as
vegetables.
Traditionally
we have defined categories as
having necessary and
sufficient features
Definition
of a Category:
"A
category refers to a group of
objects sharing the same
essential features." e.g.
bird, furniture,
fruit,
robin, etc.
There
are many essential features
that present in all fruits,
like fruits are sweet,
sour, ripe,
different
colors.
Categories
Dictionary
Definition of Fruit (A
category):
"The
edible product of a plant or a
tree consisting of a seed
and its envelop. The
envelop is juicy
and
pulpy." e.g. apple, orange
and plum etc.
Necessary
and sufficient
features
Edible,
Contains seed and
juicy/pulpy envelope
Examples:
Orange, Apple, Mango
Dictionary
Definition of a Vegetable (A
category):
"Edible
plant product eaten raw or
cooked." e.g. carrots,
spinach, tomatoes
etc.
According
to biological classification system,
"Fruit is that part of the
plant which develops out of
a
flower
and nurture seeds."
Necessary
and sufficient
features
Edible,
Plants products
Examples:
Carrots, Spinach,
Tomato
Problem
In
the biological classification
system, fruit is that part
of the plant which develops
out of a flower
and
nurtures seeds. Tomato is a
fruit in biology
For
a chef, Tomato is a vegetable.
The category vegetable does
not exist in Biology.
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Cognitive
Psychology PSY 504
VU
Is
chicken a bird or an
animal?
Categories
are not as neat and
clean as philosophers would
have liked them to be. In
Biology
Chicken
is an animal and a bird. For
a layperson, Birds have to be
able to fly: it is a
necessary
feature
of category bird. So people
consider the chicken as
animal because they eat
it. But
biologist
consider chicken as bird and
animal.
Categories
are very important. Like
letters are categories. If we
know the categories of
things we
can
recognize them even we don't
know the exact thing.
For example there are
many types of
dogs.
We used to see some specific
dog in our area; we have
not seen German shepherd
dog.
But
whenever the German shepherd
comes in front of us we can
recognize this is dog. That
is
because
of category of dog and the
essential and sufficient
features of dog's
category.
Pattern
recognition is a part of category
recognition.
Categories
of Language
Categories
are critical to our
understanding of information processes.
It helps us to know how
we
think
about things that are
around us. Language is also
very important in category
recognition.
Because
the words have different
meanings in different languages.
Sindhi, Blochi,
Punjabi,
Pashto
there are many languages
are spoken in one
country.
Dialect
versus Language
Some
languages are dialect and
some are proper
languages.
Like
some people say Punjabi is a
dialect but some say it is a
complete language.
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