PS1000: Imagery and
Consciousness
Visual Imagery
Dr. John Beech
School of Psychology
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Imagery and Consciousness
Summary of the topic
• Visual imagery: phenomena and findings: mental
rotation, mental paper folding, grain size, image
scanning, brain scanning evidence; understand the
arguments for and against the ‘picture metaphor’ view
of visual imagery.
•
States of consciousness: examining four
different states: the unconscious, dreaming, meditation
and hypnosis.
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Introduction
There has been much work on the nature of images. E.g.
imagery appears to be able represent objects and to
perform operations on those objects that are very similar
to real operations.
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Some imagery phenomena: 1. mental rotation
1. Mental rotation. Shepard and Metzler (1971) gave pictures of two
complex 3D forms that had to be compared. Were they the same
overall shape? They found that time to rotate is a constant rate.
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Some imagery phenomena: 1. mental rotation
Some more
examples:
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Some imagery phenomena: 1. Mental rotation
• This is process that
allows one representation
to be compared with
another.
• This process has a fixed
rate.
• Reaction time increases
linearly with the angle of
rotation.
• This linear increase in RT
is the same in the 2D
plane as well as in depth.
• Also found with letters,
familiar objects, faces.
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Imagery phenomena: 2. Mental paper folding
Shepard and Feng (1972): Pictures of unfolded cubes of
paper were shown with dotted lines for folds and a
shaded area for base.
An example of the kind of stimuli follows:
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2. Mental paper folding
Always maintain the grey square as fixed and as the “base” of the object. Does
the end square on the extreme right end up overlapping another square?
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2. Mental paper folding
Always maintain the grey square as fixed and as the “back” of the object.
Does the end square on the extreme bottom right end up overlapping
another square?
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2. Mental paper folding
Reaction times increased
linearly as a function of
sum of number of
squares that had to be
mentally folded. These
two experiments (mental
rotation and mental paper
folding) suggest that
mental operations can
take place in a similar
manner to actual physical
operations.
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3. 'Grain size'
'Grain size' refers to amount of detail available in an image
(like a TV). The 'grain' of the mental medium limits
amount of detail seen. The next experiments
demonstrate that what happens in an image is similar to
what happens when one actually perceives stimulus.
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Comparing line lengths
In Johnson’s (1939) experiment
participants were given two
lines of different length and
had to decide which was
longer.
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Comparing line lengths
• When difference between lengths is small, participants
take longer to decide which is longer.
• When there was a large difference, participants found it
much easier and quicker to decide.
• The logarithm of the difference in line length produces a
decrease in reaction time.
• Put another way, one gets a line sloping downwards (left
to right) plotting RT against the logarithm of the
difference in line length.
• This is a perceptual experiment as lines are actually
present while participant makes decision. This
demonstrates of 'grain size' because if differences too
small then encountering problems.
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Comparing image sizes
• Same result can be produced
by getting participants to
imagine animals (Moyer,
1973).
• Participants judged relative
sizes of two animals by
deciding which was larger.
Sizes had been estimated
beforehand by a previous
group. In all cases they
weren’t shown pictures –
they were told the animal
names and did this just in
their imagination.
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Comparing image
sizes
Examples
1. Is a bee larger than an eagle?
2. Is a dog larger than a cat?
3. Is an ant larger than an aphid?
4. Is a dinosaur larger than a fly?
When animals were closer in size,
participants took longer.
• Moyer found the same kind of
linear decrease in reaction
time as a function of the
logarithm of estimated animal
size.
• Thus imagery seems to be
similar to perception here.
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4. Image scanning
• In an image scanning experiment by Kosslyn (1975)
participants were shown ten line drawings for 10 sec.
each and they had to remember the name (e.g. “boat”).
• Kosslyn had two groups of participants: focus vs
wholistic. The first (the focusers) was told to focus in
specified region (e.g. extreme left or bottom).
• When property named (e.g. ‘anchor’), they had to find by
scanning image of boat.
• (Picture of boat not physically present.) Responded
when location reached.
• The second group (the wholistic group) imagined the
whole image, instead of focussing on a particular part
and then scanning across.
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4. Image
scanning
Kosslyn found that
moving across
the image was a
smooth process.
Like looking
slowly across a
picture? 'Picture'
metaphor
suggests that
having an image
is like having
picture in the
head.
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5. Brain scanning evidence
Roland & Friberg (1985) had participants either counted
back in 3s or imagined walking alternating left & right
turns starting from door of home. Measured blood flow in
areas of cortex.
• They found: more blood flow in visual cortex when using
imagery than when doing maths task. This pattern
similar to when perceptual tasks done.
• Imagery seems to be like perception in the beginning
processing stages in the brain, but there is more
activation during imagery (Kosslyn et al. 1993).
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Arguments against ‘picture
metaphor’
We will now look at arguments of two sets of investigators.
First, Pylyshyn (1973) argued against visual imagery.
Then we'll look at arguments of Kosslyn & Pomerantz
1977 who are pro the concept of imagery, but who look
at the arguments both for and against.
Pylyshyn's arguments
He accepts that people experience imagery, but wonders
whether the concept of imagery can actually explain
findings. A summary of some of his arguments is as
follows:
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Arguments against ‘picture
metaphor’
1. The picture metaphor
Pylyshyn notes theories of visual imagery rely heavily on
picture metaphor. Terms used include clarity and
vividness of images. This suggests that when image
formed, we produce some kind of unprocessed signal
or pattern. Then somehow this pattern is scanned
perceptually.
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Arguments against ‘picture metaphor’
However, such a position has difficulties:
1. There would be a storage capacity burden on the brain
2. Severe difficulties for retrieval processes. Does one
retrieve by placing each image before mind's eye?
However, we seem able to retrieve appropriate image
almost immediately without any false attempts.
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Arguments against ‘picture metaphor’
2. Propositional
knowledge.
Propositions are abstract
sentences describing
relationship between
entities. E.g. 'the cup is
on the saucer'.
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Arguments against ‘picture metaphor’
Pylyshyn maintained that pictures
are not sufficient to represent our
knowledge of the world. E.g.
we've concepts such as the word
“dog”, but there are an infinite
number of pictures that one could
generate for this concept or word.
But we need to be able to handle
concepts such as “dog”, without
having to think of a specific image
of a dog.
He uses the terms type vs. token to
represent this problem. The word
“dog” is a type, and the images
that could be generated would be
tokens.
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Arguments against ‘picture metaphor’
3. The need for a third code. Imagery researchers have
proposed that there are two types of codes: a visual and
a verbal. Pylyshyn proposed a third system that is
abstract and propositional. He argued this on the
grounds of economy. A single representational format
would be more parsimonious.
4. Introspective evidence. Even though people report
imagery, this does not justify using the concept in an
explanatory way.
5. Definitional problems. Imagery is poorly defined. Its
definitions vary across experiments. Thus it is difficult to
understand the common properties. It is important to
reduce the concept of imagery down to its important
elements.
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In defence of imagery
1. The picture metaphor
An analogy often made between visual image and notion of
picture in head. K & P respond that the act of perception
is not inspection of internal screen. Instead it is
analogous to processing of visual information. Images
and percepts have a common format. This format is a
different one from one involving verbal processes.
As far as Pylyshyn's argument about capacity limitations
are concerned, first, we do not know the capacity of
brain. Second, we do not have a good measure of
amount of information in image. Perhaps image
processed as chunk of information, leading to efficient
storage.
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In defence of imagery
1. The picture metaphor
Another criticism was to do with being able to retrieve
images. Imagery might be like the display on
computer screen. This is stored in a file that can be
retrieved by name. Searching is perhaps random, but
could be large parallel search done unconsciously.
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In defence of imagery
2. Propositional knowledge
Pylyshyn claimed that a propositional format is necessary
for representing knowledge. K & P agree that
knowledge may be represented this way, but images
may be another form of representation. For example,
compare two forms of representation for geographical
information. 1. A map. 2. A chart of intercity distances.
Both systems contain identical info but have different
properties. With map can decide, e.g., if three cities fall
on straight line, chart useful for computing total distance
to travel through three cities. Each has some advantage.
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In defence of imagery
3. Necessity of a third code. Pylyshyn suggested that the
need for a third code creates more problems. One has
to translate between images and propositions, and in
addition, between verbal codes and propositions. This is
more inefficient compared with translating directly
between images and verbal codes.
4. Introspections. Introspections provide additional
evidence: When one introspects about imagery, one
reports imagery experiences. These reports are not
adequate in themselves, but the fact that these
experiences are present is suggestive that they have
some role to play. A related point: Imagery theory can
account for experience of imagery. Propositional theory
cannot do this.
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In defence of imagery
5. Problems of definition. Pylyshyn complained of
fuzziness of concept. But problem of definition is
common one in psychology. K & P agree that definition
of imagery not properly formulated.
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Imagery: summary of the ground covered
Phenomena and findings:
1. mental rotation,
2. mental paper folding,
3. grain size, image scanning,
4. image scanning,
5. brain scanning evidence.
Arguments for and against the ‘picture metaphor’
1. The picture metaphor – storage and retrieval problems,
2. Propositional knowledge - “structural descriptions” and conceptual
knowledge,
3. A third code? Pylyshyn thinks it’s needed.
4. Introspective evidence.
5. Definition – imagery too fuzzy.
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Other states of consciousness
The unconscious
Dreaming
Meditation
Hypnosis
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States of consciousness
Consciousness is subject to change: being aware, reverie,
drug induced etc. Consciousness involves a subjective
assessment. Early psychologists equated with 'mind'
used introspection to study it. Behaviourism pushed it
out of favour: it said that Psychology should be about
public not private events.
Consciousness is about monitoring and controlling our
environment and ourselves.
1. Monitoring. There are too many things happening to
monitor everything. We tend to concentrate on changes.
We notice when a clock stops ticking. Survival is the top
priority: hunger and pain affect concentration.
2. Controlling. This involves planning, initiating and
guiding actions. Alternative scenarios viewed.
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The Subconsciousness
or the unconscious
We focus on limited amount of
information. Therefore, much
is ignored. However, we can
become alert: clock ticking,
hearing our name.
Our sense of balance is a good
example.
Lee & Aronson (1974): Moving
room experiment involves a
small room that can be
moved. (Its walls are on
rollers.) Stands on wooden
block. Looks at wall and falls
off. Wall has been moved
When we retrieve past
towards the participant,
memories these are called
affects balance. He or she is
'preconscious'.
unaware of movement. We
subconsciously monitor our
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balance.
The unconscious
According to Sigmund Freud and others some information
is not available to consciousness. Some memories are
emotionally painful and are 'repressed'. They can
emerge in disguised ways through dreams, mannerisms
and slips of the tongue.
These are 'Freudian slips', or unintentional remarks. E.g.
“I'm sad your better” instead of “glad”. Freud may be
right on the emotional side, but he ignored other areas
such as the large number of mental processes that
continually operate.
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Dreaming
About 90% sleep 6-9 hrs, most 8-9 hrs. Those who sleep
6-7 hrs are sleepy in the day. Patterns of sleeping
variable.
Usually after an hour EEG very active and electrodes
near eyes show rapid eye movements (REMs).
During REM our perceptual neurones are active. Almost
all report dreaming when woken during REM, but
when woken in NREMs (non-REM) dreams reported
only half the time.
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Dreaming
Sleepwalking in adults (somnambulism) is an REM
behaviour disorder occurring within a dream. During
REM our body normally releases a chemical that
makes us inactive, but this chemical is not released for
people with this disorder. Sleep walking occurs both
in REM and non-REM sleep, but most frequently
during the deep stage of non-REM sleep.
Sleepwalking usually occurs in the first third of night.
They just sit up. May leave room or house. If eyes
open, glassy.
15% of children have 1 or more episodes, but usually
stops by 15 yrs.
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Dreaming
REM dreams: visually vivid, bizarre. They occur for limited
periods usually about 4-5 times a night. Newborns
spend about half their sleep in REMs. NREM dreams:
not so visual nor so emotional. People who don't recall
dreams have as much REM as others. If one has a
distraction-free period when waking, more likely to be
able to recall. Can make notes of your dreams as soon
as you wake up.
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Dreaming
In 'implicit predream suggestions'
participants performed an experiment
wearing red goggles before sleep.
Many reported dreams tinted red.
In 'overt predream suggestion': Participants
asked to dream of personality trait they
wanted.
Most had dream with the intended trait
present.
'Posthypnotic predream suggestion' is
when detailed dream narratives were
given to high-responsive hypnotic
participant .
On post REM waking some of them had the
theme, without the specifics. Others had
specific elements.
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Meditation
Certain rituals and exercise can
produce meditation. These include
regulated breathing, restricted field
of attention, yogic body position and
mental images of an event or of a
symbol. Result: relaxed, divorced
from outside world, self-awareness
lost, feels involved in a wider
consciousness. Used in all major
religions: Buddhists, Hindus, Sufis,
Jew, & Christian.
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Meditation
Traditional meditation follows
practice of yoga, based on
Hindu religion, or Zen. 2
techniques: 1. 'Opening-up
meditation': the participant
clears his or her mind for
new experiences 2.
'Concentrative meditation'
involves actively attending to
one object, word or idea.
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Meditation
Opening-up meditation is very difficult. One
attempts to let go of mind and body. An
example of concentrative meditation:
concentrate on vase. Do not analyse
parts. Try to see the whole without
connecting to other things. Exclude other
thoughts, feelings, sounds and
sensations.
Effect of concentrative meditation: altered
more intense perception of vase and
some time shortening. There is a conflict.
It fills visual field and yet doesn't, less
distraction from external stimuli. The
state is pleasant and rewarding.
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Meditation
Transcendental meditation (TM) is a secularised form
promoted mainly in the USA. The novice is given a
'mantra' (special sound) and repeats it over and over to
produce deep rest and awareness.
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Meditation
Benson et al. (1977) suggest one
should sit comfortably in
comfortable position. Relax
muscles starting with feet. Breathe
through nose. Say “one” silently to
yourself each time breathe out. Do
20 mins. Open eyes to check time.
After sit few mins. Don't be
troubled by distracting thoughts.
Do once a day, but not within 2 hrs
of a meal. This produces reduced
state of arousal, peace of mind
and well being.
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Meditation
Nearly all studies report significant lowering of
respiratory rate, decrease in oxygen consumed,
less elimination of CO2. Heart rate lowers, blood
flow stabilises and concentration of lactate in
blood is decreased.
Experiments show that can get same state from
hypnosis, biofeedback or deep muscle relaxation.
Meditation used in sports psychology for reducing
stress before the event helps muscle relaxation.
Visualisation of future actions (e.g. a ski run) is
also v. useful.
Finally, one has to be careful of extravagant claims
of some. It has been argued that meditation no
more powerful than simply resting. But at least a
regular program does ensure that rest is taken
and not skipped.
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Hypnosis
Once associated with the bizarre and the
occult. It is a social interaction in which
suggestions (perceptual, memory,
actions) of one person are responded
to by another. The willing participant
relinquishes some control to hypnotist.
Variety of methods used. E.g.
concentrate on small target while
becoming more relaxed. Sleepiness
may be suggested. But only a
metaphor, participant told that will not
really go to sleep. One can induce
participant to be hyperalert. Thus
participant can be induced to be strong
and alert.
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Hypnosis
It is possible to hypnotise yourself. The following changes
are usual:
Planfulness ceases. In deep hypnosis participant doesn't like
to initiate activity. Prefers to wait for H.
Attention more selective than usual. If told to listen only to
hypnotist, will ignore other voices.
Enriched fantasy readily evoked.
Awareness of reality is reduced and reality distortion is
accepted. E.g. participant may converse with an imaginary
person - thus accepting an hallucinatory experience.
Suggestibility is increased. Participants have to accept
suggestions to be hypnotised, but suggestibility may be
increased under H.
Posthypnotic amnesia often present. If instructed, highly
responsive hypnotic participant will forget all or most of
session. When prearranged release signal given,
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memories are restored.
Hypnosis
About 5-10% can't be hypnotised even by skilled hypnotist.
The remainder has varying degrees of susceptibility. NB
tests of compliance don't correlate sig. with
responsiveness to hypnosis. A good predictor of
responsiveness: rich imagination and enjoys
daydreaming.
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Hypnosis
Hypnotic suggestions
Suggestions to hypnotised participant can affect motor
control, memories and perceptions:
Control of movement. E.g. Hands of participant placed
apart, hypnotist suggests they are attracted to each
other. Hands soon move together. participant feels that
not controlling this. In 'Posthypnotic response' the
participant has had hypnotic session. Participant then
feels compelled to do a particular behaviour on a
prearranged signal. E.g. opens window when hypnotist
removes glasses.
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Hypnosis: Posthypnotic Amnesia
'Posthypnotic amnesia':
Events can be 'forgotten'
at suggestion of
hypnotist, until a signal
to recall.
Cooper’s (1979) experiment
on 491 Ss:
1. Each hypnotised
participant did 10 actions
2. Given post-hypnotic
amnesia instructions to
forget.
3. Taken out of hypnosis.
4. Recalled the 10 actions
5. Signal to remember
(cancelling the
instructions to forget)
6. Second recall.
Results
At point 4: recalled range from 0-10 items.
This shows the distribution which was
bimodal. Peak of 10 forgotten items:
the hypnotic virtuosos. Another peak at
4 items representing the average.
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Hypnosis: Posthypnotic Amnesia and then age
regression
The second recall (Cooper continued)
This was after they’d been signalled that they were now to
ignore their hypnotic instructions to have amnesia.
Cooper found that the highly amnesic participants now
remembered just as much as the others.
Age regression: Some can relive episodes from earlier
life (e.g. 10th birthday). Memories can be vivid.
Sometimes a long forgotten childhood language can reemerge. USA-born boy with Japanese parents had
spoken Japanese at an early age, but had forgotten it.
He spoke it fluently again under hypnotist (Fromm,
1970).
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Hypnosis
Hallucinations: these are less common, especially the
most vivid forms.
'Positive hallucination': participant sees or hears
something not present.
'Negative hallucination': participant doesn't perceive
something normally perceived. Of course, most have
both components. For instance, to not 'see' someone in
a chair, one does not see person (negative), but must
also 'see' parts of chair masked by the person (positive).
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Hypnosis
Hallucinations can also be induced by posthypnotic
suggestion. E.g. participant thinks petting a rabbit.
Negative hallucinations can control pain. In many cases
hypnosis completely eliminates pain. Even a reduction in
pain is of course useful. Amount of pain reduction is
closely related to degree of measured hypnotisability.
Thus where chemical anaesthetics dangerous, hypnosis
can be useful for dentistry and surgery.
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Explanations of Hypnosis
Franz Anton Mesmer (1734-1815) claimed it was 'animal
magnetism'. Psychoanalytic theory suggests hypnosis is state
of 'partial regression'. Participant lacks control, so impulsive.
Causes regression to more infantile stage; hallucinations
indicate primitive mode of thought uncensored by higher
levels of control.
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Explanations of Hypnosis
Coe & Sarbin (1977) suggest that hypnotism is an
involuntary 'role enactment' to respond to social
demands. Doesn't imply participant play-acting to fool
the hypnotist. Participant becomes deeply involved in
role that actions done without conscious intent.
Another theory is that participant gets into dissociative state
so unaware of all that is occurring in consciousness. The
hypnotist can channel the direction of the participant’s
thinking.
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Other mental states: summary of the
ground covered
1. The unconscious – monitoring and controlling – the
moving room – Freudian slips.
2. Dreaming – REM and NREM – predream suggestion –
both hypnotic and implicit.
3. Meditation – ways to achieve – opening up and
concentrative – TM – biological effects.
4. Hypnosis - how it is induced. Changes: planfulness
ceases, greater selectivity, fantasy enrichment, reduced
reality, increased susceptibility and posthypnotic
amnesia - age regression – hallucinations – explanations
– Mesner: animal magnetism – role enactment –
dissociative state.
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