1 ps1000: imagery and consciousness visual imagery dr. john beech school of psychology

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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

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.

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?

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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 metaphorPylyshyn 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 knowledgePylyshyn 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 towards the participant, affects balance. He or she is unaware of movement. We subconsciously monitor our balance.

When we retrieve past memories these are called 'preconscious'.

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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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DreamingIn '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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MeditationCertain 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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MeditationBenson 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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MeditationNearly 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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HypnosisIt 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, memories are restored.

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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 actions5. 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 re-emerge. 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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HypnosisHallucinations: 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.