PS1012 & PS1014 Approaches to Psychology: John Beech

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PS1012 & PS1014 Approaches to Psychology: John Beech

The Biological Approach to Psychology

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The Biological Approach

1. General introduction

2. The history of the biological approach

3. Different aspects of consciousness:(a) A case study(b) Blindsight(c) Split-brain experiments(d) Animal consciousness

4. The mind-body problem and Greenfield’s solution(a) The properties of consciousness(b) Can we find these properties in the brain?(c) States of consciousness

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1. Introduction to the Biological Approach

This approach views humans as a biological organism.

Thought processes are based ultimately on changes within our own physical selves, our biological structures.

The main concerns of this approach are:

(1) the relationship between mind and body

(2) the influence of heredity on behaviour and to a lesser extent

(3) the effects of the mind on the body.

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2. The history of the Biological Approach

Concentrating on the first of these: the relationships between mind and body

More specifically, we are going to examine the different faces of consciousness in relation to its biological basis. But first, some history…

Today’s biological approach is: we have a brain that determines our behaviour. The 17th century view was the Christian view: the body was controlled by the soul or spirit.

Rene Descartes: Human body was similar in construction to any animal. Animals and humans operated like machines. But

human beings had souls.

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2. The history of the Biological Approach This soul interacted with the pineal gland. Known as dualism. Body and mind (or soul)

are separate, but they interact. l’âme can mean “mind” or “soul”. This view prevailed 200 years after this.

Gradual shift of biologists away from dualism to monism: the mind and the body are the one thing. Very close to that is materialism: all behaviour has a physiological basis.

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2. The history of the Biological Approach

One problem with dualism is if the mind is abstract and non-physical, how can it exert control over something physical like the body?

But monism, like dualism, is still an assumption. Materialism, which is basic to the biological approach, is becoming more influential in psychology.

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2. The history of the Biological Approach Julien de La Mettrie (1745): the

body is a machine and the mind is part of the body. He’d had a fever and noticed that it had physical and mental effects. This led to his materialist assertions. Very controversial.

Cabanis argued that the victims of the guillotine were not conscious after being beheaded as their consciousness was within the brain.

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2. The history of the Biological Approach Paul Broca (1861) examined a man unable

to talk coherently because of head injury. When he died Broca showed by post-mortem that specific area in the brain damaged. This was proof of “localisation of function”.

Role of hereditary - important aspect of developments in biology. Shows how our characteristics are transferred from one generation to the next. In the 18th century it was believed that as described in the Bible, all species had been created independently.

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2. The history of the Biological Approach Linnaeus (1735) catalogued 4,000

plant and animal species and proposed connections among species.

Charles Darwin (1859) “On the Origin of the Species”

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2. The history of the Biological Approach: Darwin

By chance there would be variations across individuals and they could be passed on genetically.

“Natural selection” proposed that if a particular alteration in a gene helped people to live and breed, then the gene was passed on.

Darwin was not only referring to what is inherited across humans, but the evolutionary links between humans and other animal species. Led to a row with the church.

Eventually Darwin’s view of evolution became dominant.

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2. The history of the Biological Approach : Conclusion The concepts of materialism and

heredity are the basis of the biological approach to psychology.

Materialism is saying that the mind has a basis in terms of the physiology of the body.

Heredity is asserting that aspects of behaviour are inherited from ones parents.

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2. The history of the Biological Approach: Conclusion

In contrast to other approaches to psychology, biology is saying that it is very important not to speculate about the mechanisms inside the black box. Instead we need to examine within.

The internal structure of the body (and especially the brain) needs to be taken into account.

An early example: if a specific area of the brain were destroyed it would severely damage speech

Similarly, Darwin tried to demonstrate that aspects of our behaviour are partly due to inheritance.

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3. Different aspects of consciousness

Not all areas of the brain involve consciousness; e.g. the cerebellum controls balance and reflexes and is automatic.

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3. Different aspects of consciousness

We can be unconscious of events (e.g. Goldiamond, 1965). He gave electric shock to S reading aloud until he stuttered. Produced stuttering. Still in same paradigm, 2 days later he was only shocked twice. But he was unaware why stuttering had been induced.Areas of the brain proposed for the seat of consciousness in the past have included: the hippocampus (O'Keefe, 1985); activity from the upper brain stem (Penfield, 1940s and 1950s) and the cerebral cortex (large number of investigators).

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3. Different aspects of consciousness: (a) a case studySome neurological

evidence to consider:

(a) Case study: trapped in the 60s

Oliver Sacks (1995) studied Greg in the 1990s.

Treatment for a tumour was delayed. Greg’s pituitary (shown later) and optic chiasma were destroyed.

There was damage to frontal and temporal lobes leaving him blind and mentally damaged. He sat motionless and silent, but if asked something responded immediately. He also had 'blindness denial'. He ‘watched’ TV, by just listening to the sound track and inventing images. They’d tried to teach him Braille, but were unsuccessful.

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3. Different aspects of consciousness: (a) a case study

Greg believed that he was in the 1960s. Hippocampal damage led to a gradient of damage to long-term memory. He was unable to remember information for very long. If ‘shown’ an object he would guess its identity. He seemed to have no sense of time, especially as he had no recent experiences to draw upon. This meant that the present was just flat.

In the MRI above TP is the “temporal pole” – the front of the temporal lobe. In the inner surface of the temporal lobe is the hippocampus outlined in white and marked HIP. AMG is the amygdala.

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3. Different aspects of consciousness: (a) a case study He had an implicit,

or unconscious memory. Learned spatial layout of the hospital and learned about the personalities of the staff.

The pituitary damage reduced his hormonal aggressiveness. Previously he'd been aggressive with his father. The diencephalon controls drives (e.g. food, sex).

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3. Different aspects of consciousness: (a) a case study If no stimulation, he went into a

daze. Sachs suggests that this state was devoid of normal thought or emotion. Taken out of this state, his behaviour was animated, perhaps inappropriate. This could be connected with frontal lobe damage.

These areas involve making judgements and planning. This changed his voice and manner. He had the 'joking disease'. The frontal lobes more developed in humans than primates. They do not stop until age of 7. They could be important for consciousness.

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3. Different aspects of consciousness: a case study: Greg and some aspects

Normal memory

STM LTM Vocabulary expands in LTM. It helps us to

socialise. It’s part of personality.

The visual systemPerception ImaginationThese two systems are not normally

confused.

EmotionsOur emotions are part of our personality. If we have

no emotion, are we human?STM LTM

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3. Different aspects of consciousness: (b) blind sight

Due to damage to part of visual cortex (or occipital lobe). Retina still picking up information. But will not be 'seen'. If moved to other parts of visual field not damaged, then will be seen.

DB had part of visual cortex removed, seen by Weiskrantz (1987). He placed stimulus in DB’s blind field and asked him to guess what it was.

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3. Different aspects of consciousness: (b) blind sight

DB had 100% accuracy, even though he said that he could not see it. However, the lower temporal lobe is also processing information from the retina.

After training DB developed awareness of items in his blind field.

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3. Different aspects of consciousness (c) split-brain

Corpus callosum completely severed so left and right cerebral hemispheres can no longer communicate with each other.

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3. Different aspects of consciousness: (c) split-brain

Sperry (1966) and others studying split-brain patients have demonstrated that the right hemisphere can perform spatial thought, musical perception, understand simple nouns and do simple arithmetic. The left hemisphere generally is able to control the output of speech.

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3. Different aspects of consciousness: split-brain

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3. Different aspects of consciousness: (c) split-brain Wilson et al. (1977) examined PS. After

operation only left could speak, but later the right learned to speak as well! Appeared that both sides conscious and independent and even had different preferences. Possibly other right hemispheres are conscious as well in other split-brain patients.

Perhaps those of us learning to type, play the piano, or do some task involving the two hands, and hence the left and right hemispheres, have also experienced how our different hemisphere learn to handle new information.

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3. Different aspects of consciousness: (d) animals Some say that animals cannot verbalise,

therefore they have no consciousness. But verbalisation is clearly not the only route.

We can think spatially, visually, musically and imagine in smell and taste and so on.

Some have said that that right hemisphere has the same level of consciousness of a chimpanzee, due to being unable to verbalise.

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3. Different aspects of consciousness: (d) animals

Chimpanzees and gorillas are able to sign. But this is dismissed by some.

Dogs appear to dream. Dolphins have a large complex cortex

and send complex sounds to each other.

An octopus appears to be quite sophisticated.

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3. Different aspects of consciousness: (d) animals

We can go down the phylogenic scale to the level of insects. The behaviour of the digger wasp appears to be mentalistic.

But a simple experiment shows a great reluctance to adapt to a new situation. Experimenter removes prey while wasp inspects cavity. Each time it searches and brings it back to hole. Eventually it realises that it should not let go and instead should simply put the prey straight into the hole. But it can take 30 to 40 trials to learn this simple change.

Thus animals can appear to be irrational as we move down the scale. There can be a strong element of mechanistic behaviour rather than mentalistic behaviour.

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4. The mind-body problem and Greenfield’s solution (a) The properties of consciousness

We’ve examined the background to the consciousness problem. There appear to be different levels of consciousness within humans and in animals. This consciousness can appear in many areas of functioning, such as in vision and language.

There have been many scientific findings that can be publicly examined; but the relationship of consciousness with the brain is different. See Gross for supplementary discussion of the mind-body problem. We will examine the detailed arguments of Susan Greenfield (1995):

(a) The properties of consiousness(b) Can we find these properties in the brain?(c) States of consciousness

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She asks: what are the relevant aspects of the brain? First, there is localisation of function and there is

parallel processing. Brain mapping, for instance, shows that verbs processed in one part of the brain, but other parts of speech elsewhere. Thus language is not a unitary function, different parts have different functions.

Thus no one area generates consciousness. But consciousness seems to be a unitary experience. What are the properties of consciousness?

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The source of consciousness is probably distributed in the brain, but our experience is of a unitary phenomenon.

It is continuously variable. Like dimmer switch. This provides a view of human development and animal consciousness. Also individuals fluctuate in their level of consciousness. Sometimes acutely aware of the world, other times one is aware of an inner world.

Consciousness derives from specific stimulus. Analogy of fish jumping around in pond. An epicentre sets a trend of consciousness.

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Summary: ‘Consciousness is spatially distributed but effectively single at any one time’. It emerges because of the continuous activity of groups of neurones in relation to an epicentre. This is analogous to an orchestra, in that the symphony is only created when the instruments are in unison.

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4. The mind-body problem and Greenfield’s solution(b) Can we find these properties in the brain?

There are millions of neurones in the brain (32 million years to count at rate of 1/sec).

Neuronal density increases as we develop. Neurones also develop according to the stimulation that they have had.

The epicentre would be an inner centre of neurones. Activation is through one of the neurotransmitters such as acetylcholine (ACh).

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4. The mind-body problem and Greenfield’s solution(b) Are these properties in the brain?

Libet et al. (1979) placed electrodes on points in the somatosensory cortex (- deals with touch receptors such as heat, pressure, vibration, limb position, movement, pain). Felt like being touched. Had to be more than ½ sec. Again, if presented stimulus to skin, took ½ sec before aware. But brain would have received this much faster. Participants claimed that immediately aware, despite the long delay.

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4. The mind-body problem and Greenfield’s solution (b) Can we find these properties in the brain?

Libet et al. (1979)Touch Electric Result Stimuln. Touch not felt.

0 500msec

Touch Electric Result Stimuln. Touch felt.

0 500msec

Libet et al worked out location in the somatosensory cortex corresponding to a point of sensation on the skin.

Then Libet et al. touched skin here AND electrically stimulated somatosensory cortex.

When interval between being touched and then being electrically stimulated was less than ½ sec, then touching not felt. Touching had been masked by electrical stimulation. Thus conscious experience is occurring ½ sec after the event. It takes some time to get events working from the epicentre before it is finally perceived.

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4. The mind-body problem & Greenfield’s solution (b) Are these properties in the brain?

Arousal may be a factor. When arousal low, few connections begin. The Yerkes-Dodson law: an optimum level of arousal will result in the best level of performance, Acetylcholine (ACh) could be the producer of low arousal, whereas dopamine and noradrenaline (DA/NA) would be high activators.

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4. The mind-body problem and Greenfield’s solution(c) States of consciousness

Greenfield proposes 4 different types of consciousness: dreaming, distracted, thinking and being bored. 'Distracted' means like being a child reacting constantly to its environment. Thinking would be engrossing and bored would be when waiting and having little to do. Let us look at just two of these states:

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4. The mind-body problem and Greenfield’s solution (c) States of consciousness

Dreaming: this involves rapid eye-movements (REMs) and is a form of consciousness. Brain patterns of wakefulness and dreaming similar. But logic is poor during REM. Consciousness is too frail.

Commonality between dreaming and schitzophrenia. During dreaming ACh is low and strength of epicentre is low. Means that only small neuronal assembly activated.

REM sleep of foetus is 24 hours a day at one point, but REM declines throughout the life span.

Penfield: stimulating same place twice got different responses. He was creating different epicentres according to the arousal level current at the time. Sometimes he got the same response stimulating different areas.

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The distracted state of consciousness: Here there is high arousal with high rates of dopamine and noradrenaline (DA/NA). Strength of the epicentre is high but the neuronal assembly is small. This activation of a small network soon dies away.

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4. The mind-body problem and Greenfield’s solution (c) States of consciousness Greenfield would group together dreaming,

schizophrenia and childhood as they all involve only a small activation of neural assemblies.

The experience of an accident could be a case of time standing still and over-arousal (Yerkes-Dodson), so recruitment is again modest.

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Going to a 'rave' with the drug ecstasy may also lead to low recruitment. Here there is a preference for music with minimal cognitive involvement.

She concludes: consciousness will never be explained by neuroscience, but should come close to describing it. In the future networks need to be studied in real time.

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The biological approach: in a nutshell

1. General introduction2. The history of the biological approach3. Different aspects of consciousness:

(a) A case study(b) Blindsight(c) Split-brain experiments(d) Animal consciousness

4. The mind-body problem and Greenfield’s solution(a) The properties of consciousness(b) Can we find these properties in

the brain?(c) States of consciousness

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(1) The biological approach views humans as biological organisms. Our thought processes come from our own biological structures.

(2) Gradual shift from the dualist, Christian view that the body and soul are distinct entities that interact with one another. This was replaced by the modern concept of materialism in which the basis of all behaviour is its underlying physiology.

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(3) The case of Greg is interesting as a description of a degraded form of consciousness based on neurological damage. For instance, his consciousness was entirely within the time era of the 1960s with no new information coming in. Also, he was unaware of his own blindness. Furthermore, he appeared to be lacking in emotions.

(4) Blindsight: patients reported not being able to see an object, but on the other hand they “knew” the identity of the object. We generally associate the visual cortex with the consciousness of an object, but there are other areas that also function in this way, such as the lower temporal lobe. Patients need training to develop awareness in such an area.

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(5) Split-brain patients are patients who have separately functioning cerebral hemispheres without the benefit of the connecting tissues of the corpus collosum. Can lead to the development of two independently operating systems, each with a separate consciousness. Generally only one has developed speech, but in one case (Wilson et al, 1977) it appears that both hemispheres have speech.

(6) Animal consciousness: Can we infer that because animals can’t verbalise that they do not have consciousness? Nowadays animal psychologists use mentalistic models to account for animal behaviour. However, at the other end of the phylogenic scale, for instance at the level of the insect, behaviour is mechanical in origin.

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(7) Greenfield’s theory of consciousness: Consciousness is probably spatially distributed across different parts of the brain during different types of operation ranging from language to music.

Consciousness is probably continuously variable, for instance, as we have grown from the foetal stage, our degree of consciousness has probably increased.

In other species the degree of consciousness is different, but nevertheless at some level.

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Greenfield has described a neurological model of consciousness. E.g. a stimulus immediately evokes a small epicentre of neurons. Subsequent activation will be influenced by the presence of neurotransmitters.

If there is an optimum level of arousal then the activation across the network of neurons in all directions will be corresponding greater, and the number of neurons involved will be greater.

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Different states of consciousness such as thinking versus dreaming can be accounted for according to variations in such things as the type of neurotransmitter that is dominant, the arousal of the network and the density of the neural structure.

This neurological model helps us understand the interplay between the mind and the brain.

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PS1012 & PS1014 Approaches to Psychology: John Beech