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Chapter 9

Chapter 9 part 2.docx

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Steve Joordens

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Psychology-chapter 9 part 2 CONSCIOUSNESS AND THE BRAIN: - Brain damage can alter human consciousness - Example: chapter 8 and the anterograde amnesia caused by brain damage to the hippocampus - Although people with this defect cannot form new verbal memories, they can learn tasks - However they remain unaware that they have learned something, even when their behaviour says they have - Brain damage does not prevent all kinds of learning but it does prevent conscious awareness of what has been learned - If human consciousness is related to speech, then it is probably related to the brain mechanisms that control comprehension and production of speech-suggests that for us to be aware of a piece of information, the information must be transmitted to neural circuits in the brain responsible for our communicative behaviour Isolation Aphasia: A Case of Global Unawareness: - Geshwind, Quadfasey, Segarra: case of a women who had suffered severe brain damage from inhaling carbon monoxide - Damage destroyed large areas of visual association cortex and isolated the speech mechanisms from other parts of the brain - Syndrome known as Isolation aphasia-a language disturbance that includes an inability to comprehend speech or to produce meaningful speech, but also an ability to repeat and to learn sew sequences of words - Womens speech mechanisms received auditory input and could control the muscles used for speech, received no information from other senses or from neural circuits that contain memories and meaning of words - Made few movements with her eyes, able to follow moving objects, could not recognize objects or people, didnt answer any questions or any sign that she understood what other people ment, she was not conscious of anything that was going on - However she could repeat words that were spoken to her, and if someone started a poem she knew she would finish it - therefore: her case suggests that consciousness is not simple activity of the brains speech mechanisms; it is activity promoted by information received from other parts of the brain concerning memories or events presently occurring in the environment Visual Agnosia: Lack of Awareness of Visual Perceptions: - People have become unaware of particular kinds of information - Example: blindsight, people with particular kind of brain damage can point to objects they cannot see-that they are not aware of seeing - Visual agnosia-the inability to recognize the identity of an object visually - Look on page 278 for example about the man with visual agnosia-he was not blind could walk around without bumping into things, could pick up objects=his disease damaged the neural circuits responsible for visual perception - However not correct: he made hand movements that were related to the object he could not identify=his visual system worked wee enough to initiate appropriate non-verbal behaviours, though not the appropriate words, once he felt what he was doing he could name the object(process shown in figure 9.11 pg 279) - Although the patient had lost ability to read, speech therapists were able to tach him to use finger spelling to read - Could not say what letter was but could make hand movements when saw it(finger-spelling) - Case supports the conclusion that consciousness is synonymous with a persons ability to talk about his or her perceptions or memories - Disruption of the normal interchange between the visual perceptual system and the verbal system prevented the patient from being directly aware of his own visual perceptions, instead it was as if his hands talked to him, telling him what he had just seen The Split-Brain Syndrome: - Surgical procedure demonstrates how various functions can be disconnected from each other and from verbal mechanisms - Used for people who have sever epilepsy that cannot be controlled by drugs - In these people violent storms of neural activity begin in one hemisphere and are transmitted to the other by the corpus callosum (large bundle of axons that connects parts of cortex on one side of brain with those on other) - Both sides of brain then engage in wild neural firing and stimulate each other, causing seizure - The split-brain operation-a surgical procedure that sever the corpus callosum, thus abolishing the direct connections between the cortex of the two hemispheres - After the two hemispheres are disconnected, they operate independently; their sensory mechanisms, memories and motor systems can no longer exchange information - Effect not obvious to observe as only one hemisphere(left) controls speech - Right hemisphere of an epileptic person with split brain can understand speech, but is poor at reading and spelling - Since Brocas speech area is located in left hemisphere, right hemisphere incapable of producing speech - After operation: patients find that there left hand seems to have a mind of its own, making surprise gestures with left hand - Because the right hemisphere controls the movements of the left hand, these unexpected movements puzzle the left hemisphere, the side of the brain that controls speech - Once exception is the olfactory systemwhen person sniffs a flower through left nostril only left brain receives a sensation of the odour, thus if the right nostril of a patient with a split brain is closed and the left nostril is open the patient will identify odours verbally. If odour enters right nostril patient will say that she smells nothing - But in fact the right brain has perceived the odour and can identify it (example in text page 281-282 figure 9.14) - Sometimes, hands create conflict and attempt to do different things - Example: a man with a split brain attempted to beat his wife with one hand and protect her with the other - The right hemisphere excels at tasks of perception and has a much greater artistic ability, if a patient with a split brain tries to use his or her right hand to arrange blocks to duplicate a design, the hand will fumble around with the blocks - Often left hand(controlled by right hemisphere) will brush the right hand aside and easily complete task - Effect of cutting the corpus callosum reinforce the conclusion that consciousness depends on the ability of speech mechanisms in the left hemisphere to receive information from other regions of the brain. If such communication is interrupted, then some kinds of information can never reach consciousness HYPNOSIS: - Hypnosis is a specific and unusual form of verbal control that enables on person to control another persons behaviour, thought, and perceptions - Under hypnosis, a person can be induced to bark like a dog - Hypnosis is important to psychology because it provides insights about the nature of consciousness and has applications in the fields of medicine and psychotherapy - Franz Anton Mesmer discovered modern hypnosis(or mesmerism)-he found that when he passed magnets back and forth over peoples bodies (attempt to restore their magnetic fluxes and cure them of disease), they would often have convulsions and enter a trancelike state during which most cures could be achieved - Later discovered that the patiesnt where not affected directly by the magnetism of the iron rods, they were responding to his undoubtedly persuasive and compelling personality Characteristics of Hypnosis: - Person undergoing hypnosis can be alert, relaxed, tense, lying quietly or exercising - No need to move an object in front of someone- Hypnotized people are very suggestible; their behaviour will conform to what the hypnotist suggests - Hypnotic suggestions are one of the three types: - 1. Ideomotor suggestions-those in which the hypnotist suggests that a particular action will occur without awareness of voluntary action, such as raising an arm - 2. Challenge suggestions- suggestions that the hypnotized individual will be unable to perform a normally voluntary action - 3. Cognitive suggestions-suggestions that the hypnotized person is undergoing distortions of sensory or cognitive experiences, such as not feeling pain or not being able to remember something - Most dramatic phenomena of hypnosis is post-hypnotic suggestibility- a person is given instructions under hypnosis and follows those instructions after returning to a non-hypnotized state - Post-hypnotic amnesia- a failure to remember what occurred during hypnosis, induced by suggestions made during hypnosis - Studies indicate that when changes in perception are induced through cognitive suggestions, the changes occur not in peoples actual perceptions but in their verbal reports about their perceptions - Example: Miller, Hennessy, Leibowitz used the PONZO ILLUSION to test the effects of hypnotically induced blindness. (see figure 9.15 and example in text page 283) - Results indicate that the visual system continues to process sensory information during hypnotically induced blindness, otherwise the participants would have perceived the lines as equal in length - Reported blindness occurs not because of altered activity in visual system but because of the altered activity in the verbal system (and in consciousness) Theories of Hypnosis: - Hypnos
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