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Neuroscience. Neurological scanning (e.g. MRI, PET) Techniques used involve neurological scanning of different parts of the brain (using complex and expensive apparatus with techniques such as Magnetic Resonance Imaging or MRI, and Positron Emission Tomography or PET). Such scanning can, for example, show which parts of the brain are active when different cognitive or emotional activity is happening. They have allowed psychologists to map the brain activity that occurs in different everyday activities.\nAnother technique measures the small electrical signals produced by the brain, using an electroencephalograph, or EEG. Different frequency ranges of signals are recorded separately, as Alpha Waves, Beta waves, Delta waves etc. Researchers have studied correlations between different brain wave activity (e.g. relative proportion of Alpha and Beta waves) with different psychological states, such as dreaming, non-dream sleep, normal waking activity, day-dreaming etc. Interesting correlations were found with things like rapid eye movement periods in dreaming (REM) and high levels of brain wave activity. Operations and case studies of brain damaged patients

One way of studying how different parts of the brain may be affecting human experience is to study the behavioural and experiential consequences of alterations to the normal brain set-up. Obviously, this cannot ethically be done as a deliberate experiment on humans (though it is sometimes carried out on animals – see section on animal research, and associated ethical issues). However, psychologists can study the resulting effects when this occurs in humans because of brain-damage (either present from birth, or due to injury), or surgical intervention. An example of the latter is the operation to sever the corpus callosum, which connects the two hemispheres of the brain (this is sometimes carried out to help very severe cases of epilepsy, for example).

Researchers such as Sperry have used special equipment in the laboratory to present different tasks to the two brain hemispheres. These studies gave considerable insight into how cognitive functions such as touch and vision appear to be processed by the different hemispheres. For example, visual stimuli presented so as to be processed by the left hemisphere of the patient could be described easily. However, when presented to the right hemisphere, they could not be described, or even properly recognised in conceptual terms, although they affected the emotions. This shows how language is a left-hemisphere function (for right-handers), and is a good example of the kind of research done with this methodology.