Cosmides 

Evolution. The theory of evolution is an explanatory framework for the diversity and form of organisms in the natural world. Darwin developed the theory in the nineteenth century. He argued that the many species observed by naturalists could have all diverged from a common ancestor by the gradual accumulation of small hereditary differences, each of which increased the bearer's chances of survival and reproduction in their immediate environment. This was in sharp distinction to the traditional orthodoxy, which held the each species had been separately created, perfect and immutable, by God. Darwin's theory, as he formulated it, was incomplete, as he had no grasp of how variations were passed from one generation to the next. \nThe synthesis of Darwin's hypotheses with the new and independently discovered science of genetics did not happen until the twentieth century, but once done it established Darwinian evolution as the foundation stone of biology. It is often alleged that evolution is just a theory, since it can never be directly observed, but this is not in fact the case. Most bacteria today show resistance to one or more types of anti-biotic drug. This is because they have evolved under our very eyes since anti-biotics were invented some fifty years ago. When a new anti-biotic is introduced in a particular area, the subsequent changes in the genetic makeup of the local bacteria populations give us an insight into evolution in action. The debate in biology today about evolution largely concerns how much of the development of organisms can be explained by adaptation to the environment, and how much of it arises as a byproduct of other factors. This debate is particularly difficult to resolve when it comes to the application of evolutionary analysis to the behaviour of contemporary humans. 

Field research can take a wide variety of forms, but its essential characteristic is that it takes place in peoples' everyday social environments, as opposed to the artificial settings of a psychological laboratory (it is therefore seen as higher in 'ecological validity'). It can take the form of either observations (i.e. with no intervention by the researcher) or experiments (involving an intervention of some kind). Although cognitive psychologists have placed an increasing emphasis on doing research based on 'everyday life', i.e. in the field, field research is particularly valuable for social psychology. Although laboratory research can allow careful control of participants and the experimental setting, the special 'social context' of the laboratory itself can make it difficult to reliably generalize the results to human social behaviour in general. Field research can be qualitative or quantitative, or involve some combination of the two. 

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\nOne 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). \nResearchers 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.