The biological approach
The biological approach sees behaviour as based within the physiology of the body, with genes, evolution, brain structures and biochemistry being the main influences. The chromosomes inherited from our parents form our genotype (our basic genetic make-up) and this interacts with environmental factors to form our phenotype (our actual behaviour and characteristics shown). The gradual process of behavioural change that occurs due to the evolutionary process of natural selection is genetically transmitted and so is also included within the biological approach.
Brain structures are also seen as important in determining and monitoring behaviour, with different brain areas associated with different types of behavioural functioning. Specific biological structures within the body connect together to determine behaviour, such as the 2 parts of the nervous system, the central nervous system (CNS) (consisting of the brain and spinal cord), which transmits information to and from the environment, and the peripheral nervous system (PNS) (the accompanying system running throughout the body that acts with the CNS), which transmits information concerning the limbs and torso. Neurons are the individual nerve cells that transmit information within the nervous system, with each individual possessing billions of them.
The biochemistry of the body consists of chemical messengers within the body. Hormones are chemical messengers that travel in blood and other bodily fluids, while neurotransmitters are chemicals that travel within the brain in cerebral fluid.
Fig 5.4 Research with identical twins is useful for investigating the basis of certain behaviours
Grootheest et al. (2005) investigated the extent to which obsessive—compulsive disorder (OCD) is an inherited condition. A meta-analysis of 28 twin studies, ranging from 1929 to the modern era (though the vast majority were carried out since 1965 under modern diagnostic criteria), was conducted. It comprised 10,034 twin pairs. It was found that OCD seemed to have a genetic component ranging from 45 to 65 per cent in children and from 27 to 47 per cent in adults. This strongly suggests that OCD has a genetic basis, especially childhood forms of the disorder. The use of twin studies demonstrates how biology, in this instance in the form of genetics, can have a dominant influence on behaviour.
• Kessler et al. (2003) used PET and MRI scans to find that people with schizophrenia had elevated levels of the neurotransmitter dopamine in the basal forebrain and substantia nigra/ventral tegemental brain areas, which illustrates how biochemistry can affect behaviour, on this occasion in the form of a mental disorder.
• Dudley et al. (2008) found that ants in salt-poor environments preferred salty solutions to sweet ones, which suggests that this is an adaptive response to maintain evolutionary fitness (salt being essential to survival). This was supported by carnivorous ants not showing the salt preference, as they get ample salt from their prey, and therefore showed how evolution can shape behaviour.
• Siegel & Victoroff (2009) found that defensive and predatory forms of aggression appear to be controlled by the limbic system in the brain, with the cerebral cortex brain area playing an important role in moderating levels of aggression. This illustrates how brain areas are related to specific forms of behaviour in line with the biological approach.
The biological approach uses scientific methods of investigation that incorporate measures which are mainly objective (not a researcher’s personal opinions). Examples include brain scanning, like MRI and PET scans, and measurements of biochemistry, like dopamine levels.
It is possible to combine the biological and cognitive approaches together, as in cognitive neuroscience, to give a fuller understanding of human behaviour. Cognitive neuroscience uses biological techniques, like brain scanning, to try and identify in which particular brain areas specific mental processes are located and managed.
The biological approach is supported by a wealth of research evidence that suggests much human behaviour has large biological elements.
Critics argue that explanations based on the biological approach are too simplistic and do not acknowledge the complexity of a lot of human behaviour. This means that such explanations are reductionist (explaining a complex phenomenon in terms of its basic parts) in nature, often failing to appreciate the important role of environment in determining behaviour. Social factors, like childhood experiences and the influence of family and friends, are ignored.
The biological approach is better at explaining behaviours which are mainly biologically determined, like Alzheimer’s disease, than those which are not so biologically determined, like emotional experiences.
Biological therapies often treat the effects of, rather than the causes of, mental disorders. This lowers support for the argument that such disorders are biologically determined.
The biological approach has led to many effective treatments for mental disorders, such as drug treatments for depression and schizophrenia, which are by far the most common treatments. There is also electroconvulsive therapy (ECT), which is used to treat severe cases of depression and treatment-resistant schizophrenia.