The main assumption of the physiological approach is that behaviour and experiences can be explained by physiological changes. This approach investigates the brain, the nervous system and other biological factors such as hormones.
What is it?
Physiological psychology focuses on the relationship between our biological makeup and our behaviour and experiences.
This area of psychology can be very convincing. For example we do know that the structure of our nervous system (including our brains) and the action of chemicals can have an effect on our behaviour. However, an important question is how much does our biology affect us?
Some physiological psychologists take a reductionist argument to answer the above question. That is, they argue that behaviour and experiences can be explained in terms of brain structure and chemicals. This reductionist argument has lead to such psychologists making great discoveries, for example, in the affect of drugs on mood and behaviour.
However, other psychologists (including many physiological psychologists) take the view that we cannot explain complex human behaviour and experience just in terms of brain structure and chemicals. There are other psychological variables which need to be considered, for example, such as how we act alone compared to how we behave in groups.
A main strength of the physiological approach is the use of sophisticated equipment such as MRI scanners which provide an objective and precise way of measuring brain structure. For example in the Maguire et al. study the researchers were able to scan living brains using MRI technology which enabled the researchers to gain lots of quantitative and objective data about the density of the grey matter of the hippocampus. Furthermore the physiological approach takes a scientific approach using laboratory type experiments. For example in the Dement and Kleitman study of sleep and dreaming the participants were studied under tightly controlled conditions.
A further strength of the physiological approach is the practical applications that it offers. Much of the research in this area is very useful as it may be used to diagnose and develop treatments and therapies for illnesses or problems. For example, Maguire et al. suggested that their study has implications for those who have suffered brain injury or disease because they demonstrate the plasticity of the brain, and Dement in later studies has demonstrated the importance of sleep in relation to mental health. However, the main applications of the physiological approach have been the development of anti-depressant drugs which are more controversial partly because of the side effects that may occur. Furthermore, the idea that changing a chemical in the brain will bring about changes in complex emotions is a reductionist one as depression probably involves other life events.
A problem with the physiological approach is that by using such a scientific approach and testing behaviour in laboratory conditions the measurement of behaviour often lacks validity. For example, Dement and Kleitman measured sleep in laboratory conditions which is not typical of how people normally sleep. Therefore asking people to sleep with electrodes attached to their scalp and face is low in ecological validity. Similarly Sperry's participants were asked to complete unusual tasks which again are not typical of everyday behaviours. However the use of this laboratory approach does mean that the researchers have more control of their procedures ensuring that extraneous variables can be controlled
A further problem with the physiological approach is that because such studies can be costly and time consuming because of the use of sophisticated equipment and lengthy procedures. This often leads to such studies having small samples such as the Dement and Kleitman study which only studied 5 participants in depth. It is possible to argue that such a sample is not representative and therefore we should be careful generalising the results. Furthermore, Sperry was only able to 11 participants because he had a very limited number of participants to choose from, that is participants who had undergone disconnection of the cerebral hemispheres. However the increasing availability of MRI scanners is enabling researchers such as Maguire to increase their sample sizes and in subsequent studies Maguire et al. have been able to scan the brains of many more participants enabling the researchers to have a large database of many more brain scans to choose from.