psychological assumptions

One of the assumptions of the Cognitive Approach is that internal mental processing should be studied. This is different to the Behaviourist Approach as they believe in behaviour that is observable but cognitive psychologists study the mind internally.
Another assumption of the Cognitive Approach is that the human mind should be compared to a computer to see how it works. Cognitive psychologists believe humans input information (senses), process it (memory, perception etc.) and output it (behaviour) like computers do.
An assumption of the behaviourist approach is that behaviour is affected by operant conditioning or learning by consequence. This means that if a person engages in a particular behaviour and is then rewarded (positively reinforced) in some way (the consequence is a good one or a pleasant one) then it is likely it will be repeated. Continuing to positively reinforce it will make it more permanent and it becomes learned. Punishment or negative reinforcement is likely to make behaviour less likely to be repeated and so it will not be continued. There are many examples of this in real life. For example giving house points or stars or sweets to a pupil who completes their homework means they will be more likely to complete their homework because they are being rewarded for doing it.
The second assumption of the behaviourist approach is based on classical conditioning. Pavlov, a Russian physiologist, found that dogs would develop associations with the sound of a food bowl (neutral stimulus) and their food (unconditional stimulus) and start to salivate. With repeated pairings the neutral stimulus would become a conditioned stimulus and the salivation became a conditioned response. Humans too develop associations such as responding to a door bell (NS) they get up to answer the door (US) then open the door to greet the person on the other side (CR).
The first assumption of the biological approach is that all behaviour has a physical biological cause. We can learn more about the causes of behaviour by looking into the structure of the brain.
Different areas of the brain have been linked to different functions- for example, the frontal lobe is linked to planning and thinking, the occipital lobe is linked to processing information, Abnormalities in the structure of the brain are a key cause of abnormal behaviour; abnormalities with the frontal lobe have been linked to a range of disorders such as anxiety and schizophrenia.
The second biological assumption is behaviour can be explained in terms of hormones. The endocrine glands secrete hormones into the blood stream which in turn affects behaviour. There are many endocrine glands throughout the body which are regulated by the pituitary gland (this is controlled by the hypothalamus in the brain)
The hormone testosterone influences the development of male physical characteristics and is linked to aggressive behaviour. The hormone adrenaline is produced in the adrenal glands and is released in large quantities under times of stress or excitement to prepare the body for ‘fight or flight’.
The first assumption of this approach is of the importance of the unconscious mind and motivation. Freud believed that much of what determines our behaviour is on a mental level that is hidden to us, and that there are three levels of consciousness: The conscious mind (Thoughts we are aware of), The preconscious mind (Memories we can invoke), The unconscious mind (Hidden thoughts, as well as instincts).

Freud used the iceberg analogy to describe our mind, in that the tip of the iceberg (conscious) is much smaller than the underwater part (preconscious and unconscious). The unconscious mind can be revealed through techniques developed by Freud, such as free association and dream analysis, as the unconscious mind tends to use symbolism in the conscious mind. Much of what was once conscious to us has been made unconscious via repression, a form of ego defence. Freud also believed that when we say something accidentally, we are actually revealing what we unconsciously didn't want to say.
Freud believed that the adult personality is structured into three parts that develop at different stages in our lives; Id - This is the impulsive (and unconscious) part of our personality, and is present at birth. It demands immediate satisfaction, which can be referred to as the pleasure principle. The main aim of the id is to gain pleasure and gratification at any cost. Ego -This is the conscious, rational part of the mind that develops around the age of two years. Its function is to work out realistic ways of balancing the demands of the id in a socially acceptable way. It is governed by the reality principle. Superego - This is the last part of our personality to develop. Forming Superego at around the age of four years, it embodies the child’s sense of right and wrong as well as his or her ideal self. The superego seeks to perfect and civilise our behaviour. It is learned through identification with one’s parents and others.