In: Psychology
Psychology is best defined at the science of behaviour and cognitive process. By the term behaviour, in other words, psychologists mean any observable action or reaction of a living organism - everything from overt action through subtle changes in the electrical activity occurring deep inside our brain. Similarly, by cognitive process, psychologists mean every aspect of our mental life that our thoughts for our memories, mental images, reasoning, decision-making, and so on - in short, all aspects of the human mind.
Formerly, psychology was treated as a branch of philosophy and psychology was discussed from the metaphysical standpoint. But at present, psychology is being treated as a distinct science separate from philosophy. As the standpoint of science is empirical and experimental, the same would be the case of psychology.
By the late 19th century, many philosophers had turned their attention to question about the human mind. How do we perceive the world around us? Do people have free will? What is the link between body and mind? Philosophers had attempted to answer these questions through careful reading. For instance Rene Descarres is a French philosopher, suggested that mind and body are distinct entities and that they interact through the pineal gland found deep into the brain; this view is known as dualism.
Other psychologists, in contrast, suggested that mind can influence body and body can influence mind - a view known as interactionism. Perhaps even more important, by the end of the 19th Century, many philosophers had reached the conclusion that questions about the human mind could not be answered solely by means of reasoning but required careful observation - a empirical approach.
This is where physiology entered the picture. Physiologists had been using the scientific method to answer questions about the nervous system and our senses for decades. During the period from 1862 to 1880 Johannes Mullar described how electrical signals were contracted by nerves within the body. Harmann Vonn showed how receptors in the eyes and ears receive the in and interpret sensation from the outside world. Gustav Fetcher demonstrated that our perceptions of physical stimuli that for instance, the loudness of a sound or brightness of a light that are related in a lawful predictable ways to the physical energies of these stimuli.