In the early part of the 20th century, there were many studies on the functional differentiation of the brain. However, many psychologists considered the brain to be a “black box”. Although there were a few psychologists who investigated the brain in relation to cognitive processes, the majority of the studies in psychology and in neuroscience were conducted independently. In the latter part of the 20th century, advancements in neuroscience research clarified the mechanisms in the brain relative to various cognitive processes, such as perception, memory, and motivation. In this era of the 21st century, there are many, newly-devised neuroscience methods, such as gene recombination, optical recording, see-through brains, optogenetics, and chemical genetics, which are used to determine brain mechanisms involved in cognitive processes, including attention, consciousness, theory of mind, and social interaction.
Recently, in many universities in Europe and in the USA, the departments of psychology have been combined with the departments of neuroscience, resulting in the departments of psychology and neuroscience. It appears that neuroscience and psychology are not distinct fields and that the fields should cooperate to clarify cognitive processes.
