The philosophy of the decentered subject can be traced back to Descartes in the 17th century. However, it is also a part of the post-structuralism school and it has intertwined itself with modern psychology. Here is the gist of it: According to Descartes, every individual possesses some form of self-awareness, self-esteem, and self-consciousness. Descartes named this “self”, or essence of individual uniqueness, the Cartesian self. To the modern mind, with so many developments in psychology and behavior, this idea may seem obvious. But back then it was (and continues in a way to be) a debate of paradigms. Do we really have a "center"? Is it a soul? Is it our brains at work? Is it our emotions?
Now, to answer your question, the decentered self is the idea that one can produce any form of communication (in art, science, literature, language, and research) with the same effectiveness if we were detached from the work itself and more focused on the process of producing the piece. The point of this philosophy is primarily to question whether we have a “self” or whether we are a product of circumstances.
An example of the decentered self would be a doctor telling a patient their prognosis. If the doctor is too involved in the process, he wouldn’t be able to give the patient the information without becoming emotional. Therefore, the doctor decenters from the situation by detaching any emotion from the situation, bringing out the information as neutrally as can possibly be. However, could this behavior be just that: A learned behavior? Or do we have something else within us that attaches us to situations that are unique to us? That is the big question.
Therefore, what the philosophers state is that it is possible to be emotionally detached from intellectual matters. However, as with every philosophical statement, we cannot just take that as a theory, but as food for thought.