How did modern psychology and science influence Oscar Wilde's writing of The Picture of Dorian Gray?

During the time that Wilde was writing The Picture of Dorian Gray, psychology was just at the beginning of its rise to scientific legitimacy. Psychology had already started as a recognized field at the beginning of the nineteenth century, but solid research and theories took a few decades to appear. During the time the book was written, around 1890, Freud was just beginning to lay out his ideas on psychology. It was this early exploration of psychology that largely influenced The Picture of Dorian Gray.
The story itself examines the consequences of allowing desire (what would later be called the id) to overtake rationality (what would later be called the superego). Dorian allows himself to give in to all temptation and this creates a split between his inner self as displayed in the hideous portrait and the beautiful appearance that he retained. The book examines this conscious fall into temptation, an arguable split identity, and the link between mind and soul. The influence of psychology on Dorian Gray does not really consist of the actual theories that are well known today, since it would be a few years after the publication of Wilde's novel that Freud and other psychologists released their theories. Rather, it was more that introspection and an interest in examining the nature of the mind were on the rise. It was this interest that led to the examination of the mind that is found in The Picture of Dorian Gray.