Well I believe that Hall was the first to have a lab in the late 1800's (that or it was the first lab in the USA) and Freud did the first psycoanaylsys in the early 1900's. I would have to say that within the last 200 years and there would be noone to accredit to this by themselves. Psycology as we know it is recent but moderen psycology came about to better explain the great questions brought to us from plato and aristotle (and even before them).

Beginning of scientific psychology Though the use of psychological experimentation dates back to Alhazen's Book of Optics in 1021, psychology as an independent experimental field of study began in 1879, when Wilhelm Wundt founded the first laboratory dedicated exclusively to psychological research at Leipzig University in Germany, for which Wundt is known as the "father of psychology" - 1879 is thus sometimes regarded as the "birthdate" of psychology. The American philosopher William James published his seminal book, Principles of Psychology, in 1890, while laying the foundations for many of the questions that psychologists would focus on for years to come. Other important early contributors to the field include Hermann Ebbinghaus (1850–1909), a pioneer in the experimental study of memory at the University of Berlin; and the Russian physiologist Ivan Pavlov (1849-1936), who investigated the learning process now referred to as classical conditioning. http://en.wikipedia.org/wiki/Psychology The De anima of Aristotle is considered the first monument of psychology as such, centered around the belief that the heart was the basis for mental activity. The foundations of modern psychology were laid by 17th-century philosopher Thomas Hobbes, who argued that scientific causes could be established for every sort of phenomenon through deductive reasoning. The mind-body theories of Rene Descartes, Baruch Spinoza, and G. W. Leibniz were equally crucial in the development of modern psychology, where the human mind's relation to the body and its actions have been significant topics of debate. In England the empirical method employed in modern psychological study originated in the work of John Locke, George Berkeley, Thomas Reid, and David Hume. David Hartley, James Mill, John Stuart Mill, and Alexander Bain stressed the relation of physiology to psychology, an important development in the scientific techniques of modern psychology. Important contributions were made in the physiological understanding of human psychology by French philosopher Condillac, F. J. Gall, the German founder of phrenology, and French surgeon Paul Broca, who localized speech centers in the brain. In the 19th cent., the laboratory work of Ernst Heinrich Weber, Gustave Fechner, Wilhelm Wundt, Hermann von Helmholtz, and Edward Titchener helped to establish psychology as a scientific discipline—both through the use of the scientific method of research, and in the belief that mental processes could be quantified with careful research techniques. The principle of evolution, stemming from Charles Darwin's theory of natural selection, gave rise to what became known as dynamic psychology. The new approach, presented by American psychologist William James in his Principles of Psychology (1890), looked at consciousness as an evolutionary process. Out of the new orientation in psychology grew the clinical experiments in hysteria and hypnotism carried on by J. M. Charcot and Pierre Janet in France. Sigmund Freud, in his influential theory of the unconscious, gave a new direction to psychology and laid the groundwork for the psychoanalytic model. Freudian theory took psychology into such fields as education, anthropology, and medicine, and Freudian research methods became the foundations of clinical psychology. The behaviorism of American psychologist John B. Watson was highly influential in the 1920s and 30s, with its suggestion that psychology should concern itself solely with sensory stimuli and behavioral reaction. Behaviorism has been important in modern psychology, particularly through the work of B. F. Skinner since the 1930s. http://www.reference.com/search?q=psychology