Early experimental psychology Wilhelm Wundt Experimental psychology emerged as a modern academic discipline in the 19th century when
Wilhelm Wundt introduced a mathematical and experimental approach to the field. Wundt founded the first
psychology laboratory in
Leipzig, Germany. Other experimental psychologists, including
Hermann Ebbinghaus and
Edward Titchener, included
introspection in their experimental methods.
Charles Bell Charles Bell was a British
physiologist whose main contribution to the medical and scientific community was his research on the
nervous system. He wrote a
pamphlet summarizing his research on
rabbits. His research concluded that sensory nerves enter at the posterior (dorsal) roots of the spinal cord, and motor nerves emerge from the anterior (ventral) roots of the spinal cord. Eleven years later, a French
physiologist,
Francois Magendie, published the same findings without being aware of Bell's research. As a result of Bell not publishing his research, this discovery was called the
Bell–Magendie law to honor both individuals. Bell's discovery disproved the belief that nerves transmitted either vibrations or spirits.
Ernst Heinrich Weber Ernst Heinrich Weber, a German physician, is credited as one of experimental psychology's founders. Weber's main interests were the sense of touch and kinesthesis. His most memorable contribution to the field of experimental psychology is the suggestion that judgments of sensory differences are relative and not absolute. This relativity is expressed in "Weber's Law," which suggests that the
just-noticeable difference or
jnd is a constant proportion of the ongoing stimulus level. Weber's Law is stated as an equation: : \frac {\Delta I} {I} = k, where I\! is the original intensity of stimulation, \Delta I\! is the addition to it required for the difference to be perceived (the
jnd), and
k is a constant. Thus, for k to remain constant, \Delta I\! must rise as
I increases. Weber's law is considered to be the first quantitative law in the history of psychology.
Gustav Fechner Fechner published in 1860 what is considered to be the first work of experimental psychology, "Elemente der Psychophysik." Some historians date the beginning of experimental psychology to the publication of "Elemente."
Ernst Heinrich Weber was not a psychologist, but it was Fechner who realized the importance of Weber's research to psychology.
Weber's law and Fechner's law was published in Fechner's work, "Elemente der Psychophysik," and Fechner, a student of Weber named his first law in honor of his mentor. Fechner was profoundly interested in establishing a scientific study of the mind-body relationship, which became known as
psychophysics. Much of Fechner's research focused on the measurement of psychophysical thresholds and
just-noticeable differences. He invented the psychophysical method of limits, the method of constant stimuli, and the method of adjustment, which are still in use.
Oswald Külpe Oswald Külpe is the main founder of the Würzburg School in Germany. He was a pupil of
Wilhelm Wundt for about twelve years. Unlike Wundt, Külpe believed experiments were possible to test higher mental processes. In 1883 he wrote Grundriss der Psychologie, which had strictly scientific facts and no mention of thought. The lack of thought in his book is odd because the Würzburg School put a lot of emphasis on mental set and imageless thought.
Würzburg School The work of the Würzburg School was a milestone in the development of experimental psychology. The School was founded by a group of psychologists led by Oswald Külpe, and it provided an alternative to the
structuralism of Edward Titchener and Wilhelm Wundt. Those in the School focused mainly on mental operations such as mental set (
Einstellung) and imageless thought. Mental set affects perception and problem solving without the awareness of the individual; it can be triggered by instructions or by experience. Similarly, according to Külpe, imageless thought consists of pure mental acts that do not involve mental images. William Bryan, an American student, working in Külpe's laboratory, provided an example of mental set. Bryan presented subjects with cards that had nonsense syllables written on them in various colors. The subjects were told to attend to the syllables, and in consequence, they did not remember the colors of the nonsense syllables. Such results made people question the validity of introspection as a research tool, leading to a decline in
voluntarism and structuralism. The work of the Würzburg School later influenced many
Gestalt psychologists, including
Max Wertheimer.
George Trumbull Ladd George Trumbull Ladd introduced experimental psychology into the United States and founded
Yale University's psychological laboratory during his time there (from 1881 to 1905). In 1887, Ladd published
Elements of Physiological Psychology, the first American textbook that extensively discussed experimental psychology. Between Ladd's founding of the Yale Laboratory and his textbook, the center of experimental psychology in the US shifted to
Johns Hopkins University, where
George Hall and
Charles Sanders Peirce were extending and qualifying Wundt's work.
Charles Sanders Peirce With his student
Joseph Jastrow,
Charles S. Peirce randomly assigned volunteers to a
blinded,
repeated-measures design to evaluate their ability to discriminate weights. Peirce's experiment inspired other researchers in psychology and education, which developed a research tradition of randomized experiments in laboratories and specialized textbooks in the 1800s. Peirce's student
Joseph Jastrow continued to conduct randomized experiments throughout his distinguished career in experimental psychology, much of which would later be recognized as
cognitive psychology. There has been a resurgence of interest in Peirce's work in cognitive psychology. Another student of Peirce,
John Dewey, conducted experiments on human
cognition, particularly in schools, as part of his "experimental logic" and "public philosophy."
20th century In the middle of the 20th century,
behaviorism became a dominant paradigm within psychology, especially in the
United States. This led to some neglect of
mental phenomena within experimental psychology. In
Europe, this was less the case, as European psychology was influenced by psychologists such as
Sir Frederic Bartlett,
Kenneth Craik,
W.E. Hick, and
Donald Broadbent, who focused on topics such as
thinking,
memory, and
attention. This laid the foundations for the subsequent development of cognitive psychology. In the latter half of the 20th century, the phrase "experimental psychology" had shifted in meaning due to the expansion of psychology as a discipline and the growth in its sub-disciplines. Experimental psychologists use a range of methods and do not confine themselves to a strictly experimental approach, partly because developments in the
philosophy of science have affected the exclusive prestige of experimentation. In contrast, experimental methods are now widely used in fields such as developmental and
social psychology, which were not previously part of experimental psychology. The phrase continues in use in the titles of a number of well-established, high prestige
learned societies and
scientific journals, as well as some
university courses of study in psychology.
Institutional review board (IRB) In 1974, the
National Research Act established the existence of the
institutional review board in the United States following several controversial experiments. Institutional Review Boards (IRBs) play an important role in monitoring the conduct of psychological experiments. Their presence is required by law at institutions such as universities where psychological research occurs. Their purpose is to make sure that experiments do not violate ethical codes or legal requirements; thus they protect human subjects from physical or psychological harm and assure the humane treatment of animal subjects. An IRB must review the procedure to be used in each experiment before that experiment may begin. The IRB also assures that human participants give informed consent in advance; that is, the participants are told the general nature of the experiment and what will be required of them. There are three types of review that may be undertaken by an IRB - exempt, expedited, and full review. More information is available on the main IRB page. == Methodology ==