Experimental psychology
Experimental psychologists employ human participants and animal subjects to study a great many topics, including (among others) sensation, perception, memory, cognition, learning, motivation, emotion; developmental processes, social psychology, and the neural substrates of all of these.
Charles Bell was a British physiologist whose main contribution to the medical and scientific community was his research on the nervous system.
[citation needed] Eleven years later, a French physiologist, Francois Magendie, published the same findings without being aware of Bell's research.
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.
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.
Such results made people question the validity of introspection as a research tool, leading to a decline in voluntarism and structuralism.
[7] 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.
With his student Joseph Jastrow, Charles S. Peirce randomly assigned volunteers to a blinded, repeated-measures design to evaluate their ability to discriminate weights.
To Peirce and to experimental psychology belongs the honor of having invented randomized experiments decades before the innovations of Jerzy Neyman and Ronald Fisher in agriculture.
[8][9][10][11] Peirce's pragmaticist philosophy also included an extensive theory of mental representations and cognition, which he studied under the name of semiotics.
[13][14][15] Another student of Peirce, John Dewey, conducted experiments on human cognition, particularly in schools, as part of his "experimental logic" and "public philosophy."
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.
In 1974, the National Research Act established the existence of the institutional review board in the United States following several controversial experiments.
[16] Sound methodology is essential to the study of complex behavioral and mental processes, and this implies, especially, the careful definition and control of experimental variables.
This notion of empiricism requires that hypotheses and theories be tested against observations of the natural world rather than on a priori reasoning, intuition, or revelation.
For example, most scientists agree that if two theories handle a set of empirical observations equally well, we should prefer the simpler or more parsimonious of the two.
Experimental psychologists attempt to define currently unobservable phenomena, such as mental events, by connecting them to observations by chains of reasoning.
Some statistics can be computed from ordinal measures – for example, median, percentile, and order correlation – but others, such as standard deviation, cannot properly be used.
In particular, within-subjects designs eliminate person confounds, that is, they get rid of effects caused by differences among subjects that are irrelevant to the phenomenon under study.
Psychophysiological experiments, on the other hand, measure brain or (mostly in animals) single-cell activation during the presentation of a stimulus using methods such as fMRI, EEG, PET or similar.
[36] Most cognitive experiments are done in a lab instead of a social setting; this is done mainly to provide maximum control of experimental variables and minimal interference from irrelevant events and other aspects of the situation.
In addition to studying behavior, experimenters may use EEG or fMRI to help understand how the brain carries out cognitive processes, sometimes in conjunction with computational modelling.
The behavioristic approach to psychology reached its peak of popularity in the mid-twentieth century but still underlies much experimental research and clinical application.
Pavlov's experimental study of the digestive system in dogs led to extensive experiments through which he established the basic principles of classical conditioning.
Developed by Carl Ludwig in the 19th century, the kymograph is a revolving drum on which a moving stylus tracks the size of some measurement as a function of time.
The most basic type in early studies was placing a subject in a room containing a specific measured amount of an odorous substance.
"[44] Critical psychologists claim that experimental psychology approaches humans as entities independent of the cultural, economic, and historical context in which they exist.
[citation needed] These contexts of human mental processes and behavior are neglected, according to critical psychologists, like Herbert Marcuse.
[citation needed] In so doing, experimental psychologists paint an inaccurate portrait of human nature while lending tacit support to the prevailing social order, according to critical theorists like Theodor Adorno and Jürgen Habermas (in their essays in The Positivist Debate in German Sociology).
