Experimental psychology
Encyclopedia
Experimental psychology is a methodological approach, rather than a subject, and encompasses varied fields within psychology. Experimental psychologists have traditionally conducted research, published articles, and taught classes on neuroscience
, developmental psychology
, sensation
, perception
, attention
, consciousness
, learning
, memory
, thinking, and language
. Recently, however, the experimental approach has extended to motivation
, emotion
, and social psychology
.
Experimental psychologists conduct research with the help of experimental methods. The concern of experimental psychology is discovering the processes underlying behavior and cognition.
introduced a mathematical and experimental approach to the field. Wundt founded the first psychology laboratory in Leipzig, Germany. Other early experimental psychologists, including Hermann Ebbinghaus
and Edward Titchener, included introspection
among their experimental methods.
, who founded Yale University
's psychological laboratory in 1879. 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 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. The Peirce–Jastrow experiments were conducted as part of Peirce's pragmatic
program to understand human perception; other studies considered perception of light, etc. While Peirce was making advances in experimental psychology and psychophysics
, he was also developing a theory of statistical inference
, which was published in "Illustrations of the Logic of Science" (1877–78) and "A Theory of Probable Inference" (1883); both publications that emphasized the importance of randomization-based inference in statistics. To Peirce and to experimental psychology belongs the honor of having invented randomized experiment
s, decades before the innovations of Neyman
and Fisher in agriculture.
Peirce's pragmaticist philosophy also included an extensive theory of mental representations and cognition, which he studied under the name of semiotics
. 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."
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 the size and number of 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 had an impact on the exclusive prestige of experimentation. In contrast, an experimental method is now widely used in fields such as developmental and social psychology
, which were not previously part of experimental psychology. The phrase continues in use, however, 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.
have eased stimulus presentation and the measurement of behavior in the laboratory. Apart from the measurement of response times and error rates, experimental psychologists often use surveys before, during, and after experimental intervention and observation methods. Experimental designs can be divided into three broad types: experimental, quasi-experimental and non-experimental.
Control of extraneous variables, minimizing the potential for experimenter bias, counterbalancing the order of experimental tasks, adequate sample size
, and the use of operational definition
s which are both reliable
and valid
, and proper statistical analysis are central to experimental methods in psychology. As such, most undergraduate programs in psychology include mandatory courses in Research Methods and Statistics.
A crucial experiment is an experiment that is meant to test all possible hypotheses simultaneously. If one hypothesis is confirmed, then it will also reject another hypothesis. This type of experiment could confirm multiple hypotheses, which will then lead a researcher to do more experiments that will lead to one confirmed hypothesis.
A field study is done in the field, just like the name would suggest. They can vary from a descriptive study to a true experiment. Due to these happening in real life settings and not in the laboratory setting the control is reduced.
While other methods of research—case study
, interview, and naturalistic observation
—are used by psychologists, the method of randomized experimentation remains the preferred method for testing hypotheses in scientific psychology.
to measure memory such as the Implicit Association Test (IAT) or the Word Stem Completion Test (WSC). Sometimes to study cognition, an experimenter will use fMRI or PET so they are able to see what areas of the brain are active from a stimulus. If experimental psychology had not developed the knowledge currently known in cognitive psychology would not have nearly as much evidence supporting its current theories today.
, B.F. Skinner, and Ivan Pavlov
. Pavlov used experimental methods to study the digestion system in dogs, which led to his discovery of classical conditioning. Watson also used experimental methods in his famous experiments with little Albert. Skinner used “Skinner boxes” to train pigeons with reinforcement. It was experiments like these that helped behaviorism become what it is today.
conducted by Philip Zimbardo
in 1971, although the extremity of this field experiment is not prototypical of the field. Another notable study is the Stanley Milgram
obedience experiment, often known as the Milgram experiment
.
." Critical psychologists claim that experimental psychology approaches humans as entities independent of the cultural, economic, and historical context in which they exist. These contexts of human mental processes and behavior are neglected, according to critical psychologists, like Herbert Marcuse
. 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).
Critical theory
has itself been criticized, however. While the philosopher Karl Popper
"never took their methodology (whatever that may mean) seriously" (p. 289), Popper wrote counter-criticism to reduce the irrationalist' and 'intelligence-destroying "political influence" of critical theorists on students (Karl Popper
pages 288–300 in [The Positivist Debate in German Sociology]). The critical theorists Adorno and Marcuse have been severely criticized by Alasdair MacIntyre
in Herbert Marcuse: An Exposition and Polemic. Like Popper, MacIntyre attacked critical theorists like Adorno and especially Marcuse as obscurantists pontificating dogma in the authoritarian fashion of German professors of philosophy of their era—before World War II—(page 11); Popper made a similar criticism of critical theory's rhetoric, which reflected the culture of Hegelian social studies
in German universities (pp. 293–94). Furthermore, MacIntyre ridiculed Marcuse as being a senile revival of the young Hegelian tradition
criticized
by Marx
and Engels (pp. 18–19, 41, and 101); similarly, "critical theorys revival of young Hegelianism and its criticism by Karl Marx was noted by Popper (p. 293). Marcuse's support for the political re-education camps of Maoist China
was also criticized as totalitarian by MacIntyre (pp. 101–05). More recently, the Critical Theory
of Adorno and Marcuse has been criticized as being a degeneration of the original Frankfurt school
, particularly the work of empirical psychologist Erich Fromm
, who did surveys and experiments to study the development of personality in response to economic stress and social change (Michael Macoby's Preface to Fromm's Social Character in a Mexican Village).
Neuroscience
Neuroscience is the scientific study of the nervous system. Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics,...
, developmental psychology
Developmental psychology
Developmental psychology, also known as human development, is the scientific study of systematic psychological changes, emotional changes, and perception changes that occur in human beings over the course of their life span. Originally concerned with infants and children, the field has expanded to...
, sensation
Sense
Senses are physiological capacities of organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception...
, perception
Perception
Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...
, attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
, consciousness
Consciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
, learning
Learning
Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...
, memory
Memory
In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....
, thinking, and language
Language
Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...
. Recently, however, the experimental approach has extended to motivation
Motivation
Motivation is the driving force by which humans achieve their goals. Motivation is said to be intrinsic or extrinsic. The term is generally used for humans but it can also be used to describe the causes for animal behavior as well. This article refers to human motivation...
, emotion
Emotion
Emotion is a complex psychophysiological experience of an individual's state of mind as interacting with biochemical and environmental influences. In humans, emotion fundamentally involves "physiological arousal, expressive behaviors, and conscious experience." Emotion is associated with mood,...
, and social psychology
Social psychology
Social psychology is the scientific study of how people's thoughts, feelings, and behaviors are influenced by the actual, imagined, or implied presence of others. By this definition, scientific refers to the empirical method of investigation. The terms thoughts, feelings, and behaviors include all...
.
Experimental psychologists conduct research with the help of experimental methods. The concern of experimental psychology is discovering the processes underlying behavior and cognition.
Wilhelm Wundt
Experimental psychology emerged as a modern academic discipline in the 19th century when Wilhelm WundtWilhelm Wundt
Wilhelm Maximilian Wundt was a German physician, psychologist, physiologist, philosopher, and professor, known today as one of the founding figures of modern psychology. He is widely regarded as the "father of experimental psychology"...
introduced a mathematical and experimental approach to the field. Wundt founded the first psychology laboratory in Leipzig, Germany. Other early experimental psychologists, including Hermann Ebbinghaus
Hermann Ebbinghaus
Hermann Ebbinghaus was a German psychologist who pioneered the experimental study of memory, and is known for his discovery of the forgetting curve and the spacing effect. He was also the first person to describe the learning curve...
and Edward Titchener, included introspection
Introspection
Introspection is the self-observation and reporting of conscious inner thoughts, desires and sensations. It is a conscious and purposive process relying on thinking, reasoning, and examining one's own thoughts, feelings, and, in more spiritual cases, one's soul...
among their experimental methods.
Charles Bell
Charles Bell was a British physiologist, whose main contribution was research involving nerves. 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. Due to Bell not publishing his research, the discovery was called the Bell-Magendie law. Bell’s discovery disproved the belief that nerves were either vibrations or spirits.Ernst Heinrich Weber
Weber was a German physician who is credited with being one of the founders of experimental psychology. His main interests were the sense of touch and kinesthesis. He studied the just noticeable difference and created Weber’s Law. Weber’s law is considered the first quantitative law in the history of psychology. During his studies, he suggested that judgments are relative and not absolute. An important portion of his work was on the two-point threshold. He published One Touch: Anatomical and Physiological Notes in 1834. That book had charts demonstrating the two-point threshold on a person’s body.Gustav Fechner
Fechner wrote what is considered to be the first work of experimental psychology in 1860 called Elemente der Psychophysik. Some historians believe that the beginning of experimental psychology begin in 1860 with Fechner’s publication of Elements. Since Weber was not a psychologist, it was Fechner who realized the importance of Weber’s research in psychology. A lot of his research focused on thresholds as well as just noticeable differences. He also established several methods to explore the mind-body relationship. These methods were the method of limits, the method of constant stimuli, and the method of adjustment. Through his work, he created psychophysics.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 Würzburg School is a cornerstone of experimental psychology history. It was founded by a group of psychologists led by Oswald Külpe. They provided alternative ideas to what Edward Titchener and Wilhelm Wundt had proposed at the time. Their main focus of study was of mental operations, specifically mental set (Einstellung) and imageless thought. Mental set is a type of problem-solving strategy that can be triggered by instructions or by experience, except the person is unaware of it. Mental set worked on an unconscious level. According to Külpe, imageless thought was pure mental acts that did not have any particular reference to images. It was an American student working in Külpe’s laboratory, named William Bryan, that provided evidence of mental set. He used cards with various nonsense syllables written on them in various colors. Subjects were instructed to attend to the syllables. The subjects’ attention was set on the syllables that they did not even remember the colors of the nonsense syllables. The results the Würzburg School had assisted the decline of voluntarism and structuralism. This also made people start to question the validity of introspection as a research tool. The Würzburg School went on to influence many Gestalt psychologists, including Wertheimer.George Trumbull Ladd
Experimental psychology was introduced into the United States by George Trumbull LaddGeorge Trumbull Ladd
George Trumbull Ladd was an American philosopher, educator and psychologist.-Early life and ancestors:...
, who founded Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
's psychological laboratory in 1879. 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
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
, where George Hall and Charles Sanders Peirce were extending and qualifying Wundt's work.
Charles Sanders Peirce
With his student Joseph JastrowJoseph Jastrow
Joseph Jastrow was an American psychologist, noted for inventions in experimental psychology, design of experiments, and psycho-physics. Jastrow was one of the first scientists to study the evolution of language, publishing an article on the topic in 1886...
, 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. The Peirce–Jastrow experiments were conducted as part of Peirce's pragmatic
Pragmaticism
Pragmaticism is a term used by Charles Sanders Peirce for his pragmatic philosophy starting in 1905, in order to distance himself and it from pragmatism, the original name, which had been used in a manner he did not approve of in the "literary journals"...
program to understand human perception; other studies considered perception of light, etc. While Peirce was making advances in experimental psychology and psychophysics
Psychophysics
Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they effect. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual...
, he was also developing a theory of statistical inference
Statistical inference
In statistics, statistical inference is the process of drawing conclusions from data that are subject to random variation, for example, observational errors or sampling variation...
, which was published in "Illustrations of the Logic of Science" (1877–78) and "A Theory of Probable Inference" (1883); both publications that emphasized the importance of randomization-based inference in statistics. To Peirce and to experimental psychology belongs the honor of having invented randomized experiment
Randomized experiment
In science, randomized experiments are the experiments that allow the greatest reliability and validity of statistical estimates of treatment effects...
s, decades before the innovations of Neyman
Jerzy Neyman
Jerzy Neyman , born Jerzy Spława-Neyman, was a Polish American mathematician and statistician who spent most of his professional career at the University of California, Berkeley.-Life and career:...
and Fisher in agriculture.
Peirce's pragmaticist philosophy also included an extensive theory of mental representations and cognition, which he studied under the name of semiotics
Semiotics
Semiotics, also called semiotic studies or semiology, is the study of signs and sign processes , indication, designation, likeness, analogy, metaphor, symbolism, signification, and communication...
. Peirce's student Joseph Jastrow
Joseph Jastrow
Joseph Jastrow was an American psychologist, noted for inventions in experimental psychology, design of experiments, and psycho-physics. Jastrow was one of the first scientists to study the evolution of language, publishing an article on the topic in 1886...
continued to conduct randomized experiments throughout his distinguished career in experimental psychology, much of which would later be recognized as cognitive psychology
Cognitive psychology
Cognitive psychology is a subdiscipline of psychology exploring internal mental processes.It is the study of how people perceive, remember, think, speak, and solve problems.Cognitive psychology differs from previous psychological approaches in two key ways....
. There has been a resurgence of interest in Peirce's work in cognitive psychology. Another student of Peirce, John Dewey
John Dewey
John Dewey was an American philosopher, psychologist and educational reformer whose ideas have been influential in education and social reform. Dewey was an important early developer of the philosophy of pragmatism and one of the founders of functional psychology...
, 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, behaviorismBehaviorism
Behaviorism , also called the learning perspective , is a philosophy of psychology based on the proposition that all things that organisms do—including acting, thinking, and feeling—can and should be regarded as behaviors, and that psychological disorders are best treated by altering behavior...
became a dominant paradigm within psychology, especially in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. This led to some neglect of mental
Mind
The concept of mind is understood in many different ways by many different traditions, ranging from panpsychism and animism to traditional and organized religious views, as well as secular and materialist philosophies. Most agree that minds are constituted by conscious experience and intelligent...
phenomena within experimental psychology. In Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
this was less the case, as European psychology was influenced by psychologists such as Sir Frederic Bartlett, Kenneth Craik
Kenneth Craik
Kenneth James Williams Craik was a philosopher and psychologist who studied philosophy at the University of Edinburgh, Scotland, and received his doctorate from Cambridge University in 1940...
, W.E. Hick and Donald Broadbent
Donald Broadbent
Donald Eric Broadbent FRS was an influential English experimental psychologist. His career and his research work bridged the gap between the pre-Second World War approach of Sir Frederic Bartlett and its wartime development into applied psychology, and what from the late 1960s became known as...
, who focused on topics such as thinking, memory
Memory
In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....
and attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
. 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 the size and number of 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
Philosophy of science
The philosophy of science is concerned with the assumptions, foundations, methods and implications of science. It is also concerned with the use and merit of science and sometimes overlaps metaphysics and epistemology by exploring whether scientific results are actually a study of truth...
have had an impact on the exclusive prestige of experimentation. In contrast, an experimental method is now widely used in fields such as developmental and social psychology
Social psychology
Social psychology is the scientific study of how people's thoughts, feelings, and behaviors are influenced by the actual, imagined, or implied presence of others. By this definition, scientific refers to the empirical method of investigation. The terms thoughts, feelings, and behaviors include all...
, which were not previously part of experimental psychology. The phrase continues in use, however, in the titles of a number of well-established, high prestige learned societies and scientific journals, as well as some university
University
A university is an institution of higher education and research, which grants academic degrees in a variety of subjects. A university is an organisation that provides both undergraduate education and postgraduate education...
courses of study in psychology.
Methodology
Experimental psychologists study human behavior in different contexts. Often, human participants are instructed to perform tasks in an experimental setup. Since the 1990s, various software packagesComparison of behavioral experiment software
Overview of software packages used in experimental psychology and related disciplines. These packages differ in various aspects . Some software is proprietary, and some is available as free software. Some packages have a graphical user interface. Some packages have a scripting language...
have eased stimulus presentation and the measurement of behavior in the laboratory. Apart from the measurement of response times and error rates, experimental psychologists often use surveys before, during, and after experimental intervention and observation methods. Experimental designs can be divided into three broad types: experimental, quasi-experimental and non-experimental.
Experiments
The complexity of human behavior and mental processes, the ambiguity with which they can be interpreted and the unconscious processes to which they are subject gives rise to an emphasis on sound methodology within experimental psychology.Control of extraneous variables, minimizing the potential for experimenter bias, counterbalancing the order of experimental tasks, adequate sample size
Sample size
Sample size determination is the act of choosing the number of observations to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make inferences about a population from a sample...
, and the use of operational definition
Operational definition
An operational definition defines something in terms of the specific process or set of validation tests used to determine its presence and quantity. That is, one defines something in terms of the operations that count as measuring it. The term was coined by Percy Williams Bridgman and is a part of...
s which are both reliable
Reliability (statistics)
In statistics, reliability is the consistency of a set of measurements or of a measuring instrument, often used to describe a test. Reliability is inversely related to random error.-Types:There are several general classes of reliability estimates:...
and valid
Validity (statistics)
In science and statistics, validity has no single agreed definition but generally refers to the extent to which a concept, conclusion or measurement is well-founded and corresponds accurately to the real world. The word "valid" is derived from the Latin validus, meaning strong...
, and proper statistical analysis are central to experimental methods in psychology. As such, most undergraduate programs in psychology include mandatory courses in Research Methods and Statistics.
Other methods
A pilot study is basically a study before a major experiment. It is meant to test out different procedures or values before the researcher moves on to the major experiment. It can help the researcher find weaknesses in the experiment.A crucial experiment is an experiment that is meant to test all possible hypotheses simultaneously. If one hypothesis is confirmed, then it will also reject another hypothesis. This type of experiment could confirm multiple hypotheses, which will then lead a researcher to do more experiments that will lead to one confirmed hypothesis.
A field study is done in the field, just like the name would suggest. They can vary from a descriptive study to a true experiment. Due to these happening in real life settings and not in the laboratory setting the control is reduced.
While other methods of research—case study
Case study
A case study is an intensive analysis of an individual unit stressing developmental factors in relation to context. The case study is common in social sciences and life sciences. Case studies may be descriptive or explanatory. The latter type is used to explore causation in order to find...
, interview, and naturalistic observation
Naturalistic observation
Naturalistic observation is a research tool in which a subject is observed in its natural habitat without any manipulation by the observer. During naturalistic observation researchers take great care to avoid interfering with the behavior they are observing by using unobtrusive methods...
—are used by psychologists, the method of randomized experimentation remains the preferred method for testing hypotheses in scientific psychology.
Measurement
As with all types of science, there are many types of measurement used by the researchers. Experimental psychology is no exception to this. The type of measurement used in the experiment depended on what was being researched.Nominal Measurement
This is, for the most part, the weakest form of measurement in experimental psychology. The researcher assigns numbers to the items in the experiment, which gives them a general definition of measurement. The numbers mean nothing other than the fact that each item is in a separate class from the other items. This means that A is not necessarily better than B, and B is not necessarily better than C. Every class is independent of the others.Ordinal Measurement
An ordinal scale is basically a rank system for items. It puts items into order by which is more or less superior based on the item’s properties. For ordinal measurements A would be superior to B, and B would be superior to C.Interval Measurement
The numbers assigned to items have an equal distance between them. For instance, a thermometer has an equal distance between 1 and 10 as does 21 and 30. In other terms, two numerical differences correspond to two experimentally equal differences. Interval measurement is also called the interval scale.Ratio Measurement
The ratio measurement is similar to the interval measurement because the ratio between two items must be equal to the ratio between two other items. Ratio measurement can also be called the ratio scale.Experimental Instruments
Instruments used in experimental psychology have been changing over time. In fact, the original instruments used by experimenters where not even designed for the use of psychologists, such as the Hipp Chronoscope and the kymograph. This was partly due to the lack of psychological laboratories in the 19th century when experimental psychology began to develop . The instruments used by researchers vary from simple to complex. Experimenters develop new instruments and tools for their varying experiments. Listed below are some of the different types of instruments used throughout the history of experimental psychology.Hipp Chronoscope/Chronograph
This instrument was originally designed to be used in physics to verify the laws of falling bodies. It was then introduced to ballistics research in the 1850s to measure the speed of bullets. After then being introduced to physiology, it was finally introduced to psychology. Researchers used the Hipp Chronoscope to measure reaction time and the duration of mental processes.Stereoscope
Helmholtz developed the first stereoscope. It presents two slightly different images, one to each eye, at the same time. The images are of the same object just at a different angle. The two images will become one when looking through the stereoscope.Kymograph
Developed by Carl Ludwig in the 19th century, the main purpose of kymograph was to register various processes in two dimensions: time and the intensity. The kymograph was originally used to measure blood pressure and it later was used to measure muscle contractions and speech sounds. In psychology, it was used to record response times. It was a revolving drum that had a moving stylus to record the data. The kymograph is similar to the polygraph. The main difference is the recording surface of a polygraph is driven along a rack instead of a drum.Photokymographs
This device is a photographic recorder. It used mirrors and light to record the photos. Inside a small box with a slit for light there are two drive rollers with film connecting the two. The light enters through the slit to record on the film. Some photokymographs have a lens so an appropriate speed for the film can be reached.Galvanometer
Used notably by Hermann von Helmholtz, this device was used to measure the rate of speed of nerve signals.Audiometer
This apparatus was designed to produce several fixed frequencies at different levels of intensity. It could either deliver the tone to a subject’s ear or transmit sound oscillations to the skull. An experimenter would generally use an audiometer to find the auditory threshold of a subject. The data received from an audiometer is called an audiogram.Colorimeters
These determine the color composition by measuring its tricolor characteristics or matching of a color sample. This type of device would be used in visual experiments.Algesiometers and Algometers
Both of these are mechanical stimulation for pain. They have a sharp needle-like stimulus point so it does not give the sensation of pressure. Experimenters use these when doing an experiment on analgesia.Olfactometer
An olfactometer is any device that is used to measure the sense of smell. The most basic type in early studies was placing a subject in a room containing a specific measured amount of an odorous substance. More intricate devices involve some form of sniffing device, such as the neck of a bottle. The most common olfactometer found in psychology laboratories at one point was the Zwaardemker olfactometer. It had two glass nasal tubes projecting through a screen. One end would be inserted into a stimulus chamber, the other end is inserted directly into the nostrils.Mazes
Probably one of the oldest instruments for studying perceptual motor skills would have to be the maze. The common goal is to get from point A to point B, however the mazes can vary in size and complexity. Two types of mazes commonly used with rats are the radial arm maze and the Morris water maze. The radial arm maze consists of multiple arms radiating from a central point. Each arm has a small piece of food at the end. The Morris water maze is meant to test spatial learning. It uses a large round pool of water that is made opaque. The rat must swim around until it finds the escape platform that is hidden from view just below the surface of the water.Electroencephalograph (EEG)
The EEG is an instrument that can reflect the summed electrical activity of neural cell assemblies in the brain. It was originally used as an attempt to improve medical diagnoses. Later it became a key instrument to psychologists in examining brain activity and it remains a key instrument used in the field today.Functional Magnetic Resonance Imaging (fMRI)
The fMRI is an instrument that can detect the increase in blood oxygen levels. The increase in blood oxygen levels shows where brain activity occurs. These are rather bulky and expensive instruments which are generally found in hospitals. They are most commonly used for cognitive experiments.Positron Emission Tomography (PET)
PET is also used to look at the brain. It can detect drugs binding neurotransmitter receptors in the brain. A down side to PET is that it requires radioisotopes to be injected into the body so the brain activity can be mapped out. The radioisotopes decay quickly so they do not accumulate in the body.Institutional Review Board (IRB)
The Institutional Review board plays a huge role in experimental psychology. Their purpose is to monitor experiments involving humans so the researcher does not violate any ethical codes and to protect human subjects from any harm. The IRB reviews all protocols of an experiment before allowing the researcher to actually begin the experiment. It is a requirement of the IRB for all participating subjects to have informed consent regarding the experiment and all that will be involved. There are three types of institutional review boards, which can be seen on the main IRB pageInspiration to Other Branches of Psychology
Other branches of psychology have taken advantage of experimental psychology to further their knowledge. Areas such as cognitive psychology, sensation and perception research, and behavioral psychology have been conducting experiments to gain knowledge in their respective field of study. Due to the development of experimental psychology, the other branches have managed to also develop their breadth of knowledge.Cognitive Psychology
Some interests of study for cognitive psychologists include memory, learning, problem solving, and attention. Most cognitive experiments are done in a lab instead of a social setting. This allows for high internal validity. Cognitive psychologists use laboratory settings to prevent outside factors from influencing the results. There are some indirect tests of memoryIndirect tests of memory
Indirect memory tests assess the retention of information without direct reference to the source of information. Participants are given tasks designed to elicit knowledge that was acquired incidentally or unconsciously and is evident when performance shows greater inclination towards items...
to measure memory such as the Implicit Association Test (IAT) or the Word Stem Completion Test (WSC). Sometimes to study cognition, an experimenter will use fMRI or PET so they are able to see what areas of the brain are active from a stimulus. If experimental psychology had not developed the knowledge currently known in cognitive psychology would not have nearly as much evidence supporting its current theories today.
Sensation and Perception
The main senses of the body (sight, touch, smell, auditory, and taste) are what generally get tested for sensation and perception. An experimenter may be interested in the effect color has on people, or what kind of sound is pleasing to a person. These answers require experimental methods to get an answer. Depending on what sense is being tested an experimenter has many experimental instruments to choose from to use in their experiment. These instruments include audio oscillator, attenuator, stroboscope, photometer, colorimeter, algesiometer, algometer, and olfactometer. Each instrument allows the experimenter to record data on what they are researching and helps expand the knowledge of sensation and perception.Behavioral Psychology
Behavioral psychology has had a vast array of experimentation completed and much more still going on today. A few notable founders of experiments in behavioral psychology include John B. WatsonJohn B. Watson
John Broadus Watson was an American psychologist who established the psychological school of behaviorism. Watson promoted a change in psychology through his address Psychology as the Behaviorist Views it which was given at Columbia University in 1913...
, B.F. Skinner, and Ivan Pavlov
Ivan Pavlov
Ivan Petrovich Pavlov was a famous Russian physiologist. Although he made significant contributions to psychology, he was not in fact a psychologist himself but was a mathematician and actually had strong distaste for the field....
. Pavlov used experimental methods to study the digestion system in dogs, which led to his discovery of classical conditioning. Watson also used experimental methods in his famous experiments with little Albert. Skinner used “Skinner boxes” to train pigeons with reinforcement. It was experiments like these that helped behaviorism become what it is today.
Social Psychology
Social psychology often employs the experimental method in an attempt to understand human social interaction. Social psychology conducts its experiments both inside and outside of the laboratory. Notable social psychology experiment is the Stanford prison experimentStanford prison experiment
The Stanford prison experiment was a study of the psychological effects of becoming a prisoner or prison guard. The experiment was conducted from August 14th-20th, 1971, by a team of researchers led by psychology professor Philip Zimbardo at Stanford University...
conducted by Philip Zimbardo
Philip Zimbardo
Philip George Zimbardo is an American psychologist and a professor emeritus at Stanford University. He is president of the Heroic Imagination Project...
in 1971, although the extremity of this field experiment is not prototypical of the field. Another notable study is the Stanley Milgram
Stanley Milgram
Stanley Milgram was an American social psychologist most notable for his controversial study known as the Milgram Experiment. The study was conducted in the 1960s during Milgram's professorship at Yale...
obedience experiment, often known as the Milgram experiment
Milgram experiment
The Milgram experiment on obedience to authority figures was a series of notable social psychology experiments conducted by Yale University psychologist Stanley Milgram, which measured the willingness of study participants to obey an authority figure who instructed them to perform acts that...
.
Frankfurt School
One school opposed to experimental psychology has been associated with the Frankfurt School, which calls its ideas "Critical TheoryCritical theory
Critical theory is an examination and critique of society and culture, drawing from knowledge across the social sciences and humanities. The term has two different meanings with different origins and histories: one originating in sociology and the other in literary criticism...
." Critical psychologists claim that experimental psychology approaches humans as entities independent of the cultural, economic, and historical context in which they exist. These contexts of human mental processes and behavior are neglected, according to critical psychologists, like Herbert Marcuse
Herbert Marcuse
Herbert Marcuse was a German Jewish philosopher, sociologist and political theorist, associated with the Frankfurt School of critical theory...
. 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
Jürgen Habermas
Jürgen Habermas is a German sociologist and philosopher in the tradition of critical theory and pragmatism. He is perhaps best known for his theory on the concepts of 'communicative rationality' and the 'public sphere'...
(in their essays in The Positivist Debate in German Sociology).
Critical theory
Critical theory
Critical theory is an examination and critique of society and culture, drawing from knowledge across the social sciences and humanities. The term has two different meanings with different origins and histories: one originating in sociology and the other in literary criticism...
has itself been criticized, however. While the philosopher Karl Popper
Karl Popper
Sir Karl Raimund Popper, CH FRS FBA was an Austro-British philosopher and a professor at the London School of Economics...
"never took their methodology (whatever that may mean) seriously" (p. 289), Popper wrote counter-criticism to reduce the irrationalist' and 'intelligence-destroying "political influence" of critical theorists on students (Karl Popper
Karl Popper
Sir Karl Raimund Popper, CH FRS FBA was an Austro-British philosopher and a professor at the London School of Economics...
pages 288–300 in [The Positivist Debate in German Sociology]). The critical theorists Adorno and Marcuse have been severely criticized by Alasdair MacIntyre
Alasdair MacIntyre
Alasdair Chalmers MacIntyre is a British philosopher primarily known for his contribution to moral and political philosophy but known also for his work in history of philosophy and theology...
in Herbert Marcuse: An Exposition and Polemic. Like Popper, MacIntyre attacked critical theorists like Adorno and especially Marcuse as obscurantists pontificating dogma in the authoritarian fashion of German professors of philosophy of their era—before World War II—(page 11); Popper made a similar criticism of critical theory's rhetoric, which reflected the culture of Hegelian social studies
Social studies
Social studies is the "integrated study of the social sciences and humanities to promote civic competence," as defined by the American National Council for the Social Studies...
in German universities (pp. 293–94). Furthermore, MacIntyre ridiculed Marcuse as being a senile revival of the young Hegelian tradition
Theses on Feuerbach
The "Theses on Feuerbach" are eleven short philosophical notes written by Karl Marx in 1845. They outline a critique of the ideas of Marx's fellow Young Hegelian philosopher Ludwig Feuerbach...
criticized
The German Ideology
The German Ideology is a book written by Karl Marx and Friedrich Engels around April or early May 1846. Marx and Engels did not find a publisher. However, the work was later retrieved and published for the first time in 1932 by David Riazanov through the Marx-Engels Institute in Moscow...
by Marx
Karl Marx
Karl Heinrich Marx was a German philosopher, economist, sociologist, historian, journalist, and revolutionary socialist. His ideas played a significant role in the development of social science and the socialist political movement...
and Engels (pp. 18–19, 41, and 101); similarly, "critical theorys revival of young Hegelianism and its criticism by Karl Marx was noted by Popper (p. 293). Marcuse's support for the political re-education camps of Maoist China
Cultural Revolution
The Great Proletarian Cultural Revolution, commonly known as the Cultural Revolution , was a socio-political movement that took place in the People's Republic of China from 1966 through 1976...
was also criticized as totalitarian by MacIntyre (pp. 101–05). More recently, the Critical Theory
Critical theory
Critical theory is an examination and critique of society and culture, drawing from knowledge across the social sciences and humanities. The term has two different meanings with different origins and histories: one originating in sociology and the other in literary criticism...
of Adorno and Marcuse has been criticized as being a degeneration of the original Frankfurt school
Frankfurt School
The Frankfurt School refers to a school of neo-Marxist interdisciplinary social theory, particularly associated with the Institute for Social Research at the University of Frankfurt am Main...
, particularly the work of empirical psychologist Erich Fromm
Erich Fromm
Erich Seligmann Fromm was a Jewish German-American social psychologist, psychoanalyst, sociologist, humanistic philosopher, and democratic socialist. He was associated with what became known as the Frankfurt School of critical theory.-Life:Erich Fromm was born on March 23, 1900, at Frankfurt am...
, who did surveys and experiments to study the development of personality in response to economic stress and social change (Michael Macoby's Preface to Fromm's Social Character in a Mexican Village).