Basic Psychology: Experimental psychology
Contents
- Introduction
- History
- Methodology
- Experimental instruments
- Institutional review board (IRB)
- Criticism
Introduction
Experimental psychology refers to the work of those who use experimental methods to study psychology and the processes that underpin it. Experimental psychologists use human and animal subjects to investigate a wide range of topics, including sensation and perception, memory, cognition, learning, motivation, and emotion; developmental processes, social psychology, and the neural substrates of all of these.
History
Early experimental psychology
- Wilhelm Wundt
When Wilhelm Wundt introduced a mathematical and experimental approach to the field in the nineteenth century, experimental psychology emerged as a modern academic discipline. In Leipzig, Germany, Wundt established the first psychology laboratory. Other experimental psychologists, such as Hermann Ebbinghaus and Edward Titchener, used introspection as one of their methods.- Charles Bell
Charles Bell was a British physiologist best known for his work on the nervous system. He compiled a pamphlet summarising his rabbit research. His research concluded that sensory nerves enter the spinal cord at the posterior (dorsal) roots and motor nerves emerge from the anterior (ventral) roots. Eleven years later, without knowing about Bell's research, a French physiologist named Francois Magendie published the same findings. Because Bell did not publish his findings, this discovery became known as the Bell-Magendie law. Bell's discovery proved that nerves did not transmit vibrations or spirits.- Ernst Heinrich Weber
Weber was a German physician who is regarded as one of the forefathers of experimental psychology. Weber was particularly interested in the sense of touch and kinesthesis. His most memorable contribution to the field of experimental psychology is his suggestion that sensory judgments are relative rather than absolute. This relativity is exemplified by "Weber's Law," which states that the just-noticeable difference, or jnd, is a constant proportion of the ongoing stimulus level.- Gustav Fechner
"Elemente der Psychophysik," which Fechner published in 1860, is widely regarded as the first work of experimental psychology. According to some historians, the publication of "Elemente" marks the beginning of experimental psychology. Weber was not a psychologist, and it was Fechner who recognised the significance of Weber's work in psychology. Fechner was passionate about developing 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 barely discernible differences, and he developed the psychophysical methods of limits, constant stimuli, and adjustment, all of which are still in use today.- Oswald Külpe
Oswald Külpe is the primary founder of Germany's Würzburg School. For about twelve years, he was Wilhelm Wundt's student. Külpe, unlike Wundt, believed that experiments could be used to test higher mental processes. In 1883, he published Grundriss der Psychologie, which contained only scientific facts and made no mention of thought. The lack of thought in his book is surprising given the Würzburg School's emphasis on mental set and imageless thought.- Würzburg School
The Würzburg School's work was a watershed moment in the evolution of experimental psychology. A group of psychologists led by Oswald Külpe founded the School as an alternative to the structuralism of Edward Titchener and Wilhelm Wundt. Those who attended the School concentrated primarily on mental operations such as mental set (Einstellung) and imageless thought. Mental set influences perception and problem solving without the individual's awareness; it can be triggered by instructions or by experience. Similarly, imageless thought, according to Külpe, 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 handed out cards with nonsense syllables written in different colours on them. The subjects were instructed to pay attention to the syllables, and as a result, they did not recall the colours of the nonsense syllables. Such findings called into question the validity of introspection as a research tool, resulting in the decline of voluntarism and structuralism. Many Gestalt psychologists, including Max Wertheimer, were influenced by the work of the Würzburg School.- George Trumbull Ladd
George Trumbull Ladd, who founded Yale University's psychological laboratory in 1879, was the first to introduce experimental psychology to the United States. Ladd's Elements of Physiological Psychology, the first American textbook that extensively discussed experimental psychology, was published in 1887. Between Ladd's establishment of the Yale Laboratory and the publication of his textbook, the epicentre of experimental psychology in the United States shifted to Johns Hopkins University, where George Hall and Charles Sanders Peirce extended and qualified Wundt's work.- Charles Sanders Peirce
Charles S. Peirce, along with his student Joseph Jastrow, randomly assigned volunteers to a blinded, repeated-measures design to assess their ability to discriminate weights. Peirce's experiment influenced other psychologists and educators, who established a research tradition of randomised experiments in laboratories and specialised textbooks in the 1800s. The Peirce–Jastrow experiments were part of Peirce's pragmatic programme to understand human perception; other studies looked at light perception, for example. Peirce 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 of which emphasised the importance of randomization-based inference in statistics. The honour of inventing randomised experiments belongs to Peirce and experimental psychology, decades before the agricultural innovations of Jerzy Neyman and Ronald Fisher.
Peirce's pragmaticist philosophy also included a comprehensive theory of mental representations and cognition, which he studied as semiotics. Throughout his distinguished career in experimental psychology, Peirce's student Joseph Jastrow continued to conduct randomised experiments, much of which would later be recognised as cognitive psychology. In cognitive psychology, there has been a resurgence of interest in Peirce's work. As part of his "experimental logic" and "public philosophy," another Peirce student, John Dewey, conducted experiments on human cognition, particularly in schools.- 20th century
In the mid-twentieth century, behaviourism emerged as the dominant paradigm in psychology, particularly in the United States. This resulted in some mental phenomena being overlooked in experimental psychology. This was less true in Europe, where psychologists such as Sir Frederic Bartlett, Kenneth Craik, W.E. Hick, and Donald Broadbent focused on topics such as thinking, memory, and attention. This laid the groundwork for the subsequent growth of cognitive psychology.
The phrase "experimental psychology" took on new meaning in the latter half of the twentieth century as psychology expanded as a discipline and the size and number of its sub-disciplines grew. Experimental psychologists use a variety of methods and do not limit themselves to a strictly experimental approach, in part because philosophical developments in science have impacted the exclusive prestige of experimentation. In contrast, an experimental method is now widely used in fields other than experimental psychology, such as developmental and social psychology. However, the phrase is still used in the titles of a number of well-established, high-status learned societies and scientific journals, as well as some university psychology courses.
- Charles Bell
Charles Bell was a British physiologist best known for his work on the nervous system. He compiled a pamphlet summarising his rabbit research. His research concluded that sensory nerves enter the spinal cord at the posterior (dorsal) roots and motor nerves emerge from the anterior (ventral) roots. Eleven years later, without knowing about Bell's research, a French physiologist named Francois Magendie published the same findings. Because Bell did not publish his findings, this discovery became known as the Bell-Magendie law. Bell's discovery proved that nerves did not transmit vibrations or spirits.
- Ernst Heinrich Weber
Weber was a German physician who is regarded as one of the forefathers of experimental psychology. Weber was particularly interested in the sense of touch and kinesthesis. His most memorable contribution to the field of experimental psychology is his suggestion that sensory judgments are relative rather than absolute. This relativity is exemplified by "Weber's Law," which states that the just-noticeable difference, or jnd, is a constant proportion of the ongoing stimulus level.
- Gustav Fechner
"Elemente der Psychophysik," which Fechner published in 1860, is widely regarded as the first work of experimental psychology. According to some historians, the publication of "Elemente" marks the beginning of experimental psychology. Weber was not a psychologist, and it was Fechner who recognised the significance of Weber's work in psychology. Fechner was passionate about developing 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 barely discernible differences, and he developed the psychophysical methods of limits, constant stimuli, and adjustment, all of which are still in use today.
- Oswald Külpe
Oswald Külpe is the primary founder of Germany's Würzburg School. For about twelve years, he was Wilhelm Wundt's student. Külpe, unlike Wundt, believed that experiments could be used to test higher mental processes. In 1883, he published Grundriss der Psychologie, which contained only scientific facts and made no mention of thought. The lack of thought in his book is surprising given the Würzburg School's emphasis on mental set and imageless thought.
- Würzburg School
The Würzburg School's work was a watershed moment in the evolution of experimental psychology. A group of psychologists led by Oswald Külpe founded the School as an alternative to the structuralism of Edward Titchener and Wilhelm Wundt. Those who attended the School concentrated primarily on mental operations such as mental set (Einstellung) and imageless thought. Mental set influences perception and problem solving without the individual's awareness; it can be triggered by instructions or by experience. Similarly, imageless thought, according to Külpe, 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 handed out cards with nonsense syllables written in different colours on them. The subjects were instructed to pay attention to the syllables, and as a result, they did not recall the colours of the nonsense syllables. Such findings called into question the validity of introspection as a research tool, resulting in the decline of voluntarism and structuralism. Many Gestalt psychologists, including Max Wertheimer, were influenced by the work of the Würzburg School.
- George Trumbull Ladd
George Trumbull Ladd, who founded Yale University's psychological laboratory in 1879, was the first to introduce experimental psychology to the United States. Ladd's Elements of Physiological Psychology, the first American textbook that extensively discussed experimental psychology, was published in 1887. Between Ladd's establishment of the Yale Laboratory and the publication of his textbook, the epicentre of experimental psychology in the United States shifted to Johns Hopkins University, where George Hall and Charles Sanders Peirce extended and qualified Wundt's work.
- Charles Sanders Peirce
Charles S. Peirce, along with his student Joseph Jastrow, randomly assigned volunteers to a blinded, repeated-measures design to assess their ability to discriminate weights. Peirce's experiment influenced other psychologists and educators, who established a research tradition of randomised experiments in laboratories and specialised textbooks in the 1800s. The Peirce–Jastrow experiments were part of Peirce's pragmatic programme to understand human perception; other studies looked at light perception, for example. Peirce 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 of which emphasised the importance of randomization-based inference in statistics. The honour of inventing randomised experiments belongs to Peirce and experimental psychology, decades before the agricultural innovations of Jerzy Neyman and Ronald Fisher.
Peirce's pragmaticist philosophy also included a comprehensive theory of mental representations and cognition, which he studied as semiotics. Throughout his distinguished career in experimental psychology, Peirce's student Joseph Jastrow continued to conduct randomised experiments, much of which would later be recognised as cognitive psychology. In cognitive psychology, there has been a resurgence of interest in Peirce's work. As part of his "experimental logic" and "public philosophy," another Peirce student, John Dewey, conducted experiments on human cognition, particularly in schools.
- 20th century
In the mid-twentieth century, behaviourism emerged as the dominant paradigm in psychology, particularly in the United States. This resulted in some mental phenomena being overlooked in experimental psychology. This was less true in Europe, where psychologists such as Sir Frederic Bartlett, Kenneth Craik, W.E. Hick, and Donald Broadbent focused on topics such as thinking, memory, and attention. This laid the groundwork for the subsequent growth of cognitive psychology.
The phrase "experimental psychology" took on new meaning in the latter half of the twentieth century as psychology expanded as a discipline and the size and number of its sub-disciplines grew. Experimental psychologists use a variety of methods and do not limit themselves to a strictly experimental approach, in part because philosophical developments in science have impacted the exclusive prestige of experimentation. In contrast, an experimental method is now widely used in fields other than experimental psychology, such as developmental and social psychology. However, the phrase is still used in the titles of a number of well-established, high-status learned societies and scientific journals, as well as some university psychology courses.
Methodology
The study of complex behavioural and mental processes requires sound methodology, which includes the careful definition and control of experimental variables.
Assumptions
- Empiricism
The most fundamental assumption of science is that factual statements about the world must eventually be based on observations of the world. This definition of empiricism requires hypotheses and theories to be tested against natural world observations rather than a priori reasoning, intuition, or revelation.- Testability
The idea that, in order to be useful, a scientific law or theory must be testable using available research methods is closely related to empiricism. Many scientists consider a theory to be meaningless if it cannot be tested in any way imaginable. Testability implies falsifiability, which is the idea that a set of observations could prove the theory wrong. Because influential or well-known theories such as Freud's have been difficult to test, testability has been emphasised in psychology.- Determinism
Most scientists, including experimental psychologists, believe in determinism. This is the belief that any state of an object or event is determined by its previous states. In other words, behavioural or mental phenomena are frequently described in terms of cause and effect. A phenomenon can be called a "law" if it is sufficiently general and widely confirmed; psychological theories help to organise and integrate laws.- Parsimony
Another guiding principle of science is parsimony, or the pursuit of simplicity. Most scientists, for example, agree that if two theories handle the same set of empirical observations equally well, we should prefer the simpler or more parsimonious of the two. The mediaeval English philosopher William of Occam made a notable early argument for parsimony, and as a result, the principle of parsimony is often referred to as Occam's razor.- Operational definition
The concept of operationism, or operational definition, was popularised by well-known behaviourists such as Edward C. Tolman and Clark Hull. The term "operational definition" refers to the process of defining a concept in terms of concrete, observable procedures. Experimental psychologists use chains of reasoning to connect previously unobservable phenomena, such as mental events, to observations.
- Testability
The idea that, in order to be useful, a scientific law or theory must be testable using available research methods is closely related to empiricism. Many scientists consider a theory to be meaningless if it cannot be tested in any way imaginable. Testability implies falsifiability, which is the idea that a set of observations could prove the theory wrong. Because influential or well-known theories such as Freud's have been difficult to test, testability has been emphasised in psychology.
- Determinism
Most scientists, including experimental psychologists, believe in determinism. This is the belief that any state of an object or event is determined by its previous states. In other words, behavioural or mental phenomena are frequently described in terms of cause and effect. A phenomenon can be called a "law" if it is sufficiently general and widely confirmed; psychological theories help to organise and integrate laws.
- Parsimony
Another guiding principle of science is parsimony, or the pursuit of simplicity. Most scientists, for example, agree that if two theories handle the same set of empirical observations equally well, we should prefer the simpler or more parsimonious of the two. The mediaeval English philosopher William of Occam made a notable early argument for parsimony, and as a result, the principle of parsimony is often referred to as Occam's razor.
- Operational definition
The concept of operationism, or operational definition, was popularised by well-known behaviourists such as Edward C. Tolman and Clark Hull. The term "operational definition" refers to the process of defining a concept in terms of concrete, observable procedures. Experimental psychologists use chains of reasoning to connect previously unobservable phenomena, such as mental events, to observations.
Experiments
Human participants in experiments frequently respond to visual, auditory, or other stimuli, following instructions from an experimenter; animals can be similarly "instructed" by rewarding appropriate responses. Since the 1990s, computers have been widely used in the laboratory to automate stimulus presentation and behavioural measurement. Behavioral experiments with humans and animals typically measure reaction time, choice between two or more alternatives, and/or response rate or strength; movements, facial expressions, and other behaviours may also be recorded. Experiments with humans may also elicit written responses prior to, during, and after the procedures. Psychophysiological experiments, on the other hand, use methods such as fMRI, EEG, PET, or similar to measure brain or (mostly in animals) single-cell activation during the presentation of a stimulus.
Extrinsic variable control, minimising the potential for experimenter bias, balancing the order of experimental tasks, adequate sample size, the use of operational definitions, an emphasis on both the reliability and validity of results, and proper statistical analysis are all important aspects of experimental methods in psychology. Because an understanding of these issues is critical for data interpretation in almost all fields of psychology, undergraduate programmes in psychology typically include research methods and statistics courses as required.
- Crucial experiment
A crucial experiment is one that is designed to test multiple hypotheses at the same time. In an ideal world, one hypothesis would be confirmed while all others would be rejected. However, the data may also be consistent with several hypotheses, implying that more research is needed to narrow the possibilities.
- Pilot study
A pilot study may be conducted prior to a major experiment to test different procedures, determine optimal values for experimental variables, or uncover flaws in experimental design. The pilot study may not be an experiment in the traditional sense; it may, for example, consist solely of self-reports.
- Field experiment
Participants in a field experiment are observed in a naturalistic setting outside of the laboratory. Field experiments differ from field studies in that a controlled portion of the environment (the field) is manipulated (for example, researchers give different kinds of toys to two different groups of children in a nursery school). Control is typically laxer than it would be in a laboratory.
Psychologists frequently employ other research methods such as case studies, interviews, opinion polls, and naturalistic observation. These are not experimental methods because they lack features such as well-defined, controlled variables, randomization, and isolation from unfavourable variables.
Reliability and Validity
- Reliability
The consistency or repeatability of an observation is measured by reliability. One method for assessing reliability is the "test-retest" method, which involves measuring a group of participants once and then testing them again to see if the results are consistent. Other methods are frequently used because the results of the first test may affect the results of the second test. In the "split-half" measure, for example, a group of participants is randomly divided into two comparable sub-groups, and reliability is measured by comparing the test results from these groups. It is important to note that a reliable measure does not have to yield a valid conclusion.
- Validity
The consistency or repeatability of an observation is measured by reliability. One method for assessing reliability is the "test-retest" method, which involves measuring a group of participants once and then testing them again to see if the results are consistent. Other methods are frequently used because the results of the first test may affect the results of the second test. In the "split-half" measure, for example, a group of participants is randomly divided into two comparable sub-groups, and reliability is measured by comparing the test results from these groups. It is important to note that a reliable measure does not have to yield a valid conclusion.
Several types of validity have been distinguished, as follows:
- Internal validity
- External validity
- Construct validity
- Conceptual validity
Scales of measurement
Measurement is defined as "the application of numerals to objects or events in accordance with rules." Almost all psychological experiments involve some form of measurement, if only to determine the reliability and validity of the results, and measurement is, of course, required if the results are to be relevant to quantitative theories. A "scale" is a rule for assigning numbers to a property of an object or event. The basic scales used in psychological measurement are listed below.
- Nominal measurement
In a nominal scale, numbers serve only as labels; a letter or name would suffice. Examples include the numbers on football or baseball players' shirts. Labels are more useful if they can be applied to more than one thing, indicating that the items are similar in some way and can be classified together.
- Ordinal measurement
An ordinal scale is formed by ordering or ranking objects in such a way that A is greater than B, B is greater than C, and so on. Many psychological experiments produce numbers of this type; for example, a participant may be able to rank odours such that A is more pleasant than B and B is more pleasant than C, but these rankings ("1, 2, 3...") would not indicate how much each odour differed from another. Some statistics, such as median, percentile, and order correlation, can be computed from ordinal measures, but others, such as standard deviation, cannot.
- Interval measurement
The equality of differences between the things measured is used to construct an interval scale. That is, when the differences between the numbers correspond to differences in the properties measured, the numbers form an interval scale. For example, the difference between 5 and 10 degrees on a Fahrenheit thermometer equals the difference between 25 and 30, but it is meaningless to say that something at 20 degrees Fahrenheit is "twice as hot" as something at 10 degrees. (On an absolute temperature scale, such as the Kelvin scale, such ratios are meaningful.) (See the following section.) "Standard scores" on an achievement test are said to be interval scale measurements, but this is difficult to prove.
- Ratio measurement
The equality of ratios is used to build a ratio scale. For example, if object A balances two identical objects B on a balance instrument, one can say that A is twice as heavy as B and give them appropriate numbers, such as "A weighs 2 grammes" and "B weighs 1 gramme." A key concept is that such ratios remain constant regardless of scale unit; for example, the ratio of A to B remains constant whether grammes or ounces are used. Ratio scales can also be used to measure length, resistance, and Kelvin temperature. A ratio scale can be used to measure some psychological properties, such as the loudness of a sound.
Research design
- One-way designs
A one-way design with only one independent variable is the most basic experimental design. The most basic type of one-way design consists of only two groups, each of which receives one value of the independent variable. A two-group design typically consists of an experimental (treatment) group and a control group (a group that does not receive treatment). The one-way design can be expanded to include multiple groups. In this case, a single independent variable has three or more levels. This type of design is especially useful because it can aid in the development of a functional relationship between the independent and dependent variables.
- Factorial designs
One-way designs have the limitation of allowing researchers to examine only one independent variable at a time, whereas many phenomena of interest are dependent on multiple variables. R.A Fisher popularised the use of factorial designs as a result of this. Factorial designs have two or more independent variables that are completely "crossed," meaning that at every level, each independent variable appears in combination with every level of all other independent variables. Factorial designs are labelled with the number of independent variables and the number of levels of each independent variable in the design. A 2x3 factorial design, for example, has two independent variables (because there are two numbers in the description), the first with two levels and the second with three.
- Main effects and interactions
The effects of independent variables in factorial studies are referred to as main effects when they are considered separately. This is the overall effect of an independent variable, calculated by averaging all levels of the other independent variables. In a one-way design, the only effect detectable is the main effect. Interactions, which occur when the effect of one independent variable on a dependent variable depends on the level of a second independent variable, are frequently more important than main effects. The ability to catch a ball, for example, may be affected by the interaction of visual acuity (independent variable #1) and the size of the ball being caught (independent variable #2). A person with good eyesight may find it easier to catch a small ball, whereas a person with very poor eyesight may find it easier to catch a large ball, so the two variables can be said to interact.
- Within- and between-subjects designs
Within-subjects design and between-subjects design are the two basic approaches to research design. Each participant in a within-subjects or repeated measures design serves in more than one or possibly all of the conditions of a study. Each participant in a between-subjects design serves in only one condition of an experiment. Within-subjects designs have significant advantages over between-subjects designs, particularly in complex factorial designs with multiple conditions. Within subjects designs, in particular, eliminate person confounds, that is, effects caused by differences among subjects that are irrelevant to the phenomenon under study. The within-subject design, on the other hand, has the serious disadvantage of possible sequence effects. Because each participant serves in more than one condition, the passage of time or the completion of an earlier task may have an impact on the completion of a later task. For example, a participant may learn something from the first task that has an impact on the second.
Experimental instruments
Instruments used in experimental psychology evolved in tandem with technological advancements and changing experimental demands. The Hipp Chronoscope and the kymograph, for example, were originally used for other purposes. The list below illustrates some of the various instruments used over the years.
- Hipp chronoscope / chronograph
This instrument, invented around 1850 by Matthäus Hipp, uses a vibrating reed to count time in 1000ths of a second. Originally intended for physics experiments, it was later adapted to study the speed of bullets. [30] It was later used in psychology to measure reaction time and the duration of mental processes after being introduced to physiology.
- Stereoscope
Wheatstone invented the first stereoscope in 1838. It simultaneously displays two slightly different images, one for each eye. The images are typically photographs of the same object taken from camera positions that mimic the position and separation of the eyes in the head. When viewed through the stereoscope, the photos combine to form a single image with a strong sense of depth and solidity.- Kymograph
The kymograph, invented by Carl Ludwig in the nineteenth century, is a revolving drum on which a moving stylus tracks the size of some measurement as a function of time. The kymograph is similar to the polygraph in that it uses a strip of paper that moves beneath one or more pens. The kymograph was invented to measure blood pressure, but it was later used to measure muscle contractions and speech sounds as well. It was frequently used in psychology to record response times.- Photokymographs
This device is a digital camera with a built-in recorder. The photos were taken using mirrors and light. Two drive rollers are connected by film inside a small box with a slit for light. Light enters through the slit to be recorded on film. Some photokymographs include a lens to achieve the proper film speed.- Galvanometer
The galvanometer was one of the first instruments used to measure the strength of an electric current. Hermann von Helmholtz used it to detect electrical signals generated by nerve impulses and, as a result, to calculate the time it takes impulses to travel between two points on a nerve.- Audiometer
This apparatus was designed to generate a number of fixed frequencies at varying intensities. It could either send the tone to the subject's ear or send sound oscillations to the skull. An audiometer is typically used by an experimenter to determine a subject's auditory threshold. An audiogram is the name given to the data obtained from an audiometer.- Colorimeters
These determine the colour composition by measuring the tricolour characteristics of the material or matching a colour sample. In visual experiments, this type of device would be used.- Algesiometers and algometers
Both of these are mechanical pain stimuli. They have a sharp needle-like stimulus point, so there is no pressure sensation. When conducting an analgesia experiment, experimenters use these.- Olfactometer
An olfactometer is any device that measures one's sense of smell. In early studies, the most basic type involved placing a subject in a room containing a specific measured amount of an odorous substance. Sniffing devices, such as the neck of a bottle, are used in more complex devices. The Zwaardemker olfactometer was once the most common olfactometer found in psychology laboratories. It featured two glass nasal tubes that were projected through a screen. One end is inserted into a stimulus chamber, while the other is inserted directly into the nostrils.- Mazes
The maze is probably one of the oldest instruments for studying memory. The goal is to get from point A to point B, but the mazes vary in size and complexity. The radial arm maze and the Morris water maze are two types of mazes that are commonly used with rats. The radial arm maze is made up of multiple arms that radiate from a central point. At the end of each arm is a small piece of food. Institutional review board (IRB)
The IRB also ensures that human participants provide informed consent in advance, which means that they are informed about the general nature of the experiment and what will be expected of them. An IRB may conduct one of three types of reviews: exempt, expedited, or full review. More information can be found on the main IRB page.Criticism
Frankfurt school
The Frankfurt School, which calls its ideas "Critical Theory," has been associated with one school that is opposed to experimental psychology. According to critical psychologists, experimental psychology approaches humans as entities separate from the cultural, economic, and historical contexts in which they exist. According to critical psychologists such as Herbert Marcuse, these contexts of human mental processes and behaviour are ignored. According to critical theorists such as Theodor Adorno and Jürgen Habermas, experimental psychologists paint an inaccurate portrait of human nature while tacitly supporting the existing social order (in their essays in The Positivist Debate in German Sociology).
- Kymograph
The kymograph, invented by Carl Ludwig in the nineteenth century, is a revolving drum on which a moving stylus tracks the size of some measurement as a function of time. The kymograph is similar to the polygraph in that it uses a strip of paper that moves beneath one or more pens. The kymograph was invented to measure blood pressure, but it was later used to measure muscle contractions and speech sounds as well. It was frequently used in psychology to record response times.
- Photokymographs
This device is a digital camera with a built-in recorder. The photos were taken using mirrors and light. Two drive rollers are connected by film inside a small box with a slit for light. Light enters through the slit to be recorded on film. Some photokymographs include a lens to achieve the proper film speed.
- Galvanometer
The galvanometer was one of the first instruments used to measure the strength of an electric current. Hermann von Helmholtz used it to detect electrical signals generated by nerve impulses and, as a result, to calculate the time it takes impulses to travel between two points on a nerve.
- Audiometer
This apparatus was designed to generate a number of fixed frequencies at varying intensities. It could either send the tone to the subject's ear or send sound oscillations to the skull. An audiometer is typically used by an experimenter to determine a subject's auditory threshold. An audiogram is the name given to the data obtained from an audiometer.
- Colorimeters
These determine the colour composition by measuring the tricolour characteristics of the material or matching a colour sample. In visual experiments, this type of device would be used.
- Algesiometers and algometers
Both of these are mechanical pain stimuli. They have a sharp needle-like stimulus point, so there is no pressure sensation. When conducting an analgesia experiment, experimenters use these.
- Olfactometer
An olfactometer is any device that measures one's sense of smell. In early studies, the most basic type involved placing a subject in a room containing a specific measured amount of an odorous substance. Sniffing devices, such as the neck of a bottle, are used in more complex devices. The Zwaardemker olfactometer was once the most common olfactometer found in psychology laboratories. It featured two glass nasal tubes that were projected through a screen. One end is inserted into a stimulus chamber, while the other is inserted directly into the nostrils.
- Mazes
The maze is probably one of the oldest instruments for studying memory. The goal is to get from point A to point B, but the mazes vary in size and complexity. The radial arm maze and the Morris water maze are two types of mazes that are commonly used with rats. The radial arm maze is made up of multiple arms that radiate from a central point. At the end of each arm is a small piece of food.
Institutional review board (IRB)
The IRB also ensures that human participants provide informed consent in advance, which means that they are informed about the general nature of the experiment and what will be expected of them. An IRB may conduct one of three types of reviews: exempt, expedited, or full review. More information can be found on the main IRB page.
Criticism
Frankfurt school
The Frankfurt School, which calls its ideas "Critical Theory," has been associated with one school that is opposed to experimental psychology. According to critical psychologists, experimental psychology approaches humans as entities separate from the cultural, economic, and historical contexts in which they exist. According to critical psychologists such as Herbert Marcuse, these contexts of human mental processes and behaviour are ignored. According to critical theorists such as Theodor Adorno and Jürgen Habermas, experimental psychologists paint an inaccurate portrait of human nature while tacitly supporting the existing social order (in their essays in The Positivist Debate in German Sociology).
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