METHODS OF SOCIAL PSYCHOLOGY
First of all, it is necessary to distinguish between quantitative and qualitative research methods.
Towards quantitative include methods for which the main procedures are measurement, categorization and coding .
Experiment
To reduce the influence of these factors, there are two possibilities: strengthening control and creating new techniques. Increased control is associated with the choice of experimental design. In addition, special procedures are created, for example, blind method and double blind method. When a blind method is used, the subject is simply deceived, i.e. give incorrect information about what the study is being conducted for. In the double-blind method, the experimenter himself, interacting with the subjects, does not know what influences were exerted on the subject and whether they were exerted at all.
Natural experiment carried out in a natural environment, in a school, hospital or on the street, during professional activities, communication and interaction with other people.
Research in a natural environment allows one to overcome the main drawback of a laboratory experiment, the inability to generalize to the real situation. Moreover, in most cases participants in a field study do not know that they are participating in an experiment. But even when they know they are involved in research, this is not comparable to the feeling of danger and suspicion that arises in the laboratory.
Main disadvantages of natural experiment are
- inability to control secondary variables,
- -difficulty in changing the independent variable and measuring the dependent one.
Experiment planning includes the following stages:
- Firstly, formulating a hypothesis, defining and operationalizing the variables under study.
- Secondly, choosing an experimental design, procedures for controlling secondary variables and drawing up a representative sample.
- Thirdly, selection of statistical methods for analyzing the obtained data taking into account the chosen experimental design.
But It is not always possible to organize an experiment. * Imagine that you want to test the hypothesis that the correct methods of education have a beneficial effect on the psyche of a developing person, and, as adults, people have better mental fitness and easily adapt to the social environment. Or, the greater a person’s height, the more successful he is in his professional activities. There may be an assumption that people who have an aptitude for the humanities lag behind in the sciences. An active experiment cannot be conducted to test these hypotheses. In some cases this is practically impracticable (you cannot vary height, abilities, gender, etc.), in others it is unethical (you cannot force parents to use bad parenting methods).
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Introduction
The main method of psychological research is experiment - the active intervention of the researcher in the activity of the subject in order to create conditions in which a psychological fact is revealed. There is a laboratory experiment, it takes place under special conditions, special equipment is used, the actions of the subject are determined by instructions, the subject knows that an experiment is being conducted, although he may not know the true meaning of the experiment until the end. The experiment is carried out repeatedly with a large number of subjects, which makes it possible to establish general mathematically and statistically reliable patterns of development of mental phenomena.
All science is based on facts. She collects facts, compares them and draws conclusions, establishes the laws of the field of activity that she studies. The specificity of scientific psychology is that it uses a whole arsenal of scientific methods to accumulate its data.
In psychology, there are three types of actual experimental (in the classical, natural science understanding of the term “experiment”) method:
Natural (field) experiment;
Simulation experiment;
Laboratory experiment.
1. Laboratory experiment
Laboratory experiment, or artificial experiment, in psychology is a type of experiment that is carried out in artificially created conditions (within a scientific laboratory) and in which, as far as possible, interaction of the subjects being studied is ensured only with those factors that interest the experimenter . The subjects under study are the subjects or group of subjects, and the factors of interest to the researcher are called relevant stimuli.
A special type of experimental method involves conducting research in a psychological laboratory equipped with special instruments and devices. This type of experiment, which is also characterized by the greatest artificiality of experimental conditions, is usually used when studying elementary mental functions (sensory and motor reactions, choice reactions, differences in sensory thresholds, etc.) and much less often when studying more complex mental phenomena (thought processes , speech functions, etc.). In a laboratory experiment, instruments and equipment are almost always used. Thus, the “lie detector” arose on the basis of an apparatus that recorded various psychophysiological reactions of the subject when he was presented with stimuli in the form of a list of words to which he gave a motor and verbal response, the latter in the form of an association that arose to the stimulus word. Based on the indicators of the device, the researcher could distinguish the subject’s specific attitude to the words presented and establish emotionally neutral and meaningful stimuli. The development of the polygraph (“lie detector”) was undertaken when a connection (correlation) was established between emotionally significant stimuli and an event that was also personally significant for the individual.
Experimental clinical psychodiagnostics in expert forensic or psychological practice on this basis refers to a laboratory experiment. In an expert situation, the naturalness of the appearance of an expert largely depends on the professionalism of the expert. Obtaining artificial, i.e. false and false data about under the expert destroys the evidentiary role of expert research, like any other experiment.
Following the tradition of positivism, many scientists consider the laboratory experiment to be most consistent with the spirit and subject of objective, scientific, materialistic psychological research.
A laboratory experiment has a number of advantages, which include obtaining more accurate results through the use of special premises, measuring equipment, and simulators; opportunities to simulate conditions that are rarely encountered in everyday life; achieving the greatest accuracy in recording the actions of the subjects in comparison with observation, etc. The disadvantage of a laboratory experiment is that artificial conditions are created for the subjects, which significantly affect the manifestation of their psyche. One should also take into account the fact that not all mental phenomena can be learned.
The specificity that distinguishes a psychological laboratory experiment from experiments in other sciences is the subject-subject nature of the relationship between the experimenter and the subject, expressed in the active interaction between them.
A laboratory experiment is performed in cases where the researcher needs to ensure the greatest possible control over the independent variable and additional variables. Additional variables are irrelevant or irrelevant and random stimuli, which are much more difficult to control in natural conditions.
2. Formative experiment
experiment practice psychodiagnostics
A psychological-pedagogical experiment, or a formative experiment, is a type of experiment specific exclusively to psychology, in which the active influence of the experimental situation on the subject should contribute to his mental development and personal growth.
A psychological and pedagogical experiment requires very high qualifications on the part of the experimenter, since unsuccessful and incorrect use of psychological techniques can lead to negative consequences for the subject.
A psychological-pedagogical experiment is one of the types of psychological experiments.
During a psychological and pedagogical experiment, the formation of a certain quality is assumed (that is why it is also called “formative”), two groups usually participate: experimental and control. Participants in the experimental group are offered a specific task, which (in the opinion of the experimenters) will contribute to the formation of a given quality. The control group of subjects is not given this task. At the end of the experiment, the two groups are compared with each other to evaluate the results obtained.
The formative experiment as a method appeared thanks to the theory of activity (A.N. Leontiev, D.B. Elkonin, etc.), which affirms the idea of the primacy of activity in relation to mental development. During a formative experiment, active actions are performed by both the subjects and the experimenter. A high degree of intervention and control over the main variables is required on the part of the experimenter. This distinguishes experiment from observation or examination.
In a formative experiment, the task is to study a psychological feature in the process of formation. To do this, at the beginning of the experiment, a diagnosis (statement) of the peculiarities of the manifestation of the n-th psychological phenomenon is made, then the subject is asked to undergo a formative experiment, carried out according to a certain experimental program. After this, a control, or final, diagnosis occurs. The experimenter has the opportunity to compare how this program contributes or does not contribute to psychological changes in a person (for example, relieving his neuropsychic stress, developing attention, expanding ways of coping with life situations, developing communicative competence, managing oneself or others, etc.) . Any psychological training that involves a research task can be considered a formative experiment. When its effectiveness is proven, it is introduced into the practice of psychological services and brings real benefits.
Specific, private formative research methods in psychology include:
transformative experiment
psychological and pedagogical experiment,
formative experiment,
experimental genetic method,
method of step-by-step formation, etc.
various varieties of the so-called social experiment, the object of which is a certain group of people.
The characteristic features of a formative experiment as a social experiment can be detected when it is described within the framework of any social practice. So, for example, in pedagogy it is:
mass experiment, i.e. statistically significant (this means that its area is the minimum - a school, a teaching staff);
long, prolonged experiment;
an experiment not for the sake of experimentation, but for the sake of the implementation of one or another general theoretical concept in a certain field of psychology (age, children's, pedagogical and other fields);
the experiment is complex, requiring the joint efforts of theoretical psychologists, practical psychologists, research psychologists, didactics, methodologists, etc. And therefore this is an experiment taking place in special institutions where all this can be organized.
According to the psychological dictionary, “a formative experiment is a method used in developmental and educational psychology to trace changes in the child’s psyche in the process of the researcher’s active influence on the subject.
A formative experiment allows one not to limit oneself to the registration of revealed facts, but through the creation of special situations to reveal patterns, mechanisms, dynamics, and trends in the mental development of personality formation, determining the possibilities for optimizing this process.”
In the scientific and educational literature there are often synonyms for formative experiment - transformative, creative, educational, training, genetic-modeling experiment, a method of active formation of the psyche.
The use of formative research methods is associated with the restructuring of certain characteristics of the educational process and identifying the influence of this restructuring on the age, intellectual and characterological characteristics of the subjects. Essentially, this research method acts as a means of creating a broad experimental context for the use of all other methods of psychology.
Formative experiments are often used to compare the effects of various educational programs on the mental development of subjects.
It is generally accepted that a formative experiment is a significant restructuring of psychological and pedagogical practice (as a joint activity of the researcher and the subject) and, first of all, a restructuring of its content and methods, leading to significant modifications in the course of mental development and characterological characteristics of the subjects. It is precisely because of these characteristics that this type of research methods in various branches of psychology reveals the reserves of mental development and at the same time constructs and creates new psychological characteristics of the subjects. Therefore, formative and educational experiments are included in a special category of methods of psychological research and influence. They allow you to purposefully form the characteristics of such mental processes as perception, attention, memory, thinking.
In conclusion, it should be noted that in the process of development of psychology, not only theories and concepts change, but also research methods: they lose their contemplative, ascertaining character, and become formative or, more precisely, transformative. The leading type of research method in the experimental field of psychology is the formative experiment.
So, the development of the methodological arsenal of modern psychology consists in a special consolidation of all research methods, when usually in psychological research not one method is used, but a whole set of different methods that, mutually intertwined, control and complement each other. The net result is the formation of a new set of research methods - a formative experiment.
Conclusion
Thus, several conclusions can be drawn:
An experiment is understood as a research method in which certain conditions are created that are necessary and sufficient for the manifestation and measurement of the connection between phenomena that interest us. The basic logic of a social experiment is that by selecting an experimental social group (or groups) and placing it in an experimental situation, i.e. under the influence of certain social factors, the direction, magnitude and sustainability of changes in the social parameters of interest to the researcher are traced.
The results of the experiment largely depend on the organization, planning and creation of appropriate conditions for its conduct
The use of an experiment requires compliance with certain requirements: goal setting; planning; putting forward a hypothesis; selection of subjects.
Bibliography
1. Goodwin J. Research in psychology: methods and planning / J. Goodwin. -- 3rd ed. - St. Petersburg: Peter, 2004.
2. Gottsdanker R. Fundamentals of psychological experiment / R. Gottsdanker. - M.: MSU, 1982.
3. Zarochentsev K.D. Experimental psychology: textbook. / K.D. Zarochentsev, A.I. Khudyakov. - M.: Prospekt, 2005.
4. Campbell D. Models of experiments in social psychology and applied research / D. Campbell. - M.: Progress 1980.
6. Nikandrov V.V. Observation and experiment in psychology / V.V Nikandrov. - St. Petersburg: Rech, 2002.
7. Solso R.L. Experimental psychology: a practical course / R.L. Solso, H.H. Johnson, M.K. Bill. - St. Petersburg: Prime-Eurosign, 2001.
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V.V. Nikandrov points out that achieving the main goal of the experiment - the utmost possible unambiguity in understanding the connections between the phenomena of internal mental life and their external manifestations - is achieved thanks to the following main characteristics of the experiment:
1) the initiative of the experimenter in the manifestation of psychological facts of interest to him;
2) the possibility of varying the conditions for the emergence and development of mental phenomena;
3) strict control and recording of conditions and the process of their occurrence;
4) isolating some and emphasizing other factors that determine the phenomena being studied, which makes it possible to identify the patterns of their existence;
5) the possibility of repeating experimental conditions for multiple verification of the obtained scientific data and their accumulation;
6) varying the conditions for quantitative assessments of the identified patterns.
Thus, a psychological experiment can be defined as a method in which the researcher himself causes the phenomena of interest to him and changes the conditions for their occurrence in order to establish the reasons for the occurrence of these phenomena and the patterns of their development. In addition, the obtained scientific facts can be repeatedly reproduced due to controllability and strict control of conditions, which makes it possible to verify them, as well as the accumulation of quantitative data, on the basis of which one can judge the typicality or randomness of the phenomena being studied.
4.2. Types of psychological experiment
There are several types of experiments. Depending on the way of organizing There are laboratory, natural and field experiments. Laboratory the experiment is carried out under special conditions. The researcher plans and purposefully influences the object of study in order to change its state. The advantage of a laboratory experiment can be considered strict control over all conditions, as well as the use of special equipment for measurement. The disadvantage of a laboratory experiment is the difficulty of transferring the obtained data to real conditions. The subject in a laboratory experiment is always aware of his participation in it, which can cause motivational distortions.
Natural The experiment is carried out under real conditions. Its advantage is that the study of an object is carried out in the context of everyday life, so the data obtained are easily transferred to reality. The subjects are not always informed about their participation in the experiment, so they do not give motivational distortions. Disadvantages: inability to control all conditions, unexpected interference and distortion.
Field The experiment is carried out according to the natural scheme. In this case, it is possible to use portable equipment that allows more accurate recording of the received data. The subjects are informed about their participation in the experiment, but the familiar environment reduces the level of motivational distortions.
Depending on the research objectives There are search, pilot and confirmatory experiments. Search the experiment is aimed at finding a cause-and-effect relationship between phenomena. It is carried out at the initial stage of the study, allows you to formulate a hypothesis, identify independent, dependent and secondary variables (see 4.4) and determine ways to control them.
Aerobatic The experiment is a trial experiment, the first in a series. It is conducted on a small sample, without strict control of variables. A pilot experiment allows you to eliminate gross errors in the formulation of a hypothesis, specify the goal, and clarify the methodology for conducting the experiment.
Confirming the experiment is aimed at establishing the type of functional connection and clarifying the quantitative relationships between variables. Conducted at the final stage of the study.
Depending on the nature of influence The test subject is divided into ascertaining, formative and control experiments. Ascertaining an experiment includes measuring the state of an object (a subject or a group of subjects) before active influence on it, diagnosing the initial state, and establishing cause-and-effect relationships between phenomena. Purpose formative experiment is the use of methods for the active development or formation of any properties in subjects. Control An experiment is a repeated measurement of the state of an object (a subject or a group of subjects) and a comparison with the state before the start of the formative experiment, as well as with the state in which the control group was located, which did not receive experimental influence.
By possibilities of influence The experimenter's independent variable is distinguished between the induced experiment and the experiment referred to. Provoked An experiment is an experience in which the experimenter himself changes the independent variable, while the results observed by the experimenter (types of reactions of the subject) are considered provoked. P. Fress calls this type of experiment “classical”. Experiment, which is referred to is an experiment in which changes in the independent variable are carried out without intervention by the experimenter. This type of psychological experiment is resorted to when independent variables have an impact on the subject that is significantly extended over time (for example, the education system, etc.). If the effect on the subject can cause serious negative physiological or psychological impairment, then such an experiment cannot be carried out. However, there are times when a negative impact (such as a brain injury) actually occurs. Subsequently, such cases can be generalized and studied.
4.3. Structure of a psychological experiment
The main components of any experiment are:
1) subject (subject or group being studied);
2) experimenter (researcher);
3) stimulation (the method of influencing the subject chosen by the experimenter);
4) the subject’s response to stimulation (his mental reaction);
5) experimental conditions (in addition to stimulation, influences that can influence the reactions of the subject).
The subject's answer is an external reaction, by which one can judge the processes occurring in his internal, subjective space. These processes themselves are the result of the influence of stimulation and experimental conditions on it.
If the response (reaction) of the subject is denoted by the symbol R, and the influence of the experimental situation on him (as a set of stimulation effects and experimental conditions) is denoted by the symbol S, then their relationship can be expressed by the formula R = =f(S). That is, the reaction is a function of the situation. But this formula does not take into account the active role of the psyche, the human personality (P). In reality, a person’s reaction to a situation is always mediated by the psyche and personality. Thus, the relationship between the main elements of the experiment can be fixed by the following formula: R = f(R, S).
P. Fresse and J. Piaget, depending on the objectives of the study, distinguish three classical types of relationships between these three components of the experiment: 1) functional relationships; 2) structural relations; 3) differential relations.
Functional relationships are characterized by the variability of the responses (R) of the subject (P) with systematic qualitative or quantitative changes in the situation (S). Graphically, these relationships can be represented by the following diagram (Fig. 2).
Examples of functional relationships identified in experiments: changes in sensations (R) depending on the intensity of the impact on the senses (S); memory capacity (R) from the number of repetitions (S); intensity of emotional response (R) on the action of various emotiogenic factors (S); development of adaptation processes (R) in time (S) and so on.
Structural relationships are revealed through a system of responses (R1, R2, Rn) to various situations (Sv S2, Sn). The relationships between individual responses are structured into a system that reflects the structure of personality (P). Schematically it looks like this (Fig. 3).
Examples of structural relationships: a system of emotional reactions (Rp R2, Rn) to the action of stressors (Sv S2, Sn); solution efficiency (R1, R2, Rn) various intellectual tasks (S1, S2, Sn) and so on.
Differential relations are identified through analysis of reactions (R1, R2, Rn) of different subjects (P1, P2, Pn) for the same situation (S). The diagram of these relationships is as follows (Fig. 4).
Examples of differential relationships: differences in reaction speed between different people, national differences in the expressive manifestation of emotions, etc.
4.4. Experimental variables and ways to control them
To clarify the relationship between all factors included in the experiment, the concept of “variable” was introduced. There are three types of variables: independent, dependent and additional.
Independent variables. A factor that can be changed by the experimenter himself is called independent variable(NP).
The NP in an experiment can be the conditions in which the subject’s activity is carried out, the characteristics of the tasks that the subject is required to perform, the characteristics of the subject himself (age, gender, other differences between the subjects, emotional states and other properties of the subject or people interacting with him). Therefore, it is customary to highlight the following types NP: situational, instructive and personal.
Situational NPs most often are not included in the structure of the experimental task performed by the subject. However, they have a direct impact on his activity and can be varied by the experimenter. Situational NPs include various physical parameters, such as illumination, temperature, noise level, as well as the size of the room, furnishings, placement of equipment, etc. The socio-psychological parameters of situational NPs may include performing an experimental task in isolation, in the presence of an experimenter, an external observer or group of people. V.N. Druzhinin points to the peculiarities of communication and interaction between the subject and the experimenter as a special type of situational NP. Much attention is paid to this aspect. In experimental psychology there is a separate direction called “psychology of psychological experiment”.
Instructional NP are directly related to the experimental task, its qualitative and quantitative characteristics, as well as methods of its implementation. The experimenter can manipulate the instructive NP more or less freely. He can vary the material of the task (for example, numerical, verbal or figurative), the type of response of the subject (for example, verbal or non-verbal), the rating scale, etc. Great possibilities lie in the way of instructing the subjects, informing them about the purpose of the experimental task. The experimenter can change the means that are offered to the subject to complete the task, put obstacles in front of him, use a system of rewards and punishments during the task, etc.
Personal NPs represent controllable characteristics of the subject. Typically, such features are the states of the experiment participant, which the researcher can change, for example, various emotional states or states of performance-fatigue.
Each subject participating in the experiment has many unique physical, biological, psychological, socio-psychological and social characteristics that the experimenter cannot control. In some cases, these uncontrollable characteristics should be considered additional variables and control methods should be applied to them, which will be discussed below. However, in differential psychological research, when using factorial designs, uncontrolled personal variables can act as one of the independent variables (for details on factorial designs, see 4.7).
Researchers also distinguish between different kinds independent variables. Depending on the presentation scales Qualitative and quantitative NPs can be distinguished. High quality NPs correspond to different gradations of naming scales. For example, the emotional states of the subject can be represented by states of joy, anger, fear, surprise, etc. Methods of performing tasks may include the presence or absence of prompts for the subject. Quantitative NPs correspond to rank, proportional or interval scales. For example, the time allotted to complete a task, the number of tasks, the amount of remuneration based on the results of solving problems can be used as quantitative NP.
Depending on the number of manifestation levels independent variables distinguish between two-level and multi-level NPs. Two-level NPs have two levels of manifestation, multi-level– three or more levels. Depending on the number of levels of manifestation of NP, experimental plans of varying complexity are constructed.
Dependent Variables. A factor whose change is a consequence of a change in the independent variable is called dependent variable(ZP). The dependent variable is the component of the subject's response that is of direct interest to the researcher. Physiological, emotional, behavioral reactions and other psychological characteristics that can be recorded during psychological experiments can act as PP.
Depending on the the method by which changes can be registered, allocate salary:
S directly observable;
S requiring physical equipment for measurement;
S requiring a psychological dimension.
To the salary, directly observable include verbal and non-verbal behavioral manifestations that can be clearly and unambiguously assessed by an external observer, for example, refusal of activity, crying, a certain statement by the subject, etc. physical equipment for registration, include physiological (pulse, blood pressure, etc.) and psychophysiological reactions (reaction time, latent time, duration, speed of action, etc.). For POs requiring psychological dimension, include such characteristics as the level of aspirations, the level of development or formation of certain qualities, forms of behavior, etc. For psychological measurement of indicators, standardized procedures can be used - tests, questionnaires, etc. Some behavioral parameters can be measured, i.e. i.e. clearly recognized and interpreted only by specially trained observers or experts.
Depending on the number of parameters, included in the dependent variable, there are unidimensional, multidimensional and fundamental PPs. One-dimensional ZP is represented by a single parameter, changes in which are studied in the experiment. An example of a one-dimensional PP is the speed of a sensorimotor reaction. Multidimensional The salary is represented by a set of parameters. For example, attentiveness can be assessed by the volume of material viewed, the number of distractions, the number of correct and incorrect answers, etc. Each parameter can be recorded independently. Fundamental ZP is a complex variable, the parameters of which have certain known relationships with each other. In this case, some parameters act as arguments, and the dependent variable itself acts as a function. For example, the fundamental dimension of the level of aggression can be considered as a function of its individual manifestations (facial, verbal, physical, etc.).
The dependent variable must have such a basic characteristic as sensitivity. Sensitivity FP is its sensitivity to changes in the level of the independent variable. If, when the independent variable changes, the dependent variable does not change, then the latter is non-positive and it makes no sense to conduct an experiment in this case. There are two known variants of the manifestation of non-positivity of the PP: the “ceiling effect” and the “floor effect”. The “ceiling effect” is observed, for example, in the case when the presented task is so simple that all subjects, regardless of age, perform it. The “floor effect,” on the other hand, occurs when a task is so difficult that none of the subjects can cope with it.
There are two main ways to record changes in mental health in a psychological experiment: immediate and delayed. Direct The method is used, for example, in short-term memory experiments. Immediately after repeating a number of stimuli, the experimenter records their number reproduced by the subject. The deferred method is used when between influence and the effect lasts for a certain period of time (for example, when determining the influence of the number of memorized foreign words on the success of translating a text).
Additional Variables(DP) is a concomitant stimulation of the subject that influences his response. The set of DP consists, as a rule, of two groups: external conditions of experience and internal factors. Accordingly, they are usually called external and internal DPs. TO external DP include the physical environment of the experiment (lighting, temperature, sound background, spatial characteristics of the room), parameters of the apparatus and equipment (design of measuring instruments, operating noise, etc.), time parameters of the experiment (start time, duration, etc.), experimenter's personality. TO internal DP includes the mood and motivation of the subjects, their attitude towards the experimenter and the experiments, their psychological attitudes, inclinations, knowledge, abilities, skills and experience in this type of activity, level of fatigue, well-being, etc.
Ideally, the researcher strives to reduce all additional variables to nothing or at least to a minimum in order to highlight the “pure” relationship between the independent and dependent variables. There are several main ways to control the influence of external DP: 1) elimination of external influences; 2) constancy of conditions; 3) balancing; 4) counterbalancing.
Elimination of external influences represents the most radical method of control. It consists of the complete exclusion from the external environment of any external DP. In the laboratory, conditions are created that isolate the subject from sounds, light, vibrations, etc. The most striking example is a sensory deprivation experiment conducted on volunteers in a special chamber that completely excludes the entry of any irritants from the external environment. It should be noted that it is almost impossible to eliminate the effects of DP, and it is not always necessary, since the results obtained under the conditions of eliminating external influences can hardly be transferred to reality.
The next method of control is to create constant conditions. The essence of this method is to make the effects of DP constant and identical for all subjects throughout the experiment. In particular, the researcher strives to make constant the spatio-temporal conditions of the experiment, the technique of its conduct, equipment, presentation of instructions, etc. With careful application of this method of control, large errors can be avoided, but the problem of transferring the results of the experiment to conditions that are very different from the experimental ones is difficult. remains problematic.
In cases where it is not possible to create and maintain constant conditions throughout the experiment, resort to the method balancing. This method is used, for example, in a situation where the external DP cannot be identified. In this case, balancing will consist of using a control group. The study of the control and experimental groups is carried out under the same conditions with the only difference being that in the control group there is no effect of the independent variable. Thus, the change in the dependent variable in the control group is due only to external DP, while in the experimental group it is due to the combined effect of external additional and independent variables.
If the external DP is known, then balancing consists of the effect of each of its values in combination with each level of the independent variable. In particular, such an external DP as the gender of the experimenter, in combination with an independent variable (the gender of the subject), will lead to the creation of four experimental series:
1) male experimenter - male subjects;
2) male experimenter – female subjects;
3) female experimenter - male subjects;
4) female experimenter - female subjects.
More complex experiments may involve balancing multiple variables simultaneously.
Counterbalancing as a way to control external DP, it is most often practiced when the experiment includes several series. The subject is exposed to different conditions sequentially, but previous conditions can change the effect of subsequent ones. To eliminate the “sequence effect” that arises in this case, experimental conditions are presented to different groups of subjects in different orders. For example, in the first series of the experiment, the first group is presented with solving intellectual problems from simpler to more complex, and the second group - from more complex to simpler. In the second series, on the contrary, the first group is presented with solving intellectual problems from more complex to simpler, and the second group - from simpler to more complex. Counterbalancing is used in cases where it is possible to conduct several series of experiments, but it should be taken into account that a large number of attempts causes fatigue of the subjects.
Internal DP, as mentioned above, are factors hidden in the personality of the subject. They have a very significant impact on the results of the experiment; their impact is quite difficult to control and take into account. Among the internal DPs we can highlight permanent And fickle. Permanent internal DPs do not change significantly during the experiment. If the experiment is carried out with one subject, then the constant internal DP will be his gender, age, and nationality. This group of factors also includes the subject’s temperament, character, abilities, inclinations, interests, views, beliefs and other components of the general orientation of the individual. In the case of an experiment with a group of subjects, these factors acquire the character of unstable internal DPs, and then, to level out their influence, they resort to special methods of forming experimental groups (see 4.6).
TO fickle internal DP includes the psychological and physiological characteristics of the subject, which can either change significantly during the experiment, or be updated (or disappear) depending on the goals, objectives, type, and form of organization of the experiment. The first group of such factors consists of physiological and mental states, fatigue, addiction, and the acquisition of experience and skills in the process of performing an experimental task. The other group includes the attitude towards this experience and this research, the level of motivation for this experimental activity, the attitude of the subject towards the experimenter and his role as a test subject, etc.
To equalize the effect of these variables on responses in different tests, there are a number of methods that have been successfully used in experimental practice.
To eliminate the so-called serial effect, which is based on habituation and uses a special order of stimulus presentation. This procedure is called “balanced alternating order,” when stimuli of different categories are presented symmetrically relative to the center of the stimulus series. The scheme of such a procedure looks like this: A B B A, Where A And IN– incentives of different categories.
To prevent influence on the subject's answer anxiety or inexperience, Introductory or preliminary experiments are carried out. Their results are not taken into account when processing data.
To prevent response variability due to accumulation of experience and skills During the experiment, the subject is offered so-called “exhaustive practice.” As a result of such practice, the subject develops stable skills before the start of the experiment itself, and in further experiments the subject’s performance does not directly depend on the factor of accumulation of experience and skills.
In cases where it is necessary to minimize the influence on the subject’s response fatigue, resort to the “rotation method”. Its essence is that each subgroup of subjects is presented with a certain combination of stimuli. The totality of such combinations completely exhausts the entire set of possible options. For example, with three types of stimuli (A, B, C), each of them is presented with the first, second and third place when presented to the subjects. Thus, the first subgroup is presented with stimuli in the order ABC, the second - AVB, the third - BAV, the fourth - BVA, the fifth - VAB, the sixth - VBA.
The presented methods for procedural equalization of internal non-constant DP are applicable for both individual and group experiments.
The attitude and motivation of the subjects, as internal unstable DPs, must be maintained at the same level throughout the entire experiment. Installation how the willingness to perceive a stimulus and respond to it in a certain way is created through the instructions that the experimenter gives to the subject. In order for the installation to be exactly what is required for the research task, the instructions must be accessible to the subjects and adequate to the objectives of the experiment. The unambiguity and ease of understanding of the instructions are achieved by its clarity and simplicity. To avoid variability in presentation, it is recommended that the instructions be read verbatim or given in writing. Maintenance of the initial setting is controlled by the experimenter through constant observation of the subject and adjusted by reminding, if necessary, the appropriate instructions in the instructions.
Motivation The subject is seen primarily as having an interest in the experiment. If interest is absent or weak, then it is difficult to count on the completeness of the subject’s performance of the tasks provided for in the experiment and on the reliability of his answers. Too much interest, “overmotivation”, is also fraught with inadequacy of the subject’s answers. Therefore, in order to obtain an initially acceptable level of motivation, the experimenter must take the most serious approach to the formation of a contingent of subjects and the selection of factors that stimulate their motivation. Such factors may include competition, various types of remuneration, interest in one’s performance, professional interest, etc.
Psychophysiological conditions It is recommended that subjects not only be maintained at the same level, but also that this level be optimized, i.e., subjects should be in a “normal” state. You should make sure that before the experiment the subject did not have experiences that were extremely significant for him, that he had enough time to participate in the experiment, that he was not hungry, etc. During the experiment, the subject should not be overly excited or suppressed. If these conditions cannot be met, then it is better to postpone the experiment.
From the considered characteristics of the variables and methods of their control, the need for careful preparation of the experiment when planning it becomes clear. In real experimental conditions, it is impossible to achieve 100% control of all variables, but various psychological experiments differ significantly from each other in the degree of control of variables. The next section is devoted to the issue of assessing the quality of the experiment.
4.5. Validity and reliability of the experiment
The following concepts are used to design and evaluate experimental procedures: ideal experiment, perfect compliance experiment, and infinite experiment.
The perfect experiment is an experiment designed in such a way that the experimenter changes only the independent variable, the dependent variable is controlled, and all other experimental conditions remain unchanged. An ideal experiment assumes the equivalence of all subjects, the invariance of their characteristics over time, and the absence of time itself. It can never be implemented in reality, since in life not only the parameters of interest to the researcher change, but also a number of other conditions.
The correspondence of a real experiment to an ideal one is expressed in such characteristics as internal validity. Internal validity shows the reliability of the results that a real experiment provides compared to an ideal one. The more the changes in the dependent variables are influenced by conditions not controlled by the researcher, the lower the internal validity of the experiment, therefore, the greater the likelihood that the facts discovered in the experiment are artifacts. High internal validity is the main sign of a well-conducted experiment.
D. Campbell identifies the following factors that threaten the internal validity of an experiment: background factor, natural development factor, testing factor, measurement error, statistical regression, non-random selection, screening. If they are not controlled, they lead to the appearance of corresponding effects.
Factor background(history) includes events that occur between the preliminary and final measurement and can cause changes in the dependent variable along with the influence of the independent variable. Factor natural development is due to the fact that changes in the level of the dependent variable may occur due to the natural development of the experiment participants (growing up, increasing fatigue, etc.). Factor testing lies in the influence of preliminary measurements on the results of subsequent ones. Factor measurement errors is associated with inaccuracy or changes in the procedure or method for measuring the experimental effect. Factor statistical regression manifests itself if subjects with extreme indicators of any assessments were selected to participate in the experiment. Factor non-random selection Accordingly, it occurs in cases where, when forming a sample, the selection of participants was carried out in a non-random manner. Factor screening manifests itself when subjects drop out unevenly from the control and experimental groups.
The experimenter must take into account and, if possible, limit the influence of factors that threaten the internal validity of the experiment.
Full Compliance Experiment is an experimental study in which all conditions and their changes correspond to reality. The approximation of a real experiment to a complete correspondence experiment is expressed in external validity. The degree of transferability of the experimental results to reality depends on the level of external validity. External validity, as defined by R. Gottsdancker, affects the reliability of the conclusions that the results of a real experiment provide in comparison with a full compliance experiment. To achieve high external validity, it is necessary that the levels of additional variables in the experiment correspond to their levels in reality. An experiment that lacks external validity is considered invalid.
Factors that threaten external validity include the following:
Reactive effect (consists in a decrease or increase in the susceptibility of subjects to experimental influence due to previous measurements);
The effect of the interaction of selection and influence (consists in the fact that the experimental influence will be significant only for the participants in this experiment);
Factor of experimental conditions (can lead to the fact that the experimental effect can only be observed in these specially organized conditions);
Factor of interference of influences (manifests itself when one group of subjects is presented with a sequence of mutually exclusive influences).
Researchers working in applied areas of psychology - clinical, pedagogical, organizational - are especially concerned about the external validity of experiments, since in the case of an invalid study, its results will not give anything when transferring them to real conditions.
Endless experiment involves an unlimited number of experiments and tests to obtain increasingly accurate results. An increase in the number of trials in an experiment with one subject leads to an increase reliability experimental results. In experiments with a group of subjects, an increase in reliability occurs with an increase in the number of subjects. However, the essence of the experiment is precisely to identify cause-and-effect relationships between phenomena on the basis of a limited number of samples or with the help of a limited group of subjects. Therefore, an endless experiment is not only impossible, but also meaningless. To achieve high reliability of an experiment, the number of samples or the number of subjects must correspond to the variability of the phenomenon being studied.
It should be noted that as the number of subjects increases, the external validity of the experiment also increases, since its results can be transferred to a wider population. To conduct experiments with a group of subjects, it is necessary to consider the issue of experimental samples.
4.6. Experimental samples
As stated above, an experiment can be carried out either with one subject or with a group of subjects. An experiment with one subject is carried out only in some specific situations. Firstly, these are situations when the individual differences of the subjects can be neglected, i.e., the subject can be any person (if the experiment studies his characteristics in contrast to, for example, an animal). In other situations, on the contrary, the subject is a unique object (a brilliant chess player, musician, artist, etc.). Situations are also possible when the subject is required to have special competence as a result of training or extraordinary life experience (the only survivor of a plane crash, etc.). They are limited to one subject even in cases where repetition of this experiment with the participation of other subjects is impossible. Special experimental designs have been developed for single-subject experiments (see 4.7 for details).
More often, experiments are carried out with a group of subjects. In these cases, the sample of subjects should represent a model general population, to which the results of the study will then be applied. Initially, the researcher solves the problem of the size of the experimental sample. Depending on the purpose of the study and the capabilities of the experimenter, it can range from several subjects to several thousand people. The number of subjects in a separate group (experimental or control) varies from 1 to 100 people. To apply statistical processing methods, it is recommended that the number of subjects in the compared groups be at least 30–35 people. In addition, it is advisable to increase the number of subjects by at least 5-10% of the required number, since some of them or their results will be “rejected” during the experiment.
To select a sample of subjects, several criteria must be taken into account.
1. Meaningful. It lies in the fact that the selection of a group of subjects must correspond to the subject and hypothesis of the study. (For example, it makes no sense to recruit two-year-old children into a group of test subjects to determine the level of voluntary memorization.) It is desirable to create ideal ideas about the object of experimental research and, when forming a group of subjects, to deviate minimally from the characteristics of the ideal experimental group.
2. Equivalence criterion for subjects. When forming a group of subjects, one should take into account all significant characteristics of the research object, differences in the severity of which can significantly affect the dependent variable.
3. Representativeness criterion. The group of individuals participating in the experiment must represent the entire part of the population to which the results of the experiment will be applied. The size of the experimental sample is determined by the type of statistical measures and the selected accuracy (reliability) of accepting or rejecting the experimental hypothesis.
Let's consider strategies for selecting subjects from the population.
Random strategy is that each member of the population is given an equal chance of being included in the experimental sample. To do this, each individual is assigned a number, and then an experimental sample is formed using a table of random numbers. This procedure is difficult to implement, since each representative of the population of interest to the researcher must be taken into account. In addition, the random strategy gives good results when forming a large experimental sample.
Stratometric sampling is used if the experimental sample must include subjects with a certain set of characteristics (gender, age, level of education, etc.). The sample is compiled in such a way that it includes equally represented subjects from each stratum (layer) with the given characteristics.
Stratometric random sampling combines the two previous strategies. Representatives of each stratum are assigned numbers and an experimental sample is randomly formed from them. This strategy is effective when selecting a small experimental sample.
Representative modeling is used when the researcher manages to create a model of an ideal object of experimental research. The characteristics of a real experimental sample should deviate minimally from the characteristics of an ideal experimental sample. If the researcher does not know all the characteristics of the ideal model of experimental research, then the strategy is used approximate modeling. The more accurate the set of criteria describing the population to which the conclusions of the experiment are supposed to be extended, the higher its external validity.
Sometimes used as an experimental sample real groups, in this case, either volunteers participate in the experiment, or all subjects are recruited forcibly. In both cases, external and internal validity are violated.
After forming an experimental sample, the experimenter draws up a research plan. Quite often, an experiment is carried out with several groups, experimental and control, which are placed in different conditions. The experimental and control groups should be equivalent at the start of the experimental intervention.
The procedure for selecting equivalent groups and subjects is called randomization. According to a number of authors, group equivalence can be achieved by pairwise selection. In this case, the experimental and control groups are composed of individuals who are equivalent in terms of secondary parameters that are significant for the experiment. The ideal option for pairwise selection is to involve twin pairs. Randomization with identification of strata consists in the selection of homogeneous subgroups in which the subjects are equalized for all characteristics, except for additional variables of interest to the researcher. Sometimes, to isolate a significant additional variable, all subjects are tested and ranked according to the level of its severity. The experimental and control groups are formed so that subjects with the same or similar values of the variable are placed in different groups. The distribution of subjects into experimental and control groups can be carried out by random method. As mentioned above, with a large experimental sample, this method gives quite satisfactory results.
4.7. Experimental plans
Experimental design is a tactics of experimental research, embodied in a specific system of experimental planning operations. The main criteria for classifying plans are:
Composition of participants (individual or group);
Number of independent variables and their levels;
Types of scales for presenting independent variables;
Method of collecting experimental data;
Place and conditions of the experiment;
Features of the organization of experimental influence and method of control.
Plans for groups of subjects and for one subject. All experimental plans can be divided according to the composition of participants into plans for groups of subjects and plans for one subject.
Experiments with group of subjects have the following advantages: the ability to generalize the results of the experiment to the population; the possibility of using intergroup comparison schemes; saving time; application of statistical analysis methods. The disadvantages of this type of experimental designs include: the influence of individual differences between people on the results of the experiment; the problem of representativeness of the experimental sample; the problem of equivalence of groups of subjects.
Experiments with one subject- this is a special case of “plans with a small N". J. Goodwin points out the following reasons for using such plans: the need for individual validity, since in experiments with a large N A problem arises when the generalized data does not characterize any subject. An experiment with one subject is also carried out in unique cases when, for a number of reasons, it is impossible to attract many participants. In these cases, the purpose of the experiment is to analyze unique phenomena and individual characteristics.
An experiment with small N, according to D. Martin, has the following advantages: the absence of complex statistical calculations, ease of interpretation of results, the ability to study unique cases, the involvement of one or two participants, and ample opportunities for manipulating independent variables. It also has some disadvantages, in particular the complexity of control procedures, difficulty in generalizing results; relative time inefficiency.
Let's consider plans for one subject.
Planning time series. The main indicator of the influence of the independent variable on the dependent variable when implementing such a plan is the change in the nature of the subject’s responses over time. The simplest strategy: scheme A– B. The subject initially performs the activity in conditions A, and then in conditions B. To control the “placebo effect”, the following scheme is used: A – B – A.(“The placebo effect” is the reactions of subjects to “empty” influences that correspond to reactions to real influences.) In this case, the subject should not know in advance which of the conditions is “empty” and which is real. However, these schemes do not take into account the interaction of influences, therefore, when planning time series, as a rule, regular alternation schemes are used (A - B – A– B), positional adjustment (A – B – B– A) or random alternation. The use of “longer” time series increases the possibility of detecting an effect, but leads to a number of negative consequences - fatigue of the subject, decreased control over other additional variables, etc.
Alternative Impact Plan is a development of the time series plan. Its specificity lies in the fact that the effects A And IN are randomly distributed over time and presented to the subject separately. The effects of each intervention are then compared.
Reversible plan used to study two alternative forms of behavior. Initially, a baseline level of manifestation of both forms of behavior is recorded. Then a complex effect is presented, consisting of a specific component for the first form of behavior and an additional one for the second. After a certain time, the combination of influences is modified. The effect of two complex interventions is assessed.
Criteria increasing plan often used in educational psychology. Its essence is that a change in the subject’s behavior is recorded in response to an increase in exposure. In this case, the next impact is presented only after the subject reaches the specified criterion level.
When conducting experiments with one subject, it should be taken into account that the main artifacts are practically unavoidable. In addition, in this case, like no other, the influence of the experimenter’s attitudes and the relationships that develop between him and the subject are manifested.
R. Gottsdanker suggests distinguishing qualitative and quantitative experimental designs. IN quality In plans, the independent variable is presented on a nominative scale, i.e., two or more qualitatively different conditions are used in the experiment.
IN quantitative In experimental designs, the levels of the independent variable are presented on interval, rank or proportional scales, i.e., the experiment uses the levels of expression of a particular condition.
It is possible that in a factorial experiment one variable will be presented in quantitative form and the other in qualitative form. In this case, the plan will be combined.
Within-group and between-group experimental designs. T.V. Kornilova defines two types of experimental plans according to the criterion of the number of groups and experimental conditions: intragroup and intergroup. TO intragroup refers to designs in which the influence of variations in the independent variable and the measurement of the experimental effect occur in the same group. IN intergroup plans, the influence of variants of the independent variable is carried out in different experimental groups.
The advantages of the within-group design are: a smaller number of participants, the elimination of individual differences factors, a reduction in the total time of the experiment, and the ability to prove the statistical significance of the experimental effect. Disadvantages include the non-constancy of conditions and the manifestation of the “sequence effect”.
The advantages of the intergroup design are: the absence of a “sequence effect”, the possibility of obtaining more data, reducing the time of participation in the experiment for each subject, reducing the effect of dropout of experiment participants. The main disadvantage of the between-groups design is the non-equivalence of the groups.
Single independent variable and factorial designs. According to the criterion of the number of experimental influences, D. Martin proposes to distinguish between plans with one independent variable, factorial plans and plans with a series of experiments. In the plans with one independent variable the experimenter manipulates one independent variable, which can have an unlimited number of manifestations. IN factorial plans (for details about them, see p. 120), the experimenter manipulates two or more independent variables, explores all possible options for the interaction of their different levels.
Plans with a series of experiments are carried out to gradually eliminate competing hypotheses. At the end of the series, the experimenter comes to verify one hypothesis.
Pre-experimental, quasi-experimental, and true experimental designs. D. Campbell proposed dividing all experimental plans for groups of subjects into the following groups: pre-experimental, quasi-experimental and true experimental plans. This division is based on the proximity of a real experiment to an ideal one. The fewer artifacts a particular design provokes and the stricter the control of additional variables, the closer the experiment is to ideal. Pre-experimental plans least of all take into account the requirements for an ideal experiment. V.N. Druzhinin points out that they can only serve as illustrations; in the practice of scientific research they should be avoided if possible. Quasi-experimental designs are an attempt to take into account the realities of life when conducting empirical research; they are specifically created to deviate from the designs of true experiments. The researcher must be aware of the sources of artifacts - external additional variables that he cannot control. A quasi-experimental design is used when a better design cannot be used.
Systematic features of pre-experimental, quasi-experimental and true experimental designs are given in the table below.
When describing experimental plans, we will use the symbolization proposed by D. Campbell: R– randomization; X– experimental influence; O– testing.
TO pre-experimental designs include: 1) single case study; 2) plan with preliminary and final testing of one group; 3) comparison of statistical groups.
At single case study One group is tested once after the experimental intervention. Schematically, this plan can be written as:
Control of external variables and independent variable is completely absent. In such an experiment there is no material for comparison. The results can only be compared with everyday ideas about reality; they do not carry scientific information.
Plan with preliminary and final testing of one group often used in sociological, socio-psychological and pedagogical research. It can be written as:
This design does not have a control group, so it cannot be argued that changes in the dependent variable (the difference between O1 and O2), recorded during testing, are caused precisely by changes in the independent variable. Between the initial and final testing, other “background” events may occur that affect the subjects along with the independent variable. This design also does not control for the natural progression effect and the testing effect.
Comparison of statistical groups it would be more accurate to call it a two-non-equivalent group design with post-exposure testing. It can be written like this:
This design allows for the testing effect to be taken into account by introducing a control group to control for a number of external variables. However, with its help it is impossible to take into account the effect of natural development, since there is no material to compare the state of the subjects at the moment with their initial state (preliminary testing was not carried out). To compare the results of the control and experimental groups, Student's t-test is used. However, it should be taken into account that differences in test results may not be due to experimental effects, but to differences in group composition.
Quasi-experimental designs are a kind of compromise between reality and the strict framework of true experiments. There are the following types of quasi-experimental designs in psychological research: 1) experimental plans for non-equivalent groups; 2) designs with pre-test and post-test of different randomized groups; 3) plans of discrete time series.
Plan experiment for non-equivalent groups is aimed at establishing a cause-and-effect relationship between variables, but it does not have a procedure for equalizing groups (randomization). This plan can be represented by the following diagram:
In this case, two real groups are involved in conducting the experiment. Both groups are tested. One group is then exposed to the experimental treatment while the other is not. Both groups are then retested. The results of the first and second testing of both groups are compared; Student’s t-test and analysis of variance are used for comparison. Difference O2 and O4 indicates natural development and background exposure. To identify the effect of the independent variable, it is necessary to compare 6(O1 O2) and 6(O3 O4), i.e., the magnitude of the shifts in the indicators. The significance of the difference in the increases in indicators will indicate the influence of the independent variable on the dependent one. This design is similar to the design of a true two-group experiment with pre- and post-exposure testing (see page 118). The main source of artifacts is differences in group composition.
Plan with pre- and post-testing of different randomized groups differs from a true experimental design in that one group is pretested and an equivalent group is exposed to the posttest:
The main disadvantage of this quasi-experimental design is the inability to control for background effects—the influence of events that occur alongside the experimental treatment between the first and second testing.
Plans discrete time series are divided into several types depending on the number of groups (one or several), as well as depending on the number of experimental effects (single or series of effects).
The discrete time series design for one group of subjects consists of initially determining the initial level of the dependent variable on a group of subjects using a series of sequential measurements. Then an experimental effect is applied and a series of similar measurements are carried out. The levels of the dependent variable before and after the intervention are compared. The outline of this plan:
The main disadvantage of a discrete time series design is that it does not allow one to separate the effect of the independent variable from the effect of background events that occur during the course of the study.
A modification of this design is a time-series quasi-experiment in which exposure before measurement is alternated with no exposure before measurement. His scheme is as follows:
ХO1 – O2ХO3 – O4 ХO5
Alternation can be regular or random. This option is only suitable if the effect is reversible. When processing the data obtained in the experiment, the series is divided into two sequences and the results of measurements where there was an impact are compared with the results of measurements where there was no impact. To compare data, Student's t-test with the number of degrees of freedom is used n– 2, where n– the number of situations of the same type.
Time series plans are often implemented in practice. However, when using them, the so-called “Hawthorne effect” is often observed. It was first discovered by American scientists in 1939, when they conducted research at the Hawthorne plant in Chicago. It was assumed that changing the labor organization system would increase productivity. However, during the experiment, any changes in the organization of work led to an increase in productivity. As a result, it turned out that participation in the experiment itself increased motivation to work. The subjects realized that they were personally interested in them and began to work more productively. To control for this effect, a control group must be used.
The time series design for two non-equivalent groups, one of which receives no intervention, looks like this:
O1O2O3O4O5O6O7O8O9O10
O1O2O3O4O5O6O7O8O9O10
This plan allows you to control the “background” effect. It is usually used by researchers when studying real groups in educational institutions, clinics, and production.
Another specific design that is often used in psychology is called an experiment. ex-post-facto. It is often used in sociology, pedagogy, as well as neuropsychology and clinical psychology. The strategy for applying this plan is as follows. The experimenter himself does not influence the subjects. The influence is some real event from their life. The experimental group consists of “test subjects” who were exposed to the intervention, and the control group consists of people who did not experience it. In this case, the groups are, if possible, equalized at the time of their state before the impact. Then the dependent variable is tested among representatives of the experimental and control groups. The data obtained as a result of testing are compared and a conclusion is drawn about the impact of the impact on the further behavior of the subjects. Thus the plan ex-post-facto simulates an experimental design for two groups with their equalization and testing after exposure. His scheme is as follows:
If group equivalence can be achieved, then the design becomes a true experimental design. It is implemented in many modern studies. For example, in the study of post-traumatic stress, when people who have suffered the effects of a natural or man-made disaster, or combatants, are tested for the presence of PTSD, their results are compared with the results of a control group, which makes it possible to identify the mechanisms of such reactions. In neuropsychology, brain injuries, lesions of certain structures, considered as “experimental exposure,” provide a unique opportunity to identify the localization of mental functions.
True Experiment Plans for one independent variable differ from others as follows:
1) using strategies to create equivalent groups (randomization);
2) the presence of at least one experimental and one control group;
3) final testing and comparison of the results of groups that received and did not receive the intervention.
Let's take a closer look at some experimental designs for one independent variable.
Two randomized group design with post-exposure testing. His diagram looks like this:
This plan is used if it is not possible or necessary to conduct preliminary testing. If the experimental and control groups are equal, this design is the best because it allows you to control most sources of artifacts. The absence of pretesting excludes both the interaction effect of the testing procedure and the experimental task, as well as the testing effect itself. The plan allows you to control the influence of group composition, spontaneous attrition, the influence of background and natural development, and the interaction of group composition with other factors.
In the example considered, one level of influence of the independent variable was used. If it has several levels, then the number of experimental groups increases to the number of levels of the independent variable.
Two randomized group design with pretest and posttest. The outline of the plan looks like this:
R O1 X O2
This design is used if there is doubt about the results of randomization. The main source of artifacts is the interaction of testing and experimental manipulation. In reality, we also have to deal with the effect of non-simultaneous testing. Therefore, it is considered best to test members of the experimental and control groups in random order. Presentation-non-presentation of the experimental intervention is also best done in random order. D. Campbell notes the need to control “intra-group events.” This experimental design controls well for the background effect and the natural progression effect.
When processing data, parametric criteria are usually used t And F(for data on an interval scale). Three t values are calculated: 1) between O1 and O2; 2) between O3 and O4; 3) between O2 And O4. The hypothesis about the significance of the influence of the independent variable on the dependent variable can be accepted if two conditions are met: 1) differences between O1 And O2 significant, but between O3 And O4 insignificant and 2) differences between O2 And O4 significant. Sometimes it is more convenient to compare not absolute values, but the magnitude of the increase in indicators b(1 2) and b(3 4). These values are also compared using Student's t test. If the differences are significant, the experimental hypothesis about the influence of the independent variable on the dependent variable is accepted.
Solomon's Plan is a combination of the two previous plans. To implement it, two experimental (E) and two control (C) groups are needed. His diagram looks like this:
This design can control for the pretest interaction effect and the experimental effect. The effect of experimental influence is revealed by comparing the indicators: O1 and O2; O2 and O4; O5 and O6; O5 and O3. Comparison of O6, O1 and O3 allows us to identify the influence of the factor of natural development and background influences on the dependent variable.
Now consider a design for one independent variable and several groups.
Design for three randomized groups and three levels of the independent variable used in cases where it is necessary to identify quantitative relationships between independent and dependent variables. His diagram looks like this:
In this design, each group is presented with only one level of the independent variable. If necessary, you can increase the number of experimental groups in accordance with the number of levels of the independent variable. All of the above statistical methods can be used to process the data obtained using such an experimental design.
Factorial experimental designs used to test complex hypotheses about relationships between variables. In a factorial experiment, as a rule, two types of hypotheses are tested: 1) hypotheses about the separate influence of each of the independent variables; 2) hypotheses about the interaction of variables. A factorial design involves all levels of independent variables being combined with each other. The number of experimental groups is equal to the number of combinations.
Factorial design for two independent variables and two levels (2 x 2). This is the simplest of factorial designs. His diagram looks like this.
This design reveals the effect of two independent variables on one dependent variable. The experimenter combines possible variables and levels. Sometimes four independent randomized experimental groups are used. To process the results, Fisher's analysis of variance is used.
There are more complex versions of the factorial design: 3 x 2 and 3 x 3, etc. The addition of each level of the independent variable increases the number of experimental groups.
"Latin Square". It is a simplification of a complete design for three independent variables having two or more levels. The Latin square principle is that two levels of different variables occur only once in an experimental design. This significantly reduces the number of groups and the experimental sample as a whole.
For example, for three independent variables (L, M, N) with three levels each (1, 2, 3 and N(A, B, C)) the plan using the “Latin square” method will look like this.
In this case, the level of the third independent variable (A, B, C) occurs once in each row and each column. By combining results across rows, columns, and levels, it is possible to identify the influence of each of the independent variables on the dependent variable, as well as the degree of pairwise interaction between the variables. Application of Latin letters A, B, WITH It is traditional to designate the levels of the third variable, which is why the method is called “Latin square”.
"Greco-Latin square". This design is used when the influence of four independent variables needs to be examined. It is constructed on the basis of a Latin square for three variables, with a Greek letter attached to each Latin group of the design, indicating the levels of the fourth variable. A design for a design with four independent variables, each with three levels, would look like this:
To process the data obtained in the “Greco-Latin square” design, the Fisher analysis of variance method is used.
The main problem that factorial designs can solve is determining the interaction of two or more variables. This problem cannot be solved using several conventional experiments with one independent variable. In a factorial design, instead of trying to “cleanse” the experimental situation of additional variables (with a threat to external validity), the experimenter brings it closer to reality by introducing some additional variables into the category of independent ones. At the same time, the analysis of connections between the studied characteristics allows us to identify hidden structural factors on which the parameters of the measured variable depend.
4.8. Correlation studies
The theory of correlation research was developed by the English mathematician K. Pearson. The strategy for conducting such a study is that there is no controlled impact on the object. The design of a correlational study is simple. The researcher puts forward a hypothesis about the presence of a statistical connection between several mental properties of an individual. In this case, the assumption of causal dependence is not discussed.
Correlation is a study conducted to confirm or refute a hypothesis about a statistical relationship between several (two or more) variables. In psychology, mental properties, processes, states, etc. can act as variables.
Correlation connections.“Correlation” literally means ratio. If a change in one variable is accompanied by a change in another, then we talk about the correlation of these variables. The presence of a correlation between two variables does not indicate the presence of cause-and-effect relationships between them, but makes it possible to put forward such a hypothesis. The absence of correlation allows us to refute the hypothesis about the cause-and-effect relationship of the variables.
There are several types of correlations:
Direct correlation (the level of one variable directly corresponds to the level of another variable);
Correlation due to a third variable (the level of one variable corresponds to the level of another variable due to the fact that both of these variables are due to a third, common variable);
Random correlation (not due to any variable);
Correlation due to heterogeneity of the sample (if the sample consists of two heterogeneous groups, then a correlation may be obtained that does not exist in the general population).
Correlation connections are of the following types:
– positive correlation (an increase in the level of one variable is accompanied by an increase in the level of another variable);
– negative correlation (an increase in the level of one variable is accompanied by a decrease in the level of another);
– zero correlation (indicates that there is no connection between the variables);
– nonlinear relationship (within certain limits, an increase in the level of one variable is accompanied by an increase in the level of another, and for other parameters, vice versa. Most psychological variables have a nonlinear relationship).
Designing a correlational study. A correlational research design is a type of quasi-experimental design in which the independent variable does not influence the dependent variables. A correlation study is divided into a series of independent measurements in a group of subjects. When simple In a correlation study, the group is homogeneous. When comparative In a correlation study, we have several subgroups that differ in one or more criteria. The results of such measurements give a matrix of the form R x O. Data from a correlation study is processed by calculating correlations along the rows or columns of the matrix. Row correlation provides a comparison between subjects. Column correlation provides information about the relationship between measured variables. Temporal correlations are often detected, i.e., changes in the structure of correlations over time.
The main types of correlational research are discussed below.
Comparison of two groups. It is used to establish the similarity or difference between two natural or randomized groups in terms of the severity of a particular parameter. The mean results of the two groups are compared using Student's t test. If necessary, Fisher's t-test can also be used to compare the variances of the indicator in two groups (see 7.3).
Univariate study of one group in different conditions. The design of this study is close to experimental. But in the case of correlation research, we do not control the independent variable, but only note the change in the individual’s behavior under different conditions.
Correlation study of pairwise equivalent groups. This design is used in twin studies using intrapair correlations. The twin method is based on the following provisions: the genotypes of monozygotic twins are 100% similar, and dizygotic twins are 50% similar, the development environment of both dizygotic and monozygotic pairs is the same. Dizygotic and monozygotic twins are divided into groups: each group contains one twin from the pair. The parameter of interest to the researcher is measured in twins of both groups. Then the correlations between the parameters are calculated (ABOUT-correlation) and between twins (R-correlation). By comparing intrapair correlations of monozygotic and dizygotic twins, it is possible to identify the shares of the influence of environment and genotype on the development of a particular trait. If the correlation of monozygotic twins is reliably higher than the correlation of dizygotic twins, then we can talk about the existing genetic determination of the trait, otherwise we talk about environmental determination.
Multivariate correlation study. It is carried out to test the hypothesis about the relationship between several variables. An experimental group is selected and tested according to a specific program consisting of several tests. The research data is entered into a table of “raw” data. This table is then processed and linear correlation coefficients are calculated. Correlations are assessed for statistical differences.
Structural correlation study. The researcher identifies differences in the level of correlations between the same indicators measured in representatives of different groups.
Longitudinal correlational study. It is built according to a time series plan with testing of the group at specified intervals. Unlike a simple longitudinal study, the researcher is interested in changes not so much in the variables themselves as in the relationships between them.
Laboratory experiment, or artificial experiment, in psychology is a type of experiment that is carried out in artificially created conditions (within a scientific laboratory) and in which, as far as possible, interaction of the subjects being studied is ensured only with those factors that interest the experimenter . The subjects under study are the subjects or group of subjects, and the factors of interest to the researcher are called relevant stimuli.
A special type of experimental method involves conducting research in a psychological laboratory equipped with special instruments and devices. This type of experiment, which is also characterized by the greatest artificiality of experimental conditions, is usually used when studying elementary mental functions (sensory and motor reactions, choice reactions, differences in sensory thresholds, etc.) and much less often when studying more complex mental phenomena (thought processes , speech functions, etc.). In a laboratory experiment, instruments and equipment are almost always used. Thus, the “lie detector” arose on the basis of an apparatus that recorded various psychophysiological reactions of the subject when he was presented with stimuli in the form of a list of words to which he gave a motor and verbal response, the latter in the form of an association that arose to the stimulus word. Based on the indicators of the device, the researcher could distinguish the subject’s specific attitude to the words presented and establish emotionally neutral and meaningful stimuli. The development of the polygraph (“lie detector”) was undertaken when a connection (correlation) was established between emotionally significant stimuli and an event that was also personally significant for the individual.
Experimental clinical psychodiagnostics in expert forensic or psychological practice on this basis refers to a laboratory experiment. In an expert situation, the naturalness of the appearance of an expert largely depends on the professionalism of the expert. Obtaining artificial, i.e. false and false data about under the expert destroys the evidentiary role of expert research, like any other experiment.
Following the tradition of positivism, many scientists consider the laboratory experiment to be most consistent with the spirit and subject of objective, scientific, materialistic psychological research.
A laboratory experiment has a number of advantages, which include obtaining more accurate results through the use of special premises, measuring equipment, and simulators; opportunities to simulate conditions that are rarely encountered in everyday life; achieving the greatest accuracy in recording the actions of the subjects in comparison with observation, etc. The disadvantage of a laboratory experiment is that artificial conditions are created for the subjects, which significantly affect the manifestation of their psyche. One should also take into account the fact that not all mental phenomena can be learned.
The specificity that distinguishes a psychological laboratory experiment from experiments in other sciences is the subject-subject nature of the relationship between the experimenter and the subject, expressed in the active interaction between them.
A laboratory experiment is performed in cases where the researcher needs to ensure the greatest possible control over the independent variable and additional variables. Additional variables are irrelevant or irrelevant and random stimuli, which are much more difficult to control in natural conditions.
Laboratory experiment
(from Latin laborare - to work, experimentum - experience) - a type of experiment conducted in specially equipped premises, which ensures particularly strict control of independent and dependent variables. Thanks to these conditions, the results of L. e. usually have a relatively high degree of reliability and validity (see). The disadvantages of L. e. sometimes attributed to a low degree of “ecological validity” - correspondence to real life situations.
Brief psychological dictionary. - Rostov-on-Don: “PHOENIX”. L.A. Karpenko, A.V. Petrovsky, M. G. Yaroshevsky. 1998 .
Laboratory experiment Etymology.
Comes from Lat. laborare - to work.
Category.Methodological strategy.
Specificity.Based on modeling the activity of an individual in special conditions. The leading feature of a laboratory experiment is to ensure the reproducibility of the characteristic being studied and the conditions for its manifestation.
Criticism.In artificial laboratory conditions, it is almost impossible to simulate real life circumstances, but only individual fragments of them.
Psychological Dictionary. THEM. Kondakov. 2000.
LABORATORY EXPERIMENT
(in psychology) laboratory experiment) is one of the varieties modeling one way or another activities human subject. Its meaning is to ensure the reproducibility of the phenomenon (activity) being studied with more complete and accurate control (and management) of the studied factors, environmental conditions and dependent variables. The test subject is given perform certain actions that, in their psychological structure, correspond to the actions of real activity. Such modeling makes it possible to study c.-l. in laboratory conditions. real activities and behavior (e.g. infants) with high recording accuracy, obtain data to verify the proposed hypotheses. However, due to the artificiality of laboratory conditions, the results obtained may differ from those that occur in real conditions of human activity. Cm. , .
Large psychological dictionary. - M.: Prime-EVROZNAK. Ed. B.G. Meshcheryakova, acad. V.P. Zinchenko. 2003 .
See what a “laboratory experiment” is in other dictionaries:
Laboratory experiment- (English laboratory experiment), or artificial experiment, in psychology this is a type of experiment that is carried out in artificially created conditions (within a scientific laboratory) and in which interaction is ensured whenever possible... ... Wikipedia
LABORATORY EXPERIMENT- see LABORATORY EXPERIMENT. Antinazi. Encyclopedia of Sociology, 2009 ... Encyclopedia of Sociology
Laboratory Experiment- a methodological strategy aimed at modeling the activity of an individual in special conditions. The leading feature of a laboratory experiment is to ensure the reproducibility of the characteristic being studied and the conditions for its manifestation. Requirement … Psychological Dictionary
laboratory experiment- — EN laboratory experiment Tests or investigations carried out in a laboratory. (Source: CEDa) Topics: environmental protection... ... Technical Translator's Guide
Dictionary-reference book on educational psychology
An experiment under specially designed conditions that allows one to isolate the so-called pure independent variable by controlling all other conditions with which its influence may be confounded... Dictionary of educational psychology
LABORATORY EXPERIMENT- (from the Latin laborare to work, experimentum experience) a type of experiment conducted in specially equipped premises, which ensures particularly strict control of independent and dependent variables. L. e. represents one of... Encyclopedic Dictionary of Psychology and Pedagogy
Laboratory experiment- scientific, experimental research conducted in artificially created, specially equipped laboratories. The personal activity approach is based on taking into account the personal characteristics and positions of all its participants, students, teachers,... ... Research activities. Dictionary
LABORATORY EXPERIMENT- a method of educational interaction between a teacher and students based on their reproduction in the conditions of an educational laboratory of natural processes and results previously obtained by science; used primarily in the study of subjects of the natural cycle.... ... Professional education. Dictionary
Laboratory experiment (psychology)- This page is proposed to be combined with Experiment (psychology). Explanation of reasons and discussion on the V page ... Wikipedia
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