Psychological diagnostics

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Psychological diagnostics (also: psychodiagnostics or assessment ) is a branch of psychology and at the same time an important part of the professional activity of psychologists . According to the WHO , it is the common denominator for most professional psychological activities.

Psychological diagnostics is an important aspect of this "application" in all areas of applied psychology . Psychological diagnostics are always in demand when rational decisions have to be found or substantiated. In this sense, it provides the methodological foundation for this.


The words diagnosis and diagnosis go back to the Greek verb “diagignoskein”, which describes different aspects of a cognitive process, from recognizing to making a decision. The verb means “to get to know thoroughly”, “decide” and “decide”.

In psychological assessment it comes to the "depth getting to know" the characteristics of a person, group, or organization by means of appropriate methods and procedures for obtaining information (z. B. means of interviews, observation or psychological tests). It presupposes a question or problem that is to be answered or solved with psychological help. The image obtained on the basis of the information is the basis for diagnostic decisions in various areas of psychological activity such as B .:

The psychological assessment but also deals with very basic, more theoretical issues such. B .:

  • Should the limited number of study places in medicine be allocated on the basis of high school graduation marks, the random principle , aptitude tests or job interviews?
  • What information guarantees a rational decision ?
  • How are the success criteria defined, and what are the results of empirical probation controls ( evaluation )?
  • Which decision benefits and which costs can be determined?

Definition of Jäger and Petermann

Reinhold Jäger and Franz Petermann give a comprehensive definition, emphasizing the orientation towards diagnostic decisions and taking into account the complexity of psychological diagnostics:

  • Psychodiagnostics is the systematic collection and processing of information with the aim of justifying, controlling and optimizing decisions and resulting actions.
    • In other words, the use of tests is part of psychological diagnostics, but the latter cannot be reduced to it. It is also about making diagnostic decisions on the basis of this information (e.g. about admission to study, suitability for a job, fitness to drive, selection of applicants when applying for a job, determination of a disease and correct therapy recommendation). In addition to tests, other information (exploration, behavioral observation) must also be taken into account.
  • Such decisions and actions are based on a complex information processing process. In this process, rules, instructions, algorithms, etc. are used. In this way, psychologically relevant characteristics of bearers of traits are obtained and given data is integrated into a judgment (diagnosis, prognosis).
    • This means that the information must be condensed, evaluated and weighted until a reliable diagnosis can be made and a well-founded decision can be made. Knowledge of these rules, instructions and procedures is not given through the application of a test alone, but requires further specialist knowledge. This knowledge is normatively part of the training of all persons who are active in psychodiagnostic activities.
  • Individuals, groups of people, institutions, situations, objects, etc.
    • In other words, it's not just about individuals. The process “recognize - decide correctly - change” is also found in a general diagnostic method.

Psychological diagnostics as an independent discipline

The assignment within the sub-areas of psychology is not uniform: Psychological diagnostics is sometimes assigned to the basic subjects, method subjects or the application subjects. Independence as a discipline is also controversial; it is often combined with differential psychology or personality psychology . A connection with methods of intervention (“diagnostics and intervention”) is also often to be found. That is why psychological diagnostics is sometimes referred to as an “integration subject”. In other words, it is a “bridge” between basic theories and, in particular, extensive, well-founded methodological knowledge, including the corresponding acquired methodological experience and the application-oriented content (theoretical as well as methodological again).

Psychological diagnostics in clinical psychology does not only refer to the detection of mental illnesses or disorders, but also includes the decisions to be derived from them (e.g. therapy necessity and motivation, choice of the right form of therapy, etc.). That is why the term “indication diagnosis ” is often used .

Relationships with other disciplines

Psychological diagnostics is closely linked with the other psychological disciplines, so that specialist knowledge from the following areas is necessary:

  • Knowledge of all basic subjects, in particular biopsychological basics, perception and perception distortions , deceptions, cognitive and memory errors, thinking, decision psychology, motivation, emotion, social psychology, developmental psychology, etc.
  • Methodology and statistics (scientific thinking and acting, functionality of the tests and information processing from characteristic to diagnosis to decision-making, intimate knowledge of dealing with conditional probabilities )
  • Applied subjects such as clinical psychology, developmental psychology, educational psychology, business psychology, etc. a. (Knowledge for decision-making, e.g. definition of disorders in clinical psychology, school requirements for school aptitude diagnostics or success criteria for a specific activity in business psychology).
  • Personality and differential psychology: The theories and systematics of the characteristics that can be used to obtain information and support decisions are necessary here - i.e. the question of how people differ and how this can be determined. In differential psychology , since William Stern and Raymond B. Cattell, numerous typical diagnostic strategies have been developed to examine the inter- and intra-individual variability of behavior from the perspective of people, situations, variables, repetitions and interactions (see personality trait ). With this in mind, Carver and Scheier (1988) designed their textbook on personality psychology Perspectives on personality in such a way that the close theoretical and methodological relationship between personality theory and special psychological diagnostic methods becomes clear. B .:

Training in psychology studies

The training within the psychology course usually takes place in two parts: in the basic course the general methodical approach is taught, in the application subjects the approaches for special questions are conveyed.

Since it is a methodologically complex, subject-specific decision-making process in the sense of a scientific procedure, psychological diagnostics not only requires application-oriented knowledge and application-related (practical) methodology, but also requires v. a. First and foremost, a basic, intensive scientific education. At the European level, an academic university degree in psychology of at least five years and a subsequent year of at least one year of practical experience, supervised by a psychologist and positively evaluated, are required. The background for this is the standard: "A high and comprehensive level of education and training in scientific psychology creates the required knowledge basis for professional competence in psychological assessment, intervention and communication." In the USA, a doctorate ( Ph . D. ) Required in scientific psychology.

Alternative names and delimitations

Term psychodiagnostics

Originally, the term psychodiagnostics was coined by Hermann Rorschach in 1921 through his book "Psychodiagnostik", which presented the Rorschach test in its application. For a long time, the significance was primarily related to this type of Rorschach diagnosis. The meaning of the term psychodiagnostics has changed in that it now encompasses all methods and approaches in this area. The term psychological diagnostics is being used increasingly today, especially at the official level . Nevertheless, the synonymous and parallel use of the term psychodiagnostics is still used today.

  • The specialist group of the German Society for Psychology is called Differential Psychology, Personality Psychology and Psychological Diagnostics
  • The majority of the corresponding chairs and departments at universities carry psychological diagnostics in their name.
  • The corresponding standard textbooks (Jäger, Fisseni, Amelang, Kubinger) have the title Psychological Diagnostics , as well as the Manual of Psychological Diagnostics from 2006

However, there is also a technical policy objective behind this change of term: the longer term expresses the relationship to the subject psychology and its quality standards for psychodiagnostics more clearly, the prefix “psycho-” indicates this subject reference less (see the term psychomarket ).

Term assessment

In the Anglo-American region, psychological diagnosis corresponds to the term assessment (psychological assessment), which is much more common than diagnosis , especially in book titles and magazines of psychology . For a long time, the textbook Personality and prediction was decisive . Principles of personality assessment by Jerry S. Wiggins (1973).

In personnel psychology , assessment is also used in German-speaking countries, in particular to avoid associations with a medical diagnosis. In terms of content and theory, however, there are no differences between psychological diagnostics and assessment .

The term assessment center is z. B. used in personal psychology and the outpatient assessment as a psychologically or psychophysiologically oriented examination in everyday life ties in with the tradition of behavioral assessment (recording of behavior in the broadest sense) introduced in the 1970s .

Differentiation from diagnostics in medicine

In medicine, diagnosis means recognizing and naming the disease on the basis of symptoms and findings ; The differential diagnosis differentiates between similar clinical pictures. The diagnostic procedure always strives for a positive diagnosis , because recognizing the underlying disease then systematically reveals the existing knowledge about the causes of the disease , typical course and most effective therapy . In contrast, psychological diagnostics have a much broader meaning, as the questions relate, for example, to the school context, personnel selection, the world of work, further training, advice and assessment.

Further delimitations or specifications

Other uses of the term relate to delimitations or partial aspects

  • Reduction to test psychology - than the application of psychological tests
  • Equation with or reduction to psychometry or general theories and methods of psychological measurement (the basis of psychological diagnostics, but not all aspects)
  • Equation with personality assessment with the aim of correctly assessing a personality: (The assessment "in itself" has become more meaningless today - also for ethical reasons, every investigation requires a reason and thus a decision objective ) ;
  • Equation with differential psychology , the search for differences between people in general: ( The identification and explanation of individual differences - without a reference to decision-making - is still an important subject of research in psychology, but is now called differential psychology. Note that differential psychology is an important one The prerequisite for psychological diagnosis is. The terms are now more clearly delimited) .

Diagnostic process

In a broader sense, psychological diagnostics are embedded in an investigation context in which the goal, the methods (such as interviews , tests , behavioral observations ) and the statistical evaluation of the data acquisition must be taken into account. In a narrower sense, the actual process of psychological diagnosis can be described with the following model.

Process model according to Jäger

Because diagnostics is seen as an activity, Jäger presented a process model with several distinguishable components as early as 1986. This has been further refined and today there is consensus that the following steps are necessary:

  • Problem analysis : (Analysis of the question and formulation of the order, determination of the "problem type" and analysis of the existing knowledge for decision-making, participants and motives, ethical and legal structures) ;
  • Investigative decision: ( Hypothesis-led acquisition of information through the use of tests and other methods and rule-based processing of the information, process step is repeated if necessary until all hypotheses have been clarified) ;
  • Terminal decision / indication : ( Making the decision or weighing up between decisions, communication with the diagnosed and, taking into account data protection, with the client, if this is not the diagnosed person himself) ;
  • Evaluation : (Proof of the decision and, if necessary, optimization of the decision. Experience building for the diagnostician).

Participants in the diagnostic process

  • Client: person, authority or organization that would like to have the question answered with psychodiagnostic help. This can be the diagnosed person himself (request for advice, request for therapy), but also a company (filling positions with the most suitable candidates), an authority (checking fitness to drive) or similar.
  • Psychodiagnostic (specialist): is responsible for compliance with all quality guidelines during the entire diagnostic process, including the scientific foundation and ethical guidelines.
  • Diagnosed (also common to diagnose or diagnose): Those affected by the decision. As a rule, most of the information is obtained from them, including information that is subject to confidentiality or data protection. The basic rule here is that forwarding the detailed information to third parties (including the client, if applicable) requires the consent of the diagnosed person. If the diagnosis has been commissioned by a third party and the person diagnosed agrees to an examination, this only applies to a limited extent to the decision and its justification. Here, psychodiagnostics and those diagnosed should clarify in advance how information should be handled.
    • The term test person is also common for those diagnosed, but is used more generally for all persons examined in tests, examinations or experiments, is more linked to the research aspect and less to a question.
  • Third parties from the social environment of the diagnosed (e.g. spouse, family members, friends, colleagues, superiors or subordinates) who can be used as sources of information (with the consent of the diagnosed) and / or influence the diagnosis process themselves (to seek professional help have advised or are a contributing cause of problems).


Classification according to the type of data acquisition

The recording and extraction of characteristics takes place with scientifically sound methods, purposefully, systematically and based on given hypotheses. The aim is to gain knowledge about the characteristic carriers and to use them for a decision about a subsequent measure such as counseling, therapy, training, etc. If measures are carried out, diagnostics can in turn be used to control and evaluate the success of these measures. The decisions mentioned are based on a complex information processing process. In this process, rules, instructions, algorithms, etc. are used. In this way, relevant characteristics of feature carriers are obtained and given data is integrated into a judgment (diagnosis, prognosis). The integration is called diagnostic judgment formation.

Psychological diagnostics are used to examine psychological characteristics. These include performance and ability characteristics, e.g. B. Perception , concentration , memory , intelligence and personality traits . z. B. fear , or extraversion .

This is usually done by psychologists with the help of scientifically recognized methods and test procedures. In addition to the various standardized procedures, which should lead to the most objective comparative statements possible through methodology that is structured and carried out in the same way for all test subjects, there are the so-called qualitative procedures, which are intended to bring the most comprehensive, meaningful information about individual individuals to light. In qualitative interviews , through targeted questioning of answers and through free telling and topic-centered explanations of the test subjects, a picture of personality or individual thinking skills that is as free of prejudice as possible and not guided by norm-based comparative interests should be generated. See also: interview

The behavioral observation is one of the methods of psychological assessment.

Key objectives of method development

A central task area of ​​psychological diagnostics is the development of standardized procedures (such as tests, questionnaires, etc.) for diagnostic work. In doing so, she aims to be able to describe systematic differences between people more and more precisely metrically (quantitatively).

The main objectives of the development of diagnostic methods describe the theoretical basic ideas in the construction of procedures for psychological diagnostics. These basic ideas relate specifically to the goal setting (what is measured?), The quality criteria of psychodiagnostic procedures (how do I recognize “good” procedures?) And the procedure for constructing a new method. Pawlik (1988) contrasts the three traditional key goals of "status diagnostics" with three alternative key goals of "process diagnostics" :

Traditional key objectives "status diagnostics"   Alternative key objectives "process diagnostics"
Measurement of systematic differences between people, these differences are considered to be stable over time and situation (= property model ).

z. B .: Recording of personality dimensions or intelligence factors

Goal setting

Assessment of the appropriateness (indication) and / or the success (evaluation) of psychological change efforts in individual cases (= modification model )

z. E.g .: recording of social skills or coping strategies

Complete coverage of the inter-individual variance through the facts ascertained with the procedure and close connection ( covariance (stochastics) ) of these values ​​with one criterion (= variance exhaustion )

z. E.g .: concepts of reliability and validity

Quality criteria

Highly useful of the procedure for decisions in the context of psychological intervention (= decision relevance )

z. E.g .: net benefit (increase achieved through the use of a procedure for the quality of a decision versus random decisions)

Selection of representative behavioral elements to record structures (= sample model )

z. B .: HAWIE


The aim is to record process components, for this it is necessary to create an inventory of all possible behavioral elements in which the intervention need and the intervention goal are mapped (= exhaustion model )

z. B .: inventory of all situations that can trigger fears in a socially anxious person; Beck Depression Inventory (depressive thoughts and ideas)

According to Pawlik, status diagnostics correspond to the classic ideas of psychological diagnostics, such as those found in general or differential psychology . It is based on the property model, so it is primarily interested in unchangeable characteristics and is intended to capture a current or future state . Correspondingly, with status diagnostics, a single measurement is sufficient to record a feature of interest. Typical status diagnostic applications are, for example, ability or aptitude tests.

Process diagnostics is more in the field of clinical psychology or organizational psychology , with the focus on changing characteristics (modification model). Typical fields of application are psychotherapy and personnel development . In order to record changes, in contrast to status diagnostics, at least two (before / after) measurements of the facts of interest are of course always necessary.

Although these key objectives appear very theoretic, they summarize the range of modern psychological diagnostics in a concise way.

Types of diagnoses and diagnostic decisions

Jäger and Petermann differentiate:

  • Selection decisions (e.g. selection decisions as assignment of the optimal therapy for a person or selection of the most suitable person for a position)
  • Modification decisions (e.g. as a change / adaptation of a certain therapy to a person)
  • Mixed strategies (both selection and adaptation, such as assigning a therapy and at the same time adapting it to the treatment of the respective disorder)

Weighing up benefits in psychological diagnostics

The psychological diagnosis should enable a rational, empirically founded decision. The relative benefit of the diagnostic method must also be taken into account. For example: How much better is this decision compared to another process (e.g. random or intuition )? Is it worth the cost compared to other methods? For which decision does z. B. the investigation of the intelligence quotient compared to the school reports? What use is a personality assessment for the selection of personnel or for the selection of psychotherapy ? These critical questions can only be countered through empirical evidence based on evaluations (probation checks).

The concept of decision benefit was developed in psychology primarily by Cronbach and Gleser (1965) in the context of allocation and classification strategies. The overall benefit is not only meant in material terms, but should be based on comprehensive benefit estimates by experts and those affected. Such trade-offs remain questionable, however, because they contain generalizations that do not do justice to all individuals, and the potential harm of a decision is even more difficult to grasp than the benefit. A fair assessment would require a process of social judgment from all involved.

Quality assurance in psychological diagnostics

In recent years there have been a number of efforts to improve the quality of psychological diagnostics . Knowledge of these initiatives is important for the client, the diagnosed and the psychodiagnostic and can also be used to orientate oneself on the rather large “psycho market” and to differentiate quality from charlatanism. With DIN 33430 , normative specifications for one area of ​​aptitude diagnostics are available in comprehensive form for the first time, which can also be applied to other areas.

See also



  • Hermann-Josef Fisseni: textbook of psychological diagnostics. With hints for intervention. 3. Edition. Hogrefe, Göttingen 2004, ISBN 3-8017-1756-9 .
  • RS Jäger, F. Petermann (ed.): Psychological diagnostics - a textbook. 4th edition. Beltz PVU, Weinheim 1999, ISBN 3-621-27273-9 .
  • Klaus D. Kubinger : Psychological diagnostics. 2nd Edition. Hogrefe Verlag, Göttingen 2009, ISBN 978-3-8017-2254-8 .
  • F. Petermann, M. Eid (ed.): Manual of psychological diagnostics . Hogrefe, Göttingen 2006, ISBN 3-8017-1911-1 .
  • L. Schmidt-Atzert, M. Amelang: Psychological diagnostics. 5th, completely revised and expanded edition. Springer-Verlag, Heidelberg 2012, ISBN 978-3-642-17000-3 .
  • G. Stemmler, J. Margraf-Stiksrud (Ed.): Textbook Psychological Diagnostics . Verlag Hans Huber, Bern 2015, ISBN 978-3-456-85518-9 .
  • M. Ziegler, M. Bühner: Basics of psychological diagnostics. VS Verlag für Sozialwissenschaften, Wiesbaden 2012, ISBN 978-3-531-16710-7 .


The following journals are specifically dedicated to the topic, but articles can also be found in numerous other journals:

Individual evidence

  1. Fisseni 2004, 1. The Corpus Hippocraticum speaks (Epidemien I, 23) with this word of the differentiation of a disease on the basis of certain symptoms. For historical semantics, cf. B. Henry George Liddell , Robert Scott : A Greek-English Lexicon. 9th edition. with additions. Clarendon Press, Oxford 1996, sv διαγιγνώσκω, p. 391 (cf. entry online after 9. A. 1940).
  2. ^ RS Jäger, F. Petermann (ed.): Psychological diagnostics - a textbook. 4th edition. Beltz PVU, Weinheim 1999, ISBN 3-621-27273-9 .
  3. EFPA Declaration on the European Standards of education and training in professional psychology
  4. ^ Society for Personality Assessment: Standards for Education and Training in Psychological Assessment: Position of the Society for Personality Assessment. In: Journal of Personality Assessment. 87 (3), 2006, pp. 355-357.
  5. E.g. Society for Personality Assessment, Journal of Personality Assessment , European Journal of Psychological Assessment .
  6. Assessment in DORSCH Lexicon of Psychology
  7. ^ RS Jäger, F. Petermann (ed.): Psychological diagnostics - a textbook. 4th edition. Beltz PVU, Weinheim 1999, ISBN 3-621-27273-9 .
  8. EJPA Homepage
  9. PTAM homepage