The longitudinal method in psychology means the systematic study of one object over a long period of time. And, as a rule, according to a pre-thought-out program, which makes it possible to predict the further development of his personality.
Typically, the longitudinal method was opposed to the cross-sectional method. If in the case of the cross-sectional method there is usually a one-time comparison of results from a group of people, then the work of the longitudinal method in psychology is presented a little differently. Research on it is carried out for a long time and affects one person or a small sample of people. In some cases, research can last for decades. An example of such experiments is the experience of Arnold Gezzel, where 165 children were involved, and the research itself was carried out for 12 years.
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What is a longitudinal study
In simple terms, longitudinal research in psychology is a systematic study of an object or group of objects over a long period of time and according to a previously prepared system. Over a specified period of time, objects can change some signs and characteristics.
Such an observation relates to the methods of developmental psychology, since it involves the study of the characteristics of individuals who belong to different age categories. And this is the main feature of a longitudinal study.
For clarity, let's give an example. Imagine a separate photograph and a photo album. In what case will you receive complete information about a person, his life or a certain stage of it? Naturally, looking at photo albums. So it is with the longitudinal method.
This method of studying a person or group of people allows you to see not only the development of the group, but also of each individual subject. Moreover, the effectiveness and meaningfulness of the results directly depends on the period of time over which the research is conducted. It can, of course, be shortened, but this requires compelling arguments.
Key Concepts
To designate the community of people in the sample by year of birth, a term such as “cohort” is used. In accordance with demographic characteristics, this concept means a certain group of individuals, designated within a geographic or other population, who experienced similar events in a given time period. The age variable represents the chronological number of years at the time of observation. During the analysis, the concept of “period” should also be clarified. It denotes the time of measurement and the stage that is covered by the life of the cohort, including historical events common to its members. Formally, the generality is defined as follows:
Cohort = Measurement period (calendar year) – age (number of years from birth).
Purpose of longitudinal studies
The main goal of the longitudinal research method is to trace the history of the development of one or more objects, as well as to assess the impact of certain events on them. Observations are carried out over a long period of time. Psychologists analyze and evaluate how the occurrence of certain events affects the state of the experimental group. To do this, it is enough to consider the behavior of the subjects before the event and after it.
It is worth noting that other research methods are also used simultaneously with longitudinal research. We are talking about testing, psychography, observation, etc.
Hypotheses
Using the example of “The Way of Generation” we see work on the hypothesis of K. Mannheim.
In his opinion, during periods of historical cataclysms, the so-called “historical generation”, which differs from previous ones in its psychology, social experience and is a catalyst for a significant “leap” in the development of society .
Mikka Titma's research made it clear that this hypothesis, if not the only correct one.
There may have been precedents in history when the political and economic situation gave rise to a radically different generation that undermined the foundations of the old society and built a new one. However, in this particular case, the hypothesis could not be proven .
The researcher conducts an experiment based on his own guesses and speculative conclusions. Such hypotheses are called causal.
A causal hypothesis is an assumption about the existence of a cause-and-effect relationship between phenomena.
In other words, the researcher puts forward a hypothesis that factor X influences individual Y and turns him into an individual with an altered psyche Y1.
Accordingly, the initial state of individual Y and the final state of individual Y1 are recorded... Or the same individual Y, if factor X did not produce any significant effect on him .
Longitudinal observation looks for relationships between the external and internal environments .
There are different types of causal hypotheses. Here are some of their types:
- development hypothesis;
- hypothesis about long-term and delayed effects of the experiment on the individual;
Testing assumptions on respondents, with proper organization of the experiment, provides an understanding of the truth or falsity of the hypothesis .
History and features of longitudinal research
The longitudinal research method was first used by its founders, William Stern and A. N. Gvozdev, who devoted time to studying the development of a child in an ordinary family.
Initially, longitudinal research was used as an alternative to the cross-sectional method in child and developmental psychology. Later it began to be used in such areas as sociology, engineering psychology, and labor psychology.
Longitudinal studies are actively carried out both in Russia and in foreign countries. In Russia, the most famous of them is considered to be “Ways of Generation,” held from 1983 to 1999 (led by M. Kh. Titma). Abroad, longitudinal studies are often used by the UK National Children's Bureau, which studies the development of children of different age categories.
Relationship with empirical observations
Testing hypotheses is the key task performed by the longitudinal method. However, despite this, conclusions about development are often drawn in accordance with the results of empirical observations. They are carried out within the framework of various psychological concepts using the cross-sectional method. It allows you to detect connections between several static variables taken in a separate time period. The use of the findings is determined by the presence of an unspoken assumption about the equivalence of the samples through which the comparison is made, as well as historical periods for different categories of subjects. This often leads to the neglect of an important source of confounding that requires special attention.
Methods and types of longitudinal research
The longitudinal research method is divided into types depending on its duration, method of conduct and characteristics.
So, according to duration, the following types of longitudinal are distinguished:
- Short term. It is used to study personality during a period of time when several developmental leaps are expected to occur at once.
- Long-term. This is a study involving the study of dynamics during the most prominent periods of development. An example is infancy.
- Accelerated. This is the study of large periods of development over a short period of time. People from several age groups are monitored here.
The method of conducting the study divides the longitudinal into the following types:
- Retrospective. A psychologist or sociologist looks at the personality and its individual characteristics in the past.
- Perspective. Study of an individual until he reaches a certain age.
- Compatible. It involves combining elements of retrospective study with prospective ones.
There are other types of longitudinal research:
- True. This is a classic option. The purpose of observing a person is to learn about mental and psychological health perspectives.
- Mixed. It intersects with the slice method, thanks to which it is possible to obtain data about objects similar to the one being studied. It is most often used to study melting groups, the number of participants of which decreases with each stage.
- Pseudolongitude. Involves determining the norm for all age groups. To calculate it, take the average indicators of each individual member of the group.
- Individual panel study. Experts study subjects over a period of time. Participants give interviews.
- Household panel studies. It's watching a person who is part of a family. Information concerning the family as a whole is considered.
- Kogornoye. The purpose of the study is to trace the development of a cohort or people of a certain age group.
There are also studies that combine data. A good example is the population census.
Consequences
Linear dependence leads to the fact that during the control of any two indicators, the third variable is also controlled. If the study uses a cross-sectional method, the sample of people also has a common “history”, but it differs for the participants in the longitudinal cross-sections and sections. This leads to a confounding factor between social circumstances and age. In this regard, when performing cross-sectional comparisons of parameters of people of different ages, the identified differences between more mature and younger subjects may express not the line of development of the main process, but cohort effects. The use of a longitudinal method with multiple sequential measurements can facilitate the discovery of results not specified as the subject of the study, but the consequences of the influence of social circumstances, as a historical stage specific to a given sample.
Longitudinal studies in sociology
They help answer a number of social questions, as well as analyze and evaluate those topics in which classical methods turned out to be ineffective. These include:
- changes in society;
- poverty level;
- changes in the labor market;
- swings in social mood;
- the impact of unemployment on a person's mental health;
- the impact of poverty on a child's future life.
Experts also study the reaction of society to some political and economic measures introduced by the state. They consider its condition before and after implementation.
Longitudinal studies in psychology
In psychology, longitudinal research allows us to analyze the following points:
- family influence on the child;
- the role of school education in education;
- effectiveness of educational activities;
- the impact on the future of children of parents' divorce and life in an incomplete family.
The study also examines the characteristics and conditions of people who often lose their jobs. The psychologist’s task in this case is to understand what complicates the job search process.
Advantages and disadvantages of the longitudinal method
Like any other study, longitudinal research has pros and cons. The advantages include the opportunity to observe the development of the same people for a long time, to see the changes taking place in life. Moreover, these changes concern not only physical condition, but also attitudes, values and priorities.
Another advantage is the ability to study the impact of a particular event on a person. Data is collected before and after it. An example is educational events or changes in the economy.
What can you say about the shortcomings?
- Studying requires a lot of investment, both financial and in terms of resources (time, effort). The most difficult thing is to conduct a repeat study.
- Technical difficulties. At each stage, new information concerning the subjects is collected. At the same time, all events that happened in life are considered, moving and other factors are taken into account. And then this data is processed, analyzed and systematized.
- The results of the study may take several years to appear. But there were cases when they did not appear at all.
- There is a risk of overlooking some events or changes in a person’s life.
And another serious drawback is that the subjects become unavailable towards the end of the study. They can refuse to participate, leave, die. In this case, the basis for comparisons is greatly reduced, which calls into question the accuracy of the longitudinal study as a whole.
Hawthorne effect
The effect got its name thanks to the Hawthorn Works company, where it was discovered during research. In 1927-1932, visiting scientist E. Mayo and his team studied the reasons for the decline in productivity in one of the workshops. They took into account several variables that could have such an effect, and came to the unexpected conclusion that it was necessary to introduce another variable - participation in the experiment.
Thoughts about the importance of what was happening, a sense of belonging, and increased attention from strangers led to a significant improvement in productivity among female employees of the company even when there were no other objective favorable circumstances.
The Hawthorne effect speaks of some qualitative changes in the phenomenon being studied, due only to the very fact of observation, in particular, about positive changes in people’s behavior with increased attention to themselves and their work. Knowing that they are being watched, they strive to live up to expectations and try to look better. This phenomenon symbolizes a significant distortion of the research results due to increased attention to the object of study.
Taking into account the listed advantages and disadvantages, we can safely say that longitudinal research is a wonderful method for in-depth study of the dynamics of mental development processes, which allows us to subsequently make forecasts and develop programs of psychological support during crisis periods in a person’s life.
Examples of longitudinal studies
The University of Madison conducts the longest longitudinal study. It started in 1957. The main goal is to study graduates’ plans for career growth, health, growing up, etc. Now specialists are monitoring both the participants and their children.
The New Zealand study is rightfully considered the largest conducted within a single country. More than 8,500 students took part in it and had 1 year left to study. The goal is to understand what determines the further success of graduates. The surveys were conducted 3 times: in 2011, 2013 and 2021. The next one is coming in 2021.
The students participated in a longitudinal study on education and careers in the UK (started in 2008). There are about 130,000 subjects in total.
