Differential psychology is the area of psychology that deals with studying the differences between the behaviors of individuals and groups. Research in this field began with Franz Gall’s intelligence and heritability studies in the 1800s.
Differential psychology research areas include personality traits, genetics, intelligence studies, motivation, self-perception, individual interests, among others.
The psychology of individual differences examines how people are similar and how they differ in their thoughts, feelings and behavior. No two people are exactly alike, but no two people are completely different either.
In the study of individual differences, we try to understand the ways in which people are psychologically similar and, in particular, what psychological characteristics vary between people. Differential psychology is interested in the regularities of differences between people.
For example, when evaluating the effectiveness of a new drug, the average effects in a group in which it was given are compared with the effects in another control group in which a placebo (or another type of drug was given). already known). In this context, differences between individuals in their reaction to experimental chemical manipulations and controls are studied.
The main method used by differential psychology is the scientific method, which follows a series of steps in a logical and rational order through which scientists arrive at conclusions about the world around us.
In the scientific method, one or more empirically verifiable hypotheses are formulated about what has been observed. A prediction is made about the outcome of the hypothesis, which is empirically tested by experimentation with valid tools (tests, interviews). After the result of the experiment, it is concluded about the veracity of the hypotheses.
History
The beginnings of the history of the study of individual differences are very old; Plato already wondered why the co-occurrence of certain appropriate characteristics in people was so infrequent.
Franz Gall and phrenology
However, the most scientific study of differences between individuals dates back to when Franz Gall invented the theory of phrenology in the early 19th century.
Phrenology was a theory of the brain which asserted that by examining the shape and nodes of the human skull, each person’s abilities and traits could be guessed, since each characteristic had its own place in the brain. This study formed one of the first theories about the psychology of individual differences.
Phrenology was so fashionable at the time that by 1832 there were 29 phrenological societies in Great Britain and many magazines and publications in the UK and US were fully devoted to the study of this field.
It has even been seriously proposed to select Members of Parliament according to the structure of their skulls. Some phrenologists came to shape the children’s heads to accentuate positive qualities and minimize those considered negative.
Although the phrenologist’s theory was proven to be incorrect, one of his assumptions was correct: the idea that various regions of the brain have specific functions.
Charles Darwin and Francis Galton
Darwin suggested that nature selects traits that succeed through “survival of the fittest” (or the most trained or prepared). His cousin, Sir Francis Galton, concluded that he could apply this principle scientifically.
Why not measure human personality traits and selectively breed superior people? Galton assumed that human traits, from height and beauty to intelligence and skills, abilities and personality traits, were inherited.
Modern psychology has formalized the study of individual differences over the last hundred years. The psychology of individual differences is still a relatively young science and is a relatively recent development in modern psychology. There are still many debates and problems to be resolved in this regard, and the information we already have will certainly change and evolve.
As there are multiple and controversial views, it is necessary to keep an open mind to adopt alternative perspectives, especially those that are used in the practice of psychology and that are supported by research.
Study object
The psychology of individual differences asks two fundamental questions:
- In what ways do we differ from each other?
- Why are people different from each other?
While it is important to answer these two questions, the field of differential psychology is not focused on being a descriptive and theoretical area.
Ways of applying the potential of differential psychology to practice are developed, for example, to predict outcomes. What characteristics make a person a successful student, for example?
Generating knowledge about how and why people differ from one another and applying it to potentially improve society are the tasks of this field of psychology. Differential psychologists are making great strides in understanding characteristic patterns of affect, behavior, cognition, and motivation.
These patterns can be conceptualized as individual differences in abilities, interests, and temperaments. Undoubtedly, the future of differential psychology is more promising than it was decades ago.
Principles of Differential Psychology
In the Western approach to the psychology of individual differences, it is generally assumed that:
- People vary in a wide range of psychological attributes.
- It is possible to measure and study these differences between individuals.
- Individual differences are useful for explaining and predicting behaviors in people.
People can be classified in terms of their psychological attributes, for example in relation to their intelligence and personality characteristics, with relative success. However, human beings are complex beings and there is still much to be explained. There are generally a large number of theories and evidence about differential psychology that sometimes conflict.
Differential Psychology and Traits
Many of the contemporary personality psychologists believe that there are five basic dimensions in the human personality, commonly called “The big five personality traits” (“The Big Five”).
The five traits described by this theory are extraversion, kindness/compliance, openness to new experiences, responsibility/conscientiousness, and neuroticism/emotional instability.
David M. Buss, professor of social psychology at the University of Texas, known for his evolutionary psychology research on individual sex differences, proposed in his book The Evolution of Personality and Individual Differences the application of the evolutionary principles of differential psychology to the big five traits. of personality. Buss explains why individuals differ in each of the five general characteristics and the evolutionary value of each:
Extroversion
Extroverts are generally ambitious, assertive, and competitive, as well as sociable, physically active, and sexually motivated. High levels of extroversion are associated with a greater number of sexual partners, which increases the chances of survival of the species.
It is also related to a higher social status and greater attention by other people, characteristics that are generally desirable in our species. Extroverted people also have greater associated physical activity. However, all these characteristics imply a certain level of risk, of accidents, illnesses, social conflicts or depletion of resources.
Consistent with this view, people who score high on extraversion have been found to have a higher risk of accidents and arrests and shorter life expectancy than those who score low.
So whether high extraversion will bring about an increase or a decrease in reproductive success depends on two things. First, there are characteristics in individuals that determine the ideal amount of extroversion.
More attractive and physically stronger individuals who have a well-functioning immune system are more ideal for developing an extroverted strategy and dealing with the risks involved.
On the other hand, there may be ecological contexts that generally favor this type of risk. When social structures are fluid or the habitat is new, there can be great rewards for taking risks. When the habitat is stable, it’s better to be more cautious.
Neuroticism/emotional instability
People who score high on neuroticism often have frequent mood swings, are irritable and anxious. These people face serious inconveniences of stress-related illnesses and difficulties in relationships as a result of their negative affect and high levels of anxiety. This would point to a selection process in the species whose aim was to reduce the level of neuroticism.
However, negative emotions exist for a reason, primarily to detect and address threats. Theory suggests that the more prevalent the threats in an environment, the more sensitive the threat detection mechanisms must be, even at the cost of producing numerous false positives, where threats are detected that do not really exist.
Responsibility / scrupulousness
A high score on this characteristic is associated with commitment to the plans that are made, which, in modern settings, have the advantage of leading to high academic and professional performance.
Being able to follow through on internally generated plans and long-term goals despite distractions may also have been advantageous in some relevant ancestral contexts, particularly when faced with repeated tasks of picking fruits and crops where outcomes are predictable.
However, some situations cannot be planned or anticipated, and in these cases it is useful to be able to respond spontaneously and without the need to reflect extensively. People who score high on this trait can become very rigid and inflexible, traits that reach a harmful extreme in OCD.
Therefore, the ideal balance between these two extremes is likely to depend on the details of the context and the individual’s personal role. This variability would be enough to support the variation of this characteristic in individuals.
kindness / complacency
High sympathy and compliance are associated with a high investment in cooperative actions and great harmony in interpersonal relationships. Humans are a very sociable species; therefore, coordinating with others in joint actions can be greatly favored by Darwinian selection.
Therefore, the advantages of high compliance are not difficult to identify. However, there are contexts where joint economic action may be of little benefit. This depends on the resources at stake and the local social structure.
Highly complacent individuals may overinvest in their social relationships at the expense of their own interests. Many studies in several countries have found higher compliance scores in women than in men, a feature that also has a cultural component.
Openness to new experiences
One of the most striking features of the fifth trait is that it is linked in the literature to positive as well as negative outcomes.
Regarding negative results, a high openness to new experiences is associated with paranormal beliefs, maintaining many contacts with psychiatrists and psychologists, with schizotypal personality disorder and even with psychosis. On the positive side, it is closely related to artistic creativity and, weaker, to intelligence.
Creativity, with a consequent increase in social and sexual attractiveness, represents an essential benefit of being open to new experiences, while unusual beliefs and possible psychotic experiences represent a negative cost.
In this case, the ecological context would not be very important when selecting different levels of openness, since these levels are optimal depending on other characteristics of the individual.
