What is personality?

Historical review

According to Encyclopedia Britannica, personality psychology was born in the 1930:ies when its founding fathers such as Gordon Allport and Henry Murray published their textbooks (Allport, 1937; Murray, 1938). The field encountered hard criticism in 1970-1980 when Walter Mischel presented in his highly influential book empirical results according to which person factors were weak predictors of behavior (Mischel, 1968). The person-situation debate ended in at least a partial victory for the person viewpoint (Kenrik & Funder, 1988).

The success of the person viewpoint was significantly enhanced by the advent of the so-called Big Five framework. With roots in cataloging of person-descriptive words in dictionaries and based on statistical factor analysis, the forming of measurement scales ended in presenting Conscientiousness, Extraversion, Agreeableness, Openness and Neuroticism or Emotional stability as both reliably measured and broadly predictive personality traits. The framework did not generate any truly novel traits but assembled the diverse earlier traits from the fifty-year research tradition under five broad traits. Many of the preceding narrower traits clustered in factor analysis onto the five big traits as their subtraits or facets.

After the low-tide period of the debate years, the advent of the Big Five framework has integrated trait conceptualizations and strengthened the scientific status of the entire discipline. Large longitudinal samples have shown remarkable stability of personality from early childhood to old age. The stability (r=.74) is on a par with that of the IQ. However, the interesting finding is that the stability plateau of intelligence is attained at the 6-8 year age but personality reaches a stability plateau only after the age of 50 (Roberts & DelVecchio, 2000). The most recent meta-analysis (Bleidorn et al., 2022), extended with samples after 2005 (nearly 250.000 subjects) shows somewhat lower overall stability, already at age of 25 stabilizing plateau and throughout life improving emotional stability. The results also point to malleability of personality, see next.

A recently published meta-analysis prompts to give up the traditional erroneous notion that personality is unchanging (Bleidorn et al., 2019). Psychotherapy has been shown to lead to personality change (DeFruit et al., 2006). In addition to maturation, major life events such as marriage, birth of the first child, first job, the death of a family member and unemployment can cause enduring personality changes (Specht et al., 2011). A recent meta-analysis (Buhler et al. 2024) brings partial confirmation to the previous by highlighting graduation, first job, new relationship, marriage and divorce as personality changing life experiences.

Two last decades have brought to the fore topics on health and well-being. Research with large longitudinal samples have shown that personality may on occasions predict longetivity and mortality better than socio-economic status (Roberts et al., 2007). The influence of life experiences and genetic factors on personality was recently studied by combining twin study samples from over 7000 individuals between ages from 14 to 90 from Croatia, Finland, Germany and UK. The results showed that the influence of life experiences increased while the influence of hereditary factors decreased with age (Kandler et al., 2021).

It is important to bear in mind what personality factors can predict and what remains beyond prediction. Belgium's entire 1997 cohort of medical students were followed throughout their seven-year medical school career (Lievens et al., 2009). The prediction strength varied from .18 level in the starting phase to .45 validity level in the ending phase. In medical education, as in other study fields the beginning phase emphasizes education in basic sciences, ie., acquisition of knowledge for which personality is not viewed to be essential. But as the education progresses to application of knowledge, to simulation exercises, to real world complex problem solving and clinical internships, personality shows significant influence on performance.

Diverse factors of personality

Drawing upon the Encyclopedia of Psychology, American Psychological Association APA defines personality as referring to individual differences in characteristic patterns of thinking, feeling and behaving (APA, 2000). The discipline's leading scholars define personality much in line with the previous. As is evident, the discipline is characterized by its immense diversity of person factors, individual differences have been sought among nearly all psychological processes. In Mayer's words: "personality psychologists have their fingers in everyone else's pie" (Mayer, 1995, 489).

Allport posed early on the question on the basic units of personality. The question has surfaced from time to time amongst the diversity of personality factors. The latest attempt to answer the question is by McAdams who also broadened the perspective from measurable units to all manifestations of individuality (McAdams & Pals, 2006). The article "New Big Five" presents five principles or information sources in reaching for the picture of the whole individual. The readily measurable units or dispositions include personality traits as well as so-called characteristic adaptations which comprise variegated motivational, cognitive and developmental factors along which individuals relate to their environments. Other information sources escaping easy measurement pertain to different self-defining life narratives in different sociocultural contexts.

According to McAdams, shared widely by others, personality traits describe habitual, across situations recurring and often directly observable behavior, ie., summaries of behavior habits. Traits are necessary and valuable first-hand outlines of previously unknown individuals. Characteristic adaptations (motives, interests, etc.) in turn relate the individual to different environments enriching and deepening understanding of the whole person. Adaptations to environments cannot be directly observed from behavior.

Traits

The roots of personality traits are in Gordon Allport's (1937) theorizing which gave birth to the extensive tradition of research in personality traits. The Big Five trait framework has attained wide popularity and served as the basis for development of a multitude of tests, standardized self-report questionnaires. The most well-known test of the five factor framework and its variants (HEXACO) is the NEO-PI-R (Costa & McRae, 1992). Meta-analyses on work and academic performance have been published by Barrick & Mount (1991), Hurtz & Donovan (2000). Zell & Lesick's "superanalysis" incorporates over half a million subjects. An interesting finding is that work and academic performance are predicted by different traits (Zell & Lesick, 2021).

Motives and interests

Motives and needs share a long history with traits in personality psychology. The theoretical roots lie in Henry Murray's taxonomy of nearly thirty needs (eg., need for achievement) and need-arousing environmental "press" (1938). The most widely known need-motive questionnaire is the PRF (Jackson, 1984). David McClelland developed the theory of achievement, power and affiliation motivation as well an original projective method for their measurement. According to the theory, people have two indepencent motivational systems incorporating implicit, nonconscious and explicit or conscious, self-reportable motives (McClelland et al., 1989, Niitamo, 1999; Schultheiss, 2008, 2021). Meta-analyses on predicting behavior from motives include Spangler (1992), Collins et al., (2004) and Van Iddekinge et al. (2018).

Occupational interests, particularly Holland's model of occupational personality (1997) has become a focus of renewed attention in work psychology. The RIASEC model incorporates six occupational interests: (R) Realistic, (I) Investigative, (A) Artistic, (S) Social, (E) Enterprising and (C) Conventional-detailed. People and occupations are described with the same terms with the goal of matching them together. Vocational interests were traditionally considered useful only in occupational choice and career coaching. Three meta-analyses indicate that they can also predict performance at work even better than personality traits (eg., Nye et al., 2017).

Toward integration

Personality traits and motives, needs and interests are different perspectives on personality. They are not rivalling nor better than the other, instead they complement each other. Traits and motives have in meta-analyses shown to predict behavior with roughly equal strength. They provide answers to different questions and are useful for different purposes. It is unfortunate that the two big research traditions of personality psychology have lived in their own silos. However, fruitful integration is shown in a longitudinal study with large datasets where the joint use of traits and motives resulted in significant prediction increments to what would be achieved with use of only one disposition class (Winter et al., 1998). Personality psychology would benefit more from integration of the current relatively established personality factors than seeking for any new factors.

Ways of thinking

Perhaps the most important example of isolation of the diverse peronality factors concerns ways of thinking. Ways of thinking or cognitive styles have led an isolated orphan's life, occasionally seen as parts of personality and occasionally of intelligence. This, despite that all leading scholars and APA incorporate thinking in their definitions of personality. The heyday of cognitive style research dates back to the period 1950 -1970 and their well-known exemplars include personal constructs, locus of control and field dependence-independence. The post-period waning of interest probably relates to the modest empirical results against the preceding expectations. On the other hand, success criteria during the industrial era emphasized external performance (career and salary progress, performance output volumes, managers' potential appraisals) where "competent thinkers" have never been succesful.

There has appeared renewed interest in ways of thinking during the last two decades. Particularly so concerning the dual-process theories (Evans & Stanovich, 2013), made known to the larger audience by the Nobel laureate Daniel Kahneman's book on "fast and slow" thinking (Kahneman, 2011). The split to intuitive and analytical thinking serves as a foundation for a whole theory of personality (Epstein, 2013). Alaybek and colleagues published recently a meta-analysis on the ability of analytic and intuitive thinking in predicting performance in work. (Alaybek et al., 2022).

The most important reason for renewed research attention to ways of thinking relates to the current transition to data-centric world. Digitalization and artificial intelligence are part of the everyday living and the major challenge is to understand and handle information. Among the top ten skills needed in 2025, listed by the World Economic Forum, the first five, from analytical thinking to creativity, pertain to thinking processes. Along the disruption of work, "doing" things is shifting over to algorithms and robots. The fate and possibility for humans remains in handling information, planning and problem solving instead of "doing" things.

Back to situations

Situational factors have also re-entered the agenda in personality psychology. In the aftermath of the person-situation debate proponents of the situation perspective acknowledged the existence of personality factors but argued that their influence depends on each situation (Mischel & Shoda, 1995).

Trait researchers have also become interested in situational specificity of behavior. According to the trait activation model (Tett et al., 2021) personality traits become activated from cues in the environment. In work life, the cues are represented by eg., organizational culture, leadership styles and job demands. The model coincides much with Murray's early taxonomy according to which environmental "press" arouse individuals' needs or motives to behave accordingly.

Shaffer and Postlethwaite published a meta-analysis (2012) showing that personality tests with their scale items or instructions framed specifically to reference work-specific behaviors reached an average validity of .24, whereas the noncontextualized, general personality tests reached only a .11 level. Situations were taken even more strongly into account in a meta-analysis on vocational interests. The results showed that the match between the individual's main interest and that of the vocation resulted in significant increments in prediction of work performance (Nye et al., 2017).

The interest arisen in situational qualities is embodied in the concept of psychological situations, presented in a recently published handbook (Rauthmann, Sherman & Funder, 2020). Focus should indeed be set planfully on situations and environments. Significant progress can be expected specifically from research on situational demands and pressures, to reach better understanding of person-situation dynamics. Only after clarification of this socio-psychological plateau may we focus on personality's interface with biological factors.