38 I. THEORETICAL  PERSPECTI vES AND  CONCEPT uAL uNITS
Note that Table 2.1 includes a very large 
number of concepts with different names. It 
illustrates how researchers, as well as practi -
tioners, in the field of personality assessment 
were faced with a bewildering array of per -
sonality scales from which to choose, with 
little guidance and no organizing theory or 
framework at hand. As Allport once put it, 
“Each assessor has [ sic](their) own pet units 
and uses a pet battery of diagnostic devices” 
(1958, p. 258). What made matters worse 
was that scales with the same name might 
measure concepts that were quite different, 
and scales with different names might mea -
sure concepts that were quite similar, a situa -
tion known as the “jingle-  jangle fallacy.” Al -
though diversity and scientific pluralism can 
be useful, systematic accumulation of find -
ings and communication among research -
ers was impossible amid this cacophony of 
competing concepts and scales. This is not 
the way to run a scientific discipline. Indeed, 
Kuhn (1962) would probably have described 
personality trait psychology in the 1980s as 
an immature science, stuck in the prepara -
digmatic phase of competing schools .
Many personality researchers at the time 
were hoping to be the one who would dis -
cover the ultimate model of personality 
structure that all others would then adopt, 
thus uniting the fragmented field into a 
community that speaks a common lan -
guage. However, we now know that such an 
integration was not to be achieved instan -
taneously or by any one researcher, or by 
any one theoretical perspective. Instead, a 
young science is expected to mature slowly 
and to eventually become paradigmatic by 
evolving and refining a global organizing 
model or theory that has great integrative 
power (Kuhn, 1962).
What personality psychology needed 
was a descriptive model, or taxonomy, of 
its subject matter. One of the central goals 
of scientific taxonomies is the definition of 
overarching domains within which large 
numbers of specific instances can be under -
stood in a simplified way. Thus, in person -
ality psychology, a taxonomy would permit 
researchers to study specified domains of 
related personality characteristics rather 
than examining separately the thousands 
of particular attributes that make human 
beings individual and unique. Moreover, a generally accepted taxonomy would facili -
tate the accumulation and communication 
of empirical findings by offering a standard 
vocabulary, or nomenclature.
After decades of research, and long de -
bates about the right number of factors and 
the best labels for these factors, the field 
has now achieved an initial consensus on a 
general taxonomy of personality traits: the 
“Big Five” personality dimensions. These 
dimensions do not represent a particular 
theoretical perspective but were derived ini -
tially from analyses of the natural-  language 
terms people use to describe themselves and 
others. Rather than replacing all previous 
systems, the Big Five taxonomy serves an in -
tegrative function, because it can represent 
the various and diverse systems of personal -
ity description in a common framework, as 
shown by the five columns organizing Table 
2.1.
Outline and Goals of This Chapter
The first version of this chapter (John, 1990) 
offered a comprehensive and detailed review 
of virtually every study published on the Big 
Five by then. This is no longer possible as 
we are writing this fourth edition, almost 
30 years later. What has happened in the 
meantime? Figure 2.1 shows the publication 
trends from 1980 to 2019 and illustrates 
how fundamentally the field has changed. 
Specifically, we show the number of publi -
cations related to the Big Five personality 
traits for each 5-year interval, beginning 
in the early 1980s, obtained from keyword 
searches of the PsycINFO data base. To pro -
vide a comparison, we also show the publi -
cation trend data for the influential models 
Cattell and Eysenck had developed earlier. 
Although both were already at retirement 
age, they remained active and their influ -
ence continued throughout the 1990s. In 
fact, both Cattell (1990) and Eysenck (1990) 
contributed chapters on personality traits 
for the first edition of this handbook.
How did the publication trends develop 
after the 1990 handbook was published? We 
had expected that publications on the Big 
Five would show a substantial increase since 
the early 1990s, with Cattell’s and Eysenck’s 
influence decreasing. But we were surprised 