162 II. BIOLOGICAL  FOuNDATIONS
Structural  Stability
This type of stability reflects the extent to 
which correlations among phenotypic dimen -
sions of temperament are invariant across the 
lifespan. An extensive body of evidence—  
based on measures of both the Big Three and 
the Big Five—has established that essentially 
identical structures can be identified in chil -
dren, high school student, college student, 
normal adult, and older adult samples (e.g., 
Costa & McCrae, 1992; Digman, 1990; Ey -
senck & Eysenck, 1975; Kohnstamm, Hal -
verson, Mervielde, & Avilla, 1998; Mack -
innon et al., 1995; Measelle, John, Ablow, 
Cowan, & Cowan, 2005). Thus, personality 
structure shows impressive stability from ad -
olescence through old age.
Fewer data exist for pre-high school 
ages, but the available evidence indicates 
that structures closely paralleling the Big 
Three and the Big Five emerge at an early 
age. For instance, Digman (1997) and asso -
ciates replicated the Big Five structure in a 
series of studies in which teachers rated the 
characteristics of elementary schoolchildren. 
Similarly, analyses of the Children’s Behav -
ior Questionnaire (CBQ; Rothbart, Ahadi, 
Hershey, & Fisher, 2001; Rothbart, Ahadi, 
& Hershey, 1994), a parent-  report instru -
ment that assesses temperament in children 
ages 3–8 years, consistently have =identi -
fied three higher-  order factors that closely 
resemble the Big Three (Ahadi et al., 1993; 
Goldsmith et al., 1997; Rothbart, Ahadi, & 
Hershey, 1994; Rothbart et al., 1994). Shiner 
and Caspi’s (2003) review of the childhood/
adolescent personality literature identified 
four robust higher-  order factors (N/NE, E/
PE, A, and C).
It is notable that these data are based not 
on self- but on other ratings; that is, the same 
structure emerges regardless of whether rat -
ers are the individuals themselves, teachers, 
or parents. A meta-  analysis of the struc -
ture of the Schedule for Nonadaptive and 
Adaptive Personality (Clark, Simms, Wu, & 
Casillas, 2014) that included not only self- 
and peer-rated data but also several different 
forms of the measure found that neither for -
mat nor rater had an appreciable effect on its 
traits’ structure (Nuzum, Ready, & Clark, 
2019). Coupled with data demonstrating the 
broad cross-  cultural robustness of personal -ity trait models (e.g., Ahadi et al., 1993; De 
Clercq et al., 2006; Jang et al., 1998), the ev -
idence provides strong support for McCrae 
and Costa’s (1997) claim that “personality 
structure is a human universal” (p. 514).
Temperament and  Psychopathology
A prominent theme of this chapter is that the 
emergence of a theoretical model of temper -
ament has led to widespread progress in the 
field. Like any good theory, this model not 
only explains a range of existing data but 
also suggests avenues for further explora -
tion; moreover, it has the power to change in 
fundamental ways how certain phenomena 
are conceptualized. Psychopathology is one 
domain that the temperament-  based para -
digm of personality has transformed. For 
decades, research in personality and psycho -
pathology developed independently, with lit -
tle cross-  fertilization. Eventually, however, 
investigators in each of these fields began 
to take notice of the work in the other, to 
note parallelisms between findings, and to 
ask how personality and psychopathology 
might be interrelated: Does personality act 
as a vulnerability factor for the development 
of psychopathology? Is personality changed 
by the experience of mental disorder? Does 
personality affect the way in which psycho -
pathology is manifested? Widiger, Verhuel, 
and van den Brink (1999) ably explored 
many of these questions and noted, for ex -
ample, that “personality and psychopathol -
ogy at times fail to be distinct conditions” 
(p. 351; see also Tackett & Mullins-  Sweatt 
[Chapter 35] and Widiger & Oltmanns 
[Chapter 36], this volume).
The first subfield to embrace this view 
was personality—  it is no longer being debat -
ed whether adaptive and nonadaptive per -
sonality fall along a continuous distribution 
(vs. personality pathology being categori -
cally distinct from normal-  range personal -
ity). This proved to be only a first step in 
a larger sea change. Clark (2005) reviewed 
the extensive literature relating personal -
ity and psychopathology, and found that 
the correlations of normal-  range person -
ality with personality pathology were no 
greater nor more extensive than its correla -
tions with other forms of psychopathology. 
Given “the similarity in the magnitude of 