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Individual Lives and Individual Differences: The Multidisciplinary Study of Personality (1900–1930) 183

histories based on their investigations of clients and their
families. Psychologists’ role in these interdisciplinary teams
“generally came down to the construction and application of
scales that would subject ‘personality’ to the rigors of mea-
surement and so convert it from merely an object of social in-
tervention to an object of science” (Danziger, 1990, p. 164).
The movement thus supported psychologists as purveyors of
expert scientific knowledge of personality in the form of test
scores.

American Psychology

Twentieth-century American experimenters wanted general

laws, not remarkable phenomena involving special persons.

(Porter, 1995, p. 211)

In the preceding sections, we have referred to the iden-
tification of psychologists with psychometric and statistical
approaches to personality. Here, we examine several inter-
related factors in the development of these approaches, and in
psychologists’ resistance toward studies of individuals, dur-
ing the early decades of the twentieth century.

Scientific Ethos

As many historians have suggested, psychometric approaches
reflected the positivistic, “natural science” ethos that had pre-
vailed in American psychology since the late 1800s (see, e.g.,
Danziger, 1990; see the chapter by Fuchs & Milar in this vol-
ume; Hornstein, 1988; Porter, 1995). Psychologists were par-
ticularly concerned with producing “objective” knowledge
and eliminating sources of “subjectivity”:

For experimental psychologists, being scientific meant creating

distance. It meant opening up a space, a “no man’s land,” be-

tween themselves and the things they studied, a place whose

boundary could be patrolled so that needs or desires or feelings

could never infiltrate the work itself. Every aspect of the experi-

mental situation was bent toward this goal—the “blind subjects,”

the mechanized recording devices, the quantified measures, and

statistically represented results. (Hornstein, 1992, p. 256)

From this perspective, case studies and life histories, relying
on subjective reports or interpretations, appeared unscientific.
The tendency to consider case studies unscientific was al-
ready clear just after the turn of the century in comments on
the work of two respected psychologists who drew heavily on
personal documents. While observing that the “personal con-
fessions” in William James’s (1902) The Varieties of Reli-
gious Experiencewere “extraordinary in range and fulness

[sic],” Coe (1903, p. 62) suggested that James’s results would

be “doubly valuable” if they were supplemented by “an ex-

perimental and physiological study of the same types” (p. 63)

and commented on the “romanticism, not to say impression-

ism” (p. 65) in his method. G. Stanley Hall’s Adolescence

(1904), which was illustrated with quotations from autobi-

ographies, literature, and answers to questionnaires, drew

similar criticism. “Dr. Hall is as much an artist as a scientist,”

commented one reviewer, adding, “It is to be regretted that

much of the questionnairedata...has not been secured or

tabulated according to the most approved statistical and

scientific methods” (Kirkpatrick, 1904, p. 692).

Practical Demands

During the first two decades of the twentieth century, as

American psychologists became increasingly concerned with

practical problems, “the primary goal of psychology became

the prediction and control of the ‘other,’ a science of the

acts (and by a short extension, the behavior) of people rather

than of their mental experiences” (Tweney & Budzynski,

2000, p. 1015; see also the chapter by Benjamin et al. in this

volume). Psychologists developed “mental tests” for selec-

tion, diagnosis, and placement in an effort to establish their

professional expertise in solving problems associated with

educational institutions, labor unions, and immigration, and

with the national war effort in 1917 and 1918 (Danziger,

1990; Parker, 1991; Sokal, 1984; Vernon, 1933). Designed to

screen soldiers vulnerable to shell shock, Woodworth’s Per-

sonal Data Sheet was probably the first objective self-report

personality “inventory” based on the mental test format (see

Camfield, 1969; Woodworth, 1919, 1932).

Following World War I, opportunities expanded for psy-

chologists to administer mental tests in military, manager-

ial, industrial, and educational settings (Danziger, 1990;

O’Donnell, 1985; Samelson, 1985; Sokal, 1984). In the early

1920s, however, critics began to question the predictive util-

ity of intelligence tests (Parker, 1991) and suggested that

measures of personality or character traits would improve the

prediction of performance (e.g., Fernald, 1920). Although

early measures of character and personality took various

forms, the less “efficient” methods were soon replaced by

tests based on the mental test model of adding scores on sep-

arate multiple-choice or true/false items to get a total (see

Parker, 1991). According to the psychometric approach to

personality, individual differences, conceived as coefficients

in prediction equations, could be used to predict and control

behavior. (Years later, Raymond B. Cattell’s “specification

equation” [1957, pp. 302–306] would become perhaps the

most fully developed example of such prediction equations.)