This paper studies the constellations of attitudes––sentimental, moral, epistemological, and social––that three leading psychologists active in turn-of-the-twentieth-century America took to be essential to the production of scientific knowledge. William James, G. Stanley Hall, and Edward Titchener located the virtues and traits proper to the scientific frame of mind, and combined them into normative images of the man of science, or, ‘scientific personae’ as I use the term here. I argue that their competing formulations of the scientific ethos informed their psychological (...) practice and epistemological commitments. James, Hall, and Titchener mobilized their representations of the man of science in order to reconfigure the field of psychology and redefine its boundaries, as well as to promote forms of sociability and define the proper role of scientists both within the academy and in the wider polity. (shrink)