This paper reports on research to study the benefit of a punctual self-directed learning experience with a hypermedia in the appropriation of a foreign language. Twenty-eight educational sciences students took a 55 item pretest on English notions. The students then engaged in a self-directed learning session using the CD-ROM, "L'anglais d'aujourd'hui en 90 lecons," (a "Studio Multimedia" product) and later took a post-test consisting of the same 55 questions as the pretest. Results are discussed in the following areas: (1) the concept of "spectrum of performances," i.e., the distribution of a student's answers according to their type along a spectrum from incorrect with a high degree of confidence to correct with a high degree of confidence; (2) the notion of "ideal spectral evolution"; (3) quantification of the four hemispectrum shapes; and (4) categorization of individual cases as outnorming students, ideal students, stationary students, radicalized students, weak students aware of their progresses, and students unaware of their progresses. Figures and tables illustrate: confidence degrees; states of partial knowledge; ideal spectral evolution; expected spectral evolution; skewness coefficients; and one student's spectrum of performances, performances card, and realism graphs. Contains 22 references. (DLS)