ANTIPERSPIRANT RESULTS 197 (6) (7) (8) (9) (lo) (11) (12) (13) (14) (15) w. Wooding and P. Finklestein, A critical comparison of two procedures for antiperspirant evalua- tion, J. Soc. Cosmet. Chem,, 26, 255-275 (1975). W. Cochran and G. Cox, Experimental Designs (John Wiley & Sons, New York, 1957). G. Milliken and D. Johnson, Analysis of Messy Data, Volume I: Designed Experiments (Lifetime Learning Publications, Belmont, CA, 1984). J. Fleiss, The Design and Analysis of Clinical Experiments (John Wiley & Sons, New York, 1986). A. I. MacLennan and K. A. Whinney, Hot-room testing of antiperspirant products, Chemistry and Industry, 13 (1987). N. Laird, Further comparative analyses of pretest~posttest research designs, The American Statistician, 37, 329-330 (1983). M. J. Egger, M. Coleman, J. Ward, J. Reading, and H. Williams, Uses and abuses of analysis of covariance in clinical trials, Controlled Clinical Trials, 6, 12-24 (1985). E. J. Stanek, Choosing a pretest-posttest analysis, The American Statistician, 42, 178-183 (1988). B. J. Winer, Statistical Principles in Experimental Design (McGraw-Hill, New York, 1971). L. Kupper and K. Hafner, How appropriate are popular sample size formulas? The American Statisti- cian, 43, 101-105 (1989).

j. Soc. Cosmet. Chem., 42, 199-210 (May/June 1991) Effects of olfactory stimulation on performance and stress in a visual sustained attention task JOEL S. WARM, WILLIAM N. DEMBER, and RAJA PARASURAMAN, Department of Psychology, University of Cincinnati, Cincinnati, OH 45221 (J.S.W., W.N.D.), and Department of Psychology, The Catholic University of America, Washington, DC 20064 (R.P. ). Received December 5, 1990. Presented at the Annual Meeting of the Society of Cosmetic Chemists, San Francisco, May 1990. Synopsis Subjects performed a visual sustained attention (vigilance) task for 40 minutes during which they received periodic 30-second whiffs of pure air or a hedonically positive fragrance, Muguet or Peppermint, through a modified oxygen mask. The former fragrance had been independently judged as relaxing, the latter as alerting. Subjects receiving either fragrance detected significantly more signals during the vigil than unscented air controls. Subjective reports of mood and workload indicated that the subjects experienced the vigilance task as stressful and demanding. However, the fragrances had no impact on the latter measures. These results provide the initial experimental evidence to indicate that fragrances can enhance signal detectability in a task demanding sustained attention, though the exact characteristics of effective fragrances have yet to be determined. INTRODUCTION Vigilance, or sustained attention, tasks require observers to remain alert and to detect infrequent and unpredictable stimulus events over prolonged periods of time (1-2). Although subjects engaged in such tasks are required only to dedicate themselves to looking or listening for the specified events that constitute signals for detection, their performance on these tasks is remarkably fragile, and the tasks tend to induce consid- erable stress. The brittle character of vigilant behavior is revealed through the decrement function, a decline in the frequency and/or speed of signal detections over time. This decline is often complete from 20 to 35 minutes after the initiation of the vigil (1-2) in some cases, it can even be observed as early as the first five minutes of watch (3). Along with the decrement function, vigilance performance is accompanied by increased catecholamine and cortisol output, indicating physiological stress (4-5), and by subjective reports indicating that monitors feel less energetic, more strained, bored, irritated, drowsy, and 199