206 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Z O 90 80 7O 6O 5O 40 30 I I I I I I I I 1 2 3 4 I Air i • Muguet ß Peppermint I PERIODS OF WATCH (10MIN.) Figure 3. Percentage of correct detections as a function of periods of watch for subjects in the air, Muguet, and Peppermint conditions. difference between groups reached statistical significance [F(2,33) = 3.25 p = 0.05] and that performance efficiency deteriorated significantly over time [F(3,99) = 6.30 p 0.001]. The groups X periods interaction lacked significance [F(6,99) = 1.17 p 0.05]. False alarms were generally few in all conditions. Mean percentages of false alarms for the four periods of watch were 2.7%, 1.8%, 2.0%, and 2.3 %, respectively, for the air group 8.9%, 6.7%, 6.2%, and 5.9%, respectively, for the group exposed to Muguet and 12.4%, 7.2%, 9.3%, and 7.0%, respectively, for subjects exposed to Peppermint.

EFFECTS OF OLFACTORY STIMULATION 207 An analysis of variance of the percentage of false alarms showed that their overall frequency declined significantly over time [F(3,99) = 7.42 p ( 0.001], a typical finding in vigilance experiments (1). All of the remaining sources of variance in the analysis lacked significance (p) 0.05). STRESS AND WORKLOAD RATINGS Mean pre-test and post-test scores on the Thackray, Stanford, and Yoshitake scales are presented for each fragrance group in Table II. Preliminary inspection of the data for the Thackray ratings of attention, sleepiness, strain, boredom, and irritation indicated that the results for the five subscales were similar. Consequently, the scores in Table II for this instrument represent summated values (possible range is 5-45, with 25 as the midpoint) across the subscales. Increments in negative feelings are reflected in lower post-test as compared to pre-test scores. In the case of the Stanford and Yoshitake scales, however, increments in fatigue and sleepiness are revealed through higher post-test as compared to pre-test scores. Perusal of Table II will show that the subjects in this study found the vigil to be quite stressful. Composite feelings of increased inattentiveness, sleepiness, strain, boredom, and irritability after the vigil are evident in the Thackray ratings, along with increased feelings of sleepiness and fatigue on the Stanford and Yoshitake scales. In the case of the Yoshitake scale, pre-test and post-test differences were dramatic. On average, symptoms of fatigue increased by 257% in the post-test measure. Analyses of variance performed on the data of all three scales revealed significant phase effects [F(1,33) ) 48 p ( 0.001] in each case. In no case, however, were the groups or the groups X phase components of the analyses significant (p) 0.05), indicating that the self reports of stress in this study were not attenuated by exposure to accessory olfactory stimulation. Mean workload scores for the practice period and for the main task in the three fragrance conditions are displayed in Table III. It is evident in the table that the subjects rated the workload of both the 10-minute practice period and the 40-minute vigil to be high. All scores are in the upper range of the TLX scale. Moreover, there is a trend for the air group to show a greater increment in workload from the 10-minute practice session to the 40-minute vigil than for the Table II Mean Pre-Test and Post-Test Scores on the Thackray, Stanford, and Yoshitake Scales for Subjects in the Air, Muguet, and Peppermint Groups Scales Thackray Stanford Yoshitake Groups Pre Post Pre Post Pre Post Air 32.5 25.6 2.3 3.6 2.5 7.4 Muguet 33.6 25.1 2.4 3.8 3.3 7.1 Peppermint 34.2 25.7 2.2 3.3 2.7 7.2 Mean 33.4 25.5 2.3 3.6 2.8 7.2