A good odour to breathe? The effect of pleasant ambient odour on human visual vigilance.

The present study examined the effect of an alerting and a relaxing odour on human visual vigilance. Three groups of undergraduates (N = 54) completed a sustained visual vigilance task which required them to respond whenever a target stimulus appeared on a computer monitor. One group completed the task in the presence of an alerting odour (peppermint), another did so in the presence of a relaxing odour (bergamot) and a third group completed the task in an unscented environment. A 2×3×2 (sex×odour×diurnal preference) MANOVA was performed in order to determine group differences in response times and number of correct detections. Participants in the bergamot condition detected fewer targets correctly within 1.25 seconds of the target appearing than did those in the peppermint or no-odour groups. Exposure to bergamot was also associated with significantly fewer correct detections in the second than in the first half of the task, when compared with the other two conditions. The results suggest that sustained exposure to a relaxing odour can impair visual vigilance.