Research Article Expectancy of Stress-Reducing Aromatherapy Effect and Performance on a Stress-Sensitive Cognitive Task Irina Chamine 1 and Barry S. Oken 2 1 Department of Behavioral Neuroscience, Oregon Health & Science University, Mail Code CR120, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA 2 Departments of Neurology, Behavioral Neuroscience and Biomedical Engineering, Oregon Health & Science University, Mail Code CR120, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA Correspondence should be addressed to Irina Chamine; fonareva@ohsu.edu Received 3 November 2014; Accepted 23 December 2014 Academic Editor: Karin Meissner Copyright © 2015 I. Chamine and B. S. Oken. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective. Stress-reducing therapies help maintain cognitive performance during stress. Aromatherapy is popular for stress reduction, but its efectiveness and mechanism are unclear. Tis study examined stress-reducing efects of aromatherapy on cognitive function using the go/no-go (GNG) task performance and event related potentials (ERP) components sensitive to stress. Te study also assessed the importance of expectancy in aromatherapy actions. Methods. 81 adults were randomized to 3 aroma groups (active experimental, detectable, and undetectable placebo) and 2 prime subgroups (prime suggesting stress-reducing aroma efects or no-prime). GNG performance, ERPs, subjective expected aroma efects, and stress ratings were assessed at baseline and poststress. Results. No specifc aroma efects on stress or cognition were observed. However, regardless of experienced aroma, people receiving a prime displayed faster poststress median reaction times than those receiving no prime. A signifcant interaction for N200 amplitude indicated divergent ERP patterns between baseline and poststress for go and no-go stimuli depending on the prime subgroup. Furthermore, trends for benefcial prime efects were shown on poststress no-go N200/P300 latencies and N200 amplitude. Conclusion. While there were no aroma-specifc efects on stress or cognition, these results highlight the role of expectancy for poststress response inhibition and attention. 1. Introduction Stress-management approaches can ameliorate negative con- sequences of stress on health and cognition [1]. Aromather- apy, therapeutic use of inhaled essential oils, is a popular stress-reducing approach due to low side efects [2, 3], but its efectiveness is questioned. Despite research supporting aromatherapy efectiveness, the existing evidence is not convincing, according to a comprehensive review, due to the poor quality of previous studies [4]. Small samples, mostly subjective outcomes, and inadequate controls and blinding are the major criticisms about previous research [4, 5]. Lack of convincing evidence for aromatherapy actions is also linked to insufcient understanding of aromatherapy mechanism. Te criticisms raised by the previous reviews were add- ressed by evaluating stress-reducing properties of lavender (Lavandula angustifolia) essential oil in a more rigorous study. Lavender, popular for relaxation and stress reduction [6], has been previously shown to improve cognition [7] and decrease agitation [8, 9], stress [10–13], and anxiety [14–17]. However, some studies demonstrated no specifc lavender efects concluding that the changes afer aromatherapy expo- sure occur solely due to expectancy of improvement [18, 19] and considered aromatherapy an “inefective treatment but an efective placebo” [20]. To evaluate this idea, the role of expectancy in aromatherapy actions was the focus of our investigation. As a part of a larger trial assessing aromatherapy efects on physiological and cognitive functions [21], this study was rigorously designed and used objective outcomes, two diferent controls, and assessors blinded to the groups assig- nment. Stress-reducing lavender aromatherapy properties Hindawi Publishing Corporation Evidence-Based Complementary and Alternative Medicine Volume 2015, Article ID 419812, 10 pages http://dx.doi.org/10.1155/2015/419812