Brief Peppermint Odour Exposure and Immediate Free Recall of a Visual Object Array: A Three-Arm Randomised Experiment
- 1Üsküdar University
Abstract
Background: Odours reach limbic and prefrontal targets through a uniquely direct pathway and are often claimed to enhance cognition, yet experimental evidence for specific essential oils is mixed and frequently confounded by expectancy. We tested whether a brief inhalation of peppermint or clove essential oil, compared with no odour, alters immediate free recall of a visual object array. Methods: Sixty healthy adults aged 18-50 years were randomly allocated to peppermint oil, clove oil or no odour (n = 20 each). After 30 s of inhalation (or none), participants studied a 4 x 4 array of 16 pictured items for 20 s and then wrote down every item they could recall, without time limit. Groups were compared with one-way and Welch ANOVA, Welch-corrected pairwise tests with Holm correction, Hedges' g with 95% confidence intervals and Bayes factors. Results: Recall differed across conditions (Welch F(2, 37.0) = 8.53, p < .001; omega2 = 0.14). Participants exposed to peppermint recalled more items (11.20 +/- 2.14) than those exposed to no odour (8.45 +/- 2.04; g = 1.29, 95% CI [0.61, 1.97], p(Holm) < .001, BF10 = 134). Clove (9.55 +/- 3.19) did not differ reliably from either no odour (g = 0.40, p(Holm) = .203) or peppermint (g = 0.60, p(Holm) = .127; BF10 = 1.29). Conclusions: A single brief exposure to peppermint oil was associated with substantially better immediate recall than no odour. Because the peppermint-clove contrast was inconclusive and no placebo odour was used, the data do not establish an odour-specific effect; general arousal and expectancy remain plausible contributors. Pre-registered, laboratory-based replications with placebo odours, blinding and arousal measures are required.
Related
- A randomised feasibility trial of VR-enhanced cue exposure therapy versus neutral VR exposure for cocaine use disorder, with wearable monitoring and JITA-EMA: Feasibility randomised controlled trial protocol
- A single day of natural daylight exposure and physical activity does not conclusively change circadian phase: A Bayesian crossover experiment
- The Paraventricular Nucleus of the Thalamus Differentiates Threat and Safety Cues During Delayed Recall in Humans
- 793 PD1 expression in LAG3+ exhausted T cells restrains memory recall responses through a mechanism involving TCR repertoire diversity and non CD8+ T cell populations
- Naturalistic recall preserves temporal specificity despite cortical feature reorganization
BibTeX
@misc{akar2026brief,
title = {{Brief Peppermint Odour Exposure and Immediate Free Recall of a Visual Object Array: A Three-Arm Randomised Experiment}},
author = {B. Akar and T. Altıntas},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.31.763290},
url = {https://www.biorxiv.org/content/10.64898/2026.10.31.763290v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Brief Peppermint Odour Exposure and Immediate Free Recall of a Visual Object Array: A Three-Arm Randomised Experiment
AU - B. Akar
AU - T. Altıntas
PY - 2026
DA - 2026/10/31
PB - bioRxiv
DO - 10.64898/2026.10.31.763290
UR - https://www.biorxiv.org/content/10.64898/2026.10.31.763290v1
AB - Background: Odours reach limbic and prefrontal targets through a uniquely direct pathway and are often claimed to enhance cognition, yet experimental evidence for specific essential oils is mixed and frequently confounded by expectancy. We tested whether a brief inhalation of peppermint or clove essential oil, compared with no odour, alters immediate free recall of a visual object array. Methods: Sixty healthy adults aged 18-50 years were randomly allocated to peppermint oil, clove oil or no odour (n = 20 each). After 30 s of inhalation (or none), participants studied a 4 x 4 array of 16 pictured items for 20 s and then wrote down every item they could recall, without time limit. Groups were compared with one-way and Welch ANOVA, Welch-corrected pairwise tests with Holm correction, Hedges' g with 95% confidence intervals and Bayes factors. Results: Recall differed across conditions (Welch F(2, 37.0) = 8.53, p < .001; omega2 = 0.14). Participants exposed to peppermint recalled more items (11.20 +/- 2.14) than those exposed to no odour (8.45 +/- 2.04; g = 1.29, 95% CI [0.61, 1.97], p(Holm) < .001, BF10 = 134). Clove (9.55 +/- 3.19) did not differ reliably from either no odour (g = 0.40, p(Holm) = .203) or peppermint (g = 0.60, p(Holm) = .127; BF10 = 1.29). Conclusions: A single brief exposure to peppermint oil was associated with substantially better immediate recall than no odour. Because the peppermint-clove contrast was inconclusive and no placebo odour was used, the data do not establish an odour-specific effect; general arousal and expectancy remain plausible contributors. Pre-registered, laboratory-based replications with placebo odours, blinding and arousal measures are required.
ER -