Brief Peppermint Odour Exposure and Immediate Free Recall of a Visual Object Array: A Three-Arm Randomised Experiment

A single 30 s inhalation of peppermint essential oil improved immediate free recall of a 4×4 visual object array in 60 healthy adults, versus no odour (g = 1.29, BF10 = 134).

• Why it matters: Odours are often claimed to enhance cognition via limbic and prefrontal pathways, but evidence for specific essential oils is mixed and expectancy can confound findings.
• What they did: In a three-arm randomized experiment, 60 adults (18–50) were assigned to peppermint, clove, or no odour (n = 20 each), then studied 16 pictured items for 20 s and recalled them freely.
• The result: Recall differed by condition (Welch F(2, 37.0) = 8.53, p < .001; omega2 = 0.14); peppermint (11.20 ± 2.14) exceeded no odour (8.45 ± 2.04), while clove (9.55 ± 3.19) was not reliably different from either.

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