Limonene Selectively Modulates Visual Attention Through P300 Suppression: A Comparative Event-Related Potential Study...

Odor stimuli can influence cognitive processes, including selective attention. However, whether these effects are driven by the chemical properties of odor compounds or by their semantic or emotional associations remains unclear. This study aimed to clarify the mechanism by which olfactory inputs influence visual attention by isolating the effects of specific odor compounds from those of affective or semantic factors.

To investigate this question, we assessed the effects of limonene, a key compound found in citrus odors, and lemon essential oil on visual attention, as indexed by the P300 component of event-related potentials, which reflect the allocation of selective attention. Participants completed a visual oddball task under three odor conditions: no odor, limonene, and lemon essential oil.

Limonene presentation significantly reduced P300 peak amplitudes compared with the no-odor condition, whereas lemon essential oil showed not significantly reduce. Subjective ratings of pleasantness, congruency, and arousal did not differ significantly between the two odors.

Our results suggest that limonene modulates selective attention primarily through its chemical properties rather than through mood or semantic influences. This study provides new evidence for chemically specific olfactory-visual interactions and underscores the importance of distinguishing chemical effects from psychological mechanisms in cross-modal cognitive modulation.