Wood Odor Mapping on Arousal Axes: Exploring Correspondence with Physiological Indices of Stress Recovery

This study mapped a wide range of naturally derived odors, including those derived from wood, on the two-dimensional axes of tense arousal (TA) and energetic arousal (EA), and examined whether quadrant differences influenced recovery following stress. In the context of Attention Restoration Theory and biophilic design, the study provided preliminary evidence that olfactory stimuli can be treated as a designable element in a functional and reproducible manner. In Experiment 1, wood flours, wood essential oils, and non-wood oils were mapped based on subjective ratings conducted under identical conditions, and differences in their TA-EA positions were revealed. Ratings of "naturalness" were associated with lower EA, suggesting that quadrant mapping can capture meaningful dimensions of odor perception. In Experiment 2, Hinoki and camphor were selected as contrasting stimuli. Hinoki facilitated initial recovery of autonomic nervous system activity, as shown by lower heart rate compared with no odor, whereas camphor showed no effect. These findings demonstrate that TA-EA quadrant mapping provides a practical framework for olfactory design in indoor environments.