Sniffing the context: divergent effects of odor valence on intertemporal choice in loss vs. gain frames

Olfactory cues, processed via direct limbic connections, can strongly modulate affective states, yet their influence on complex decisions like intertemporal choice (involving trade-offs between immediate and delayed outcomes) remains underexplored. Grounded in hyperbolic discounting models, this study employed a within-subjects design to systematically investigate the impact of olfactory emotional valence on temporal discounting behavior. Forty-four participants performed an intertemporal choice task under pleasant (sweet orange essential oil) and unpleasant (valeric acid) odor conditions, alongside a neutral (propylene glycol) control. Analysis of variance confirmed the sign effect within the gain-loss framework. The findings indicate that unpleasant odors consistently increase decision impulsivity relative to pleasant and neutral odors. Critically, interaction analyses revealed a strong situational dependency: the impulsivity-enhancing effect of unpleasant odors was statistically significant only under gain-frame conditions. Results from linear mixed-effects models illustrated dynamic modulation by task sequence. In the gain context, both the influence of odor valence on reaction time (RT) and the relationship between discount rate (k) and RT varied with task sequence. Under loss conditions, the effect of odor valence and its interaction with k were markedly sequence-dependent, with unpleasant odors exhibiting a non-linear, increasing influence across successive trials. This research reveals a context-specific mechanism by which olfactory emotions shape intertemporal choice, offering novel insights into the environmental sensory modulation of decision-making.