Hygiene is a cornerstone of public health. Poor hygiene is closely tied to infection, disease transmission, and preventable illness, which is why public health researchers have long sought to understand the psychological drivers of behaviors such as handwashing, housecleaning, and personal grooming. Decades of work on disgust—the emotion thought to have evolved as a behavioral defense against pathogens—have established that people who are more easily disgusted tend to engage in more protective hygiene behavior. At the same time, olfaction has repeatedly been implicated in this picture: the sense of smell is our most direct chemical sensor of the environment, capable of detecting spoilage, contamination, and body odors that signal potential health threats.

The new research set out to connect these threads more rigorously. Rather than treating olfaction as a single, undifferentiated capacity, the team distinguished between olfactory metacognition—how people think and feel about their own sense of smell—and olfactory function measured objectively in the laboratory. The central hypothesis was that olfactory functioning relates to hygiene behavior at least partly through disgust sensitivity, the tendency to experience revulsion in response to potential contaminants. To test this, the researchers conducted two studies with distinct designs and measurement approaches.

Study 1 recruited 270 participants and focused on three indicators of olfactory metacognition: odor awareness, the subjective importance people attach to their sense of smell, and self-rated olfactory ability. Each of these indicators was positively associated with self-reported hygiene behavior. Crucially, when the researchers used mediation analysis to examine indirect pathways, each indicator showed a significant indirect effect through disgust sensitivity. In other words, people who were more attuned to odors, who valued their sense of smell more highly, and who rated their olfactory ability as stronger also tended to report higher disgust sensitivity—and that heightened disgust, in turn, was associated with more frequent and thorough hygiene practices.

These findings align with a conceptual framework in which disgust functions as part of the so-called behavioral immune system, a suite of psychological mechanisms that guard against disease threat before pathogens ever reach the body. According to this view, sensory inputs—especially smells—provide cues about potential contamination, and disgust converts those cues into avoidance and cleaning behavior. The Study 1 results suggest that individual differences in how prominently smell figures in daily awareness may shape the intensity of this disgust-based defense, and thereby the vigor of one’s hygiene routine.

But subjective self-reports are not the same as measured sensory ability. Study 2 therefore extended the investigation with 66 participants who completed psychophysical odor-threshold testing and suprathreshold ratings for one pleasant and one unpleasant odor. This design allowed the researchers to ask whether the ability to detect faint odors—rather than merely one’s beliefs about one’s own nose—also relates to hygiene behavior, and whether the valence of the odor matters. The results were more nuanced here. Odor sensitivity itself was not directly associated with hygiene behavior, a finding that echoes earlier work suggesting that disgust sensitivity relates to affective responses to odors rather than to the raw capacity to detect them.

Yet the indirect pathway through disgust sensitivity did appear in Study 2, though selectively. A significant indirect effect through disgust sensitivity was observed for the pleasant odor but not for the unpleasant odor. That an unpleasant smell failed to show the same pathway may seem counterintuitive, but the authors caution that a bootstrap comparison did not support a statistically reliable difference between the two indirect effects. In other words, the apparent pleasant-versus-unpleasant asymmetry at the threshold level should be interpreted with care, as the data could not confirm that the two odor conditions truly differed in the strength of this mediated pathway.

Where odor-condition differences did emerge clearly was at the suprathreshold level—when participants judged clearly perceivable odors. The associations of hygiene behavior with odor pleasantness and familiarity differed significantly between the pleasant and unpleasant odor conditions, with positive associations observed specifically for the pleasant odor. This suggests that how people appraise and contextualize everyday smells—their emotional coloring and their sense of familiarity—may relate to hygiene behavior differently depending on the hedonic character of the odor in question, whereas simple detection ability appears less consequential.

Taken together, the two studies paint a differentiated picture: subjective and psychophysical aspects of olfactory functioning are related to hygiene behavior in partly different ways. Disgust sensitivity emerges as one affective correlate of these associations, providing a plausible psychological route by which smelling and thinking about smells translates into washing, cleaning, and grooming. Meanwhile, odor valence effects were more clearly supported for conscious appraisal of suprathreshold odors than for basic odor sensitivity, implying that the emotional meaning of smell, rather than the acuity of the nose per se, drives much of the connection to hygiene.

The findings carry practical weight for public health. If disgust sensitivity mediates the link between olfaction and hygiene behavior, interventions aimed at improving hygiene might benefit from strategies that engage the sense of smell and the emotion of disgust together—approaches that earlier experimental and field-based work on hand hygiene has begun to explore. At the same time, the authors emphasize limits: the indirect pathway was not uniformly observed across odor conditions, the pleasant-versus-unpleasant asymmetry in threshold-based mediation was not statistically reliable, and the data underlying the study will be shared only on reasonable request to the corresponding author. Future research with larger and more diverse samples will be needed to determine when, and for whom, the nose-disgust-hygiene pathway operates most strongly—and whether it can be harnessed to promote healthier behavior at the population scale.

Subject of Research: The relationship between olfactory functioning, disgust sensitivity, and hygiene behavior

Article Title: Disgust sensitivity as an indirect pathway linking olfactory functioning and hygiene behavior

Article References: Jiang, C., Modi, U., & Han, P. (2026). Disgust sensitivity as an indirect pathway linking olfactory functioning and hygiene behavior. Current Psychology, 45(17), Article 1487. https://doi.org/10.1007/s12144-026-10057-0

Image Credits: AI Generated

DOI: 10.1007/s12144-026-10057-0

Keywords: olfaction, disgust sensitivity, hygiene behavior, odor awareness, olfactory metacognition, odor threshold, odor valence, behavioral immune system, public health, psychology, sensory perception, handwashing