Are humans constantly but subconsciously smelling themselves?

Abstract

All primates, including humans, engage in self-face-touching at very high frequency. The functional purpose or antecedents of this behaviour remain unclear. In this hybrid review , we put forth the hypothesis that self-face-touching subserves self-smelling. We first review data implying that humans touch their faces at very high frequency. We then detail evidence from the one study that implicated an olfactory origin for this behaviour: This evidence consists of significantly increased nasal inhalation concurrent with self-face-touching, and predictable increases or decreases in self-face-touching as a function of subliminal odourant tainting. Although we speculate that self-smelling through self-face-touching is largely an unconscious act, we note that in addition, humans also consciously smell themselves at high frequency. To verify this added statement, we administered an online self-report questionnaire. Upon being asked, approximately 94% of approximately 400 respondents acknowledged engaging in smelling themselves. Paradoxically, we observe that although this very prevalent behaviour of self-smelling is of concern to individuals, especially to parents of children overtly exhibiting self-smelling, the behaviour has nearly no traction in the medical or psychological literature. We suggest psychological and cultural explanations for this paradox, and end in suggesting that human self-smelling become a formal topic of investigation in the study of human social olfaction. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.

Limitations in odour simulation may originate from differential sensory embodiment

“…One could speculate that imagery of body odours is different from that of other odours, since children may be able to manipulate body odours to some extent. Although, to the best of our knowledge there are no data on mental imagery of body odours, this special issue presents novel data that humans regularly sniff themselves to sample their own odour [61]. This fascinating observation could suggest that body odours are different in kind.…”

“…R. Soc. B 375: 20190273 to one's own body odour and self-sampling [61] will provide the first reference stimulus that can be used for volitional olfactory imagery.…”

Sniffing Out New Friends: Similarity in Body-Odor Predicts the Quality of Same-Sex Non-Romantic Dyadic Interactions

“…Humans are constantly but mostly subconsciously sniffing themselves (21) and their conspecifics (20). These odors then have a host of effects, and may carry a host of information.…”

“…Non-human mammals rapidly obtain complex social information from body-odor ( 19 ). Humans also constantly sniff conspecifics ( 20 ), and themselves ( 21 ), to obtain social information, and similarity in the sniffed body-odor infers kinship with self ( 22 , 23 ), or between strangers ( 22 , 24 ). Moreover, growing evidence implies that humans can infer the emotional state of conspecifics, whether it be fear ( 25 ) or happiness ( 26 ), from body-odor alone.…”

Human olfactory communication: current challenges and future prospects

“…Then, Perl et al [87] examine olfaction at very close range, namely the act of self-sniffing hands. They argue that very high rates of face-touching provide a way in which humans sample the odour of their own bodies and of those they have touched.…”