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Scent Integration with VR: Determining Avatar's 'Age'

The sense of smell is undoubtedly one of the most prominent of the primary senses, with the deepest connection to the brain's memory centres. A familiar scent is much more likely to conjure a swift memory to mind, whether pleasant or otherwise, than a sight or sound is. Additionally, it is a very strong method of confirming what the other senses are telling the person – which is are but a couple of the reasons why scent integration with VR has always been pursued so vigorously.

We have many other articles detailing the specifics of the difficulties inherent in creating such an interface, and many others on actual scent interfaces currently or once-upon-a-time upon the market. This is not one of them, but discusses an important use of smell in human social affairs, that is so instinctive, it has been all but overlooked. As the title of this article already gives away, we determine the rough age of those we are interacting with, by their body odour strength and type.

The 'old person smell' is ubiquitous across cultures, recognisable in every interaction. The same with the scent of a newborn, or even gauging the experience level of a young professional by how much 'muck' stench they have managed to get on themselves, versus another professional who stays cleaner.

We use body odour scent without even realising it, as a subconscious gearstick to alter how we interact with others. Yet, its not something most VR system researchers have even thought about the necessity of adding to our avatars. Once scent interfaces are more commonly applied in VR systems, it is almost a necessary aspect to add to a given avatar to fully enable our subconscious social interaction to proceed most naturally.

From the Monell paper:

A) Mean intensity ratings for each body odor category divided by sex of body odor donor.

B) Mean pleasantness ratings for each body odor category divided by sex of the body odor donor. Negative values indicate ratings on the unpleasant spectra whereas positive values indicate ratings on the positive spectra.

C) Mean discrimination performance, measured in percentage correct responses, according to comparison and donor sex. Solid line in graph represents chance performance (50%).

D) Left hand side indicates total correct pairings of each body odor category and right hand side indicates mean correct age labeling of the body odors. In all graphs, error bars denote standard error of the mean (SEM).

The discovery that humans determine in part, an age estimation from scent, comes from work done by the Monell Center in Philadelphia in the US.

“Similar to other animals, humans can extract signals from body odours that allow us to identify biological age, avoid sick individuals, pick a suitable partner, and distinguish kin from non-kin,” said senior author Johan Lundström, a sensory neuroscientist at Monell.

Indeed, contrary to popular supposition, the so-called ‘old-person smell’ is rated as less intense and less unpleasant than body odours of middle-aged and young individuals. Because studies with non-human animals at Monell and other institutions have demonstrated the ability to identify age via body odour, Lundström’s team examined whether humans are able to do the same. Evaluators were able to discriminate the three donor age categories based on odour cues. Statistical analyses revealed that odours from the old-age group were driving the ability to differentiate age. Interestingly, evaluators rated body odours from the old-age group as less intense and less unpleasant than odours from the other two age groups.

“Elderly people have a discernible underarm odour that younger people consider to be fairly neutral and not very unpleasant,” said Lundström. “This was surprising given the popular conception of old age odour as disagreeable. However, it is possible that other sources of body odours, such as skin or breath, may have different qualities.”

Future studies will both attempt to identify the underlying biomarkers that evaluators use to identify age-related odours and also determine how the brain is able to identify and evaluate this information. This will give further information which we will be able to use as we decide how to integrate human age-scents into avatar creation, whilst we wait for scent interfaces to become commonplace in our simulated worlds.


The Special Scent of Age

The Smell of Age: Perception and Discrimination of Body Odors of Different Ages (Paper)

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