An emerging trend in virtual reality – incorporating smell – could be exciting news not just for gaming but for health care as well.
A growing number of hospitals across the country are using virtual reality to help patients manage pain, overcome phobias, and calm anxiety. Providers and patients report mostly good results, save for the high price tag. And VR therapies may start to become more common, particularly if insurers begin to cover the cost.
But despite its potential in health care, VR continues to fall short in one way: We still can't smell it.
"[Smell] hasn't been explored enough in virtual reality, but it deserves to be," says Judith Amores, PhD, senior researcher at Microsoft Research and research affiliate at the MIT Media Lab. “The potential benefits are incredible.”
Amores has researched connecting VR with smell to enhance a person's response. In one experiment, she had participants wear a VR headset that depicted calming nature scenes and a smart necklace she developed capable of releasing lavender scent. When bursts of lavender were added to the VR, the participants reported feeling 26% more relaxed than they had without the scent. A device that monitors brain activity confirmed it: The participants' physiological response had increased by 25% when scent was added.
The study was small (just 12 people), but Amores says it represents a direction that demands to be explored with more people in peer-reviewed research. A 2022 systematic review of research on virtual reality using multiple senses backs her up: “Smell and taste are still underexplored,” the review says, “and they can bring significant value to VR applications” – including health.
When we smell something, receptor cells in the nose message the olfactory bulb at the base of the brain. That information is shuttled to the amygdala and hippocampus, brain areas responsible for processing memory and emotion, Amores explains.
"Your sense of smell goes directly into the emotional center of the brain," says Amores. "That means you can literally change how you feel based on what you're smelling."
Thus, smell has the power to immerse us deeper into virtual reality, which could make VR treatments faster and more effective, Amores says.
New Smell Technology Could Drive Research Forward
While medical research in this area may be slow, the entertainment industry's efforts could help push it forward. No VR systems that incorporate smell are available yet, Amores says, but that may change as soon as this year.
At the international Consumer Electronics Show (CES) held earlier this month, Vermont-based OVR Technology unveiled a headset with eight primary aromas that can be combined to create thousands of scents. The ION3, as it's called, is scheduled to be released later this year.
Meanwhile, a study published in the International Journal of Human-Computer Studies describes an odor machine that was tested with a virtual reality headset from tech giant HTC. The researchers suggest such technology could, among other uses, help enhance “smell training” for those who've lost their sense of smell due to COVID-19.
Boosting VR Therapies With Smell
Smell-enhanced VR therapies could be explored for all kinds of clinical uses, Amores says, like to treat anxiety, sleep disorders, or even Alzheimer's disease (smell is linked to memory).
VR “exposure therapy” has already been used to treat PTSD in military veterans, immersing them into a virtual environment that triggers a traumatic memory, desensitizing them to the memory so they learn their thoughts are safe. A 2021 article in Brain Research noted that incorporating smell into such therapy is “critically needed,” since odors can trigger traumatic memories, in some cases more fiercely than sounds. A distressing scent (like diesel fuel or the smell of something burning) could be followed by, or layered with, a relaxing scent such as pine, eucalyptus, or cinnamon in a gradual way to reduce or even eliminate smell triggers, according to the paper.
Those with addictions may benefit from VR exposure therapy too, learning to manage or resist cravings triggered by certain cues, some research suggests. VR has the power to transport them anywhere – to a bar or a party, say – and the scent of wine or cigarettes may add to the realism needed to elicit cravings.
Another application could be surgery prep, Amores says. A patient has a VR session complete with relaxing smells – walking through a forest and breathing in the scents of pine and moss, for example – lowering anxiety before the procedure, and potentially reducing the amount of pain medication needed and improving outcomes.
Those smells could be deployed again during hospitalization or recovery — with or without the VR — to quickly return the patient to a calm state. It's a kind of Pavlovian conditioning that would be easy to replicate, says Amores.
At Cedars-Sinai in Los Angeles, VR is being researched and used to help patients alleviate pain across a variety of conditions, including irritable bowel syndrome and chronic lower back pain.
Melissa Wong, MD, an OB/GYN specializing in maternal-fetal medicine at Cedars-Sinai, has studied VR for pain and stress relief during labor and childbirth, possibly delaying the use of an epidural.
"There is absolutely something about the mind-body connection when it comes to pain,” says Wong, “and the use of VR could tap into that." Making it more immersive by adding scent would likely amplify those effects, she adds.
As research continues to highlight the power of smell, we'll likely see the sense being implemented more and more in clinical treatment, Amores predicts. It may not be long before “Smell-o-Vision” comes to your hospital.
Judith Amores, PhD, senior researcher, Microsoft Research, research affiliate, MIT Media Lab.
Melissa Wong, MD, OB/GYN specializing in maternal-fetal medicine, Cedars-Sinai, Los Angeles.
PLOS One: “Provider experiences of virtual reality in clinical treatment.”
2018 IEEE 15th international conference on wearable and implantable body sensor networks: “Promoting relaxation using virtual reality, olfactory interfaces and wearable EEG.”
IEEE Transactions on Visualization and Computer Graphics: “Do Multisensory Stimuli Benefit the Virtual Reality Experience? A Systematic Review.”
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