Simulator offers a taste of what the internet may have in store for users
The internet is a perfect tool for allowing us to see and hear things happening at locations where we're not physically present. It's not so good, however, at doing the same thing with taste. We can't taste things without physically putting flavours into our mouths - until now.
Researchers at the Keio-NUS CUTE Centre at the National University of Singapore have come up with a simulator that tricks the brain into thinking it has experienced a taste. The centre is part of a collaboration between NUS and Japan's Keio University that looks into possible futuristic everyday applications of interactive media.
"We can control audio and video very well at the moment," says Nimesha Ranasinghe, who led the research, which started out as his PhD project. "But we can't do the same with taste, which is an equally important sense, and it's undermining digital interaction."
To use the simulator, called a Digital Taste Interface, two electrodes are attached to their tongue of the user, one on top and the other underneath.
A combination of electrical and thermal stimulation can recreate the primary tastes - sweet, salty, sour, bitter and umami - plus a few more complex variations like minty.
Changes to electrical current, frequency and polarity result in changes to the taste experienced by the user. The tastes delivered to users can be controlled over the internet using a taste-over-internet protocol developed by the team.
"It's a matter of stimulating the tongue and telling the brain what it's sensing," says Ellen Do, a visiting research professor at NUS, who is also a professor in the Schools of Industrial Design and Interactive Computing at Georgia Institute of Technology in the US.
"At the moment we're not stimulating flavours," says Ranasinghe. "Flavour is a very complex concept involving thousands of elements. We're stimulating primary tastes.
"So at a low frequency, about 100 to 400 Hertz, the taste is salty, while at about 800 to 1,000 Hertz and up, the taste is sour. Reverse the polarity so that the sensation comes from the bottom surface [of the electrode], and you get a bitter sensation."
The researchers are at pains to stress that the device is in its early stages, and any potential practical applications are purely theoretical and yet to be tested - but the implications are certainly intriguing.
The entertainment industry will be interested in the potential for more immersive sensory experiences, and the possibility of taste-based rewards systems in games: the completion of a level, for example, could be accompanied by a pleasant sweet or minty taste.
But there are also more serious possibilities, including medical ones - particularly when it comes to conditions in which food intake plays a vital role, such as diabetes, high blood pressure and obesity.
"If I'm a diabetes patient and I'm not allowed sugar, maybe it can give me a sensation which will make me feel satisfied, so I feel like I've had iced lemon tea with sugar, but actually I'm happy with just plain water," says Do. "Even without chemical ingredients, you can fool the brain. I think that's amazing."
Cancer patients could also benefit, she adds. "After chemotherapy, nothing tastes good, everything has no flavour and you don't want to eat. This could possibly help people rehabilitate their brains so they can perceive tastes again."
As well as needing more research into ways to create more complex flavours, and other contributors to a satisfying gustatory experience such as texture, the Digital Taste Interface is also a bit big at the moment - the electrodes measure 40mm by 15mm by 0.2mm. But the team is working on a smaller version less than a third of the current size, at 12mm by 4mm by 0.2mm.
Do says that even smaller electrodes are already possible, but only at the cost of sacrificing the thermal element.
One hurdle on the road to creating more realistic flavours is that individuals perceive taste differently.
That's down to fixed differences like the density of the taste buds and even a person's sex (apparently women have more sensitive mouths than men). Environmental factors such as temperature, noise level, what else that individual has consumed recently, and whether they smoke, also play a part. So does a previous experience with a flavour.
"Everybody senses taste differently, and we don't yet have enough understanding of how that works," says Do.
"There are people who seem to be taste-blind, in the way that people are colour-blind, but we don't know what that is. We also don't have the vocabulary for describing texture."
So the research into the Digital Taste Interface raises some interesting questions about the nature of taste perception in general - questions which Do says the team is working with neuroscientists to answer.
"There are more questions than answers at the moment," she says. "But the best way to predict the future is to invent it," she says.