Goggles that trick the wearer into thinking the plain snack in their hand is a chocolate cookie, or make biscuits appear larger have been unveiled in Japan, offering hope to weak-willed dieters everywhere.

Researchers at the University of Tokyo have developed devices that use computer wizardry and augmented reality to fool the senses and make users feel more satisfied with smaller — or less appealing — treats.

On one device goggle-mounted cameras send images to a computer, which magnifies the apparent size of the cookie in the image it displays to the wearer while keeping his hand the same size, making the snack appear larger than it actually is.

In experiments, volunteers consumed nearly 10 percent less when the biscuits they were eating appeared 50 percent bigger.

They ate 15 percent more when cookies were manipulated to look two-thirds of their real size.

Professor Michitaka Hirose at the university’s graduate school of information science and technology said he was interested in how computers can be used to trick the human mind.

“How to fool various senses or how to build on them using computers is very important in the study of virtual reality,” he told AFP.

Hirose said standard virtual reality equipment that attempts to cater to complex senses like touch often results in bulky equipment.

But he said using one or more senses to fool the others was a way around this problem.

“Reality is in your mind,” he said.

In another project, Hirose’s team developed a “meta cookie”, where the headgear uses scent bottles and visual trickery to fool the wearer into thinking the snack they are eating is anything but a plain biscuit.

Users can set the device to their favourite taste so they think they are eating a chocolate or strawberry-flavoured cookie.

Hirose says experiments so far have shown 80 percent of subjects are fooled.

The team has no plans as yet to commercialise their invention, but would like to investigate whether people wanting to lose weight can use the device.