Studies have shown that people rate food as tasting better, and they eat more of it, when eating with one or more other people. The effect is known as the "social facilitation of eating," and scientists don't fully understand why it happens. In a new study from Japan's Nagoya University, however, it was found that the phenomenon also occurs when solo diners eat in front of a mirror.

"We wanted to find out what the minimum requirement is for the social facilitation of eating," says Ryuzaburo Nakata, lead author of a paper on the study. "Does another person have to actually be physically present, or is information suggesting the presence of others sufficient?".

In the study, volunteers dined by themselves – once with a mirror present (so they could see themselves eating), and once with a monitor displaying a wall. When the mirror was used, they ate more food and reported that it tasted better. Interestingly, replacing the mirror with a monitor displaying a photo of that person eating had a similar effect.

The study was conducted using both young and old test subjects, although the findings may be particularly applicable to the elderly.

"Studies have shown that for older adults, enjoying food is associated with quality of life, and frequently eating alone is associated with depression and loss of appetite," says corresponding author Nobuyuki Kawai. "Our findings therefore suggest a possible approach to improving the appeal of food, and quality of life, for older people who do not have company when they eat."

The paper was recently published in the journal Physiology & Behavior.