25 September 2014

Use the illusion: see more and eat less

Trompe l'oeil - making portions look bigger can help reduce consumption
Science has revealed a simple and incredible trick that will help you lose weight. 

No fooling! Or rather, by fooling your eye, you may get the desired result.

The trick is to make portions appear bigger than they are. This leads people to serve and eat less.

We know that bigger portions lead us to eat more (bite-size version here), but portions that appear bigger have the reverse effect.

**The value of illusions**

Visual illusions have long fascinated humans but mostly they are viewed as problems to be explained.

Philosophers study illusions for the challenges they offer to ontology and epistemology.

Psychologists study them for the light they throw on our understanding of how the human brain works and its limits. 

FoodScape by Carl Warner
Representational artists make money by illusions. The two- or three-dimensional images they create such as Carl Warner’s foodscapes (created entirely out of food) are illusory representations of reality.

Consumer scientists like Brian Wansink and Koert van Ittersum have been exploring how optical illusions can be of practical help in reducing consumption and so tackle the growing prevalence of obesity.

**Use smaller plates**

Using smaller plates is a fairly obvious solution to limit portion sizes. However, there is more to this solution than simply providing less space.

The research shows that a portion served on a small plate will look bigger than it is. Consequently, people tend to under-serve on small plates and so consume less. 

The use of bigger plates leads to the reverse effect with the portion looking smaller than it is. This may underlie the common criticisms of nouvelle cuisine as providing "tiny portions" that are more art form than food.

Nouvelle cuisine - looks smaller than it is
The illusory effect of plate size on portion size is explained by the Delboeuf and the Ebbinghaus illusions. (Click on the links to see how much you are affected by these illusions - and how much you might reduce your consumption.)

**Create colourful contrasts**

The Delboeuf and Ebbinghaus illusions are thought to critically depend on the contrast in size between the target (the circle in the centre) and the surrounding context.

A portion of food appears smaller when served on a bigger plate encouraging us to over-serve. But the size contrast is complicated by the issue of colour contrast.

The tendency to over-serve on big plates is amplified where there’s not much of a contrast in the colour of the food and the plate, such as pasta with a creamy sauce served on a white plate. Over-serving on bigger plates is also more likely if there’s high contrast between the plate colour and the tablecloth colour.
So, if you have large plates, choose plates in a colour different from the food and similar to the tablecloth.

**Use tall, thin glasses**

If you want to reduce your intake of sweetened drinks or alcohol, use tall, thin glasses in place of short, wide glasses.

People pour less and drink less juice from a tall, thin glass than a short, wide glass with the same volume. This effect is displayed by adults and is stronger among children.

The effect also holds for the pouring of alcohol, even after training, and even among experienced bar-tenders.

This illusion is so persuasive that many are surprised to find the volume of large sizes is often little different from one size down. 

Sports fans have used YouTube clips to show how a Seattle stadium and an Idaho stadium sold small and large cups of beer that held roughly the same volume, even though the larger one cost substantially more.

Recently, similar claims have been made about more mainstream retailers such as McDonalds and Tim Hortons, a Canadian coffee shop chain. Hortons' response is that there is a difference. But it’s not much!

The reason why the illusion operates is not clear although it may be related to human orientation anisotropy which is the well-known tendency to perceive a vertical line as longer than an equivalent horizontal line as in the vertical-horizontal illusion.

**Takeaway message**

Restaurants love creating an atmosphere using trompe l’oeil murals. 

One restaurant in Paris has taken trompe l’oeil one step further. All the dishes are created to appear like desserts. Whether this helps tackle obesity is uncertain.

Pompeii, c.70 CE
What does appear to be true is that trompe l’oeil can be brought to the table to help the masses lose weight.

To encourage yourself and others to serve less, and to eat less:
  1. use smaller plates
  2. if using big plates, maximise the colour contrast between the food being served and the dinner service, and minimise the colour contrast between the dinner service and the tablecloth
  3. use tall, thin glasses (e.g., wine-tasting glasses)
You can also use the over-serve bias to encourage more consumption of healthy food. For instance, use big, green plates for vegetables, and short, wide glasses for water.

Fool yourself into eating less. The fact is that these little fictions may help us lose fat.

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