The Delboeuf illusion is an optical illusion that Belgian philosopher Franz Joseph Delboeuf documented in 1865. It starts with two dots of similar size; when a large circle surrounds one dot, and the other is surrounded with a small circle, the dot with the small circle looks bigger. According to McClain et al. (2013), slight alterations to the food environment can change food size perceptions, influence what is eaten and how people serve food. Van Ittersum and Wansink (2011) carried out four laboratory experiments to investigate the serving biases based on the Delboeuf illusion. A field experiment was also carried out to help the researchers develop findings that may be critical to improving consumer welfare.
Advice to mom
Use Smaller Plates
Plate size is an easy factor to manipulate how people serve food at the re-union. It has been observed that an increase in plate size is simultaneous with the upsurge in obesity rates in America. The three most popular health-related websites (WebMD.com, NIH.gov, and Medicinenet.com recommend using smaller dinnerware to reduce food consumption. The visual perception angle is influenced by the close resemblance of plates and the two Delboeuf concentric circles. According to the research, mom should serve the linguini on smaller plates, leading to people serving almost 13% lesser than usual.
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The following facts were proven right in the research by Van Ittersum and Wansink (2012):
For plates with a diameter ratio lower than 0.5 but larger than 0 between the preferred serving size and the dinnerware, people serve more food than the targeted serving size.
For plates with a diameter ratio higher than 0.5 but smaller than one between the preferred serving size and the plates, people serve less food than the targeted serving amount.
In experiment 1, food on larger plates looked five percent larger in diameter than those with a thinner rim. The consumers were more likely to pick a larger plate with the perception that it had more food than a smaller plate.
However, it is essential to note that as the diameter ratio between the preferred serving size and the plate’s approaches zero or one, the perceptual visual illusion disappears because there is no contrast.
Use Contrasting Colors Between the Food and the Plate by Using Rim-Colored Plates
It was confirmed that rim coloring has a psychological effect on how people serve food. However, the impact of edge-colored plates is more significant with smaller food portion sizes. Rim coloring resulted in making food look larger for small food portions.
According to the results of the experiment by McClain et al. (2013);
There was evidence that remarkable rim coloring affected how consumers interacted with food portion sizes, and the effect was more significant in smaller food portions.
It was also proven that consumers were 2.3 times more likely to choose the rims with a solid blue color with the assumption that it has more food than the plates that lacked edge coloring. The effect reduces for bigger food sizes as consumers were only 0.6 times more likely to assume the rim-colored plates had a higher serving as opposed to plates with no coloring.
Food portion diameter size is overestimated in a range between 1.5-1.6% when the food is observed on a colored plate as opposed to a plain white plate.
Use Table Cloths with Similar Colors as the Plates
Decreasing the color contrast between the table cloth and the plate lessens the inducing circle’s effect. The visitors at the re-union are more likely to serve lesser alfredo pasta due to the insignificant color contrast. According to the hypothesis on previous papers done by Van Ittersum and Wansink (2012), applying the low-color contrast method with the tablecloth and the plate will yield the following results;
Decreases excessive serving when the dinner ratio between the serving amount and the dinnerware is smaller than 0.5 but larger than 0.
Decreases underserving when the diameter ratio between the serving amount and the dinnerware is bigger than 0.5 but smaller than 1.
References
McClain, A. D., Van den Bos, W., Matheson, D., Desai, M., McClure, S. M., & Robinson, T. N. (2013). Visual illusions and plate design: The effects of plate rim widths and rim coloring on perceived food portion size. International Journal of Obesity , 38 (5), 657-662. https://doi.org/10.1038/ijo.2013.169
Van Ittersum, K., & Wansink, B. (2012). Plate size and color suggestibility: The Delboeuf illusion’s bias on serving and eating behavior. Journal of Consumer Research , 39 (2), 215-228. https://doi.org/10.1086/662615
