Applications of the Delbouef Illusion

Which circle below looks bigger?

Having already learned about the Ebbinghaus illusion, you were probably right in guessing that the circle with the ring around it appears larger than the non-surrounded circle. This is an example of the Delboeuf illusion, first identified by Belgian philosopher and mathematician Joseph Delbouef in 1887 or 1888. Modern psychologists have tested this illusion in various experiments, including one to determine if eyeshadow makes eyes look bigger (it does), and others to determine if the quantity of food on a plate looks larger if the plate is smaller.
Studies by Koert Van Ittersum and Brian Wansink^[1] at the Cornell Food and Brand Lab have studied the effect of the Delbouef illusion on eating and serving behavior. In several different experiments, they measured if people would take more or less than a typical serving size depending on the size of their plate, the color of the plate, the color of the tablecloth, and how much they knew about the Delboeuf illusion.

Assignment:

You are in charge of providing meals at the upcoming family reunion and are worried about not having enough linguini alfredo (a white pasta) to serve the entire crew. You want to ensure that no one takes too much food.

STEP 1: Read through the study, “Plate Size and Color Suggestibility: The Delboeuf illusion’s bias on eating and serving behavior” by Koert Van Ittersum and Brian Wansink. You can find the full article by searching online or using your library’s database.

STEP 2: Write a plan for yourself with some advice on what size plates you should use, what color they should be, and what color tablecloths you should buy. Read through the study, then explain in a few paragraphs (between 200-400 words) how you can utilize the Delboeuf illusion to minimize costs at the reunion. Cite specific pieces of evidence (at least four quantitative examples) from the research.

Sample Grading Rubric