title: Visual illusions and plate design: the effects of plate rim widths and rim coloring on perceived food portion size.
abstract: OBJECTIVE
  The Delboeuf Illusion affects perceptions of the relative sizes of concentric shapes. This study was designed to extend research on the application of the Delboeuf illusion to food on a plate by testing whether a plate's rim width and coloring influence perceptual bias to affect perceived food portion size.
  
  
  METHODS
  Within-subjects experimental design. Experiment 1 tested the effect of rim width on perceived food portion size. Experiment 2 tested the effect of rim coloring on perceived food portion size. In both experiments, participants observed a series of photographic images of paired, side-by-side plates varying in designs and amounts of food. From each pair, participants were asked to select the plate that contained more food. Multilevel logistic regression examined the effects of rim width and coloring on perceived food portion size.
  
  
  RESULTS
  Experiment 1: participants overestimated the diameter of food portions by 5% and the visual area of food portions by 10% on plates with wider rims compared with plates with very thin rims (P<0.0001). The effect of rim width was greater with larger food portion sizes. Experiment 2: participants overestimated the diameter of food portions by 1.5% and the visual area of food portions by 3% on plates with rim coloring compared with plates with no coloring (P=0.01). The effect of rim coloring was greater with smaller food portion sizes.
  
  
  CONCLUSIONS
  The Delboeuf illusion applies to food on a plate. Participants overestimated food portion size on plates with wider and colored rims. These findings may help design plates to influence perceptions of food portion sizes.
authors.affiliation: Division of General Pediatrics, Department of Pediatrics and Stanford Prevention Research Center, Department of Medicine, Solutions Science Lab, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: McClain
authors.affiliation: Department of Psychology, Stanford University, Stanford, CA, USA.
authors.forename: W
authors.initials: W
authors.lastname: van den Bos
authors.affiliation: Division of General Pediatrics, Department of Pediatrics and Stanford Prevention Research Center, Department of Medicine, Solutions Science Lab, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Matheson
authors.affiliation: Quantitative Science Unit, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Desai
authors.affiliation: Department of Psychology, Stanford University, Stanford, CA, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: McClure
authors.affiliation: 1] Division of General Pediatrics, Department of Pediatrics and Stanford Prevention Research Center, Department of Medicine, Solutions Science Lab, Stanford University School of Medicine, Stanford, CA, USA [2] Center for Healthy Weight, Stanford University and Lucile Packard Children's Hospital at Stanford, Stanford, CA, USA.
authors.forename: T N
authors.initials: TN
authors.lastname: Robinson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001066:Appetite / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology; D004032:Diet / Q000523:psychology*; D002149:Energy Intake / Q000502:physiology; D005260:Female; D005518:Food Preferences / Q000523:psychology*; D006801:Humans; D007088:Illusions / Q000523:psychology; D016015:Logistic Models; D008297:Male; D062407:Meals / Q000523:psychology; D016017:Odds Ratio; D064787:Portion Size / Q000523:psychology*; D012858:Size Perception