title: Children's accuracy of portion size estimation using digital food images: effects of interface design and size of image on computer screen.
abstract: OBJECTIVE
  To test the effect of image size and presence of size cues on the accuracy of portion size estimation by children.
  
  
  METHODS
  Children were randomly assigned to seeing images with or without food size cues (utensils and checked tablecloth) and were presented with sixteen food models (foods commonly eaten by children) in varying portion sizes, one at a time. They estimated each food model's portion size by selecting a digital food image. The same food images were presented in two ways: (i) as small, graduated portion size images all on one screen or (ii) by scrolling across large, graduated portion size images, one per sequential screen.
  
  
  METHODS
  Laboratory-based with computer and food models.
  
  
  METHODS
  Volunteer multi-ethnic sample of 120 children, equally distributed by gender and ages (8 to 13 years) in 2008-2009.
  
  
  RESULTS
  Average percentage of correctly classified foods was 60·3 %. There were no differences in accuracy by any design factor or demographic characteristic. Multiple small pictures on the screen at once took half the time to estimate portion size compared with scrolling through large pictures. Larger pictures had more overestimation of size.
  
  
  CONCLUSIONS
  Multiple images of successively larger portion sizes of a food on one computer screen facilitated quicker portion size responses with no decrease in accuracy. This is the method of choice for portion size estimation on a computer.
authors.affiliation: USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030-2600, USA. tbaranow@bcm.tmc.edu
authors.forename: Tom
authors.initials: T
authors.lastname: Baranowski
authors.forename: Janice C
authors.initials: JC
authors.lastname: Baranowski
authors.forename: Kathleen B
authors.initials: KB
authors.lastname: Watson
authors.forename: Shelby
authors.initials: S
authors.lastname: Martin
authors.forename: Alicia
authors.initials: A
authors.lastname: Beltran
authors.forename: Noemi
authors.initials: N
authors.lastname: Islam
authors.forename: Hafza
authors.initials: H
authors.lastname: Dadabhoy
authors.forename: Su-heyla
authors.initials: SH
authors.lastname: Adame
authors.forename: Karen
authors.initials: K
authors.lastname: Cullen
authors.forename: Debbe
authors.initials: D
authors.lastname: Thompson
authors.forename: Richard
authors.initials: R
authors.lastname: Buday
authors.forename: Amy
authors.initials: A
authors.lastname: Subar
mesh_terms: D000293:Adolescent; D002648:Child; D004435:Eating; D002149:Energy Intake; D005260:Female; D005502:Food; D005518:Food Preferences; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D015596:Nutrition Assessment; D010781:Photography / Q000592:standards*; D011897:Random Allocation; D012858:Size Perception / Q000502:physiology*; D011795:Surveys and Questionnaires