Public Health Nutrition

HOT TOPIC – Assessment and methodology

Children’s accuracy of portion size estimation using digital food images: effects of interface design and size of image on computer screen

Tom Baranowskia1 c1, Janice C Baranowskia1, Kathleen B Watsona1, Shelby Martina1, Alicia Beltrana1, Noemi Islama1, Hafza Dadabhoya1, Su-heyla Adamea1, Karen Cullena1, Debbe Thompsona1, Richard Budaya2 and Amy Subara3

a1 USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030-2600, USA

a2 Archimage, Inc., Houston, TX, USA

a3 National Cancer Institute, Bethesda, MD, USA


Objective To test the effect of image size and presence of size cues on the accuracy of portion size estimation by children.

Design 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.

Setting Laboratory-based with computer and food models.

Subjects 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.

(Received January 21 2010)

(Accepted June 02 2010)

(Online publication November 15 2010)


c1 Corresponding author: Email