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

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.

Comparison of a Web-based versus traditional diet recall among children.

Self-administered instruments offer a low-cost diet assessment method for use in adult and pediatric populations. This study tested whether 8- to 13-year-old children could complete an early version of the Automated Self Administered 24-hour diet recall (ASA24) and how this compared to an interviewer-administered 24-hour diet recall. One-hundred twenty 8- to 13-year-old children were recruited in Houston from June through August 2009 and randomly assigned to complete either the ASA24 or an interviewer-administered 24-hour diet recall, followed by the other recall mode covering the same time interval. Multivariate analysis of variance, testing for differences by age, sex, and ethnic/racial group, were applied to percentages of food matches, intrusions, and omissions between reports on the ASA24 and the interviewer-administered 24-hour diet recall. For the ASA24, qualitative findings were reported regarding ease of use. Overall matches between interviewer-administered and ASA24 self-administered 24-hour diet recall was 47.8%. Matches were significantly lower among younger (8- to 9-year-old) compared with older (10- to 13-year-old) children. Omissions on ASA24 (18.9% overall) were most common among 8-year-olds and intermediate among 9-year-olds. Eight- and 9-year-olds had substantial difficulties and often required aid in completing ASA24. Findings from this study suggest that a simpler version of an Internet-based diet recall program would be easier for children to use.