Body-image marking. Validity of body-width estimates as operational measures of body image.
Mirror-marked body-width guesses are too inaccurate to trust.
01Research in Context
What this study did
The researchers asked adults to mark how wide they thought their body was on a life-size mirror. They then compared those marks to real body size and to other body-image tests. The goal was to see if mirror marking could serve as a quick measure of body image.
What they found
The mirror marks rarely matched true body width. The errors were large and did not line up with scores on standard body-image surveys. The team concluded the method is too flawed for research or clinical use.
How this fits with other research
Falcomata et al. (2012) also tested a visual tool—personal digital photos—for recording dietary intake. Their photos proved both reliable and valid, showing that pictures can work when the method is sound.
McIntyre et al. (2002) looked at another kind of marking: proctors grading student tests. They found accuracy improved when two people scored the same page, again showing that human marking can be fixed with extra checks.
Jones et al. (2010) simply gave people with Prader-Willi syndrome a figure-rating scale and found clear body dissatisfaction. They did not question their tool, unlike D et al. who warn that untested marking methods can mislead.
Why it matters
If you plan to measure body image, skip mirror-width tasks. Pick tools that already show good reliability, such as figure-rating scales or validated surveys. Before adopting any new quick-and-easy visual method, demand the same proof you would for an academic test: clear data that it measures what it claims.
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02At a glance
03Original abstract
The relation of image-marking estimates of body width (IM) to actual widths, to other indices of body-size perception, and to measures of body satisfaction were examined using data obtained in a nonclinical sample of 200 women. The results of regression and correlational analyses were as follows: (a) actual widths accounted for only a small proportion of the variance in IM estimates, (b) the variance in IM estimates remaining after actual width was accounted for was not meaningfully related to other body-image indices, and (c) actual widths were more highly correlated with other body-image indices than were differences between estimated and actual widths (IM estimate-actual width). The current results suggest that most of the variance in IM estimates is error variance. Possible methodological confounds, which may bias women's estimates of body widths in the direction of overestimation, are discussed.
Behavior modification, 1991 · doi:10.1177/01454455910152009