The development of the Body Morph Assessment version 2.0 (BMA 2.0): Tests of reliability and validity
Introduction
Body image is a multifaceted construct with many dimensions that may be objectively studied (Thompson, 2004). This study tested the reliability and validity of a new computerized measure of body image called the Body Morph Assessment version 2.0 (BMA 2.0). The BMA 2.0 measures current body size estimates (CBS), ideal body size estimates (IBS), acceptable body size estimates (ABS), body image/size dissatisfaction (CBS–IBS discrepancy) (Williamson, Gleaves, Watkins, & Schlundt, 1993) and provides an estimate of body size over/underestimation as compared to individuals of the same sex and body mass index. For the purpose of the present study, body distortion/body size overestimation was defined as, “the degree to which an individual misperceives current body size” (Stewart & Williamson, 2004, p. 498). Body image/size dissatisfaction was defined as, “the discrepancy between an individual's perceived current body size and perceived ideal body size” (Stewart & Williamson, 2004, p. 498), which has been established as valid measure of body dissatisfaction (Williamson et al., 1993).
Researchers generally agree that body image is multidimensional phenomenon (Prunzinsky & Cash, 2002). There are three main dimensions that have been identified in the classification of assessment measures: (a) attitudinal measures, which examine the attitudinal, cognitive, and affective components of body image; (b) perceptual measures, which examine the size perception aspect of body image, e.g., over or underestimation of body size; and (c) behavioral measures, which assess behaviors related to body image including body checking and/or avoidance behaviors. Some figural stimuli measures, e.g., the Body Image Assessment (BIA; Williamson, Davis, Bennett, Goreczny, & Gleaves, 1989), Body Image Assessment for Obesity (BIA-O; Williamson et al., 2000), the Body Morph Assessment (BMA; Stewart, Williamson, Smeets, & Greenway, 2001) estimate both size estimation as well as measure body size dissatisfaction.
Over the years, many weaknesses of figural stimuli measures have been noted: Such weaknesses include: (a) coarse response scales, (b) method of presentation, (c) scales of measurement, and (d) content validity problems (Gardner, Friedman, & Jackson, 1998; Russell & Bobko, 1992; Russell, Pinto, & Bobko, 1991). For example, with the use of silhouettes, individuals are typically asked to select one choice from a limited number of choices for a continuous variable (body size) which has been shown to alter their responses (Russell and Bobko, 1992, Russell et al., 1991). Silhouette measures are often presented in a fashion where all cards are on the table at once and some measures even place cards in ascending order from smallest to largest body size. This method allows the individual to use other cards as a point of reference for their choices and allows for very high test–retest reliability. Most silhouette measures do not increase in size in equal intervals from one to the other which presents statistical problems (Gardner et al., 1998). Further, silhouette measures have questionable content validity as they are typically animated type drawings or grossly unrealistic sketches of human figures and it is difficult for individuals to relate to in reference to their own body. Few of these measures have been validated on obese populations, men, and different ethnic groups. Despite their weaknesses, figural stimuli measures are often selected for use because they provide a quick, unobtrusive measure of body image dissatisfaction for clinicians and researchers.
The BMA 2.0 addresses many of the difficulties associated with traditional figural stimuli measures of body image. The BMA 2.0 employs a continuous response scale in that it has 100 figures from the thin endpoint to the obese endpoint that increase in size equally throughout the measurement tool. In the method of presentation, the individual only sees one figure at a time in the form of a movie, so it appears to them that they are seeing one body that “grows” on a fine gradient. Therefore, they have no reference points by which to make choices for their given instruction, e.g., current body size, as they would if all the figures were presented to them at once. Finally, the figures are created from high quality graphic animation software that aimed to more closely represent human figures compared to existing figural stimuli methods. The figures are also matched for gender and race to the participant.
This new version of the BMA 2.0 replaces the original BMA (version 1.0) that was tested in an earlier study and found to be reliable and valid for measuring body image of Caucasian women (Stewart et al., 2001). The BMA 2.0 is designed for use with African-American and Caucasian men and women ranging from a very thin body size to an obese body size. The BMA 2.0 is an efficient (10–15 min to complete) and an unobtrusive (participants do not have to remove clothing or be photographed) measure. It captures the data from the assessment automatically to a spreadsheet format and the instructions for participants’ use is on board the program. Participants who have used it report it as a pleasant assessment experience.
Section snippets
Participants
The study sample included 563 participants recruited from universities, research studies, and the community. Participants who were recruited in the university setting (n = 358; 297 female, 162 male), signed up for the study via an online system and were given course credit for participation. Participants who were recruited as part of other research studies were offered the opportunity to participate in the BMA 2.0 and paid $10 per assessment to participate (n = 159; 88 female, 71 male). Individuals
Quality control
On the BMA 2.0, the figures begin at frame 1 (thinnest figure) and end at frame 100 (largest figure). In the trials, there is both forward and backward presentation (thin to obese, and obese to thin). The average of the four trials for each BMA 2.0 instruction, forward (two trials) and backward (two trials) is taken to form the official estimate for the trial. This procedure was established to control for anchoring effects, in which the participant may make choices that were influenced by the
Discussion
The BMA 2.0 was found to be a reliable and valid measure of body image in Caucasian women and men and African-American women and men. The BMA 2.0 represents a technological improvement to existing figural stimuli measures as it utilizes a wider range of stimuli (100 stimuli in range), it accommodates both sexes and different ethnic groups (i.e., African-American and Caucasian), it utilizes a fine grained assessment that allows for greater precision in measurement than previous measures of its
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