Allowed response time and estimated average body size influence visual body size estimates

Studies show that body size estimates exhibit a contraction bias wherein participants with a lower-than-average BMI overestimate their bodies while participants with a higher-than-average BMI underestimate. We attempted to replicate this effect and test its relationship to allowed response time and estimates of average body size. Neurotypical female Dutch participants (n = 277) estimated their body size using a forced-choice task, which we modified to modulate allowed response time, and a method-of-adjustment task. They also estimated the average body size (for their age and gender) and their ideal size. We found no direct evidence of a contraction bias in either task. However, estimates of average body size predicted misestimation of own body size (consistent with a contraction bias). Finally, we found that greater allowed response time caused greater body size overestimation amongst participants with higher BMIs (in our forced-choice task). Our results support the context-sensitive nature of the contraction bias and the influence of allowed response time on visual body size misestimation.