Waiting longer, feeling fatter: Effects of response delay on tactile distance estimation and confidence in females with anorexia nervosa

Research suggests that anorexia nervosa (AN) patients overestimate their own body size. However, researchers are divided over whether this overestimation stems from perceptual or non-perceptual differences. In this study, we investigated the influence of non-perceptual factors in tactile size estimation, in a sample of AN patients (N = 30), recovered AN (REC) patients (N = 29) and healthy controls (N=31), by manipulating the role of allowed response time. We further investigated the relationship between allowed response time and participants’ confidence in their tactile judgments. Participants were asked to estimate tactile distances presented on the skin of either a salient (abdomen) or non-salient (arm) body part, either directly after stimulus presentation or after a 5 second delay. Confidence of estimation accuracy was measured after each response. Results showed that allowing AN and REC more time to respond caused them to estimate tactile distances as larger. Additionally, AN patients became less confident when given more time to respond. These results suggest that non-perceptual influences cause AN patients to increase their estimates of tactile distances and become less certain of these estimates. We suggest that previous findings—where AN patients estimate tactile distances as larger than HC—may be due to non-perceptual differences.