A sense of commitment to activity on Facebook: Evidence from a web-based paradigm.

The present study was designed to test whether actions on Facebook such as commenting on others' posts can create a sense of commitment to continue performing similar actions in the future. Across four online experiments, we found evidence that regularly commenting on others' Facebook posts generates a sense of commitment to commenting on similar posts in the future, leading people to feel worse about not commenting on a post if they have done so regularly in the past than if they have not done so, and leading them to expect a Facebook friend to be more disappointed if they do not comment when there has been this previous history of commenting. These findings may contribute to illuminating the feelings associated with social media use, including its compulsive aspects and its effects on well-being.

Depictive and metric body size estimation in anorexia nervosa and bulimia nervosa: A systematic review and meta-analysis.

A distorted representation of one's own body is a diagnostic criterion and core psychopathology of both anorexia nervosa (AN) and bulimia nervosa (BN). Despite recent technical advances in research, it is still unknown whether this body image disturbance is characterized by body dissatisfaction and a low ideal weight and/or includes a distorted perception or processing of body size. In this article, we provide an update and meta-analysis of 42 articles summarizing measures and results for body size estimation (BSE) from 926 individuals with AN, 536 individuals with BN and 1920 controls. We replicate findings that individuals with AN and BN overestimate their body size as compared to controls (ES=0.63). Our meta-regression shows that metric methods (BSE by direct or indirect spatial measures) yield larger effect sizes than depictive methods (BSE by evaluating distorted pictures), and that effect sizes are larger for patients with BN than for patients with AN. To interpret these results, we suggest a revised theoretical framework for BSE that accounts for differences between depictive and metric BSE methods regarding the underlying body representations (conceptual vs. perceptual, implicit vs. explicit). We also discuss clinical implications and argue for the importance of multimethod approaches to investigate body image disturbance.