Aims of the study

The researchers set out to explore whether people with anorexia nervosa consistently perceive themselves as larger than their actual size, and if this misjudgement specifically affects how they assess actions involving their own body, or if it indicates a more general issue with perceptual discrimination.

Key research questions

• Do anorexic patients overestimate their body size when judging if they can pass through an opening?
• Is this overestimation limited to their own body (first-person perspective), or does it extend to judging others (third-person perspective)?
• How does this relate to a general problem in perceptual discrimination, which is the ability to accurately judge sizes and spaces?

The hypothesis was that anorexic participants would make more errors in estimating actions for their own body compared to a matched control group, as previous studies showed they often believed they could not fit through wide-enough spaces.

Participants in the study

Sample details

• Anorexic group - Consisted of 25 female patients with anorexia nervosa.
• Control group - Included 25 female students, matched to the anorexic group on age and education level.
• Additional measurements - Body Mass Index (BMI) and shoulder width were recorded for all participants to provide an objective indication of actual body size.
• Screening checks - Researchers ensured clear vision and no co-morbidities. Weight changes were tracked from before the disorder onset, six months prior, and one month before the study.

Procedure of the study

Key steps in the procedure

1. Participants were presented with 51 different door-like apertures (openings) projected onto a wall, ranging from 30 cm to 80 cm in width.
2. For the first-person perspective, each participant imagined walking through the opening at normal speed without turning sideways and judged whether their own body could pass through.
3. For the third-person perspective, they estimated whether the experimenter (another person in the room) could pass through the same opening.

Results of the study

Main findings

• First-person perspective - Anorexic participants showed a higher passability ratio compared to controls, meaning they believed openings needed to be wider for their own body to pass through. This suggests they perceived themselves as larger than their actual size.
• Third-person perspective - No significant difference between groups; anorexic participants accurately judged whether the experimenter could pass through, indicating the distortion was specific to their own body.
• Correlations - The degree of overestimation (higher passability ratio) was positively linked to the severity of body and eating concerns. It also correlated with body weight before the onset of anorexia nervosa, implying long-term influences on body perception.
• Supporting evidence - Participants with anorexia nervosa self-reported feeling larger than they were, aligning with the passability judgements.

These results highlight that body overestimation in anorexia nervosa affects action judgements selectively for one's own body, not for others.

Conclusions and implications

Key conclusions

• Body overestimation in anorexia nervosa influences judgements about physical actions, but only when related to the patient's own body. This suggests a specific deficit in updating the body schema to reflect their current, emaciated state.
• Anorexia nervosa arises from complex interactions, including genetic factors, environmental influences, and social factors.

Implications for understanding anorexia nervosa

While the research provides valuable insights, it highlights the need for further studies on how these distortions interact with genetic and social elements to fully explain the disorder.