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Guardia et al. (2012) - Coggle Diagram
Guardia et al. (2012)
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This study wanted to test wether the inability of patients with anorexia to gauge their own body size extended beyond the individual to others To see if people with anorexia nervosa (AN) overestimate body size even in action.
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Procedure
Image of 2-metre high door projected on a wall (see left) Width varied 30-80 cm. 51 images altogether, each shown four times.
Independent variable represented in two experimental conditions, completed by both groups: • 1PP (1st-person perspective) - participant stood 5.9m from wall and imagined walking through a "door' (decided if she could do so at normal speed without turning sideways).
• 3pp (3rd-person perspective) - experimenter stood 5.9 m from wall and participant decided if experimenter could walk through the 'door' without turning sideways. 'Perceived passability ratio' (PPR) calculated for apparent body size).
25 females with AN (12 restricting, 13 binge-eating/purging subtypes), and a matched control group of 25 healthy female students
BMI of AN group: 15.6kg/m squared
BMI: of controls: 22.1 kg/m squared
shoulder width of AN group: 37.7cm
shoulder width of control group: 41.5cm
Body weight (measured six months and one month before the study and again at the start). Body Shape Questionnaire (BSQ, assesses body dissatisfaction), Eating Disorder Inventory-2 (EDI-2, assesses weight and shape concerns).
Findings
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AN participants scored significantly higher than controls on median EDI-2 total score, median drive for thinness score, median body dissatisfaction score and median SQ score.
1PP condition, mean PPRs were significantly higher in AN group (1.3 compared to 1.1 for control group).
3PP condition, mean PPRs were higher for AN group but not significantly (1.227 compared to 1.128).
groups of patients with anorexia showed a significant overestimation of body size in themselves, judging that they would be unable to fit through the door frames that were considerably bigger than their actual body size
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- the evidence from the control group found that they showed no significant difference in their ability to accurately predict the ‘passability’ of either themselves or the ‘other person’
- correlation found between the ‘passability’ judgements made by AN group and their pre-illness body weight/size
No significant differences between the groups in age, educational level and height.
Conclusion
Differences between 1PP and 3PP ratios suggest that people with AN overestimate their own body size but their schema for bodies in general is not disrupted.
Overestimation of body schema in AN may be linked to an impaired ability to integrate conflicting sensory inputs (e.g seeing a thin body but feeling inside as if it is much bigger)
'Passability ratio' findings support clinical findings that people with AN feel their body is bigger than it really is.
- patients haven’t adapted their internal body image to take into account their ‘new’ body size after developing the disorder
- they suggest that the brain still perceives the body to be a larger size despite the visual information that would contradict this
patients that had lost weight in the six months prior to the study showed a greater difference between their own and the ‘other person’ passability perceptions
-this suggests that when anorexics lose weight their CNS can’t update the body image schema quick enough to provide an accurate representation of current body size
-this may explain why some patients with anorexia continue to see themselves as bigger than they are
Evaluation
case et al. (2012) studied size-weight illusion (if you compare two objects of equal weight but different size, people tend to judge smaller object as heavier).
This is the result of normal integration of two senses, visual and tactile (touch). But people with AN are less affected by the illusion. This supports Guardia et al!'s conclusion that the ability to integrate information from multiple senses is disturbed in AN.
CA However, research on the rubber hand illusion (RHI, see right) doesn"t Support this. Eshkevar et al, (2012) showed that participants with AN had a Stronger RHI than controls. Perception of RHI depends on ability to integrate information from multiple sensory inputs but there was no sign of an An related impairment in this study.
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in passing through an aperture. The researchers recognised that this is not identical to the real activity of passing through a doorway and changing position if necessary. This means the perceived passability ratio (PPR) is not an ecologically valid measure of the participants' true behavior.
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the control participants bodies than the AN participants' bodies. This makes it 'easier' for the control participants to imagine the experimenter passing through the 'door' (or not). This variable may affect the experience of the AN and control participants in the 3PP condition, so the differences between the groups may not be valid.
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The findings imply that a cognitive impairment underlies AN (disrupted self-bodv schema). If true, forms of cognitive therapy could be more effective. For instance, virtual reality could be used to counter distorted cognitions by demonstrating 'own' and 'other' body sizes passing through doorways. This is especially valuable because such a treatment would address an underlying cause of AN.
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