# Body image (neuroscience)

Body image is a complex construct, often used in the clinical context of describing a patient's cognitive perception of their own body. The medical concept began with the work of the Austrian neuropsychiatrist and psychoanalyst Paul Schilder, described in his book The Image and Appearance of the Human Body first published in 1935. The term "body image" was officially introduced by Schilder himself and his widely used definition is: “body image is the picture of our own body we form in our mind, that is to say the way in which the body appears to ourselves”. In research with the term “body image” we currently refer to a conscious mental representation of one’s own body, which involves affects, attitudes, perceptual components and cognition. On the contrary, the term "body schema" was initially used to describe an unconscious body mental representation fundamental for action. Keizer and colleagues (2013) suggest the following definition: "[body schema is] an unconscious, sensorimotor, representation of the body that is invoked in action". In light of recent scientific developments regarding the multisensory integration of body sensations, the distinction between body image and body schema appears simplistic and probably no longer useful for scientific research and clinical purposes.
Engaging in social comparisons, particularly upward comparisons to individuals perceived as superior, can negatively affect self-evaluations and body image. Research indicates that exposure to idealized media images, such as models embodying cultural beauty standards, often leads to unfavorable body-image outcomes. Specifically for women, who are more likely to engage in upward appearance comparisons. Individual differences play a crucial role in which appearance comparison tendencies occur. Identifying modifiable risk factors linked to appearance comparisons is crucial for reducing their frequency and preventing body dissatisfaction. The Identity Disruption Model suggests that early adverse experiences, such as abuse or neglect, can disrupt identity development, leading to low self-concept clarity and an increased tendency to compare oneself to others.

## Clinical significance

In the clinical setting, body image disturbances are relatively frequent and involve both psychiatric and neurological disorders. Disturbances in the perception of one's body are present in psychiatric disorders such as:
* anorexia nervosa
* bulimia nervosa
* binge eating disorder
* psychotic spectrum disorders
* body dysmorphic disorder
* body integrity dysphoria (not included in DSM-5).
* Cotard's syndrome
Body image disorders are common in eating disorders and are referred to as "body image disturbance".
Disturbances in the body image are also present in neurological conditions such as:
* somatoparaphrenia
* unilateral neglect
* Alice in Wonderland syndrome

### Measurements

Attempts by researchers to measure variances in body image include the FAI index, developed in a 2014 study (Zaccagni 2014). The FAI (feel-status minus actual-status inconsistency) index is used to assess someone's weight perception. FAI scores range from -3 to +3: Negative FAI values mean weight status underestimation, positive FAI values mean weight status overestimation and a FAI score of 0 means a realistic perception of one's weight status. The study found that women tend to have positive FAI values (overestimating their weight) while men had negative FAI values (underestimating their weight). Further studies have used the FAI index to study body image among natives and immigrants in Italy and North Africa.
Another study (Zaccagni 2020) developed a refined version of the FAI index, called the FAI$^{FAT}$ index. This index (feel-fat-status minus actual-fat-status inconsistency) was meant to address possible fat status perception inconsistencies by bioelectrical impedance analysis (BIA).