The Brain Mechanism Of Appearance Social Comparison In Young Female

The body image was introduced by Paul Schilder in the 1930 s to the field of psychology.Body image was thought to be a dynamic and extensional concept which was related to cognition and attitudes.From the 20 th century to now,researchers used the questionnaire and the current electronic imaging technology to study the external factors of the body image,influencing factors and the brain time and space processes.Early studies of body images focus on the neuropathological basis of body images.After a large number researches of aspects of the body image,inc luding: cognit ive,emotional,consciousness,behavior,social med ia influence and other research,each school put forward the interpretation of the body image theory model including symbolic interaction theory,social comparison theory,information processing theory,Objectif ication theory,social and cultural perspective and biological point of view.The Social comparison theory suggest that the individual's own evaluation requires a certain standard,but the community does not have a clear standard,so individuals continue to compare with others and under the influence of the internal driving force to get others to their own evaluation.Social Comparisons include two directions of comparison.Upward comparison is compared with more "good" objects than themselves.Downward comparison refers to objects that are more "worse" than they are,and the effect of the two directions of comparison on individual self-evaluat ion or satisfaction is different.The appearance of social comparison is one of the risk factors and maintenance factors of adolescent body image.A large number of studies have shown that women are usually having upward appearance social comparison,that is to say,they are used to compare with the ones which own more attractive body,and it lead to more negative body image satisfaction.The researches of the male also suggest that it is usually up ward appearance social comparison,the comparison of the object is lean and muscular body image,and the appearance social comparison also lead to men's more negative body satisfaction.In this study,we used the comparative paradigm of appearance and combined with ERPs and f MRI techniques to study the brain mechanism of appearance social comparison in young female.Study one: a total of 36 students(age range 19-25 years,mean age,20.50 ± 1.44 years)were enrolled in the ERPs experiment.The body mass index(BMI)was between 16.94 and 27.34(mean 20.83 ± 2.34).Experimental design using 2(appearance of social comparison direction: up ward comparison vs.dow n ward comparison)× 2(personal narrative: first person vs.third person)experimental design,both factors are the internal factors.The experimental material used 50 pictures showing the body parts of the obese body and 50 pictures showing the slim body parts.The picture was taken from the study of Gao,X(2010).Body pictures are divided into fat body pictures and thin body pictures,are female body parts pictures,these parts can clearly show the fat and thin women's body.To reduce the difference of the body pictures,we uniformed the specifications and color of all pictures.The results of study one show that: 1)the effect of comparative direction is signif icant.In particular,at the processing intensity,the down ward comparison resulted in a larger P2 peak in the extensive area of the anterior midline of the scalp,and a 240-330 ms time window induced a smaller N300 mean amplitude in the anter ior midline of the scalp.From the processing time,in the late positive component,the up ward comparison is lower than the down ward in the 370-560 ms time window in the top pillow induced a greater average amplitude;in the 560-680 ms time window,the average under both conditions There was no signif icant difference in amplitude,and in the 680-1000 ms time window,the down ward comparison induced a larger average amplitude compared to the up ward.2)The effect of the narrative is significant.The first person in the 370-1000 ms induced LPC average amplitude greater than the third person did.Study two had 25 participants,their body mass index(BMI)was between 16.23 and 28.94(mean,22.44 ± 4.08),and the age ranged from 20 to 25 years(mean age,20.50 ± 1.50 years).The experiment used a two-task model,including the appearance social comparative tasks and clothes coverage area tasks,two tasks randomly presented.The experimental material used 32 images showing the obese body parts and 32 pictures of the slim body parts.The picture was selected from the study of Gao,X(2010).The material was the same as the study one.f MRI results showed that the appearance of the up ward social comparison activated the brain area with occipital lobe,prefrontal cortex,parietal lobe,insula;appearance of the down ward social comparison activate the brain frontal lobe,posterior central,parietal lobe,temporal lobe;up ward appearance social comparison contrast down ward appearance social comparison of brain activation with occipital lobe.The results of interest area analysis showed that the active area of up ward appearance social comparison was activated with the medial prefrontal cortex,the praecuneus,the amygdala,the insula,the cingulate gyrus.The active area of down ward appearance social comparison was activated with the medial prefrontal cortex,the praecuneus,the amygdala,the hippocampus,cingulate gyrus.and The active area of appearance social comparison was activated with the anterior frontal lobe,the praecuneus,the amygdala,the caudate nucleus,the hippocampus,the cingulate gyrus;there was no significant result with up ward appearance social comparison contrasting down ward appearance social comparison.Conclusions: The P2 recorded in the scalp frontal and central regions reflects the perceived differences in the stimulus physical characteristics between the up ward and down ward appearance social comparison,and the differences in the activation of the frontal lobes and the parietal lobe confirm the results of the P2 ERPs,also the results of the ROI analysis also found that there were differences in the activation of the primary visual processing cortex in both directions,which was caused by differences in the characteristics of the stimulus;in the time window of 240-330 ms,the N300 recorded in the anterior midline of the scalp reflects the difference between the up ward and the down ward appearance social comparison started to influence the body self,and the activation of the f MRI results in the insula,the amygdala,the praecuneus,the hippocampus also indicated that cognitive processing of emotion and self related information had work to deal with stimuli related information,and both of the up ward comparison and down ward comparison lead to negative emotions,the up ward appearance social comparison lead to the negative emotion about their own physical body anxiety,and the down ward appearance social lead to fear of obesity.LPC reflects the up ward appearance social comparison was earlier started and completed than down ward appearance social comparison.And the two direction of appearance social comparison consumed same amount of cognitive resources,and the f MRI results showed that there was no significant difference in the activation of the brain between the two types of processing.In addition,the appearance of the social comparison of the human effect might reflect a different degree of self-reference processing.More research was needed in the future to re-validate and explore these findings.