Question: It seems like my tween constantly compares herself to others. She didn't do this when she was younger. Why the change?
Answer: You're right - your child almost certainly is making more social comparisons these days than she used to. During early and middle childhood, most kids are content with their efforts, regardless of how anyone around them is doing. Their handwriting or art skills may be a "mess" relatively speaking, yet they're darn proud of how far they've come. During or just before the tween years, however, children begin to look at their peers before judging their own performance. In other words, they begin to believe that what they can do is "good" only if it's as good as or better than what their peers can do. These social comparisons can be either upward or downward.
Kids increasingly tend to make social comparisons for two major reasons.
First, cognitive development plays a role. Making social comparisons is a relatively complex cognitive task: you must think about your own performance and another's performance simultaneously. Doing so requires memory, logical reasoning and the ability to make relative judgments. In addition, advanced cognitive skills give rise to adolescent egocentrism. This can make kids highly critical of themselves and cause them to think that others are judgmental of them, as well.
Secondly, social reasons make these social comparisons more likely to occur. For many kids, school provides the first arena in which children's efforts are measured and ranked. A child can suddenly see that he is not, in fact, the best at reading or spelling. This especially becomes the case as children move into the middle school years, when performance tends to be emphasized over effort.
Therefore, tweens make social comparisons due to being in an increasingly-competitive school setting and their own improving cognitive abilities. While these social comparisons can potentially lead to low self esteem, with parent encouragement and guidance, the comparisons can be helpful instead of harmful.
Manning, Maureen A. Self-Concept and Self-Esteem in Adolescents. Student Services. February 2007. Accessed on May 9, 2011 at www.nasponline.org/families/selfconcept.pdf
McAdams, Dan, & Olson, Bradley. Personality Development: Continuity and Change Over the Life Course. Annual Review of Psychology. 2010. 61: 517-542.
Myers, David G. Social Psychology, 10th edition. New York: McGraw-Hill.