Compared to the prevalence of advertising targeted at teens, our understanding of their vulnerability to advertising has been limited due to the cognitive/developmental view adopted by most previous research. However, cognitive development is not the most significant aspect that differentiates adolescents from adults. Adolescence is when teenagers start to take on more responsibility in defining themselves and become more skilled at using consumption to construct and signal their identity. On one hand, teens have a growing desire to express their unique identity as autonomous and distinctive individuals, separate from their family and differentiated from others. On the other hand, they are nearly obsessed with what others think about them, striving to belong to a group and feeling devastated by signs of disapproval from peers. This conflict between the need for assimilation and the need for differentiation is especially pronounced during adolescence when teenagers increasingly seek the approval of their peers while expressing their uniqueness. As a result, their sense of self is in a constant state of flux. This "shaky" self-identity has been shown in previous research to coincide with low self-esteem, which is associated with a high level of materialism.