<P> Social behaviors can be promoted or discouraged by social groups, and several studies have shown that aggression and prosociality are susceptible to peer influence . A longitudinal study done in 2011 focused on these two behaviors . A sample of adolescents was followed over a one - year period, and results showed that adolescents who joined an aggressive group were more likely to increase their aggression levels . Also, adolescents were likely to display prosocial behaviors that were similar to the consistent behaviors of the group they were in . An adolescent's peer group plays a role in shaping him or her into an adult, and the lack of positive behavior can lead to consequences in the future . </P> <P> Adolescence is also characterized by physical changes, new emotions, and sexual urges, and teenagers are likely to participate in sexual activity . A longitudinal study done in 2012 followed a group of adolescents for thirteen years . Self - reports, peer nominations, teacher ratings, counselor ratings, and parent reports were collected, and results showed a strong correlation between deviant peer groups and sexual promiscuity . Many teens claimed that the reasons for having sex at a young age include peer pressure or pressure from their partner . The effects of sexual activity at a young age are of great concern . Pregnancy and sexually transmitted diseases are only a few of the consequences that can occur . </P> <P> In one cross-sectional, correlational study, four different developmental stages were examined: preadolescence (Grades 5 and 6), early adolescence (Grades 7 and 8), middle adolescence (Grades 9 and 10) and late adolescence (Grades 11 and 12). Self - report measures were used in which adolescents completed questionnaires . First, the students rated the importance of being in a popular group . Next, positive and negative behaviour were assessed . The extent to which students were bothered by negative behaviour targeted at them by others in their groups was also assessed . Structural group properties were also examined, including: group leadership or status hierarchy, group permeability, and group conformity . </P> <P> Researchers found that middle adolescents reported placing more importance on being in a popular group and perceived more group conformity and leadership within their groups than pre - and late adolescents . Early and middle adolescents also reported more negative interactions and fewer positive interactions with group members and more negative interactions with those not part of their peer groups . Girls reported having more positive group interactions, being more bothered by negative interactions, and having more permeable group boundaries . Boys reported more negative interactions with those outside their groups and are more likely to have leaders in their peer groups. Researchers believe that the decrease in conformity throughout adolescence relates to the decrease in importance of leadership in late adolescence because having a group leader provides a person to model oneself after . They also note the relationship between the importance of being in a popular peer group and conformity . Both become less important in late adolescence, showing that it is less important to conform when the value of group membership decreases . It is believed that positive interactions outside of peer groups increase and negative interactions outside of peer groups decrease by late adolescence because older adolescents feel more comfortable and have less need to control the behaviours of others . Findings that boys have more leaders are consistent with research showing that boys partake in more dominance struggles . </P>

Which of the following is an important aspect of peer relationships that occurs in early adolescence