There are several developmental trends of social relationships in adolescence:

• There is an increasing interest in other-sex relationships.
• The peer group is used as a reference group (i.e. for a sense of identity).
• The definition of peers changes from shared outside activities to shared mindsets and attitudes.

There are developmental changes regarding peers. They go from being playmates to self-disclosing soulmates and friendships become more stable with age. There are different types of peer relationships:

1. Peers (i.e. people who have aspects in common)
2. Friends (i.e. valued, mutual relationships).
3. Clique (i.e. small group of friends, regular social group).
4. Crowds (i.e. larger, reputationally-based group; share similar norms, interests and values but are not necessarily friends).
5. Dating relationships (i.e. relationships that provide autonomy, gain status, allow distance from family but also brings emotional risks).

Although the definition of a peer changes, cliques are often focused around similar activities (e.g. making music). There is a preference for friends above family during adolescence. However, this may differ depending on topic (e.g. prefer to talk to parents about education but prefer friends to talk about sexuality). Adolescents feel good when they are with friends. This may be because friends mirror one’s own emotions and friends may understand one better. Friendships allow for a feeling of freedom and openness.

Cliques (i.e. 3 to 12 people) refer to small groups of friends who know each other well. They form a regular social group and can be defined by distinctive shared activities. There are five stages of clique development:

1. Stage 1 (i.e. adolescents have same-sex cliques)
2. Stage 2 (i.e. mixed-sex cliques become more common)
3. Stage 3 (i.e. gender divisions break down as clique leaders form romantic relationships).
4. Stage 4 (i.e. cliques and crowds are mixed-sex groups)
5. Stage 5 (i.e. structure of cliques and crowds break down as a result of romantic relationships)

Crowds refer to larger, reputation-based groups of adolescents who are not necessarily friends and do not necessarily spend much time together. The function of crowds is helping adolescents locate themselves and others within the school social structure. It helps them define their own and others’ identity. The types of crowds are typically elites (i.e. populars) (1), athletes (2), academics (3), deviants (4) and others (5). Crowd development parallels the course of identity development.

There are culture differences regarding friendships in adolescence. Generally speaking, there is a greater focus towards peers and friends than family in adolescence but this is less so in traditional cultures compared to Western cultures. People in collectivistic cultures value family members higher and friends lower on companionship and enjoyment. This means that people in collectivistic cultures like spending time with their family.

Time spent with same-sex friends remains stable and time with other-sex friends increases in adolescence. The relationships with friends and family change in quality and quantity. Intimacy refers to the degree to which two people share knowledge thoughts and feelings. There is an increased dependence on friends for intimacy. The need for intimacy intensifies in early adolescence and this is partly due to increases in capabilities for perspective taking and empathy. Friends promote further enhancement of perspective taking because they share their thoughts. However, parents are still preferred to discuss topics related to education and future occupation.

Intimacy enhances development by promoting further perspective taking. It increases personal knowledge (e.g. more knowledge about sex through self-disclosure and emotional labelling) as friends in adolescence discuss their emotions and label their emotions. Intimacy also enhances personal thoughts and feelings. There is a reciprocal relationship between perspective taking and intimacy.

Children’s friendships are typified by shared activities while adolescent friendships are more dependent on loyalty (1), trust (2) and intimacy (3). Self-disclosure promotes emotional closeness in young women and shared activities is the basis of emotional closeness for young men. Adolescents have greater abilities for complex thought and this allows them to discuss the complexities of social relationships (e.g. gossip) and this promotes the exchange of personal knowledge and perspectives that constitutes intimacy. There are some gender differences in the intimacy of adolescent friendships:

• Girls spend more time than boys talking to their friends.
• Girls place a higher value on talking together as a component of their friendship.
• Girls rate their friendships higher in affection, helpfulness and nurturance.
• Girls tend to have more intimate friendships than boys.

This may be due to puberty emphasizing gender more and intimacy being associated with being female. Friendships may change in emerging adulthood in four ways:

• The importance of friendships increase as adolescents leave their parental home.
• The importance of friendships decrease as romantic relationships develop.
• There are more other-sex friendships.
• Intimacy becomes more important.

One of the key reasons why people become friends is similarity. There is a reciprocal relationship between one’s own characteristics and characteristics of friends. This means that people become friends with people who are more similar (i.e. selection effect) and friends become more similar over time. This also holds for risk behaviour.

Friends are important for building self-esteem and developing social understanding. They may provide four types of support:

1. Information support (i.e. advice and guidance in personal problems).
2. Instrumental support (i.e. help with tasks).
3. Companionship support (i.e. support in social activities).
4. Esteem support (i.e. encouragement or consoling).

There are several social effects that adolescents experience:

1. Peer pressure
   This refers to influence from the larger group (i.e. crowd) but this has weaker effects compared to friends’ influence.
2. Friends’ influence
   This refers to the influence from friends on behaviour. This has a substantial influence on adolescents and can be both positive (e.g. focus more on school) and negative (e.g. use drugs).

This is demonstrated by a driving experiment. This shows that adolescents take more risks in the presence of peers compared to young adults and adults. The strength of friends’ influence increases in early adolescence, peaks in the mid-teens and declines in late adolescence.

Sarcasm and ridicule occur in adolescent friendships and clique interactions. Antagonistic interactions refer to interactions which include sarcasm and ridicule. This may promote the establishment of a dominance hierarchy and may reinforce clique conformity.

Cyberbullying (1), online intimidation (2) and privacy issues (3) are realistic and serious concerns about social media. The prevalence of cyberbullying is 23%. There is a robust relationship with risk of depression. Children and adolescents typically do not have good strategies to deal with cyberbullying.

Relational aggression refers to a form of non-physical aggression that harms others by damaging their relationship. It includes ridicule (1), sarcasm (2), gossiping (3), spreading rumours (4) and exclusion (5). This is more common among girls while physical aggression is more common among boys.

Social media influences how children and adolescents interact. No use of social media is problematic (i.e. it indicates isolation) while a lot of use of social media is also problematic. Websites are platforms where young people can get to know each other (1), socialize (2), learn (3), get information (4). Adolescents are in a vulnerable period (e.g. influence of peers) and there is relatively low self-regulation. This is important to take into account when assessing the effects of social media.

The brain of young children and adolescents is in full development (e.g. prefrontal cortex). Adolescence is a sensitive period for social interactions and judgment. There are subcortical areas related to affective properties which have heightened sensitivity to social interactions and judgment in adolescence. Dopaminergic systems and the striatum are easily triggered in adolescence. These are potential mechanisms of action for risk behaviour and social reinforcement.

The degree to which the adolescent has control over the cognitive system is dependent on motivation. Cognitive abilities are used flexibly depending on social-affective involvement and hormones in puberty. The brain reacts differently depending on the situation.

People are uniquely attuned to the complexities of interpersonal relationships during adolescence. Escalation of risk taking may be the result of the changes and reorganization in the dopaminergic system and related regions in the striatum. The presence of peers is associated with increases in the nucleus accumbens (i.e. hub of reward circuitry). Peer influence is a means by which adolescents learn how to behave appropriately in their sociocultural environment.

Adolescents are more likely to ‘like’ a photo when it had received more likes from peers, regardless of whether risk behaviour is depicted. Adolescents are also especially likely to like their own photo when it had more likes and this may reflect the importance of self-presentation. Self-presentation can be rewarding and a motivation for using social networks.

There was more brain activity in areas associated with social cognition and social memories when a photo had more likes. Adolescents perceive information online in a qualitatively different way when they believe it is more valued by peers. Risk taking may be the result of heightened neural sensitivity to reward combined with immature capacity for cognitive control as the cognitive control network in the brain becomes less active when viewing risky photos. There could thus be more adoption of risky behaviour as a result of reinforcement (i.e. the likes). A like could be seen as a social cue related to the cultural sphere of adolescents.

There are several reasons for adolescents to form love relationships:

• Recreation
• Intimacy
• Status
• Learning
• Companionship
• Courtship

Recreation, intimacy and status are the most important reasons. Sex is not mentioned in early adolescence. It is mentioned in late adolescence and emerging adulthood.

Dating scripts refer to cognitive models which guide love relationships. A proactive script refers to being more proactive (e.g. initiating) and is more common in males. A reactive script refers to being more reactive (e.g. waiting for the other to make the first move) and is more common in females. However, the gender differences have been decreasing.

Romantic relationships involve more intense emotions, both positive (e.g. love) and negative (e.g. anxiety). It typically involves sexual activity (1), the feeling of being cared for (2) and includes a social companion in leisure activities (3).

Sternberg’s theory of love states that there are three qualities of love:

• Passion (e.g. physical affection; desire)
• Intimacy (e.g. emotional attachment; mutual understanding; open communication)
• Commitment (e.g. idea that there is love despite fluctuations)

According to this theory, these qualities can be combined in different ways to lead to different forms of love.

1. Consummate love
   This refers to a combination of all three qualities of love. 
2. Infatuation
   This refers to only passion.
3. Romantic love
   This refers to passion and intimacy but does not include intimacy.
4. Liking
   This refers to intimacy without passion or commitment.
5. Companionate
   This refers to intimacy and commitment but no passion.
6. Fatuous love
   This refers to passion and commitment but no intimacy.
7. Empty love
   This refers to only commitment.

In (early) adolescence, relationships are typically very short and consummate love is very uncommon as adolescents try out different types of love. Passion and intimacy are most common in adolescence as commitment tends to develop in emerging adulthood.