During early childhood (age 2 to 6 years) the child begins to engage in social interaction. He or she wants to be the center of attention. By encouraging the child to respect boundaries and providing discipline to control impulsive behavior, the child will learn a responsible way of living. 

Adolescence (age 12 to 18 years) is a time of identity crisis. At this stage, the child asks, "Who am I?" If the child can integrate values learned during previous childhood stages (trust, independence, impulse control, and intellectual curiosity), then they will have a strong identity and readiness to be an adult. If not, confusion can occur and they will be unable to make decisions about their role in life. 

The regressed behaviors of this client are characteristic of the “trust vs. mistrust” stage. When a child experiences trauma or neglect during this stage they are unable to develop a secure sense of trust with himself or herself or their caregiver. This leaves them feeling either excessively dependent or excessively detached. The client also demonstrates early development behaviors such as thumb sucking, which are indicative of an emotional age of about 1 year old in Erickson's model. 

The "industry vs. inferiority" stage most often occurs between the ages of 6 and puberty. It involves learning to master one's skills in order to develop a sense of competence. "Trust vs. mistrust" is the first stage that occurs during infancy, with the goal being to develop a sense of trust in the caregiver. The second stage is "autonomy vs. shame and doubt," which occurs between 1 and 3 years of age and involves developing a sense of independence. "Initiative vs. guilt" is the third stage, which occurs from ages 3 to 6 and involves assuming responsibility. "Integrity vs. despair" is the final stage of development and involves reflecting on one's life. 

Psychologist James Marcia developed a theory of adolescent identity development. This theory focuses on the presence of crisis and commitment. Maria is in the "foreclosure" state, which is characterized by accepting a ready-made identity. Maria has not experienced an identity crisis, but has made a commitment. "Moratorium" involves the presence of a crisis but no commitment. "Identity diffusion" occurs when a person experiences neither a crisis nor commitment. "Identity achievement" involves successfully resolving a crisis and committing to an identity. Last, "differentiation" is not a term used in this theory. 

Erik Erikson's theory includes 8 stages of psychosocial development that individuals go through from infancy to late adulthood. This theory assumes that individuals experience a crisis at each stage, and can either successfully or unsuccessfully complete a stage. Anne is in the “generativity vs. stagnation” stage, which includes being productive, giving back, and focusing on the future generation. On the other hand, “trust vs. mistrust” is the first stage, with the goal being to develop trust in caregivers. "Industry vs. inferiority" is the fourth stage and occurs between ages 5 and 12. The goal of this stage is to develop competence and a sense of pride in one's work. “Intimacy vs. isolation” is the sixth stage and occurs during early adulthood. The goal of this stage is to develop deep and meaningful relationships with others. “Ego integrity vs. despair” is the final stage and includes looking back on one's life and accomplishments. 

Intimacy vs. isolation occurs between adolescence and middle age during emerging adulthood. During this stage, individuals are tasks with developing intimate relationship with others and commitment to another person. Identity vs. role confusion is the crisis that happens during adolescence. Trust vs. mistrust is the first crisis that occurs during the first year of life. Industry vs. inferiority occurs in childhood from ages 6-12.

A child with anxious-resistant insecure attachment has a conditioned response to inconsistent caring from the parent. The child will become distressed when the parent leaves the room, but will then not approach the parent upon their return to the room. Secure attachment style is indicative of a child likely to explore a novel situation and grow up with a secure attachment style. The child who cries but still approaches likely has a disorganized attachment. The child that is not distressed about being left alone is exhibiting anxious-avoidant insecure attachment.