Miguel has just moved to a new school. It is the beginning of his senior year, and he doesn’t know anyone. He is worried about making friends and...

Let's answer this question as you suggested--by methodically considering the impact each term might have on Miguel's social abilities and happiness!

Locus of control refers to the degree a person believes that he or she can control the events which may affect him or her. Those with a strong internal locus of control think that they are responsible for what happens to them, while those with a strong external locus of control believe that external factors dictate the course of their lives. If Miguel has a strong internal locus of control, this will be positive, as he will feel empowered to make friends and become familiar with his new environment. If Miguel has a strong external locus of control, this will be negative, as Miguel will feel that he is at the whim of the perceptions of his peers.

Ingroup refers to the social group a person may psychologically identify him or herself with. An outgroup refers to the social group a person does not psychologically identify with. If Miguel finds himself as part of the "ingroup" at his new school (in other words, if he is able to locate those with a similar racial, cultural, religious, etc. background), this will be positive due to in-group favoritism (a preference for one's similarities with others). If Miguel finds himself as part of the "outgroup," this will be negative due to outgroup derogation (the perception of another's differences as threatening).

Stereotyping refers to a group of thoughts that are consciously generated about others as a consequence of expectations and beliefs about those who are different than us (those falling into the "outgroup"). If Miguel is in the ingroup at his new school and participates in the stereotyping of others, this will be negative in that it promotes ignorance. If Miguel is in the outgroup, this is also negative, as it means that he will be at risk of being stereotyped himself. 

Groupthink refers to the phenomenon in which a group conforms to an irrational thought or decision to avoid conflict and criticism. This is generally negative. Since Miguel is the new student at school, he poses a threat as an "outside influence" to already established social groups and, thus, may become the target of groupthink and efforts to reject him socially out of his peers' loyalty to their current groups. This may be especially problematic since Miguel is a new Senior, and the rest of the Seniors at his school have had four years to form their social groups. 

Mere-exposure effect explains an individual's preference for something out of familiarity. This is negative for Miguel. Miguel may have trouble fitting in and finding new friends because he has a preference established for the environment of his previous school and cannot adapt his tastes to his new one. Miguel also may face this phenomenon in his peers if they will not be as open to him due to their lack of familiarity with his presence. 

Fundamental attribution error refers to an individual's tendency to explain the behavior of someone else through their characteristics rather than external factors in the situation. This could be negative for Miguel if his nervousness about starting at a new school is incorrectly perceived as an unfavorable personality characteristic (unfriendly, hostile, etc.) rather than as an outcome dictated by his situation (being new).