Inoculation theory suggests that an original belief can be protected against persuasion (i.e. inoculated against a persuasive attack) by anticipating the argument before it occurs and coming up with counter arguments or discrediting the points of the argument. Other answers did include anticipating the argument, but not the second part of inoculation theory (i.e. discrediting the points of the argument). Providing arguments to support the initial belief prior to the attack could be helpful, but does not necessarily protect against a strong counter attack.

Soloman Asch's Conformity Study had a very similar set up to the given scenario. In his experiment, a subject was asked to compare lengths of lines that had obvious differences. The subject was in a group of other "subjects" (confederates) and often conformed to the answer that all of the other group members provided rather than sticking to the obviously correct answer. Clark and Clark's doll preference study involved a task for White and Black children to select the doll that they liked most. Milgram's obedience study involved subjects obeying direct instructions from an experimenter to administer shocks to another participant (confederate). Zimbardo's prison experiment involved members of assigned groups assuming roles (i.e. prison guards, prisoners). 

John Bowlby and colleagues have studied attachment styles and their correlates by examining the health of adult relationships. The choices provided are terms that Bowlby coined to capture the four major categories of attachment styles. As the name implies, secure attachment denotes the healthiest style and the surest predictor of happy and trusting relationships.

Sternberg proposed a tri-pointed model of romantic love that he entitled, "Triangular Theory of Love." While communication is always at the core of a healthy relationship, it is not one of the three primary factors in his model whereas the remaining three responses listed in this question are. For Sternberg, intimacy, passion, and commitment coalesce into what he calls consummate love. 

The 2010 movie 'She's Out of My League' captured this social psychological concept with comedic accuracy. The matching hypothesis describes the well-documented social tendency of pairing with a romantic partner who society would deem roughly equivalent in terms of physical attraction. Even if that's not what we value most highly, looks seem to set a range for whom we consider.

The disclosure reciprocity effect describes the process by which the act of two people sharing their feelings and/or secrets can facilitate emotional closeness between the two and increase attraction.

Tuckman proposed four elements of group formation in 1965. He proposed that all groups—from therapy groups to school boards—go through these processes. Moreover, the most typical chronological order is forming, storming, norming, and performing. He viewed this progression as both normal and healthy.

Out-group homogeneity is the assumption that the individuals in an out-group are all the same, while the individuals in a specific person’s in-group possess a wide degree of variation. In the example, the biologists appreciate the differences between their work and subject matter but cannot do the same for the English majors—the biologists assume that they study the same literary concepts.

Out-group homogeneity is the assumption that the individuals in an out-group are all the same, while the individuals in a specific person’s in-group possess a wide degree of variation. In the example, the biologists appreciate the differences between their work and subject matter but cannot do the same for the English majors—the biologists assume that they study the same literary concepts.

Members of collectivist cultures are more likely to value harmony, loyalty to one's family, and hierarchical relationships. In contrast, members of individualist cultures tend to value privacy, speaking one's mind, and taking care of the self (as opposed to the family).