In adults
In their review of the sociological literature, Semin and Fiedler concluded that the perception of strangers tends to be based primarily on group membership, and their identity as a member of an out-group, because a stranger is, by definition, not known individually. This may magnify the perceived motives or intentions of the stranger, but may also vary greatly according to the circumstances and the environment. Among environmental factors, physical uncomfortably, such as presence in a room that is hot and crowded, have been shown to increase negative attitudes toward strangers.
Laboratory evidence has indicated that individuals are likely to behave less modestly when meeting face-to-face with strangers, when no friends or acquaintances were present. As explained by Joinson and colleagues, "they tend to present more of their ideal self-qualities to strangers than they do to friends." However, this appeared to be reversed when two strangers met one another online in the absence of friends, which elicited the most modest self-presentation, more so than online interactions with strangers conducted in the presence of friends.
In willingness to disclose information, researchers have identified what has been dubbed the stranger-on-the-train phenomenon, wherein individuals are inclined to share a great deal of personal information with anonymous individuals. This may be influenced by the temporary nature of their relationship, and the knowledge that the stranger themselves have no access to an individual's wider social circle. As one author put it, the phenomenon is ironically best described by the words of travel writer Paul Theroux, saying:
The conversation, like many others I had with people on trains derived an easy candour from the shared journey, the comfort of the dining care, and the certain knowledge that neither of us would see each other again.
This may be helpful in eliciting self-disclosure in the context of therapy or counseling, and can encourage openness and honesty. However, research also suggests that this phenomenon is mediated by the expectation of future interaction with the stranger.
