Milgram's 1972 experiment
In 1972, Milgram and his students conducted an experiment to test how widespread the phenomena of familiar strangers was.[1] His students took photographs of people waiting at commuter railway stations during a morning commute. One week later, they returned to the same platform, distributed the photos, and asked recipients to label anyone they either recognized or to whom they had spoken. 89% of the people recognized at least one of the individuals shown in the photos. The average commuter claimed to recognize 4.0 individuals who they had never spoken to, compared to 1.5 individuals they had conversed with. In addition, the experiment observed "socio-metric stars" who were recognized by a large portion of commuters. In qualitative interviews, commuters noted that they imagined what kinds of lives familiar strangers led and what kinds of jobs they held. Milgram described this as a "fantasy relationship that may never eventuate in action."
From this study, Milgram made a number of observations about how familiar stranger relationships are maintained. He noted that the further removed familiar strangers were from their routine encounters, the more likely they would be to engage in interaction and break the familiar stranger relationship. But he also observed the opposite: that in routine settings, a person would be more likely to interact with a complete stranger than a familiar stranger as the complete stranger had no pre-existing interpersonal barriers to overcome. Finally, he noted that breaks in routines, such as health emergencies or natural disasters would cause familiar strangers to interact with each other.
Milgram attributed the phenomena of familiar strangers to urban information overload. He noted that perceptual processing of others is much less cognitively taxing than socially processing them. Thus people perceptually recognize the familiar stranger but cut off any further interaction.
The 1972 paper was based on two independent research projects conducted in 1971, one at City University of New York and the other at a train station. Psychology Today published a second paper on the subject by Milgram, "Frozen world of the familiar stranger: a conversation with Stanley Milgram", in 1974.
Milgram revisited
In 2004, researchers at the Berkeley Intel Research Laboratory revisited Milgram's study.[2] Their goal was to observe changes in familiar stranger relationships since the initial study and to see how familiarity can affect an individual's comfort in a public place. Recreating Milgram's original experiment, they found similar but slightly lower levels of the phenomena. They found 77.8% of people recognized at least one familiar stranger with an average of 3.1 strangers recognized. They too found evidence of "socio-metric stars" who stood out to many people due to unique visual characteristics like a wheelchair, flowers, or dirty long hair.
Familiar strangers were also found to affect how comfortable people feel in a public location. Four dimensions determined how familiar strangers affected comfort in a public place: the number of familiar strangers, the level of their familiarity, the history of the familiar people in the location, and whether the familiar strangers are found in other contexts.