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The Familiar Stranger: Anxiety, Comfort, and Play in Public Places
Eric Paulos and Elizabeth Goodman
IRB-TR-03-038
October, 2003
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1
The Familiar Stranger:
Anxiety, Comfort, and Play in Public Places
Eric Paulos
Intel Research
2150 Shattuck Avenue #1300
Berkeley, CA 94704
paulos@intel-research.net
Elizabeth Goodman
Intel Research
2150 Shattuck Avenue #1300
Berkeley, CA 94704
elizabeth.s.goodman@intel.com
ABSTRACT
As humans we live and interact across a wildly diverse set
of physical spaces. We each formulate our own personal
meaning of place using a myriad of observable cues such as
public-private, large-small, daytime-nighttime, loud-quiet,
and crowded-empty. Unsurprisingly, it is the people with
which we share such spaces that dominate our perception
of place. Sometimes these people are friends, family and
colleagues. More often, and particularly in public urban
spaces we inhabit, the individuals who affect us are ones
that we repeatedly observe and yet do not directly interact
with – our Familiar Strangers. This paper explores our
often ignored yet real relationships with Familiar Strangers.
We describe several experiments and studies that lead to a
design for a personal, body-worn, wireless device that
extends the Familiar Stranger relationship while respecting
the delicate, yet important, constraints of our feelings and
relationships with strangers in pubic places.
Author Keywords
Strangers, urban space, wireless, wearable, ambient, public
place, digital scent, community awareness, ambiguity,
dérive, détournement
ACM Classification Keywords
H.5.3 Group and Organization Interfaces
INTRODUCTION
The Familiar Stranger is a social phenomenon first
addressed by the psychologist Stanley Milgram in his 1972
essay on the subject [1]. Familiar Strangers are individuals
that we regularly observe but do not interact with (see
Figure 1). By definition a Familiar Stranger (1) must be
observed, (2) repeatedly, and (3) without any interaction.
The claim is that the relationship we have with these
Familiar Strangers is indeed a real relationship in which
both parties agree to mutually ignore each other, without
any implications of hostility. A good example is a person
that one sees on the subway every morning. If that person
fails to appear, we notice.
There are exceptions to the non-interaction rule with
Familiar Strangers. The further away from our routine
encounter with a Familiar Stranger, the more likely we are
to establish direct contact because of a shared knowledge
and place. Thus, we are likely to treat our subway Familiar
Strangers in San Francisco as close friends if we encounter
them in Rome. Similarly, extraordinary events such as an
injury, earthquake, etc. will also provide the impetus to
interact with our Familiar Strangers.
There is a special class of Familiar Strangers called the
“socio-metric stars.” These are individuals who stand out
in a community or group and are readily recognized by an
extremely high percentage of people.
Familiar Strangers form a border zone between people we
know and the completely unknown strangers we encounter
once and never see again. While we are bound to the people
we know by a circle of social reciprocity, no such bond
exists between us and complete strangers. Familiar
Strangers buffer the middle ground between these two
relationships. Because we encounter them regularly in
familiar settings, they establish our connection to individual
places.
It is also not uncommon for people to personalize their
Familiar Strangers by giving them names and/or concocting
fictitious stories and backgrounds of their personal lives
[2]. The epiphany of the Familiar Stranger relationship is
when an individual realizes that they are likely someone
else’s Familiar Stranger, complete with names and stories.
Figure 1: Familiar Strangers in a typical urban setting
2
MOTIVATION
Wireless, personal, digital technologies are rapidly
transforming our relationship to people and place in public
urban settings. Emerging mobile communication systems
are fundamentally reshaping the spatial and temporal
constraints of all aspects of human communications in both
work and play. A myriad of new interactions and potential
interactions between individuals are dramatically
increasing the capacity and efficiency of information flow
within urban settings. Mobile phones are simply the first
wave of an imminent invasion of portable, personal digital
communication tools. These future devices will
undoubtedly lead to a transformation of individuals’
perceptions of self and the world and consequently the way
they collectively construct that world. Mobile
communication devices will have a profound effect on our
cities as they are woven into the daily routines of urban
inhabitants.
While today’s mobile communication tools readily connect
us to friends and known acquaintances, we lack mobile
devices to explore and play with our subtle, yet important,
connections to strangers and the unknown – especially the
Familiar Strangers whom we regularly see. Will these
systems provide a new lens to visualize and navigate our
urban spaces? How will these systems provide an interface
to strangers and unknown urban settings? What will such
devices look like? How will we interact with them? What
will they reveal about ourselves and strangers? Will they
alter our perception of place? Of the strange and unknown?
As computer and social scientists we have the
responsibility to look critically at such underlying forces
and trends. In this paper we take the urbanist’s perspective
on the application of these new technologies within cities
by their inhabitants. We think of the city not simply in
spatial terms, but temporally. We are interested in the
movement and activities of people as well as the familiar
patterns that comfort individuals within a seemingly
chaotic, crowded landscape of urban strangers.1
Urban Life and Public Places
The spectacular image of the modern urban city is that of a
facilitator of commercial exchange, a place where people
go to shop: the city as mall. The city is also a workplace – a
center for government and business functions. While work,
commerce, and business are the focus of cities, it is also a
place for individuals and communities – a place where
people can play. People come there to eat, drink, dance,
meet friends, and just hang out. The potential for sociable
exchange and the pursuit of happiness is vast. For its
workers, the city also provides leisure zones – what
Foucault calls “sites of temporary relaxation” [3].
1 To focus our task we are interested in exploring only the social
phenomenon of the Familiar Stranger within urban settings. The concept
of the Familiar Stranger is radically different in rural or suburban settings.
However, the nature and locations of these social
encounters are not always predictable. Whyte’s “Street Life
Project” [4] observed that usage of New York’s downtown
plazas varied wildly and bore little relation to extant
theories of constructed space. Similarly, Lynch and
Milgram exposed the difference between peoples mental
maps of the city and the physical city plan [1, 5]. Jacobs
talks about the creation of small neighborhoods in large
cities [6].
Unfortunately, public urban spaces also manifest a degree
of anxiety and fear. The 1964 murder of Kitty Genovese
exposed the tenuous and conditional links urban dwellers
have to their neighbors and community of Familiar
Strangers. Genovese was murdered on the streets of New
York City while her neighbors listened to her die. Not one
called the police or came to her aid [7]. Afraid for their
own safety, they were psychologically handicapped and
emotionally bankrupt, unable to even telephone the police
for help.
While massive physical changes are still rare in urban
settings, a new social landscape is emerging. The extensive
use of personal, wireless communication technologies
enables behavior in urban spaces to transgress the lines and
protocols between public and private space. Boundaries
between home, office, automobile, and street are
increasingly blurred [8]. Jain exposed how individuals used
mobile phones within a city to influence the nature,
negotiation, and navigation of urban space [9].
Recent research focuses on the use of new personal
wireless devices, such as mobile phones, that allow us to
communicate with those that we know at a distance.
However, we are interested in exploring the implication of
personal wireless devices that provide a loose connection
(but not explicit communication) to those nearby whom we
do not know – our Familiar Strangers.
At the same time, current trends in mobile phone usage
increasingly divide people from co-located strangers within
their community. Uncomfortable in strange situations or
public places, people reach for their mobile phones,
dramatically decreasing the chance of interacting with
individuals outside of their social groups. We hope that our
exploration of the Familiar Stranger will promote
discussion around tools that work to improve community
solidarity and sense of belonging in urban spaces.
Encouragingly, newly emerging mobile phone uses draw us
into acceptable social contact with strangers. Flash and
Smart Mobs repurpose our existing personal wireless
mobile technology to create impromptu social gathering
between strangers [10].
Strangers
While we initially think of strangers as “removed and
disconnected from us”, Simmel reminds us that
“strangeness means that he, who also is far, is actually
near” [11]. Although both qualities of nearness and farness
3
are found to some extent in all relationships, a special
proportion and reciprocal tension between these two factors
produce the specific form of the urban relationship to the
stranger. In fact, for Bauman, society can only define itself
against its strangers [12].
In public urban settings we navigate using familiar
landmarks such as signs, trees, fences, etc. Milgram’s
initial interest in the Familiar Stranger was in
understanding how the changing urban landscape of the
1960’s was resulting in a mental remapping of navigational
cues and landmarks from objects to people. He was
interested in how people are used as markers of place and
how they influence other people’s sense of belonging in a
place as a result.
We also find artists exploring issues of strangers and public
places. Artist Sophie Calle returned to her native Paris and
intentionally followed people around the streets in order to
rediscover her city. She soon learned how much she could
ascertain about the lives and habits of her own unknown
subjects. Calle became obsessed with the people she was
following, especially the physical details of their existence.
Eventually this obsession brought her to Venice, where she
tracked down and secretly photographed a man she had
previously followed in Paris. She then published a
collection of photographs and writings in her book: Suite
Ventienne, Please Follow Me [13].
In contrast to Calle’s covert urban performances, Guy
Debord and the Situationists sought to reinvent everyday
life in urban spaces by constructing situations which disrupt
the ordinary and normal in order to jolt people out of their
customary ways of thinking and acting. Using dérive (the
urban flow of acts and encounters) and détournement
(rerouting of events and images), the Situationist developed
a number of experimental techniques that stressed the
relationship between events, the environment, and its
participants – urban strangers [14].
The Role of Culture and Strangers
The perception, role, and existence of Familiar Strangers
are deeply embedded within the culture of communities
(see Figure 2). In communities of less than 150 people –
under the threshold Goffman calls “the nod line” –
members are obligated to exchange polite greetings when
they meet [15]. In cities, the opposite holds true. Urbanites
are expected to maintain “civil inattention” in public places
such as the subway platform or the elevator [16]. Both
Milgram and Goffman attribute the phenomenon to the
sense of urban overload caused by the sheer density of
daily social interactions. Familiar Strangers make the city
feel smaller while avoiding the impossible task of making
small talk with everyone we habitually see.
Mobility is a key factor in the existence of strangers. For
Simmel, the observer and the stranger were two poles in a
binary opposition between mobility and stability. The
stranger, by definition from elsewhere, represents mobility.
The observer represents a fixed point by which mobility is
measured. In an increasingly mobile and densely populated
world, we feel ourselves to be strangers more frequently,
and feel other people to be strangers to us. In the Kitty
Genovese case, Milgram points out that Genovese died not
because she had was alone in the world, but because she
had moved far away from the friends and family who felt
responsible for her safety.
Strangers also take on different meanings throughout
individuals’ lives. Adults warn children against strangers –
even familiar ones – while themselves feeling safe in
striking up casual conversations with people they do not
know on buses.
GOALS
The research goal is to identify the properties and
phenomenon of the Familiar Stranger relationships we
currently observe in public places. We believe that
extensions to this relationship using small personal wireless
object can allow individuals to more acutely gauge their
social relationship to people, places, and crowds around
them over time. We also believe that such a device is
capable of encouraging community solidarity, even
transitory solidarity, in places where it is currently difficult
to build such ties. Overall, such a system has a great
potential to allow individuals to gain an improved sense of
belonging within and across their communities, cultivating
new views of comfort, safety, and inclusion. To break
down these boundaries, the technology must allow
individuals to retain an active sense of participation and
inclusion across the public social landscape. As a result, we
hope that such a tool may expand and improve our own
impressions and beliefs of the strangers with which we
share our daily lives. However, we are ultimately designing
for ambiguity [17], leaving to the users to modify, re-
appropriate, play, and adapt the system across a myriad of
unintended uses.
CONSTRAINTS
While there are hints of McLuhan’s global village meme
within our approach [18], we are more acutely aware of
Mitchell’s concern for the preservation of the public
sphere, entreating that technological enhancements to the
urban landscape should improve everyday life while
respecting humanity [19].
Figure 2: Overview of social network calcifications (left), and
cultural differences of Familiar Strangers in cities (center)
compared to small towns and villages (right)
4
To that end it is necessary to declare that we are not
interested in designing a friend finder, matchmaking
device, or system that explicitly attempts to convert our
strangers into our friends. Strangers are strangers exactly
because they are not our friends, and any such system
should respect that boundary. Having strangers on our
urban landscape is not a negative thing. On the contrary,
the very essence of individual and community health of
urban spaces intrinsically depends on the existence of
strangers. Their complete removal would almost certainly
be detrimental.
RELATED WORK
We have been influenced by a number of projects that
emphasize the importance of familiar people and places in
systems that allow mutual strangers to annotate shared
locations. Whether the result is displayed on large screens
[20] or PDAs [21], they allow strangers to collaboratively
create and access location-based content. Since interaction
with the system can be asynchronous, it does not facilitate
face-to-face interaction between strangers. Also interesting
is the ease and spontaneity advocated by the LoveBomb, a
conceptual project that encourages synchronous interaction
between strangers in groups [22]. Physical proximity of
users serves as a preliminary step to further acquaintance
by allowing users to anonymously express private emotions
in public places.
STUDY #1: MILGRAM REVISITED
Our initial experiment’s primarily goals were to:
• Establish a baseline for the current state of our
relationship with Familiar Strangers in urban spaces
• Expose changes to the Familiar Stranger relationship
based on the 30 year old initial study
• Discover how familiarity affects perception of place
and thus participation in a typical urban public space
Anecdotally, it was obvious that the Familiar Stranger
relationship still existed. However, it was unclear to what
degree the phenomenon was operating in typical public
urban settings, especially in light of the widespread
adoption of wireless mobile phones and other electronic
devices that did not exist during the initial 1972 study. We
updated Milgram’s experiment to see whether his
observations were still applicable.
Procedure
In the original experiment, Milgram’s students at The City
University of New York photographed people waiting on
the platform of a suburban light rail station during the
morning rush hour. A week later, Milgram’s students
returned at the same time of day and distributed duplicates
of the photographs (see Figure 3). The people waiting on
the platform were asked to label individuals in the
photograph that they recognized or regularly spoke to.
We focused our research on a similar urban space in
downtown Berkeley, California named Constitution Plaza.
This public plaza is an exemplar of the type of small urban
space that Urbanist such as Whyte described as central to
the health of public life in large cities [4].
Constitution Plaza is a high-traffic, block-long rectangle in
the center of Berkeley’s downtown. Anchored at one end
by an imposing entrance to Berkeley’s primary
underground train station (BART2), and at the other by a
central bus transfer point, the plaza sees a continual flow of
pedestrians. While many cross the plaza without stopping,
others pause to make phone calls, eat, or rest on the
benches. Observations suggested two potential Familiar
Stranger populations: (1) the office workers and students
who eat lunch on the benches and (2) the commuters who
wait for one of the 15 bus lines. The bus riders are a
contemporary equivalent of Milgram’s commuters; as a
basis for comparison, we included the lunchtime group.
Following Milgram’s study, we photographed clusters of
people in each area during their respective busiest hours:
noon in the seating area and 5:00pm at the bus stop. We
returned a week later at the same times of day to distribute
the set of four pages of photographs (see Figure 4). In order
to test for Familiar Strangers common to the two groups,
we distributed the same photographs to everyone. Like
Milgram, we asked participants to label those in the
photographs they recognized and those they regularly
spoke to. We also asked them to note any information they
had about the people they recognized. Along with the
photographs, we distributed a questionnaire on
relationships to the plaza and attitudes toward public place
in general – especially those most familiar places, like their
home neighborhoods. Participants were recruited by
approaching everyone within the target place and time to
get a somewhat representative sampling of the population.
As with Milgram’s study, the participants completed the
surveys without our assistance and returned them by mail
using an included self-addressed stamped envelope.
Participants were asked to complete as little or as much of
the questionnaire as they desired. We encouraged
participation and disclosure of contact information by
offering a chance to win a $100 USD gift certificate to a
local bookstore.
2 BART is the Bay Area Rapid Transit system, a below and above ground
light-rail system covering the San Francisco Bay Area.
Figure 3: Stanley Milgram’s 1972 Familiar Stranger study
5
Results
Within the sample size (n=23)3 of our survey, it seemed
clear that the Familiar Stranger relationship is common.
While we found less familiarity than Milgram, the numbers
are still significant. Eighty-nine percent of those Milgram
surveyed recognized at least one person. Our study found
lower (77.8%) but still high recognition. In contrast to
Milgram’s average of 4.0 people recognized, our survey
found an average 3.1 people recognized (out of 63
pictured), with a median of 2. The numbers are particularly
high given that participants were recruited by approaching
everyone within the target areas at the appropriate times.
This inevitably included a higher percentage of non-
residents and the cognitively impaired than the Milgram
study did.
Clearly, the Familiar Stranger relationship is tied to the
daily routines of urban life. When we spend more time in
public spaces with others, we are more likely to recognize
them (even if we have never talked to them). Lunchtime
participants recognized on average far more (3.9) people
than their counterparts at the bus stop (2.3). The
demographics of the two groups did not differ noticeably,
but the lunchtime group spent a median 15 minutes on site,
while the rush hour group spent a median 5 minutes.
Within each social group, there was no definite correlation
between the amount of time individuals spent in any one
place and the number of Familiar Strangers they reported.
Routinely spending time with strangers improves facial
recognition on average, but some people are more adept at
noticing and remembering the people around them.
Some people are also more recognizable than others:
Milgram’s socio-metric stars. Thirty-three of the 63 people
in the photographs (52.4%) were recognized by at least one
person. But a few people were recognized more
consistently: a man in a wheelchair, a flower vendor with a
lavish display, and a long-haired homeless man. Milgram’s
socio-metric star also had a consistent, unusual attribute –
3 There was actually a high participation rate. We handed out 80
photo/questionnaires and 23 were returned, nearly 30% participation.
she wore a mini-skirt even in winter. The socio-metric stars
identified through the Berkeley survey suggest another
factor – prevalence. Many seemingly forgettable people
were recognized because they were seen often in one place4
or occasionally in many places5.
There was no correlation between the number of familiar
strangers and positive attitudes toward the plaza, however.
Even high levels of familiarity (6-12 people recognized)
did not necessarily result in positive descriptions of the
plaza. One woman, who recognized 6 people, described it
as “unpleasant – dirty – aggressive people.” What did
correlate to positivity, however, were the respondent’s
reasons for visiting the plaza. People using the plaza solely
to catch a bus were more likely to describe it in negative or
neutral terms, while people who chose eat lunch there
typically described it more positively. Since bus riders had
no choice but to use the bus stop, their negative opinions of
it did not radically change their behaviors.
STUDY #2: URBAN WALKING TOUR
Observations from the Milgram Revisited study suggested a
relationship between recognition of strangers and
experience of place. To situate our investigation of a
mobile application within the real context of potential
users, we interviewed nine Bay Area residents on a walk
through Berkeley’s business district to address four issues:
• Evaluate ideas about familiarity and place derived
from the observations of the plaza
• Clarify importance of social familiarity to perceptions
of place
• Elicit input from users into design process
• Validate initial design decisions
Procedure
Over the course of a week, we arranged nine 45-minute
“walking tours”. Each tour involved one interviewer and
one subject on walking interview to four nearby, yet
functionally distinct, public outdoor locations. Participants
were encouraged to interrupt the tour at any time to
nominate their own significant places. Starting at the plaza,
the interviewer walked with participants to each location:
• Constitution Plaza – described in previous study
• Main Berkeley post office – a government building
with narrowly-defined functions and limited hours
• Civic Center Park – a small park with a lawn and
paved fountain area, frequented by soccer players,
sunbathers, and the homeless who sleep there
• An inexpensive restaurant patronized by locals
4 “I always see him here.” (comment from Berkeley study)
5 “I’ve seen this guy on Shattuck [Street], Telegraph [Avenue], and on
campus.”
Figure 4: One of several questionnaires used in the Berkeley
version of the Familiar Stranger study
6
In order to determine whether the social aspects of each
location significantly affected participants, the interviewer
asked them at each stop to rate their perceived sense of
comfort on a scale of 1–5, identify any familiar people,
then rank the following reasons for their reported sense of
comfort in order of importance6:
• People around you
• Physical characteristics of place (architecture and
amenities)
• Current environmental attributes (weather and time)
Using results from our initial observations and first survey,
we had arrived at four quantifiable factors that we believed
affected social comfort in urban public places:
• Amount: How many familiar people are around?
• History: How familiar are these people?
• Turf: Have familiar people visited this place in the
past? Is this “my kind of place?
• Tribe7: Do the people currently here visit the same
places I do? Are they “my kind of people?”
The first three occur without any technological
intervention. As shown in the first survey, Berkeley citizens
routinely recognize strangers and act on the basis of their
past behavior. Moreover, they routinely use physical
evidence (such as graffiti) and their memories to determine
whether familiar people have visited a specific location in
the past. The fourth factor is not part of the current Familiar
Stranger relationship because one must verbally query
every nearby person to discover the answer. However, it
can be captured by the proposed Familiar Stranger device
and hence was included in the study.
To evaluate the relevance of these factors to participants’
perceptions of urban public places, we asked them to rate,
at that very moment in each place, the importance to their
own social comfort of each of the first three factors:
Amount, History, and Turf. We encouraged participants to
express place- and time-specific reactions – to explain, for
example, why the park differs from evening to afternoon.
In order to introduce the fourth factor and reassess the
importance of the first three factors in the wake of a
technological intervention, we created a Wizard of Oz
scenario with a hypothetical mobile device that monitored
each of the four factors. Without prototypes or props, we
asked participants to rate the importance of those four
factors to them if they had the actual device at that moment
in each place. Users who are asked to “act-out in context”
and imagine using a future application under real world
6 Participants were also asked to name any additional factors they believed
were important. Over 36 individual stops, this only occurred twice.
7 Turf is the degree to which the now place has common past people while
Tribe is the degree to which the now people have common past places
conditions produce suggestions that are more quickly
incorporated before expensive hardware is built.
After the tour, the interviewer initiated a participatory
design exercise. Participatory design brings users into the
design process and incorporates their input early, before
final testing and has been found especially useful in testing
mobile application concepts. Participants were asked to
sketch their own representations of the data from the
walking tour and complete two structured templates. The
sketches then fueled a discussion of privacy issues
surrounding the idea of such a wearable device. Would the
user want it to visible? Why or why not?
Results
Comfort levels varied from place to place, with women
exhibiting more variation than men. On average,
participants were most comfortable at the post office and
least comfortable in the park, with women significantly less
comfortable there than men. “The people around me” was
consistently ranked highest of three factors (people,
physical characteristics, and environmental conditions)
contributing to a perception of comfort, most notably in the
park, where people felt most uncomfortable.
Those interviewed valued information about familiar
people most when they felt unsafe and when they had a
choice of options. In the Wizard of Oz section, they rated
information delivered by the imaginary device most
important at the park and restaurant, and least at the post
office. As one man said, “A park is someplace you’d want
to hang out in – unlike the post office.” At the park, anxiety
about street people created the need for social data. People
most valued the number of familiar people nearby, as they
wanted assurances of reliability for those around them. As
one man said, “I don’t feel comfortable seeing people with
all their worldly possessions with them…Knowing people
who came here would increase my comfort level.” Another
participant thought knowing “moms and kids” visited the
park would be reassuring. One Participant wanted to
differentiate the restaurant from the other “cheap joints”
stating, “If lots of people I knew ate here, I’d have more
respect for it. It would be interesting to see where other
familiar people eat.”
New design ideas emerged from the participatory design
exercise. By fusing participatory design with acting-out in
context, participants drew from their experiences on the
tour to create interfaces that responded to their expressed
needs and concerns. After walking through a street fair, one
woman included a request for a “discreet” interface and a
“festival” interface. Since many users organized their
sketches around social groups, we added user-defined
groups (i.e. “students,” “moms and kids,”) to the concept.
The exercise revealed tensions in users between a desire for
social data and concerns about privacy in public places.
The “radar” metaphor – a representation of the social and
physical space that maps others’ positions in relation to the
user – was a favored invention of the participants,
7
occurring six times over nine interviews. However, privacy
concerns rendered it unusable. Users liked combining
spatial and social data to create a “social landscape,” but
did not want other people to have that kind of information
about them. Concerns about safety arose because visible
wearable displays tie digital data to bodies: “What if my
device showed that I didn’t know anyone? I would feel
worried about my safety in a crowd.”
Milgram saw Familiar Strangers as a response to social
overload. The mixed responses to the idea of wearable
displays confirm his insight about the variability of desire
for social interaction. As one woman said: “It depends
whether I’m looking for people, for connections. When I’m
on my own business I’d be more discrete.”
SYSTEM ARCHITECTURE
Our previous formal studies and anecdotal observations
guided a design for a personal, wearable, wireless device
that would capture and extend the essence of the Familiar
Stranger relationship. These devices can either be attached
to fixed objects, such as a bus stop platform, or
carried/worn by individuals (see Figure 5). Each device is
wireless and emits a short range (20m) radio beacon with a
random but unique identifier. The wireless transceiver on
the device allows each to be able to detect and record all of
the other nearby beaconing devices. As two people
approach one another, each device transparently detects and
records the others unique ID. Over time each device
accumulates a log of unique entries of people that have
been previously encountered. There is no central server
that stores, manages, or processes the data. The logs are
unique and stored only on each individual device. Using
this data there are several previously identified social
factors that can be extracted and displayed.8
Amount
Intersecting the set of currently nearby detected Familiar
Strangers with the stored set of those previously
encountered, it is trivial to render a notion of amount of
currently present Familiar Strangers.
History
We can measure how long or how many times each
Familiar Stranger has been encountered as a notion of
history. Using hysteresis to avoid measurement errors in
the sampling, each device stores attributes for count and
elapsed time with each log entry. Recurring encounters
with Familiar Strangers simply increase the count or
elapsed time attributes for that log entry. Later, by looking
up the currently present Familiar Strangers in each log, a
greater sense of established frequency, time, history, and
familiarity is calculated.
8 We are also preparing to conduct an additional user study of 60
operational prototype devices in an urban setting.
Turf
The fixed beacons allow measurements related to place.
Fixed beacons emit a signal to differentiate them from the
mobile individually worn body devices. Fixed beacons are
attached to objects in places by people. Typically, a person
would tag a location that is perhaps significant or holds
special meaning using a fixed device. The tagging is
driven by the personal desires and interest of individuals.
A fixed beacon communicates and logs all of the strangers
that pass by it. It also broadcasts this list to mobile devices
in its vicinity. Nearby mobile devices intersect this
broadcast list with their internal log of previously
encountered strangers. This intersection is the set of
strangers that have been encountered before and that have
also been to this current place. The larger the set the more
the current place is “your turf”.
DESIGN
The Familiar Stranger hardware prototype is based on the
MicaDot2 Mote, a 23mm diameter wireless embedded
processor. Motes are the design predecessors to Smart
Dust [23] and operate using low power and short wireless
connectivity, a perfect match to the Familiar Stranger
design constraints of detecting nearby people and places.
Form Factor
The device needed to support easy viewing access for
checking its status. Unlike mobile phones carried in
pockets and bags, the Familiar Stranger device design took
on several externally displayed form factors such as a belt
clip, watchband slip-on, bracelet, and book bag clip (see
Figure 6). The obvious tradeoff for ease of access is the
semi-public display of the device’s status as commented on
by users in the Urban Walking Tour study (see results).
Figure 6: Experience prototypes seen in context
Figure 5: Fixed (square) and mobile (circles) Familiar
Stranger devices in context
8
Interface
The major interface challenge was representing and
interacting with complex social data on very small, low-
resolution displays. It was also important to visualize the
freshness of the real-time data and the passage of time.
Finally, we avoided the look and feel of a tracking device
by displaying Familiar Strangers collectively rather than as
individuals.
The interface (see Figure 7) is a diffused circular lens
divided into three color regions (red, green, and blue) with
two corresponding selection buttons (blue and green).
Using an array of concentric LED rings a user can see the
degree of familiarity of a place. The red region renders the
general state of familiarity by turning on LEDs
corresponding to the amount of Familiar Strangers that you
have passed who have also frequented the current location
(solid LED) as well as the number currently nearby
(pulsing LED). This provides a sense of history and
freshness of data within a single display.
As discussed in the Urban Walking Tour study, not all
Familiar Strangers are equivalent. Typically, a few have
meaning attached to a particular place such as a bus stop,
street corner, or club. Others may be ones in your own
neighborhood. While the red area depicts the general state
of familiarity, the blue and green are for specific personal
groupings. Users’ categorize the Familiar Strangers nearby
by selecting the green (or blue) button. Later, when
members of these groups are re-encountered, their presence
will contribute to illuminating both the red (general
familiarity) and green (or blue) personalized grouping.
TWO SCENARIOS
A woman who has recently graduated from college has
moved to a new city and doesn’t feel at home. The display
on her device reinforces her growing sense of integration
with her new neighborhood, and reassures her that familiar
people are nearby, even if she does not recognize their
faces. When she explores unfamiliar neighborhoods in the
larger city, she is occasionally surprised to discover how
many people around her she has encountered before.
In the midst of a frustrating day, an urban professional
decides that he doesn’t want to eat lunch in his usual spot.
After years at the same job, the large city seems more like a
small town. He sees the same people every day in the same
places. He wants to escape. As he walks quickly away from
his work, he occasionally checks his device to see if there
are any Familiar Strangers nearby. When he finds a street
that the device tells him is completely unfamiliar, he
chooses a restaurant. He feels as if he’s exploring new
territory and though he is still surrounded by other people,
he feels much less crowded than he did 15 minutes ago.
CONCLUSION
The very essence of place and community are being
redefined by personal wireless digital tools that transcend
traditional physical constrains of time and space. New
metaphors for visualizing, interacting, and interpreting the
real-time ebb and flow of urban spaces will emerge.
Crucial to this discussion will be the often ignored yet vital
role of our Familiar Strangers. Without a concerted effort
to develop new knowledge and tools for understanding the
implications of these new technologies, computer and
social scientists, city planners, and others run the risk of
losing touch with the reality of our urban streets and their
inhabitants. This paper initiates the groundwork towards
exploring this space.
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Figure 7: Interface for Familiar Stranger device
