Journal of Personality and Social Psychology
1968, Vol. 8, No. 4, 377-383
BYSTANDER INTERVENTION IN EMERGENCIES:
DIFFUSION OF RESPONSIBILITY3
JOHN M. BARLEY
BIBB LATANfi
New York University
Columbia University
Ss overheard an epileptic seizure. They believed either that they alone heard
the emergency, or that 1 or 4 unseen others were also present. As predicted
the presence of other bystanders reduced the individual's feelings of personal
responsibility and lowered his speed of reporting (p < .01). In groups of
size 3, males reported no faster than females, and females reported no slower
when the 1 other bystander was a male rather than a female. In general,
personality and background measures were not predictive of helping. Bystander
inaction in real-life emergencies is often explained by "apathy," "alienation,"
and "anomie." This experiment suggests that the explanation may lie more
in the bystander's response to other observers than in his indifference to
the victim.
Several years ago, a young woman was
stabbed to death in the middle of a street in
a residential section of New York City. Although such murders are not entirely routine,
the incident received little public attention
until several weeks later when the New York
Times disclosed another side to the case: at
least 38 witnesses had observed the attack—
and none had even attempted to intervene.
Although the attacker took more than half
an hour to kill Kitty Genovese, not one of
the 38 people who watched from the safety
of their own apartments came out to assist
her. Not one even lifted the telephone to
call the police (Rosenthal, 1964).
Preachers, professors, and news commentators sought the reasons for such apparently
conscienceless and inhumane lack of intervention. Their conclusions ranged from "moral
decay," to "dehumanization produced by
the urban environment," to "alienation,"
"anomie," and "existential despair." An analysis of the situation, however, suggests that
factors other than apathy and indifference
were involved.
A person witnessing an emergency situation, particularly such a frightening and
1
This research was supported in part by National
Science Foundation Grants GS1238 and GS1239.
Susan Darley contributed materially to the design
of the experiment and ran the subjects, and she and
Thomas Moriarty analyzed the data. Richard
Nisbett, Susan Millman, Andrew Gordon, and
Norma Neiman helped in preparing the tape
recordings.
377
dangerous one as a stabbing, is in conflict.
There are obvious humanitarian norms about
helping the victim, but there are also rational
and irrational fears about what might happen
to a person who does intervene (Milgram &
Hollander, 1964). "I didn't want to get
involved," is a familiar comment, and behind
it lies fears of physical harm, public embarrassment, involvement with police procedures,
lost work days and jobs, and other unknown
dangers.
In certain circumstances, the norms favoring intervention may be weakened, leading
bystanders to resolve the conflict in the direction of nonintervention. One of these circumstances may be the presence of other onlookers. For example, in the case above, each
observer, by seeing lights and figures in other
apartment house windows, knew that others
were also watching. However, there was no
way to tell how the other observers were
reacting. These two facts provide several
reasons why any individual may have delayed
or failed to help. The responsibility for helping was diffused among the observers; there
was also diffusion of any potential blame for
not taking action; and finally, it was possible
that somebody, unperceived, had already
initiated helping action.
When only one bystander is present in an
emergency, if help is to come, it must come
from him. Although he may choose to ignore
it (out of concern for his personal safety,
or desires "not to get involved"), any pres-
,178
JOHN M. DARLEY AND BIBB LATANTC
sure to intervene focuses uniquely on him.
When there are several observers present,
however, the pressures to intervene do not
focus on any one of the observers; instead
the responsibility for intervention is shared
among all the onlookers and is not unique
to any one. As a result, no one helps.
A second possibility is that potential blame
may be diffused. However much we may wish
to think that an individual's moral behavior
is divorced from considerations of personal
punishment or reward, there is both theory
and evidence to the contrary (Aronfreed,
1964; Miller & Bollard, 1941, Whiting &
Child, 19S3). It is perfectly reasonable to
assume that, under circumstances of group
responsibility for a punishable act, the punishment or blame that accrues to any one
individual is often slight or nonexistent.
Finally, if others are known to be present,
but their behavior cannot be closely observed,
any one bystander can assume that one of
the other observers is already taking action
to end the emergency. Therefore, his own
intervention would be only redundant—perhaps harmfully or confusingly so. Thus,
given the presence of other onlookers whose
behavior cannot be observed, any given bystander can rationalize his own inaction by
convincing himself that "somebody else must
be doing something."
These considerations lead to the hypothesis
that the more bystanders to an emergency,
the less likely, or the more slowly, any one
bystander will intervene to provide aid. To
test this propostion it would be necessary to
create a situation in which a realistic
"emergency" could plausibly occur. Each subject should also be blocked from communicating with others to prevent his getting
information about their behavior during the
emergency. Finally, the experimental situation should allow for the assessment of the
speed and frequency of the subjects' reaction
to the emergency. The experiment reported
below attempted to fulfill these conditions.
PROCEDURE
Overview. A college student arrived in the laboratory and was ushered into an individual room from
which a communication system would enable him
to talk to the other participants. It was explained
to him that he was to take part in a discussion
about personal problems associated with college life
and that the discussion would be held over the
intercom system, rather than face-to-face, in order
to avoid embarrassment by preserving the anonymity of the subjects. During the course of the discussion, one of the other subjects underwent what
appeared to be a very serious nervous seizure similar to epilepsy. During the fit it was impossible for
the subject to talk to the other discussants or to
find out what, if anything, they were doing about
the emergency. The dependent variable was the
speed with which the subjects reported the emergency to the experimenter. The major independent
variable was the number of people the subject
thought to be in the discussion group.
Subjects. Fifty-nine female and thirteen male students in introductory psychology courses at New
York University were contacted to take part in an
unspecified experiment as part of a class requirement.
Method. Upon arriving for the experiment, the
subject found himself in a long corridor with doors
opening off it to several small rooms. An experimental assistant met him, took him to one of the
rooms, and seated him at a table. After filling out a
background information form, the subject was given
a pair of headphones with an attached microphone
and was told to listen for instructions.
Over the intercom, the experimenter explained that
he was interested in learning about the kinds of
personal problems faced by normal college students
in a high pressure, urban environment. He said
that to avoid possible embarrassment about discussing personal problems with strangers several
precautions had been taken. First, subjects would
remain anonymous, which was why they had been
placed in individual rooms rather than face-to-face.
(The actual reason for this was to allow tape
recorder simulation of the other subjects and the
emergency.) Second, since the discussion might be
inhibited by the presence of outside listeners, the
experimenter would not listen to the initial discussion, but would get the subject's reactions later, by
questionnaire. (The real purpose of this was to
remove the obviously responsible experimenter from
the scene of the emergency.)
The subjects were told that since the experimenter
was not present, it was necessary to impose some
organization. Each person would talk in turn, presenting his problems to the group. Next, each person
in turn would comment on what the others had said,
and finally, there would be a free discussion. A
mechanical switching device would regulate this discussion sequence and each subject's microphone
would be on for about 2 minutes. While any microphone was on, all other microphones would be off.
Only one subject, therefore, could be heard over
the network at any given time. The subjects were
thus led to realize when they later heard the seizure
that only the victim's microphone was on and that
there was no way of determining what any of the
other witnesses were doing, nor of discussing the
event and its possible solution with the others.
When these instructions had been given, the discussion began.
BYSTANDER INTERVENTION IN EMERGENCIES
In the discussion, the future victim spoke first,
saying that he found it difficult to get adjusted to
New York City and lo his studies. Very hesitantly,
and with obvious embarrassment, he mentioned that
he was prone to seizures, particularly when studying
hard or taking exams. The other people, including
the real subject, took their turns and discussed
similar problems (minus, of course, the proneness to
seizures). The naive subject talked last in the
series, after the last prerecorded voice was played.2
When it was again the victim's turn to talk, he
made a few relatively calm comments, and then,
growing increasingly louder and incoherent, he
continued:
I-er-um-I think I-I necd-er-if-if could-er-er-somebody er-er-er-er-er-er-er give me a liltle-er-give
me a little help here because-er-I-er-I'm-er-erh-h-having a-a-a real problcm-er-right now and
I-er-if somebody could help me out it would-it
would-er-er s-s-sure be-sure be good . . . becausecr-there-er-cr-a cause I-er-I-uh-I've got a-a one of
the-er-sei
er-cr-things coming on and-and-and
I could really-er-use some help so if somebody
would-er-give me a little h-help-uh-er-er-er-er-er
c-could somebody-er-er-help-er-uh-uh-uh (choking
sounds). . . . I'm gonna die-er-er-I'm . . . gonna
die-er-help-er-er-seizure-er-[chokes, then quiet].
The experimenter began timing the speed of the
real subject's response at the beginning of the victim's speech. Informed judges listening to the tape
have estimated that the victim's increasingly louder
and more disconnected ramblings clearly represented a breakdown about 70 seconds after the
signal for the victim's second speech. The victim's
speech was abruptly cut off 125 seconds after this
signal, which could be interpreted by the subject
as indicating that the time allotted for that speaker
had elapsed and the switching circuits had switched
away from him. Times reported in the results are
measured from the start of the fit.
Group size variable. The major independent variable of the study was the number of other people
that the subject believed also heard the fit. By the
assistant's comments before the experiment, and also
by the number of voices heard to speak in the first
round of the group discussion, the subject was led
lo believe that the discussion group was one of three
sizes: either a two-person group (consisting of a
person who would later have a fit and the real
subject), a three-person group (consisting of the
victim, the real subject, and one confederate voice),
or a six-person group (consisting of the victim, the
real subject, and four confederate voices). All the
confederates' voices were tape-recorded.
Variations in group composition. Varying the kind
as well as the number of bystanders present at an
2
To test whether the order in which the subjects
spoke in the first discussion round significantly affected the subjects' speed of report, the order in
which the subjects spoke was varied (in the sixperson group). This had no significant or noticeable
effect on the speed of the subjects' reports.
379
emergency should also vary the amount of responsibility felt by any single bystander. To test this,
several variations of the three-person group were
run. In one three-person condition, the taped bystander voice was that of a female, in another a
male, and in the third a male who said that he was
a premedical student who occasionally worked in
the emergency wards at Bellevue hospital.
In the above conditions, the subjects were female
college students. In a final condition males drawn
from the same introductory psychology subject pool
were tested in a three-person female-bystander
condition.
Time to help. The major dependent variable was
the time elapsed from the start of the victim's fit
until the subject left her experimental cubicle. When
the subject left her room, she saw the experimental
assistant seated at the end of the hall, and invariably went to the assistant. If 6 minutes elapsed
without the subject having emerged from her room,
the experiment was terminated.
As soon as the subject reported the emergency,
or after 6 minutes had elapsed, the experimental
assistant disclosed the true nature of the experiment, and dealt with any emotions aroused in the
subject. Finally the subject filled out a questionnaire
concerning her thoughts and feelings during the
emergency, and completed scales of Machiavellianism, anomie, and authoritarianism (Christie, 1964),
a social desirability scale (Crowne & Marlowe, 1964),
a social responsibility scale (Daniels & Berkowitz,
1964), and reported vital statistics and socioeconomic
data.
RESULTS
Plausibility of Manipulation
Judging by the subjects' nervousness when
they reported the fit to the experimenter, by
their surprise when they discovered that the
fit was simulated, and by comments they
made during the fit (when they thought
their microphones were off), one can conclude that almost all of the subjects perceived
the fit as real. There were two exceptions in
different experimental conditions, and the
data for these subjects were dropped from
the analysis.
Effect of Group Size on Helping
The number of bystanders that the subject perceived to be present had a major effect on the likelihood with which she would
report the emergency (Table 1). Eighty-five
percent of the subjects who thought they
alone knew of the victim's plight reported
the seizure before the victim was cut off, only
31% of those who thought four other bystanders were present did so.
380
JOHN M. DARLF.V AND BIBB LATANIR
TABLE 1
'KCTS 01? GROUPS SIZE ON LIKELIHOOD AND
SPEED or RESPONSE
Group size
N
% responding Time Speed
by end of fit in sec. score
85
62
31
13
2 (5 & victim)
3 (S, victim, & 1 other) 26
6 (.9, victim, & 4 others) 13
52
93
166
.87
.72
.51
Note.—p value of diffciences: x2 = 7.91, p < .02; 7'' = 8.09,
p < .01, for speed scores.
Every one of the subjects in the twoperson groups, but only 62% of the subjects
in the six-person groups, ever reported the
emergency. The cumulative distributions of
response times for groups of different perceived size (Figure 1) indicates that, by
any point in time, more subjects from the
two-person groups had responded than from
the three-person groups, and more from the
three-person groups than from the six-person
groups.
Ninety-five percent of all the subjects who
ever responded did so within the first half
of the time available to them. No subject
who had not reported within 3 minutes after
the fit ever did so. The shape of these distributions suggest that had the experiment
been allowed to run for a considerably longer
time, few additional subjects would have
responded.
Speed of Response
To achieve a more detailed analysis of the
results, each subject's time score was transloo
formed into a "speed" score by taking the
reciprocal of the response time in seconds
and multiplying by 100. The effect of this
transformation was to deemphasize differences between longer time scores, thus reducing the contribution to the results of the
arbitrary 6-minute limit on scores. A high
speed score indicates a fast response.
An analysis of variance indicates that the
effect of group size is highly significant
(/> < .01). Duncan multiple-range tests indicate that all but the two- and three-person
groups differ significantly from one another
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