Latane, B., Williams, K., & Harkins, S., Many Hands Make Light The
Work: The Causes and Consequences of Social Loafing, JPSP, 37, 822-832.
"Two experiments found that when asked to perform a physically
exerting tasks of clapping and shouting, people exhibit a sizable decrease
in individual effort when performaing in groups as comapred to when they
In a previous study over 50 years ago a German researcher had people alone
and in groups pull on a rope attached to a strain guage to measure the pull
force. Surprisingly, the sum of the individual pulls did not equal the
total of the group pulls. Three people pulled at only 2.5X the average
individual performance, and 8 pulled at less than 4x. The group result
was much less then the sum of individual efforts.
This vilolates the notion that group effort and a sense of team participation
leads to increased effort. Other social psychology studies would seem to
suggest that individual performance does increase in a group for simple
tasks with well-learned, dominant responses.
However, from a social pressure perspective, the social pressure to pull
is further diluted for each person with increasing group size. From this
perspective, if we assume people will work in proportion to the pressure
they feel to do so, then bigger group sizes should result in less individual
Experiment 1: Clap Your Hands and Shout Out Loud
The researchers chose clapping and shouting as a test exercise because people
do these things in group setting and they are "maximizing, unitary,
They recruited subjects and put them in a semi-circle. Individually and
in various group numbers, they asked people to either clap or shout as loud
as they could. The measured noise level with a machine in sound pressure
As with the rope pulling exercise, the level of noise increase with group
size, but not in direction proportion. People averaged 3.7 dynes/sq cm
alone, 2.6 in pairs, 1.8 in foursomes, and 1.5 in groups of six. There
was no block effects (indicating tiredness or lack of practice).
The results don't fit with either Zajonc's social facilitation theory or
evaluation apprehsion theory, They labeled this new drop in individual
average performance in groups as "social loafing".
Another explanation is that individual effort does not decrease, but the
group product decreases due to group inefficiency. However, another researcher
duplicated the Ringelmann rope experiment and included a situation where
people were blindfolded and led to believe others were pulling with them.
They still observed a drop-off in performance with group size.
Another explanation may be acoustical -- the voices may cancel each other
out or are not synchronized to be completely additive. The second experiment
was designed to test this effect.
Subjects were separated and put into rooms with headphones. Some were led
to believe they were shouting alone, others believed they were shouting
with a group. They repeated each trials with individual and group size
The results were higher than the first experiment, but the trends were the
same. Average individual performance decreased with group size. Groups
ot two were 66% of capacity, groups of six at 36% of capacity. Even in
situations where people thought they shouted together but in fact shouted
alone, the "loafing effect" was present.
When performers belived one other person was yelling, they shouted 82% as
intensly as alone. When they believe five others were yelling, they shouted
at 74% as intensly as alone.
Discussion: The causes of social loafing
Three possible options are:
1. Attribution and Equity. Maybe subjects heard other's shouts as less
than their own (because they were farther away than one's own voice) and
felt the others were "slacking", leading them to back off on their
shouting too. While the headphones should have made it very difficult to
detect this kind of loafing, people could have come in with pre-conceived
notions of how people slack off in groups.
2. Submaximal Goal Setting. Maybe subjects perceived there is some well-defined
standard of loudness, and with more people they feel they can work less
at it. The task would become an optimizing one than a maximizing one.
(But the researchers felt that given the repeated exhortations to shout
as loud as you can this couldn't be the case).
3. Lessened contingency between input and outcome. Maybe people felt they
could "hide in the crowd" and avoid the negative consequences
of slacking off, or maybe they felt "lost in the crowd" and unable
to get their fair share of positive consequences for working hard. Only
when performing alone can people be appropriately evaluated and rewarded.
Maybe by instiituting a payoff scheme that would avoid the benefits of a
"free ride" in the group would this "social loafing"
Social Loafing and Social Impact Theory
The three theories can be explained with Latanes social impact theory.
"If a person is the target of social forces, increasing the number
of other persons diminishes the relative social pressure on each person.
If the individual inputs are not identifiable the person may work less
hard. Thus if the person is dividing up the work to be performed or the
amount of reward he expects to receive, he will work less hard in groups."
Social impact theory suggests that effort in group tasks should decrease
as an inverse power function of the number of people in a group.
Other studies have also shown the "loafing effect" to hold in
industrial production, bystander intervention, and participation in church