7.14 Information Technologies to Assist Social Systems
149
But these are technological systems. Could we also build tools to assist social
systems? Yes, we can! Sometimes, the design of social mechanisms is challenging,
but sometimes it is easy. Imagine trying to share a cake fairly. If social norms allow
the person who cuts the cake to take the first piece, this will often be bigger than the
others. If he or she should take the last piece, however, the cake will probably be
distributed in a much fairer way. Therefore, alternative sets of rules that are intended
to serve the same goal (such as cutting a cake) may result in completely different
outcomes.
As Appendix 7.2 illustrates, it is not always easy to be fair. Details of the interactions matter a lot. But with the right set interaction rules, we can, in fact, create a
better world. In the following, we will discuss how the social mechanisms embedded
in our culture can make an important difference and how one can support cooperation
and social order in situations where an unfavorable outcome would otherwise result.
7.15 Appendix 1: Faster-Is-Slower Effect
One interesting traffic scenario to study is a multi-lane freeway with a bottleneck
created by an entry lane through which additional vehicles join the freeway. The
following observations are made: When the density of vehicles is low, even large
disruptions (such as large groups of cars joining the freeway) do not have lasting
effects on the resulting traffic flow. In sharp contrast, when the density is above 30
vehicles per kilometer and lane or so, even the slightest variation in the speed of a
vehicle can cause free traffic flow to break down, resulting in a “phantom traffic jam”
as discussed before. Furthermore, when the density of vehicles is within the so-called
“bistable” or “metastable” density range just before traffic becomes unconditionally
unstable, small disruptions have no lasting effect on traffic flow, but disruptions
larger than a certain critical size (termed the “critical amplitude”) cause a traffic
jam. Therefore, this density range may produce different kinds of traffic patterns,
depending on the respective “history” of the system.
This can lead to a counter-intuitive behavior of traffic flow (see Fig. 7.10). Imagine
the traffic flow on a freeway stretch with an entry lane is smooth and “metastable”,
i.e. insensitive to small disruptions, while it is sensitive to big ones. Now suppose
that the density of vehicles entering this stretch of freeway is significantly reduced
for a short time. One would expect that traffic will flow even better, but it doesn’t.
Instead, vehicles accelerate into the area of lower density and this can trigger a traffic
jam! This breakdown of the traffic flow, which is caused by faster driving, is known
as the “faster-is-slower effect”.
How does this effect come about? First, the local disruption in the vehicle density
changes its shape while the vehicles travel along the freeway. This produces a vehicle
platoon (i.e. a cluster of vehicles related with a locally increased traffic density). This
platoon moves forward and grows over time, but it eventually passes the location of
the entry lane. Therefore, it seems obvious that it would finally leave the freeway
stretch under consideration. Conversely however, at a certain point in time, the cluster
149
But these are technological systems. Could we also build tools to assist social
systems? Yes, we can! Sometimes, the design of social mechanisms is challenging,
but sometimes it is easy. Imagine trying to share a cake fairly. If social norms allow
the person who cuts the cake to take the first piece, this will often be bigger than the
others. If he or she should take the last piece, however, the cake will probably be
distributed in a much fairer way. Therefore, alternative sets of rules that are intended
to serve the same goal (such as cutting a cake) may result in completely different
outcomes.
As Appendix 7.2 illustrates, it is not always easy to be fair. Details of the interactions matter a lot. But with the right set interaction rules, we can, in fact, create a
better world. In the following, we will discuss how the social mechanisms embedded
in our culture can make an important difference and how one can support cooperation
and social order in situations where an unfavorable outcome would otherwise result.
7.15 Appendix 1: Faster-Is-Slower Effect
One interesting traffic scenario to study is a multi-lane freeway with a bottleneck
created by an entry lane through which additional vehicles join the freeway. The
following observations are made: When the density of vehicles is low, even large
disruptions (such as large groups of cars joining the freeway) do not have lasting
effects on the resulting traffic flow. In sharp contrast, when the density is above 30
vehicles per kilometer and lane or so, even the slightest variation in the speed of a
vehicle can cause free traffic flow to break down, resulting in a “phantom traffic jam”
as discussed before. Furthermore, when the density of vehicles is within the so-called
“bistable” or “metastable” density range just before traffic becomes unconditionally
unstable, small disruptions have no lasting effect on traffic flow, but disruptions
larger than a certain critical size (termed the “critical amplitude”) cause a traffic
jam. Therefore, this density range may produce different kinds of traffic patterns,
depending on the respective “history” of the system.
This can lead to a counter-intuitive behavior of traffic flow (see Fig. 7.10). Imagine
the traffic flow on a freeway stretch with an entry lane is smooth and “metastable”,
i.e. insensitive to small disruptions, while it is sensitive to big ones. Now suppose
that the density of vehicles entering this stretch of freeway is significantly reduced
for a short time. One would expect that traffic will flow even better, but it doesn’t.
Instead, vehicles accelerate into the area of lower density and this can trigger a traffic
jam! This breakdown of the traffic flow, which is caused by faster driving, is known
as the “faster-is-slower effect”.
How does this effect come about? First, the local disruption in the vehicle density
changes its shape while the vehicles travel along the freeway. This produces a vehicle
platoon (i.e. a cluster of vehicles related with a locally increased traffic density). This
platoon moves forward and grows over time, but it eventually passes the location of
the entry lane. Therefore, it seems obvious that it would finally leave the freeway
stretch under consideration. Conversely however, at a certain point in time, the cluster