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Modeling Opinion Flow in Humans Using Boids Algorithm & Social Network Analysis

September 28, 2006 Article Start Previous Page 2 of 8 Next

Elements of Social Network Analysis that we are Using

Social Network Analysis (SNA) is a fairly new science. It is fairly intuitive. (It has to be. It is a science about us!) We all live in groups and communicate with the people around us.

From the entire SNA tool kit, below are the few elements that we will be using.

Element 1. Actors

The basis of all social networks is the Actor. In general, Actors are people, but not always so. Our actors will be people and news sources.

The composition of the actors is an important question that the game designer will have to answer: How many actors will be prone to radicalization or will just plain not change their mind on the topic at hand?

Figure 1 . An actor can be an individual or news source.

Element 2. Connections

The idea of 'connections' between people is intuitive. Most people feel connected to the people around them; their family, friends, co-workers, etc. Measuring 'connectivity' is difficult, and relationships do not need to be symmetrical. (Jim may respect Bill, but Bill may have no respect for Jim.) But we will assume its possible to get an idea of an average number of connections that the actors have.

When considering the connectivity important for opinion flow two things will generally be important: frequency of communication and the respect the partners hold for each other in the topic at hand.

In our model, a high positive connection strength will indicate respect, and a high negative number will indicate contempt.

Figure 2. Actors have connections.

Element 3. Networks

Groups of connected individuals form a network.

In this study we won’t group the people in family units, tribal units, or other sorts of hierarchies – although that is possible to do. Instead we will take the simple approach that in the large population connections are basically random, and in a small population the game creator will dictate it.

Figure 3. Groups of actors form networks.

Force Calculation

As mentioned in the introduction, we are reducing the actor’s opinions on the topic at hand into one simple number. We will call this number the alignment score. Some people believe strongly in an idea. Others are lukewarm, or may believe in the opposite. The strength of someone’s belief influences how likely they are to transmit it to others3.

The scale selected for the alignment scores is arbitrary. One simply has to be able to indicate people who support or disagree with an opinion, and indicate how strong they are in their opinions. An example scale is shown in Table 2. On this scale +1 indicates a normal follower of King John and +3 a radical follower.









Strong Belief






Strong Disbelief

Table 2. Initial alignment scores will need to be assigned to the actors.

We will calculate the average alignment felt by the actor (weighted by the strength of their connections) and then measure the distance from that to the actor’s current alignment. If there is no difference (for example, if the people around an actor support King John, and he or she already supports King John) then they will feel no force to change their opinion.


Force = Average Alignment felt by Actor – Actors Alignment

Figure 4. The force pulling on the actor comes from their distance from the crowd.

We are getting the ‘crowd opinion’ from what the actor sees around him or her. There will be a component roughly analogous to each of the terms in the Boids algorithm:

Total Force = Force (alignment) + Force (cohesion) + Force (separation)

Force Alignment

Calculate the force on an actor based on what they perceive to be the majority opinion.

Force Cohesion

Calculate the average alignment on the topic at hand across all of the individuals nearby that this individual respects.

Force Separation

Calculate the average alignment on the topic at hand across all of the individuals nearby for which this individual has contempt.

Table 3. Review of forces acting on an individual.

By allowing actors to be either other individuals or news sources, we are effectively combining our forces of cohesion and alignment, respectively. Originally it was considered that the force of alignment would be the force that the nebulous ‘them’ out there have. For example, someone in the communist Soviet Union would have had know that there were millions of capitalists. That knowledge could make one reassess that the people nearby are saying ‘communism beats capitalism.’

But one has to consider that we only know about the nebulous ‘them’ from our news sources. Since some leaders seek to control news sources, knowledge of the nebulous ‘them’ may be restricted. It is better to treat these news sources, and the respect that an actor may have for them, individually.

Article Start Previous Page 2 of 8 Next

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