Gamethink

Sunday, June 13, 2004

Behaviour Maps

posted by Geoff

One of the common misconceptions about roleplaying games is that it is possible for a gamemaster to develop a storyline for a game session a priori. People often think this because they are used to seeing stories told to them in books and films and thinking that the sequence of events that the characters experience – the story – can be mapped out. Unfortunately in an RPG session, the players have a choice over the direction the plot follows and it is remarkably easy to move beyond the series of events that the GM has planned. This forces the GM to try to make the players stick to the unseen script or to throw the whole pre-planned storyline out completely. So if the storyline of the game isn't something that appears until after the game has been played, what tools can the GM use to help guide selection of events that the characters will experience and still the flow of events coherent?

In his book Fuzzy Thinking, Bart Kosko presents the idea of a fuzzy cognitive map. It's a directed graph, where the nodes in the graph represent conditions within a system and the directed lines between the nodes represent a causality link. The node at the source end of the line is said to directly cause a change in the node at the target end of the line. Normally, each of these lines is annotated with either a "+" or a "-" sign, denoting whether the source node causes either an increase or a decrease in the target node.

Fuzzy Cognitive map from
Figure 1: Fuzzy Cognitive map from Fuzzy Thinking by Bart Kosko


One of the examples Kosko provides in Fuzzy Thinking deals with cocaine sales and its flow on-effects (see Figure 1). Kosko and one of his colleagues wanted to test whether the political policy being put forward at the time would have any effect on the war on drugs. They developed this fuzzy cognitive map and ran it through a computer program that would calculate the rise and fall of each node's value over time, given the changes in the rest of the system. In the book, Kosko starts by increasing demand for cocaine, simulated by increasing the value in the "Drug Usage" node. Because of the directed links between nodes – which represent causality links between the concepts the nodes represent – this causes an increase in the "Cocaine Price" node, which in turn increases the values in the "Cartels" node and the "Street Gangs" node, while actually decreasing the value in the "Drug Usage" node. The increase in the "Cartels" and "Street Gangs" nodes increases the "Drug Availability", which in turn increases "Drug Usage" and "American Police Interdiction" (amongst other things).

Around the time I was working on the early ideas for the communities chapter of the Gamma World Player's Handbook, James Maliszewski posted an entry on the late Rock Scissors Blog, dealing with the need for rules governing melodrama in games. For some reason, this got me thinking about Kosko's fuzzy cognitive maps and ways they could be used in gaming as a GM tool. I found the idea of one concept creating a causal increase or decrease in another to potentially have useful ramifications for a GM running a free-flowing game. This led to the development of the Community Behaviour Map, which first appeared in the Gamma World Player's Handbook and later in the Advanced Player's Guide, both from Sword and Sorcery Studios.

Put simply, a Behaviour Map tries to encapsulate likely responses to a given event by having nodes which represent specific conditions or behaviours. The causal links to other nodes, which – as in the fuzzy cognitive map – can either be causal increase or causal decrease depending on the situation. It's important to realise that a "+" sign on a link means that if the effect in the source node increases, then the effect in the target node will likewise increase. Similarly, if the effect in the source node decreases, then the effect in the target node will also decrease. Conversely, if the link has a "-", an increase in the source node effect will cause a decrease in the target node effect, while a decrease in the source node will result in an increase in the target.

To use the behaviour map, a GM would determine which node a particular event is related to. She would then follow the causal links and think up ideas that match either the increase or decrease in the node at the other end of the link, depending on the link's sign. These events would then be presented to the player(s) as the consequences of their actions. For those who subscribe to the use of "bangs" (as first presented in Ron Edward's Sorcerer RPG), the subsequent events be used to provide the bangs for the character or characters involved. Once the character responds to the secondary event, subsequent events will flow on from there as described by the behaviour map.

Drug Usage Behaviour Map Example
Figure 2: Drug Usage Behaviour Map example


For example, Figure 2 describes a very simple behaviour map dealing with the results of a character taking drugs (to follow on from Kosko's example in Figrue 1). Let's say that when the game begins, the character in question is a lawyer, who is happily married, has good relationships with his friends and employer and is reasonably well off financially.

Now, as an opening event, the character is at a party and is convinced to take a few hits of cocaine by a friend. This event plays into the "Drug Usage" node. After the party, this guy goes home to his wife, and as he comes down off the hit, he starts getting paranoid. He acts strange around his wife, who gets upset with him. (Drug Usage decreases Good Relationships). His wife may continue to hound him for a couple of days, putting more pressure on him, so he decides to get another hit of cocaine, so he can feel good (a decrease in "Good Relationships" increases "Drug Usage"). But the second hit starts to make this guy addicted to cocaine, which increases his involvement with crime ("Drug Usage" increases "Crime Involvement" and "Addiction") but it also costs money (increased "Drug Usage" decreases "Finances"). The additional spending and evidence of drug use both continue to put more pressure on this marriage. And the game can continue to play out from there.

Choosing the nodes in the Behaviour Map takes some trial and error. I've discovered that it's best to have the nodes represent something "concrete", such as "Drug Usage" or "Good Relationships" rather than describing an action on those concepts. In my original draft of Figure 2, I had "Pressure on Relationships" rather than "Good Relationships". However, I replaced the node description when I realised that I couldn't model, for example, a friend taking the character aside and trying to get him to give up the drugs; an increase in the "Good Relationships" node should result in a decrease in drug usage.

Some nodes should also work in opposition to others. There should always be a mixture of "+" and "-" signs on the causal links. If you start to find that when you're creating a Behaviour Map and all your links have one sign, that's usually an indicator that you may have at least one of your node concepts wrong. You should revise it so that you can get the conflict back into the map. After all, it's conflict that drives a good story along.

Behaviour Maps are not intended to be used to the exclusion of all other GMing tools. They do not, for example, provide any indication of where a particular character – either player character or GM character – fits into the storyline. Instead, they can be used in conjunction with other GMing tools such as relationship maps or Coterie diagrams to assist the GM in coming up with events at game time. They are merely a guide to help provide inspiration, rather than being something to constrain the free-flowing nature of the story as it develops in play.