The law of unintended consequences

Posted on December 9th, 2008 in Management by siddharta || No Comment

I gave a talk on programmer spaces in the recently concluded Chennai BarCamp. During the presentation, the conversation moved to actions taken by managers that ended up having unintended consequences.

Linear Mental Models

Mental models are models that we have based on which we take decisions.  A linear mental model is a model where an action causes an outcome. This model is shown below

Linear Mental Model

For example, we could say that working longer hours leads to more work done. In this case, “working longer hours” is the action and “more work done” is the outcome. Using this model,we can work in reverse and determine the action that will cause a given outcome. So if “more work done” is the desired outcome, then “working longer hours” could be one possible action to cause the outcome.

Most managers intuitively apply linear models to determine the actions required to drive the system towards a desired outcome. Here are some examples

  • Desired outcome: More work done. Action: Work longer hours
  • Desired outcome: More work done. Action: Add more developers
  • Desired outcome: Improve performance. Action: Introduce competitive bonus structure

Circular Models

Unfortunately, most systems are not simple cause -> effect structures. A cause may have side effects which are not accounted for in the linear model. The outcome could also have a feedback which works against the original goal. The model looks something like this

Circular Mental Model

Lets take an example to illustrate. Our desired outcome is to get more work done. To achieve this, we tell the developers to work longer hours. According to the linear mode, working more hours should get more work done. But there is a hidden side effect: Developers get mentally and physically tired. This side effect is not taken into consideration in the linear model. The outcome of the developers tiring is that they start to get less work done per hour. Thus, the side effect impacts negatively on the desired outcome.

Work more model

The red line indicates that it has a negative effect on the outcome. The developers are not tired to start with, so output shows an initial increase, causing people to believe that the decision is working. But developers keep getting tired as time goes and the desired output keeps dropping over time. After a point output falls below the initial value.

Output Graph

Once output drops, what does the manager do to increase the output? Work even more of course! Which only makes matters worse. This is the problem with applying a linear mental model to systems that have circular models.

Unintended Consequences

As in the previous example, applying a linear model to systems with circular models leads to decisions that can have unintended consequences. The intuitive response in such a situation is to push harder on the original action, but as shown above, this only makes matters worse. The correct response is to try to understand the entire model and work on the side effects and feedback effects. In future blog posts, I’ll talk about various examples of situations where a given action caused unintended consequences.

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