Understanding the environment: Flows and feedback
Understanding the environment: Flows and feedback

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Understanding the environment: Flows and feedback

3 Section activities

Activity 4A: Exploring dynamic relationships using sign graphs

Here is where things start getting really interesting in terms of system dynamics! So far, most of your modelling work has been pretty static, with a limited sense of how things change over time. In fact, the behaviour of complex systems is rarely stable. Sometimes change is exponential (e.g. the growth of the World Wide Web); sometimes systems crash and burn (e.g. extinction of populations); but often systems demonstrate repetitive patterns of behaviour (e.g. economic boom and bust cycles). A few systems are truly chaotic and unpredictable as different feedback processes interact with each other through different timescales and magnitudes. All of these different behaviours are determined by complex webs of feedback relationships.

The aim of this activity is to develop your skills in systems thinking through the use of the sign graph diagramming technique. This is one of the most useful techniques for visualising the impact of feedback relationships. You should be aware that this technique is commonly called ‘causal loop diagramming’, however, when the technique was adopted for teaching systems at the Open University, it was decided that this common name could be confused with ‘multiple cause diagramming’. Hence the technique’s name was changed to ‘sign graph’ to emphasise the characteristic use of +/- signs. If you haven’t done so already, please read through the sign graphs section in the Diagramming Resource.


Your challenge in this activity is to explore one of the themes raised in the ‘Powerdown Show’ programme and to develop a sign graph to show how you think various causes and effects create a series of positive feedback loops which will lead to an escalating crisis.

Once you have developed your sign graph, I would then like you to identify at least five key areas of intervention within it, for averting the one or more crises you have identified. In other words, each intervention should describe the positive feedback loop(s) that it is affecting. It should be clear by now that these interventions should initiate or support negative feedback loops, i.e. counter-balancing relationships in order to dampen the escalating effects of the threats. To avoid over-complicating this exercise, you can just consider these as an initial one-way intervention (that is, there is no need to diagram your interventions as loops).


This is my own interpretation/model of escalating social breakdown inspired by the content of the ‘Powerdown Show’ programme, but also drawing on personal experiences and other information sources. The theme that I chose doesn't directly reflect the content of one programme in particular, but I liked working on it because it allowed me to explore a range of issues that spanned a wide diversity of subjects. Once again, this is in no way ‘the right answer’, and if you have chosen the same theme, you may very well have identified different areas of intervention and different positive feedback loops. The crucial thing that you should have aimed for was to produce a visual model that can readily communicate a story to your target audience. This is what you should concentrate on getting right.

Drawing sign graphs can take some application and will probably require several iterations – I had seven attempts! The key is to brainstorm as many negative and positive relationships as possible and then to look for the positive feedback loops. Remember that feedback loops are the backbone of systems, so even if you can identify some clear linear relationships, you have to think very hard about whether you want to retain these in your final diagram. My final diagram, presented in Figure 4.9 below, demonstrates a range of positive feedback loops which could work in concert to worsen social conditions. My first attempt looked like a can of worms and I had to be ruthless in simplifying the diagram to show what I thought were several key positive feedback loops. You will notice that my sign graph includes components that operate at different organisational, temporal and spatial scales – from the local to global. Presenting a systemic understanding to a particular scale of human organisation (individuals, groups, communities, companies, governments, etc.) doesn’t necessarily imply that your analysis must restrict itself to the components only apparent at that scale. Figure 4.10 shows you where I have identified five key ‘dampening’ factors and the place where they could intervene. Even here, the interventions are not necessarily restricted to one particular scale of organisation. Although we sometimes feel that we can only intervene at the organisational scale we are currently involved with, this scale can also lobby for change at other scales of organisation. For example, it is often the case that our personal actions are often restricted and determined by other scales of organisation, so in order to deliver change, we must intervene at other scales by, for example, supporting (or creating) institutions and/or social movements which have the potential or actual power to force change.

Figure 4.9
Figure 4.9 Sign graph exploring my interpretation of causes and effects leading to social breakdown
Figure 4.10
Figure 4.10 Sign graph showing five key interventions that I believe would reverse social breakdown

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