A Success to the Successful structure consists of two reinforcing structures which interact in such a way as for create a single reinforcing structure. Consider a situation where there are two project managers, Jane and Tom, responsible for managing similar projects. Their manager, Sarah, has a fixed amount of resources which she allocates to their projects. Initially both projects are progressing equally well. Then, for some reason, Sarah chooses to allocate more resources to Jane's project than to Tom's.
When Sarah performs an allocation to Jane instead of Tom it adds to the resources to Jane and, since there are a fixed amount of resources, it subtracts from the resources to Tom. Then the resources to Jane add to the success of Jane, and the success of Jane promotes further allocation to Jane instead of Tom.
The resources to Tom still add to the success of Tom, but since there are fewer resources there is less success for Tom. The success of Tom subtracts from the allocation to Jane instead of Tom, and since the success of Tom is less, it subtracts less.
As such the success of Jane overshadows the success of Tom and encourages Sarah to allocate to Jane instead of Tom, since she'd much rather support a winner than a loser. What Sarah doesn't realize is that she is in fact creating the winner and the loser through her allocation scheme.
This structure can be redrawn as a single reinforcing structure which should make the interaction even clearer.
The above redrawn version of the Success to the Successful structure makes its reinforcing nature much more obvious. It is the Success to the Successful structure which is at the heart of so many self-fulfilling prophesies, which are actually the result of unperceived influences on our own part.
There are actually two strategies for dealing with a Success to the Successful situation.