Reinforcing Loop

A reinforcing loop is one in which an action produces a result which influences more of the same action thus resulting in growth or decline. The reinforcing loop is one of the two foundational structures of systems thinking, the other being the Balancing Loop. Consider the following example which describes a savings account.

Periodically the principal in the savings account interacts with the interest rate and adds to the interest. The interest rate in this example is assumed to be constant. The interest then adds to the principal causing it to increase. In the next period the cycle repeats, only now the principal is greater than it was before so it's interaction with the interest rate adds an even greater amount to the interest. This larger interest then again adds to the principal. The graph to the right above principal shows the resultant growth of the principal.

Because of the manner in which this structure reinforces itself it generally produces an exponential growth or decline. This exponential change may be unnoticeable for a period of time until it reaches a certain threshold. The structure then seems to change very rapidly causing one to wonder how it began all at once, when in fact it really didn't. The growth just wasn't substantial enough to be noticed.

Effective Strategies

Areas of Concern

The reinforcing structure is one of the simplest structures and seldom ever occurs in isolation from additional influences. As was indicated above, nothing grows forever so there are extensions of this structure to be concerned about. The most prevalent extensions of the reinforcing structure are identified in the following areas of concern.


The following examples are intended to provide some specific instances in which a reinforcing structure is the primary structure.

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