The idea of Reciprocal Determinism flows from Bandura's description of the effect that environmental factors have on behavior. Bandura shared that behavior can influence the environment and that cognitive processes are an important part of the of the formula.
Take a look at the chart linked below to get a feel for how Bandura explains this concept:
This diagram created using Inspiration® 7 by Inspiration Software®, Inc.
nAs evidenced above, observers can be reinforced directly by the model. In this case, the observer will be reinforced by a model when the observer imitates the model. nObservers can also be reinforced by a third party. This occurs when an observer imitates a model and is reinforced by a third party, such as friends parents. Imitating behavior can also lead to reinforcing consequences. Finally, behavioral consequences may have a vicarious effect. –This takes place when reinforcement or punishment occurs when an observed behavior is reinforced or punished leading to a change in the observers behaviors.