What is a key characteristic of token economies?

A key characteristic of token economies is the use of a medium of exchange within the system. Token economies operate on a system where individuals earn tokens for exhibiting desired behaviors. These tokens serve as a form of currency that can later be exchanged for various backup items or privileges, reinforcing the targeted behaviors. This structure creates a clear and tangible method for individuals to understand the relationship between their behavior and the rewards they can earn. The use of tokens facilitates motivation and helps in managing behavior effectively.

The other options do not capture this essential feature: verbal instructions alone do not encompass the mechanism of exchange in a token economy, and the lack of a link between behaviors and rewards contradicts the fundamental principle of how token economies are designed. Additionally, the use of backup items is crucial for the effectiveness of a token system, as they provide the incentive for individuals to earn and exchange their tokens.