Rewarding Mary with a candy every time she perform well in exams is an example of positive reinforcement in Psychology. The behavior introduces a desirable stimulus that encourages Mary to continue passing exams. This theory was introduced by Skinner in 1948 (Troussas, Krouska, & Virvou, 2017). In the learning environment, tangible rewards and positive remarks direct behavior towards specific learning objectives. As a result, the receiver exerts energy and effort, which increases the initiation of the activities that perfect cognitive processes (Troussas, et al., 2017).
Thus, it is important to reward the natural tendencies towards good behavior among the individuals undergoing a training to yield persistence in better performance.
Troussas, C., Krouska, A., & Virvou, M. (2017, August). Reinforcement theory combined with a badge system to foster student's performance in e-learning environments. In 2017 8th International Conference on Information, Intelligence, Systems & Applications (IISA) (pp. 1-6). IEEE.