Maria is a manager at a consumer electronics manufacturing plant. She recently initiated a study to observe the productivity of assembly line workers with the goal of improving efficiency. After implementing observation cameras and having supervisors more frequently check on the workers, she noticed a significant but temporary increase in productivity. Maria suspects that this increase may not reflect genuine improvements in work processes. In Maria's observation of her assembly line workers, which phenomenon might explain the temporary increase in productivity following the introduction of more frequent supervisory checks and observation cameras?