Sometimes, changes in consequences are accompanied by a clear stimulus change explicitly arranged by the experimenter. Other times when new consequences are in effect, there is little or no accompanying stimulus change explicitly arranged by the experimenter. These differences can be seen in the laboratory as multiple (signaled) schedules and mixed (unsignaled) schedules. The current study used college students and a single-subject design to examine the effects of introducing signaled and unsignaled schedules, and the transitions between them. In one phase, a card was flipped from purple to white every time the schedule was switched from VR-3 to FT-10. In another phase, the schedule still changed periodically, but the card always remained on the purple side. Results showed that the participants' responding was controlled by the schedule of reinforcement, by the color of the card, or both. These results suggest that changes in patterns of reinforcement lead to changes in stimulus control. In addition, the stimulus control for a behavior can come from several different sources. During teaching, it may facilitate the development of stimulus control to change the environment when a new behavior is required.