Definition
A functional stimulus class consists of a group of stimuli that evoke the same behavior or have the same effect on behavior, regardless of their physical appearance. The stimuli within this class share a functional relationship with the behavior they influence, meaning that the stimuli serve the same purpose or function in altering the individual’s behavior.
Example
In a classroom setting, both the sound of a bell and a teacher’s verbal instruction “Time to clean up” might serve as stimuli that prompt students to start cleaning up their work areas. Although the stimuli (the bell and the verbal prompt) are different in form, they belong to the same functional stimulus class because they both serve the same function: signaling the behavior of cleaning up.