| A functional class refers to a circumstance in which multiple forms of responding are controlled by singular stimulus conditions, as exemplified in the formation of concepts. It is argued that a process of substitution of stimulus functions is needed to distinguish among functional classes of different kinds. We examined derived categorical responding in the context of an equivalence preparation by exposing participants to two different tests in which proximal relations among stimuli, supplemented by specific contextual conditions, provided the basis for their organization into stimulus classes. Derived categorical responding was observed in the majority of the participants. These findings suggest that the shared functional relation among the members of a stimulus class exerts control over responding with respect to an array of stimulus objects in the absence of direct training. |
