Constructing a behavioral account of the language-related performances that characterize responding to logical and symbolic relations between stimuli is commonly viewed as a problem for the area of stimulus control. In response to this inadequacy the notion of joint control is presented here, and its ability to provide an interpretative account of these kinds of performances is explored. Joint control occurs when the currently rehearsed topography of a verbal operant, as evoked by one stimulus, is simultaneously evoked by another stimulus. This event, the onset of joint stimulus control by two stimuli over a common response topography, then sets the occasion for a response appropriate to this special relation between the stimuli. Though the mechanism described is simple, it seems to have broad explanatory properties. In what follows these properties are applied to provide a behavioral interpretation of two sorts of fundamental, putatively cognitive, performances: those based on logical relations and those based on semantic relations, The first includes responding to generalized conceptual relations such as identity, order, relative size, distance, and orientation. The second includes responding to relations usually ascribed to word meaning. These include relations between words and objects, the specification of objects by words, name-object bidirectionality, and the recognition of objects from their description. Finally, as a preview of some further possibilities, the role of joint control in goal-oriented behavior is considered briefly.
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