In this article, I discuss the concepts of "private stimuli," "covert responses," and "private events," emphasizing three aspects: the conditions under which private stimuli may acquire discriminative functions to verbal responses, the conditions of unobservability of covert responses, and the complexity of events or phenomena described as private. I argue that the role of private stimuli in the control of self-descriptive verbal responses is dependent on a relation (correlation or equivalence relation) with public stimuli, and that responses vary along a continuum of observability. These remarks on private stimuli and covert responses are introductory to an examination of the varying complexity of phenomena described as private. I argue that "private events" is a verbal response emitted under the control of phenomena of different degrees of complexity, and I interpret these phenomena, based on the principle of selection by consequences. I introduce the notion of "inclusiveness" to suggest that some phenomena related to privacy are less or more complex as they include relations of a phylogenetic, ontogenetic, and cultural origin.