AbstractSubjective experience is experience in time. Unfolding in a continuous river of moments, our experience, however, consists not only in the changing phenomenological content per se but, further, in additional retrodiction and prospection of the moments that immediately preceded and followed it. It is in this way that William James’s ‘specious present’ presents itself as extending between the past and future. While the phenomenology of temporality always happens, in normal waking states, tosomeone, and the notions of self-representation and temporal experience have continuously been associated with each other, there has not yet been an explicit account of their relationship. In this paper, the emergence of the subjective experience of temporal extension will be conceived of as arising out of a difference-relation between counterfactual and actual self-representations. After presenting the proposed relationship on both a conceptual level and a formalized and neuronally realistic level of description using information theory, convergent empirical evidence from general findings about temporal experience and inference, altered states of consciousness, and mental illness is examined. The Self-Simulational Theory of temporal extension is able to explain systematic variations in the subjectively experienced length of the temporal Now across numerous domains and holds potentially wide implications for the neuroscience of consciousness, as well as for a deeper understanding of different forms of mental illness.