Schacter and Addis (2007a, 2009) have attempted to accommodate such differences in discussions of the constructive episodic simulation hypothesis, proposing that the finding of greater neural activity for future relative to past events reflects the more extensive constructive processes required by imag- ining future events relative to remembering past events. That is, whereas both past and future event tasks require the retrieval of information from memory, imagining future experiences—but not remembering past experiences—requires that details extracted from past experiences are flexibly recombined into a novel event. More recently, additional factors have been suggested as explaining the increased hippocampal activation for future events, including the fact that imagining future events requires the generation of new mental representations, resulting in a greater degree of encoding than that for previously stored information (Martin et al., 2011).