The Contribution Of Episodic And Semantic Memory In Familiar And Novel Episodic Future Thinking

Episodic future thinking (EFT) is the psychological process which projects someone to think and experience future event in advance. It depends on human memory in a large part. Abundant evidences from behavioral and neuroscience researches suggest that episodic and semantic memory both are necessary and important for EFT. A successful EFT likely comprises various episodic and semantic details that are flexibly recombined to create a coherent and integrated representation of a specific future event. However, the familiarity of event may affect the extent of the contribution of these two memories in EFT. So, in this study, we aimed to study whether imaging familiar and novel future episodic events depend on episodic and semantic memory differently. We proposed both familiar and novel EFT should rely on episodic and semantic memory, but familiar EFT would rely largely on episodic memory relative to novel EFT, and conversely, relative to the familiar, novel EFT relies mostly on semantic memory.Two experiments were designed to test this hypothesis. In Experiment 1, a signal factor experiment was conducted. Participants were asked to complete the EFT and memory task one by one (the memory task asked participants to think back and record the memories which they have used during the EFT task). Then those memories were coded by 3 coders as into episodic or semantic memory referencing to a given standard. The results suggested that:(1) Familiar and novel EFT both relied on episodic memory mostly; (2) Familiar EFT relies more on episodic memory (vs. novel EFT) and novel EFT relies more on episodic memory (vs. familiar EFT).As to confirm the results of Experiment 1 and explore more further, Experiment 2 was designed. In Experiment 2, we supposed that if the results of Experiment 1 was reliable and stable, episodic priming would have an impact on both familiar and novel EFT, especially to the former. And semantic priming would affect EFT possibly, if it does, novel EFT would be the one mostly influenced. In Experiment 2, a 2 (event familiarity:familiar vs. novel)×3 (memory priming condition:episodic vs. semantic vs. control) was conducted. The results showed:(1) Episodic priming had a significant effect on familiar EFT, this effect behaved as episodic priming prolonged the RT to construct a familiar episodic future event, and participants reported more subjective experiences, but episodic priming had no significant effect on novel EFT; (2) Semantic priming impact EFT indeed, but just reduced the subjective experiences during imaging a novel episodic future event.Moreover, the results of both two experiments also indicated when imaging familiar and novel episodic future events, there is no significant difference on their sensorial details, and neither on the subjective experiences. These results are not in accordance with western results.Above all, the present study including 2 experiments confirmed our hypothesis in general. These results will help us to understand how episodic and semantic memory contribute to EFT further. Nevertheless, in order to acquire the content of EFT, the participants were asked to report or record what they had imagined, consequently, the effect of narrate could not be excluded. Besides, ecological validity may be undermined due to the construction-elaboration paradigm design.