Emotional learning selectively distorts the temporal organization of memory: A quantitative synthesis.

Episodic memory allows us to remember when an event occurred by situating it within a coherent temporal context. Pavlovian fear conditioning, a widely studied form of associative emotional learning, creates implicit memories for neutral stimuli paired with aversive outcomes. However, conditioning's influence on the temporal organization of episodic memory remains poorly understood. We addressed this by analyzing data from 17 multi-session hybrid conditioning-memory experiments (N = 474). Participants encoded non-repeating category items, with items from one category (CS+) being aversively reinforced (shocks) during threat conditioning but presented without shock before and after conditioning. The next day, recognition memory ('did you see this image yesterday?') and temporal source memory ('when did you see this image?') were tested for each category item. We had two aims; (1) examine the robustness of temporal memory distortion across different experiment groups, and (2) test whether these temporal effects were associated with recognition memory performance. CS+ category exemplars were disproportionately (mis)attributed to the conditioning phase, even if they were encoded before or afterwards, and this effect strongly predicted selective recognition memory (CS+ > CS-). Overall temporal source bias effects and source-item memory associations were largely resistant to between-experiment variations, including month-long encoding-retrieval intervals, varying shock intensities, and enhanced extinction. Paradoxically, salient emotional experiences may enhance memory for neutral events by distorting their perceived position in time. This mechanism may safeguard potentially relevant information by anchoring otherwise forgettable experiences to salient contexts, supporting their preservation in long-term memory.